# Technical Bulletin No. DoR-132/2023: Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health

Ajeet Kumar, Sunita Kumari Meena, Lalita Rana, Sanjeew Kumar Sinha, Sanjay Kumar Singh, A.K. Singh

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Ajeet Kumar, Sunita Kumari Meena, Lalita Rana, Sanjeew Kumar Sinha, Sanjay Kumar Singh, et al.. Technical Bulletin No. DoR-132/2023: Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health. DR. RAJENDRA PRASAD CENTRAL AGRICULTURAL UNIVERSITY BIHAR, PUSA, SAMASTIPUR-848125, INDIA. 2023, pp.1-64. hal-04962141

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Technical Bulletin
On

Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health

भूजल में नाइट्रेट संदूषण पर नाइट्रोजनयुक्त उर्वरक के गहन उपयोग का प्रभाव और मानव स्वास्थ्य के लिए जोखिम

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Department of Soil Science
Sugarcane Research Institute

Dr. Rajendra Prasad Central Agricultural University
Pusa (Samastipur)-Bihar- 848125

2023
**Technical Bulletin No. DoR-132/2023: Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health**

Technical Bulletin, May, 2023

Sugarcane Research Institute,
RPCAU, Pusa (Samastipur)-848125, Bihar, India

ISBN: 978-93-5913-075-0

Published by

**Dr. A.K. Singh**

Director Research

Directorate of Research

RPCAU, Pusa (Samastipur)-848125, Bihar

Phone: 9415920101

Email:dssripusa12@gmail.com

Web site: https://www.rPCAU.ac.in/sri/

Year of publication: May, 2023

Copy right reserved

All rights reserved. No part of this publication shall be reproduced or transmitted in any form by print, microfilm or any other means without written permission of the Director Research, Directorate of Research, RPCAU, Pusa (Samastipur)-848125, Bihar.

Authors: Designed and written by

**AJEET KUMAR**, Assistant Professor-cum-Scientist (Soil Science), SRI, RPCAU, Pusa, Bihar.

**SUNITA KUMARI MEENA**, Assistant Professor (Soil Science), SRI, RPCAU, Pusa, Bihar.

**LALITA RANA**, Assistant Professor (Agronomy) SRI, RPCAU, Pusa, Bihar.

**S.K.SINHA**, HoD, Department of Soil Science, SRI, RPCAU, Pusa, Bihar.

**SANJAY KUMAR SINGH**. Assistant Professor (Soil Science), TCA, Dholi, RPCAU, Pusa, Bihar.

Conceptualized, critically reviewed and edited by

**A. K. SINGH**, Director, SRI & Director Research, RPCAU, Pusa, Bihar

Designed and Print by

**MITHUN KUMAR**, Sr. Technician, SRI, RPCAU, Pusa, Bihar, India

**Citation**

Kumar, A., Meena, S.K., Rana, L., Sinha, S.K., Singh, S.K. and Singh, A.K. (2023). Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health. Technical Bulletin No. DoR-132/2023. Sugarcane Research Institute, RPCAU, Pusa (Samastipur)-Bihar, India, pp. 1-64.
# Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health

By

AJEET KUMAR
SUNITA KUMARI MEENA
LALITA RANA
SANJEEW KUMAR SINHA
SANJAY KUMAR SINGH
A.K. SINGH

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Department of Soil Science
**Sugarcane Research Institute**
DR. RAJENDRA PRASAD CENTRAL AGRICULTURAL UNIVERSITY
PUSA, SAMASTIPUR-848125, BIHAR, INDIA

2023
FOREWORD

Nitrate is one of the most common chemical contaminants of the groundwater. It is an important unqualified factor of rural groundwater of Bihar. Cropland is a main source of global nitrogen pollution. Mitigating nitrogen pollution from global croplands is a challenge because the nature of non-point-source pollution from millions of farms and the constraints in implementing the pollution-reduction measures, such as lack of financial resources and limited nitrogen-management knowledge of farmers. We have to focus on best nutrient management practices to reduce the nitrogen losses from croplands to air and water by 30-70%, while increasing crop yield and nitrogen use efficiency by 10-30% and 10-80%, respectively. More than 85% of drinking water supplies typically come from groundwater resources, and major urban and rural population is dependent upon groundwater in India. In order to assess the risk of exposure to nitrate enriched drinking water for adults and juveniles, monitoring of the nitrate concentrations in drinking water used to assess the human health risk of nitrate pollution in groundwater.

Caption for the image: [Image of a man in a suit and tie, standing in a room with a window view of a cityscape. A tree is in the background.]

[Caption for the image: A photo of a man in a suit and tie, standing in a room with a window view of a cityscape. A tree is in the background.]

There is meagre number of comparable technical information that have analyzed and summarized with case studies on the application of nitrogenous fertilizer. This technical bulletin is an first attempt to bridge this research gap. The theory motivating our analysis is linked to a socio psychological mechanism that facilitates the formation of an informal code of conduct in the application of fertilizer that permits nitrate contamination. We focus on Bihar because of the puzzle that the country has a modern and technologically advanced agricultural sector which would normally allow efficient nitrogen fertilizer application, but at the same time faces strong water pollution of its groundwater and surface water bodies.

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The authors have done commendable job to compile such valuable information at a glance and brought them in a usable form. I hope this technical bulletin entitled "*Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health*" will act as a valuable guide to researchers, farmers, policy planners and fertilizer manufacturing industries directly and indirectly associated with crop cultivation.

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(A K, Singh)
Director Research
RPCAU, Pusa
CONTENTS

<table><thead><tr><td>Sl. No.</td><td>PARTICULARS</td><td>PAGE</td></tr></thead><tbody><tr><td>1.</td><td>Introduction</td><td>6-8</td></tr><tr><td>2.</td><td>Review of Available Information</td><td>8-</td></tr><tr><td>3.</td><td>Nitrate in surface and ground water</td><td>8-9</td></tr><tr><td>4.</td><td>Vulnerability of ground water resource and nitrate contamination</td><td>9-10</td></tr><tr><td>5.</td><td>Leaching of Nitrate in Soil, Health Effects of High Nitrate Levels, Effects on human health, Carcinogenicity, Effects on animals</td><td>10-12</td></tr><tr><td>6.</td><td>A Case Study: Samastipur District</td><td></td></tr><tr><td>7.</td><td>Physiographic situation, Climatic conditions,</td><td>12-15</td></tr><tr><td>8.</td><td>Collection and preparation of soil, water and plant samples</td><td>16-19</td></tr><tr><td>9.</td><td>Method of analysis for nitrate in soil, Methods for analysis of water, Analysis of carbonate and bicarbonate in water</td><td>20-21</td></tr><tr><td>10.</td><td>Analysis of sulphate in water, Analysis of nitrate in water, Analysis of sodium in water, SAR (Sodium Absorption Ratio), Residual sodium carbonate (RSC),</td><td>21-23</td></tr><tr><td>11.</td><td>Soil Organic Carbon, Available Nitrogen, Nitrate-Nitrogen, Compositi of Anions in Water, Composition of Anions in Ground Water</td><td>24-37</td></tr><tr><td>12.</td><td>Composition of Anions in Surface Water, Composition of Cations in Water, Composition of Cations in Ground Water, Composition of Cations in Surface Water,</td><td>37-38</td></tr><tr><td>13.</td><td>Nitrate in Water of Samastipur District, Nitrate in Ground Water of Samastipur District, Nitrate in Surface Water of Samastipur District</td><td>38-40</td></tr><tr><td>14.</td><td>Correlation of the soil properties with nitrate content in soils</td><td>40-44</td></tr><tr><td>15.</td><td>Correlation of the soil properties with nitrate content in groundwater</td><td>44-51</td></tr><tr><td>16.</td><td>Correlation between nitrate content in ground water and nitrogen application in soil</td><td>51-52</td></tr><tr><td>17.</td><td>Summary and conclusions</td><td>53-56</td></tr><tr><td>18.</td><td>References</td><td>57-64</td></tr></tbody></table>

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INTRODUCTION

One of the most crucial inputs for the sustainability of agriculture is nitrogen. Natural sources of nitrogen in the soil include precipitation, plant waste, animal waste, and microbial fixation of atmospheric nitrogen. Significant amount of soil organic nitrogen are getting mineralized, which are taken up by plants or lost to the atmosphere or leached downward. Ammonium is easily converted to nitrate, that is why the content of ammonium in most soils is usually low. Anthropogenic nitrate in ground water is caused by nitrate-containing fertilisers, human and industrial waste, organic manures and other factors. Leaching, or the downward flow of nitrate with water via soil, contaminates ground water when nitrate nitrogen supply exceeds plant demand. A large portion of the water we use for domestic, agricultural or commercial purpose is made up by groundwater. Aquifers are the source of the majority of groundwater, including a good proportion of our drinking water. In rural areas of India, groundwater is a crucial supply of water for agriculture and drinking purpose. The socioeconomic growth of rural areas is highly influenced by the quality of the groundwater because it directly affects both plant growth and human health. The poor quality of the groundwater hampers economic growth and hinders the improvement of living standards of rural households. Changes in the natural composition of ground water are also brought on by human activity. Many studies have found a strong link between agriculture and nitrate levels in groundwater, which has ramifications for the economy, ecology, and human health. This problem is seemed to be more severe in locations where intensive agriculture has been adopted for a long time and nitrogenous fertilizers have been used liberally. The fertilizers and manures applied in agriculture, act as non-point pollution sources which are often dispersed over large areas and pose great threat to fresh ground water system. Heavy use of fertilizers (chemical) in farms and careless disposal of human and animal waste on land causes residual nitrate to leach into ground water, resulting in high nitrate concentrations. Many factors influence the amount of nitrate leaching to ground water, including the texture and hydraulic conductivity of the soil, the type of crop grown, the amount of nitrogenous fertilizers used, the depth of the aquifer, the nature of gravel and sand underlying the profile and so on. The intrinsic hydrologic system or geologic constitution of the concern area, however, is the main element influencing nitrate
leaching. Along the profile, the activity of denitrifying organisms that convert nitrate to gaseous N₂ or N₂O may also be important. Nitrate, a common agricultural contaminant, lowers dissolved oxygen levels, creates hazardous algal blooms, and drives fish and coral species to extinction in aquatic environments. Due to the extensive use of nitrogen fertilizers, NO₃⁻ is lost from soils and accumulates in groundwater.

Drinking water with a high NO₃⁻ concentration has also been linked to methemoglobinemia in neonates and human birth abnormalities. Concentration levels of nitrate in groundwater are less than 2 ppm when they occur naturally. Water should not contain more nitrate than 10 ppm (WHO standard, 2011). Agricultural practises can easily cause nitrate concentration to rise to several hundred ppm. In an agricultural area of India, ground water had concentrations of up to 1500 ppm. In India, ground water is the only source of drinking water for 90 percent of the people. Due to economic and environmental problems, such as water pollution, studies on water and nitrate flow through the soil are gaining attraction. Any endeavour to safeguard water requires a thorough understanding of the nitrate leaching mechanisms. Nitrate accumulation in the soil, soil structure, and water movement all influence the amount and pattern of nitrate leaching. The main factor causing nitrate toxicity in humans, is the transformation of nitrate to nitrite. Nitrate's role in the oxidation of healthy Hb into metHb, which is unable to carry oxygen to the tissues, is the main biological effect of nitrate in humans. Methemoglobinemia is a disorder that causes cyanosis and, at greater concentrations, asphyxia. It is clinically obvious when metHb values reach 10% of normal Hb concentrations and above. A metHb level of less than 2% is typical for humans, whereas a level of less than 3% is typical for newborns less than 3 months. Compared to older children and adults, young infants' Hb is more susceptible to the generation of metHb. Additionally, those who lack glucose-6-phosphate dehydrogenase or metHb reductase may be more susceptible to metHb formation during pregnancy. Asphyxia (USEPA, 1985), methemoglobinemia, cancer (WHO, 1996), adverse effect on thyroid function are reported due to intake of nitrate more than safe limit.

Current agricultural practices having more emphasis on nitrogenous fertilizers which causing the adverse effects on nitrate contamination in water body, leads to major threats on human health. The compiled information from research work entitled
**"Impact of intensive use of nitrogenous fertilizer on nitrate contamination in groundwater and risk to human health"** has been presented in technical bulletin, will act as a valuable guide to researchers, farmers, policy planners and fertilizer manufacturing industries directly and indirectly associated with crop cultivation.

## Review of Available Information

Nitrate is a frequent agricultural contaminant that causes harmful algal blooms, lowers the amount of dissolved oxygen, and eliminates fish and coral species from aquatic environments. Nitrate is a nitrogen oxyanion formed by removal of a proton from nitric acid with the formula of $NO_3^-$ and molecular weight of 62.0049. One basal nitrogen atom is surrounded by three oxygen atoms in a triangular planar arrangement and thus forms one nitrate molecule. In room temperature almost all inorganic nitrates are soluble in water. Nitrate is a common component of fertilizers and explosives. As nitrates are highly soluble and biodegradable, they are mainly used as fertilizers in agriculture. Ammonium, potassium, sodium and calcium are the main nitrate salts. The literature available on these aspects has been critically reviewed and presented below under the following headlines:

### Nitrate in surface and ground water

Agriculture is the largest source of nitrate supplied to ground water and surface water, according to research undertaken globally. One of the main things that have improved agricultural production is the intensive use of nitrogenous fertilisers, but it also has a negative effect on water quality. Numerous studies demonstrate a direct correlation between nitrogen fertilisation rates and/or past fertilisation history and groundwater nitrate concentrations. Nitrate concentrations have raised alongside the growing use of N-fertilizers even on a regional scale in sensitive shallow ground water situations. Reddy *et al*. (2009) conducted an experiment and found that excess (> 45 ppm) $NO_3^-$-N content in groundwater in Andhra Pradesh, India, caused 65% of the total samples to be unsuitable for drinking purpose in the pre monsoon season and 45% in the post monsoon season. The main contributors of nitrate in shallow and moderately deep aquifers were intensive agricultural practices and improper organic waste and sewage disposal. The population in the area, particularly new-borns, is most susceptible to the health dangers posed by nitrate while drinking and utilising well water. Kumar *et al*. (2010 a) reported that the concentration of $NO_3^-$ in the
ground water samples of cultivated areas of Varanasi ranged between 1.95 to 58.52
ppm with a mean value 27.23 ppm.

In order to identify reasonable agri-environmental indicators that support the
design, implementation, and surveillance of governmental policies, Wick *et al.* (2012)
identified key predictors of groundwater nitrate contamination. They discovered a
positive correlation between groundwater nitrate content and the proportion of
farmland in a particular area. Environmental elements like temperature and
precipitation are also significant co-factors. Lower nitrate pollution of groundwater is
a result of higher average temperatures, presumably as a result of higher
evapotranspiration. Nitrate concentration in groundwater is further decreased by
higher average precipitation dilution of nitrates in the soil. The gross nitrogen balance
is a statistically significant predictor of nitrate contamination, according to regression
analysis. Wongsanit *et al.* (2015) studied nitrate contamination in groundwater and its
effect on human health. In India's north-western alluvial aquifer, Lapworth
*et al.* (2017) evaluated the quality of the ground water and came to the conclusion that
there was evidence of NO₃⁻ breakthrough from the shallow groundwater to deep. The
vulnerability of deep drinking water sources to pesticide and other anthropogenic
contaminants is also affected by the nitrate poisoning of rural parts of the India.

Vulnerability of ground water resource and nitrate contamination

Nitrate contamination values between 1 and 360 ppm in more than 200 tube
wells. Groundwater level and gradient of elevation were found to be in three different
arrangements:

1) NO₃⁻ hot spots linked to very deep aquifer levels and low aquifer elevation gradient suggest a small groundwater reserve with no horizontal flow, followed by degradation of quality of ground water from recycling through pumping and return flow;

2) High aquifer elevation gradient, moderate NO₃⁻ concentrations suggest that significant horizontal flow prevented NO₃⁻ enrichment; and

3) Low NO₃⁻N content, low groundwater elevation gradient, and shallow groundwater levels suggest a great reserve.

From the result they also concluded that irrigating the soil with NO₃⁻
containing ground water indicates a “hidden” supply of nitrogen to the crop field
which can reach 200 kg N ha⁻¹ yr⁻¹ in hotspot areas, which also enhance ground water contamination. Such hidden sources, if considered into account in fertilizer management, the fertilizer application rate would be optimized.

## Leaching of Nitrate in Soil

One of the major reasons behind elevated level of nitrate-N in water bodies is intensive nitrogenous fertilizer application. When nitrogenous fertilizers, may be urea or ammonium applied in soil, converted biochemically to nitrate. This nitrate is liable to leach beyond the root zone to reach the aquifer. Using an existing model and GIS, calculated nitrate leaching in groundwater in an agricultural area of the state of Karnataka. It was discovered that agricultural sources had substantially higher levels of nitrate leaching than cesspools did. From the research area, it was calculated that 87.81 to 381.96 kg yr⁻¹ could leak to groundwater. Singh and Craswell (2021) reviewed the nitrate poisoning of surface and ground water system and concluded that more than 50% of applied N cannot be used by the field crop, but based on the soil, climate and management practices a fraction of the applied N is lost through different processes including leaching as nitrate. Not only the applied nitrogen fertilizer is the source of nitrate-N in water bodies but also organic matter and manures, city sewage, animal excreta are important source. The best fertiliser management strategy for preventing nitrate-N leaching from the soil-plant system is application of the recommended fertiliser N rates. By altering the time of N application to correspond with the N uptake of crops, the amount of nitrate leaching can also be decreased.

## Health Effects of High Nitrate Levels

Organisms which intake groundwater contaminated with nitrate nitrogen show harmful biological consequences. Naturally, the first consideration when establishing standards for acceptable limits of nitrate and good agricultural practises is human interest. The permitted limit of nitrate in drinking water, according to the United States Environmental Protection Agency, is 10 ppm (equal to 10 ppm nitrate nitrogen or 45 ppm nitrate), based on the risk to human health from nitrate consumption.

## Effects on human health

The toxicity of nitrates is due to conversion of nitrate to nitrite by reduction. This nitrite reacts with haemoglobin of human blood and form methaemoglobin
which can't transport oxygen to tissue and thus lead to possible asphyxia (USEPA, 1985). Blue-baby syndrome cases typically arise in rural settings where wells serve as the main source of drinking water. Wells with inadequate or damaged casings and those that were dug rather than drilled are typically the most affected. Wells with dangerously high nitrate concentrations were typically overlooked until health issues were brought to light until increasing knowledge of the dangers of nitrate-contaminated groundwater encouraged testing for nitrate concentrations along with other contaminants. Methemoglobinemia is the condition in the blood which causes infant cyanosis, or blue-baby syndrome. Infant methemoglobinemia can also be identified by gastrointestinal issues such vomiting and diarrhoea, a relative lack of discomfort when severely cyanotic but irritability when minimally cyanotic, and blood that is a dark brown colour.

## Carcinogenicity

It has been demonstrated that nitrite and nitrosatable substances in the human stomach can combine to generate N-nitroso compounds. Although some of the most easily produced N-nitroso compounds, like N-nitrosoproline, are not carcinogenic in humans, several of these N-nitroso compounds have been proven to be carcinogenic in all the animal species studied. The N-nitroso compounds are cancer-causing in animal species and almost certainly also in people. The information from several epidemiological research is, however, only suggestive at best. If relatively high doses of both nitrite and nitrosatable chemicals are given to several animal species at the same time, the endogenous production of N-nitroso compounds is also seen in those animals. As a result, it is conceivable to link the risk of developing cancer to endogenous nitrosation brought on by a high intake of nitrate, nitrite, and nitrosatable substances (WHO, 1996). The endogenous production of N-nitroso compounds may contribute to the elevated risk of gastric cancer under conditions of low stomach acidity. Patients with achlorhydria were shown to have high mean levels of N-nitroso compounds and high levels of nitrate in their gastric juice, making them a unique risk group for gastric cancer when it comes to nitrate and nitrite levels (WHO, 1985).

## Effects on animals

The acute oral LD50 for sodium nitrate in rats has been observed to range from 46 to 120 mg/kg. The initial lethal impact in some species, such as horses, is caused by nitrite-induced vasodilatation, which causes cardiovascular collapse and
shock. This is in contrast to the effect in humans, in which nitrate is thought to be
responsible for the synthesis of methaemoglobin (USEPA, 1985). In a three-week
investigation on mice drinking water, higher methaemoglobin levels were seen in 50-
day-old mice given nitrate ion levels of 133 and 178 mg/kg/day, but not at 88
mg/kg/day. High nitrate levels in drinking water have been linked to congenital
abnormalities and cardiovascular health risk (WHO, 1985). Since nitrate
competitively limits iodine uptake, it has been investigated whether there are any
links between nitrate intake and effects on the thyroid. Epidemiological research
found evidence of a nitrate anti-thyroid effect in humans, in addition to effects on the
thyroid seen in animal studies and in livestock. The effect of nitrate is mild, with a
tendency to zero, if dietary iodine is present in an appropriate range (equivalent to a
daily iodine excretion of 150-300 g/day). If there is also a concurrent nutritional
iodine shortage, the nitrate effect on thyroid function is significant. According to Van
Maanen et al. (1994), endemic goitre is mostly caused by inorganic nitrate in drinking
water. Both experimental and epidemiological investigations have suggested that
"nitrate in drinking-water has a bigger influence on thyroid function than nitrate in
diet," which has been confirmed. The different thyroid effects may be due to the
different nitrate kinetics after consumption of drinking water versus food.

A Case Study: Samastipur District

Physiographic situation

Geographically the district Samastipur is situated between 25°30′00″ of Northern latitude to 26°05′00″ of Northern latitude and 85°37′50″ of Eastern longitude to 86°23′30″of eastern longitude and at an altitude of 53m /174 feet above the mean sea level (MSL) in the Gangatic plain of Bihar. Samastipur is an important agricultural zone, which comes under North West Alluvial Plain Zone with semi-arid to sub-tropical climate. The district is surrounded by Darbhanga in North, Khagaria in the East, Muzaffarpur and Vaishali in the west and Begusarai and Patna in the south. The location of the study area is depicted in the fig.1.

Climatic conditions

The climate is warm and temperate in Samastipur district of Bihar. In winter, there is much less rainfall in Samastipur than in summer. The Koppen-Geiger climate classification is Cwa. The average annual temperature is 25.2 °C in Samastipur. The
annual rainfall is 1236 mm. The driest month is November and the most precipitation falls in July. The warmest month of the year is May while January has the lowest average temperature. Average weekly data of different weather parameters have been presented in fig. 2.
<figure><img src="image_8.png" /><figcaption>Fig.1: Location map of the study area</figcaption></figure>
<figure><img src="image_9.png" /><figcaption>Fig.2. Monthly weather data recorded during January, 2021 to December, 2021 of Samastipur district</figcaption></figure>
## Collection and preparation of soil, water and plant samples

During the collection of soil, water and sugarcane samples, information regarding the sugarcane crop, cropping system, nature and amount of nitrogenous fertilizer used, method and frequency of irrigation and depth of bore wells were collected from each sampling site. Soil samples were collected from four different depths of 0-30 cm, 30-60 cm, 60-90 cm and 90-120 cm with the help of augur before start of the experiment from 16 different locations. For this purpose, 2 blocks were selected - Hasanpur and Rosera. About 500 grams of soil after thoroughly blending and quartering were collected in clean polythene bags with a proper label. After reaching to the laboratory about 150 g of each soil samples were immediately transferred into the refrigerator. These samples were used for analysis of nitrate. The remaining samples were air-dried and ground with a wooden roller on a clean surface and sieved through 2 mm sieve. The samples were then stored in polythene bags for subsequent chemical analysis. The soil samples collected from surface (0-30 cm) depth using core sampler for determination of bulk density. The planning and other details of soil sampling have been presented in fig. 3.3 and table 3.2. V1, V2, V3, V4, V5, V6, V7 & V8 used to denote the village Rasulpur Dharha, Shasan, Mahuli, Chakthat West, Jahangirpur South, Rampur Rajawa, Jagarnathpur & Rohua respectively while F1 & F2 stand for the two selected farmers from each village.

For assessment of nitrate concentration and other chemical properties of water, the samples were collected from dominated sugarcane growing areas of Samastipur district of Bihar following standard protocols (Kundu and Mandal, 2009). For this purpose, 2 blocks were selected – Hasanpur and Rosera. All together of 24 ground water samples were collected from various water sources viz, hand pump (HP), deep tube wells (DTW). In addition, 8 samples were collected from ponds and trenches and the river Bagmati. The water samples (1000 ml) were collected in polythene bottles and preserved by toluene in laboratory after analysis of pH and EC for further analysis. During collection of water samples from the hand pump and deep tube wells the depth of tube were recorded. The locations and global position along with depth of the tube are given in Table 2. V1, V2, V3, V4, V5, V6, V7 & V8 used to denote the village Rasulpur Dharha, Shasan, Mahuli, Chakthat West, Jahangirpur South, Rampur Rajawa, Jagarnathpur & Rohua respectively while A, B & C stand for Ground Water samples and D denotes Surface Water samples.
<figure><img src="image_10.png" /><figcaption>Fig. 3: Plan of soil and sugarcane sampling</figcaption></figure>
<table><caption>Table.1: Details of soil and sugarcane sampling from sugarcane growing areas Samastipur districts of Bihar</caption><thead><tr><th>Sl. No.</th><th>Name of the village</th><th>Farmer ID</th><th>Name of the block</th><th>Latitude</th><th>Longitude</th><th>Cropping system</th></tr></thead><tbody><tr><td>1.</td><td rowspan="2">V1</td><td>V1F1</td><td>Rosera</td><td>N25° 46' 51.17"</td><td>E86° 2' 14.26"</td><td>Wheat/Maize-Sugarcane-Ratoon</td></tr><tr><td>2.</td><td>V1F2</td><td>Rosera</td><td>N25° 46' 51.25"</td><td>E86° 2' 48.87"</td><td>Wheat/Rice-Sugarcane-Ratoon</td></tr><tr><td>3.</td><td rowspan="2">V2</td><td>V2F1</td><td>Hasanpur</td><td>N25° 40' 43.82"</td><td>E86° 12' 6.48"</td><td>Rice/Wheat-Sugarcane-Ratoon</td></tr><tr><td>4.</td><td>V2F2</td><td>Hasanpur</td><td>N26° 10' 6.99"</td><td>E86° 15' 54"</td><td>Sugarcane-Ratoon-Wheat</td></tr><tr><td>5.</td><td rowspan="2">V3</td><td>V3F1</td><td>Hasanpur</td><td>N25° 45' 51.06"</td><td>E86° 5' 6.89"</td><td>Rice/Maize-Sugarcane-Ratoon</td></tr><tr><td>6.</td><td>V3F2</td><td>Hasanpur</td><td>N25° 46' 5.86"</td><td>E86° 4' 58.57"</td><td>Rice/Wheat-Sugarcane-Ratoon</td></tr><tr><td>7.</td><td rowspan="2">V4</td><td>V4F1</td><td>Rosera</td><td>N25° 44' 3.37"</td><td>E86° 1' 8.95"</td><td>Sugarcane-Ratoon</td></tr><tr><td>8.</td><td>V4F2</td><td>Rosera</td><td>N25° 43' 48.81"</td><td>E86° 2' 12.73"</td><td>Rice/Maize-Sugarcane-Ratoon</td></tr><tr><td>9.</td><td rowspan="2">V5</td><td>V5F1</td><td>Rosera</td><td>N25° 48' 27.97"</td><td>E86° 0' 4.01"</td><td>Sugarcane-Ratoon-Wheat</td></tr><tr><td>10.</td><td>V5F2</td><td>Rosera</td><td>N25° 47' 11.58"</td><td>E86° 0' 22.43"</td><td>Rice/Wheat-Sugarcane-Ratoon</td></tr><tr><td>11.</td><td rowspan="2">V6</td><td>V6F1</td><td>Hasanpur</td><td>N25° 42' 59.95"</td><td>E86° 10' 28.80"</td><td>Sugarcane-Ratoon</td></tr><tr><td>12.</td><td>V6F2</td><td>Hasanpur</td><td>N25° 42' 38.45"</td><td>E86° 10' 56.05"</td><td>Sugarcane-Ratoon</td></tr><tr><td>13.</td><td rowspan="2">V7</td><td>V7F1</td><td>Hasanpur</td><td>N25° 47' 33.01"</td><td>E86° 9' 0.14"</td><td>Sugarcane-Ratoon</td></tr><tr><td>14.</td><td>V7F2</td><td>Hasanpur</td><td>N25° 47' 39.25"</td><td>E86° 9' 4.95"</td><td>Sugarcane-Ratoon</td></tr><tr><td>15.</td><td rowspan="2">V8</td><td>V8F1</td><td>Rosera</td><td>N25° 45' 47.46"</td><td>E86° 0' 4.15"</td><td>Sugarcane-Ratoon</td></tr><tr><td>16.</td><td>V8F2</td><td>Rosera</td><td>N25° 45' 25.02"</td><td>E85° 59' 1.51"</td><td>Sugarcane-Ratoon</td></tr></tbody></table>
<table><caption>Table.2: Details of water sampling from sugarcane growing areas of Samastipur district</caption><thead><tr><th>S. No.</th><th>Village ID</th><th>Sample ID</th><th>Latitude</th><th>Longitude</th><th>Depth (ft.)</th></tr></thead><tbody><tr><td>1</td><td rowspan="4">V1</td><td>V1A</td><td>N25° 41' 18.46"</td><td>E86° 11' 41.97"</td><td>50</td></tr><tr><td>2</td><td>V1B</td><td>N25° 41' 22.01"</td><td>E86° 11' 0.55"</td><td>70</td></tr><tr><td>3</td><td>V1C</td><td>N25° 41' 28.22"</td><td>E86° 11' 4.31"</td><td>40</td></tr><tr><td>4</td><td>V1D</td><td>N25° 46' 15.97"</td><td>E86° 2' 30.99"</td><td>SW</td></tr><tr><td>5</td><td rowspan="4">V2</td><td>V2A</td><td>N25° 45' 52.66"</td><td>E86° 4' 55.09"</td><td>70</td></tr><tr><td>6</td><td>V2B</td><td>N25° 46' 21.42"</td><td>E86° 5' 33.50"</td><td>50</td></tr><tr><td>7</td><td>V2C</td><td>N25° 46' 11.23"</td><td>E86° 5' 3.91"</td><td>50</td></tr><tr><td>8</td><td>V2D</td><td>N25° 41' 55.66"</td><td>E86° 11' 27.79"</td><td>SW</td></tr><tr><td>9</td><td rowspan="4">V3</td><td>V3A</td><td>N25° 42' 33.31"</td><td>E86° 10' 50.37"</td><td>60</td></tr><tr><td>10</td><td>V3B</td><td>N25° 43' 22.22"</td><td>E86° 11' 9.12"</td><td>40</td></tr><tr><td>11</td><td>V3C</td><td>N25° 43' 7.47"</td><td>E86° 11' 6.86"</td><td>60</td></tr><tr><td>12</td><td>V3D</td><td>N25° 46' 4.78"</td><td>E86° 5' 11.29"</td><td>SW</td></tr><tr><td>13</td><td rowspan="4">V4</td><td>V4A</td><td>N25° 47' 31.06"</td><td>E86° 9' 4.32"</td><td>80</td></tr><tr><td>14</td><td>V4B</td><td>N25° 47' 38.90"</td><td>E86° 8' 54.78"</td><td>80</td></tr><tr><td>15</td><td>V4C</td><td>N25° 47' 47.03"</td><td>E86° 8' 28.01"</td><td>50</td></tr><tr><td>16</td><td>V4D</td><td>N25° 43' 18.70"</td><td>E 86° 11' 10.42"</td><td>SW</td></tr><tr><td>17</td><td rowspan="4">V5</td><td>V5A</td><td>N25° 46' 46.35"</td><td>E86° 2' 45.58"</td><td>60</td></tr><tr><td>18</td><td>V5B</td><td>N25° 46' 47.26"</td><td>E86° 2' 8.41"</td><td>80</td></tr><tr><td>19</td><td>V5C</td><td>N25° 46' 15.90"</td><td>E86° 2' 27.17"</td><td>70</td></tr><tr><td>20</td><td>V5D</td><td>N 25° 47' 46.66"</td><td>E 86° 8' 46.59"</td><td>SW</td></tr><tr><td>21</td><td rowspan="4">V6</td><td>V6A</td><td>N25° 43' 59.39"</td><td>E86° 1' 50.13"</td><td>40</td></tr><tr><td>22</td><td>V6B</td><td>N25° 44' 13.15"</td><td>E86° 1' 33.96"</td><td>60</td></tr><tr><td>23</td><td>V6C</td><td>N25° 44' 7.53"</td><td>E86° 2' 13.30"</td><td>70</td></tr><tr><td>24</td><td>V6D</td><td>N 25° 43' 47.18"</td><td>E 86° 1' 7.56"</td><td>SW</td></tr><tr><td>25</td><td rowspan="4">V7</td><td>V7A</td><td>N25° 47' 31.79"</td><td>E86° 6' 0' 9.87"</td><td>40</td></tr><tr><td>26</td><td>V7B</td><td>N25° 48' 39.28"</td><td>E85° 59' 53.10"</td><td>60</td></tr><tr><td>27</td><td>V7C</td><td>N25° 49' 29.35"</td><td>E85° 59' 34.52"</td><td>80</td></tr><tr><td>28</td><td>V7D</td><td>N 25° 47' 49.68"</td><td>E 86° 0' 8.73"</td><td>SW</td></tr><tr><td>29</td><td rowspan="4">V8</td><td>V8A</td><td>N 25° 45' 18.02"</td><td>E85° 59' 10.80"</td><td>70</td></tr><tr><td>30</td><td>V8B</td><td>N 25° 45' 47.82"</td><td>E85° 59' 31.71"</td><td>80</td></tr><tr><td>31</td><td>V8C</td><td>N 25° 45' 48.69"</td><td>E85° 58' 58.92"</td><td>50</td></tr><tr><td>32</td><td>V8D</td><td>N 25° 45' 33.92"</td><td>E 85° 59' 32.82"</td><td>SW</td></tr></tbody></table>
## Method of analysis for nitrate in soil

Nitrate in soil was determined by the 2M KCl soil extract method by the Flow Injection Autoanalyzer for nitrate estimation (FIASTAR 5000, FOSS Analytical AB, Sweden). Nitrate in the soil sample was extracted by the KCl. 10 g of moist soil was taken (as collected from sugarcane field) into a 100 ml conical flask. Added 50 ml of 2M KCl and shaken for 1 hour. Transferred the suspension to a centrifuge tube and centrifuge for 5 min. Then filter the supernatant solution through Whatman no. 1 filter paper. The filtrate was then introduced in a flow injection system. The chemical principle for determination of nitrate is reduction to nitrite in a cadmium reductor. The described method determines the sum of nitrite and nitrate originally present in the extract.

## Methods for analysis of water

### Analysis of total calcium and magnesium in water

The total $Ca^{2+}$ + $Mg^{2+}$ was measured using Ethylene Diamine Tetra Acetic Acid in a complexometric titration (Na-EDTA). Na-EDTA, also known as ‘Versenate’ or ‘Trilon’, has a significant complexing power with metal ions, particularly alkaline earth metals, in a sequence determined by the complex’s dissociation constant. In a conical flask, 10 mL of water was pipetted out. 5 mL buffer ($NH_4OH$ + $NaCl$) solution (pH 8 to 10) and 5-6 drops Erichrome Black-T indicator were added, and the colour was titrated against standard Na-EDTA solution until the colour changed from wine red to blue.

### Analysis of carbonate and bicarbonate in water

The calculation is based on a simple acidimetric titration with several indicators that work in either an alkaline pH range (above 8.2) or an acidic pH range (below 6.0 or 4.5). Titrating the water with standard sulphuric acid (0.01N) and then methyl orange indicator can be used to assess carbonate and bicarbonate levels. In a 100 mL conical flask, a 10 mL water sample was obtained. It was titrated with normal acid and 1-2 drops of phenolphthalein added until the pink colour faded completely. It was noted how much standard acid was used. 1-2 drops of methyl orange indicator were added to the colourless solution from the titration (or to the initial sample of water if there was no colour of phenolphthalein), then the titration was continued with stirring to the methyl orange end point (yellow) and the final reading was taken.
## Analysis of sulphate in water

The turbidimetric method of Chesnin and Yien (1951) was used to determine sulphur as barium sulphate. In a 25 mL volumetric flask, 10 mL of water was collected. To keep the pH around 4.8, 10 mL of sodium acetate-acetic acid buffer was added, along with 1 mL of gum acacia and 1 g of BaCl₂ crystal. The turbidity was measured in a spectrophotometer at 440 nm using a blue filter after volume make-up. Standard curves were used to determine sample concentrations (K₂SO₄).

## Analysis of nitrate in water

Nitrate in water was determined by the FIASTAR 5000 analyser. The water as collected, was introduced in a flow injection system. The chemical principle for determination of nitrate is reduction to nitrite in a cadmium reductor. The described method determines the sum of nitrite and nitrate originally present in the extract. However, the original concentration of nitrite is in most of the cases negligible in comparison with the nitrate concentration.

## Analysis of sodium in water

The software-based flame photometer was used to determine Na⁺ using the necessary filter and a standard solution that was made by taking known sodium concentrations (NaCl). The concentration of Na⁺ in the unknown sample was noted directly from flame photometer.

## SAR (Sodium Absorption Ratio)

As a more accurate metric for determining the risk of Na pollution in irrigation water, the SAR was proposed by USSL (1954). This indicator estimates the proportion of sodium to calcium and magnesium ions in a sample. In contrast to sodium, which makes soil particles scatter, calcium causes soil particles to flocculate (stay together). This leads to problems with soil crusting and water infiltration as well as permeability concerns (Bauder et al., 2007). It is a common observation to see calcium carbonate precipitate as scale in boilers, distribution lines, and water heaters. When irrigation water is applied to a field, this reaction may also occur. The ratio of sodium to calcium rises when calcium precipitates, and the SAR value also increases. The following equation is used to compute the sodium adsorption ratio (SAR):

$$SAR = \frac{Na^{+}}{\sqrt{(Ca+Mg)/2}}$$
<table><caption>Table.3: Different sodicity classes with their SAR ranges</caption><thead><tr><td>Classes</td><td>Quality of water</td><td>SAR value</td><td>Suitability</td></tr></thead><tbody><tr><td>S<sub>1</sub></td><td>Low sodium</td><td>&lt; 10</td><td>Safe</td></tr><tr><td>S<sub>2</sub></td><td>Medium sodium</td><td>10-18</td><td>Used safely in coarse textured soil</td></tr><tr><td>S<sub>3</sub></td><td>High sodium</td><td>18-26</td><td>Unsuitable for irrigation</td></tr><tr><td>S<sub>4</sub></td><td>Very high sodium</td><td>&gt;26</td><td>Very unsuitable water</td></tr></tbody></table>

## Residual sodium carbonate (RSC)

It is an index that shows the risks associated with soil irrigation water's alkalinity. It is used to determine whether irrigation water is appropriate for soil with a relatively high cation exchange capacity. If there is a lot of dissolved sodium in the water, clay-containing soil will expand and disperse.

$$ \text{RSC Index} = [\text{HCO}_3^- + \text{CO}_3^{2-}] - [\text{Ca}^{2+} + \text{Mg}^{2+}] $$

<table><caption>Table 4: Different irrigation water classes based on RSC value</caption><thead><tr><td>Irrigation water classes</td><td>RSC Value (meL<sup>-1</sup>)</td><td>Suitability</td></tr></thead><tbody><tr><td>C1</td><td>&lt; 1.25</td><td>Safe for irrigation</td></tr><tr><td>C2</td><td>1.25-2.5</td><td>Certain management is needed</td></tr><tr><td>C3</td><td>&gt; 2.5</td><td>Unsuitable for irrigation purpose</td></tr></tbody></table>

## Statistical analysis

Data obtained from all the observations were statistically analysed. The correlation of ground water and soil parameters with nitrate content were statistically calculated as per the standard procedures as suggested by Gomez and Gomez (1984). Microsoft Excel was used to statistically calculate the correlation between ground water and soil characteristics and nitrate levels.
<figure><img src="image_11.png" /><figcaption>Nitrate estimation in Laboratory</figcaption></figure>

<figure><img src="image_12.png" /><figcaption>Soil sampling from different depth</figcaption></figure>

<figure><img src="image_13.png" /><figcaption>Water sampling from pond</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>Water sampling from hand pump</figcaption></figure>
# Salient Findings

## Physical Properties of Soils

### Particle distribution and textural classes of soils

The soil texture (USDA) of sugarcane growing area of Samastipur district was varying from sandy loam to sandy clay (Fig.4).

<figure><img src="image_15.png" /><figcaption>**Fig.4: Percent of soil samples under different textural classes in the study area**</figcaption></figure>

The maximum average sand percentage (61%) was found in the village Mahuli at 30 cm depth and the minimum sand (%) was found in the village Chakthat West (50.75%) & Rasulpur Dharha (50.75%) at 120 cm depth. While, maximum average silt was recorded to be 23.25 % in the village Rasulpur Dharha and minimum average silt content (15.25%) was recorded to be in the village Rohua at 120 cm depth. Maximum average clay content (32%) was recorded in the village Jahangirpur South at 120 cm depth while minimum average clay content (18.00%) was reported from the village Shasan at 30 cm depth.

The textural class of all the selected villages were determined using Whitney textural triangle. With increasing depth, the sand and silt content were decreasing while clay content was increasing as we go deeper. The reason behind the increasing content of clay with increasing depth may be the illuviation of clay at lower depth. A loam soil has a balanced mixture of fine and coarse particles with properties intermediate between sand, silt, and clay. The loam soil is proved best soil for sugarcane growth.
<table><caption>Table 5: Descriptive statistical analysis of physical properties of soil in sugarcane growing areas of Samastipur</caption><thead><tr><th rowspan="3">DESCRIPTIVE<br>STATS</th><th colspan="4">Sand (%)</th><th colspan="4">Silt (%)</th><th colspan="4">Clay (%)</th><th>B.D.<br>(Mg m<sup>-3</sup>)</th></tr><tr><th colspan="12">Depth of soil (cm)</th></tr><tr><th>0-30<br>cm</th><th>30-60<br>cm</th><th>60-90<br>cm</th><th>90-120<br>cm</th><th>0-30<br>cm</th><th>30-60<br>cm</th><th>60-90<br>cm</th><th>90-120<br>cm</th><th>0-30<br>cm</th><th>30-60<br>cm</th><th>60-90<br>cm</th><th>90-120<br>cm</th><th>0-30<br>cm</th></tr></thead><tbody><tr><td>Mean</td><td>59.02</td><td>57.44</td><td>55.72</td><td>52.25</td><td>20.56</td><td>19.56</td><td>18.47</td><td>16.94</td><td>20.42</td><td>23.00</td><td>25.81</td><td>30.81</td><td>1.51</td></tr><tr><td>Standard Error</td><td>0.60</td><td>0.53</td><td>0.45</td><td>0.45</td><td>0.70</td><td>0.61</td><td>0.50</td><td>0.42</td><td>0.85</td><td>0.74</td><td>0.53</td><td>0.42</td><td>0.02</td></tr><tr><td>CV</td><td>1.02</td><td>0.92</td><td>0.81</td><td>0.85</td><td>3.39</td><td>3.10</td><td>2.70</td><td>2.51</td><td>4.18</td><td>3.20</td><td>2.06</td><td>1.38</td><td>1.32</td></tr><tr><td>Median</td><td>59.32</td><td>57.38</td><td>55.25</td><td>51.88</td><td>20.88</td><td>19.88</td><td>18.50</td><td>16.88</td><td>19.88</td><td>23.00</td><td>25.88</td><td>30.88</td><td>1.53</td></tr><tr><td>Standard Deviation</td><td>1.70</td><td>1.49</td><td>1.27</td><td>1.26</td><td>1.97</td><td>1.72</td><td>1.41</td><td>1.20</td><td>2.42</td><td>2.08</td><td>1.50</td><td>1.20</td><td>0.06</td></tr><tr><td>Sample Variance</td><td>2.90</td><td>2.21</td><td>1.61</td><td>1.59</td><td>3.89</td><td>2.94</td><td>1.99</td><td>1.44</td><td>5.84</td><td>4.34</td><td>2.26</td><td>1.44</td><td>0.00</td></tr><tr><td>Kurtosis</td><td>-1.52</td><td>-1.45</td><td>-1.77</td><td>-1.80</td><td>-1.06</td><td>-1.79</td><td>-1.73</td><td>-1.13</td><td>2.37</td><td>1.08</td><td>1.05</td><td>2.91</td><td>-1.14</td></tr><tr><td>Skewness</td><td>-0.40</td><td>-0.24</td><td>0.24</td><td>0.16</td><td>-0.21</td><td>-0.18</td><td>0.11</td><td>0.09</td><td>1.48</td><td>0.84</td><td>-0.62</td><td>-1.45</td><td>-0.62</td></tr><tr><td>Range</td><td>4.50</td><td>3.75</td><td>3.25</td><td>3.00</td><td>5.75</td><td>4.50</td><td>3.75</td><td>3.50</td><td>7.50</td><td>6.75</td><td>5.00</td><td>3.75</td><td>0.15</td></tr><tr><td>Minimum</td><td>56.50</td><td>55.25</td><td>54.00</td><td>50.75</td><td>17.50</td><td>17.25</td><td>16.75</td><td>15.25</td><td>18.00</td><td>20.25</td><td>23.00</td><td>28.25</td><td>1.42</td></tr><tr><td>Maximum</td><td>61.00</td><td>59.00</td><td>57.25</td><td>53.75</td><td>23.25</td><td>21.75</td><td>20.50</td><td>18.75</td><td>25.50</td><td>27.00</td><td>28.00</td><td>32.00</td><td>1.57</td></tr><tr><td>Sum</td><td>472.13</td><td>459.50</td><td>445.75</td><td>418.00</td><td>164.50</td><td>156.50</td><td>147.75</td><td>135.50</td><td>163.38</td><td>184.00</td><td>206.50</td><td>246.50</td><td>12.10</td></tr><tr><td>Count</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td></tr></tbody></table>
## Soil Organic Carbon (SOC)

The increased fertilization rate with continuous cropping in rice- sugarcane cropping system is the reason behind higher organic carbon content (Mandal *et al*., 2013). According to the current study, the amount of organic matter as well as organic carbon was higher on the soil's upper surface and decreased as soil depth increased. This can be the impact of manure application in soil and *in-situ* plant residue incorporation on the top layer. This result was similar with the finding of Amgain *et al*. (2020). Soil organic carbon enhances soil structure, water holding capacity, soil aeration and infiltration, nutrient providing ability of soil, and feeds soil microflora and fauna that is why soil organic carbon is the basis of healthy and productive soils.

## Available Nitrogen

The outcome revealed that with increment of soil depth, the available nitrogen decreased. The range of available nitrogen in 0-30 cm layer was 169.35 to 244.61 kg ha⁻¹, showing considerable variance. The range of soil-available nitrogen with increasing soil depth (30-60 cm) was 131.71-175.62 kg ha⁻¹, with a mean value of 156.02 kg ha⁻¹ (Table 5). Similarly, in 60-90 cm depth the available nitrogen was varied from 68.99 to 125.44 kg ha⁻¹ with a mean value of 104.27 kg ha⁻¹. In 90-120 cm depth available nitrogen ranged between 31.36 to 87.81 kg ha⁻¹ with a mean of 65.86 kg ha⁻¹. In the village Rasulpur Dharha maximum available nitrogen (244.61 kg ha⁻¹) was found at 30 cm depth. At 120 cm depth of Rampur Rajawa village minimum amount of available nitrogen (31.36 kg ha⁻¹) was recorded.

The outcome indicated that available nitrogen's mean value was of low status at all the four depths in all the villages. In general, it was discovered that the available nitrogen content was highest in surface soils and gradually decreased as soil depth increased. This could be because organic matter has a tendency to decrease with depth and becomes more mineralized in surface soil. crop cultivation is primarily restricted to the surface horizon, and decreased nitrogen content was replenished by fertilizers added from outside. Since nitrogen is mostly found in organic form (95-98%), the value of available nitrogen exhibits a similar pattern to that of organic carbon. Mishra *et al*. (2015) also reported gradual decrement of available nitrogen with increment in depth.
<table><caption>Table 6: Descriptive statistical analysis of chemical properties (pH, EC & OC) of soil in sugarcane growing areas of Samastipur</caption><thead><tr><th rowspan="3">DESCRIPTIVE<br>STATS</th><th colspan="4">pH</th><th colspan="4">EC (dS m<sup>-1</sup>)</th><th colspan="4">Organic carbon (%)</th></tr><tr><th colspan="12">Depth of soil (cm)</th></tr><tr><th>0-30<br>cm</th><th>30-60<br>cm</th><th>60-90<br>cm</th><th>90-120<br>cm</th><th>0-30<br>cm</th><th>30-60<br>cm</th><th>60-90<br>cm</th><th>90-120<br>cm</th><th>0-30<br>cm</th><th>30-60<br>cm</th><th>60-90<br>cm</th><th>90-120<br>cm</th></tr></thead><tbody><tr><td>Mean</td><td>7.92</td><td>7.98</td><td>8.07</td><td>8.15</td><td>0.132</td><td>0.153</td><td>0.168</td><td>0.188</td><td>0.44</td><td>0.24</td><td>0.17</td><td>0.09</td></tr><tr><td>Standard Error</td><td>0.03</td><td>0.03</td><td>0.03</td><td>0.02</td><td>0.004</td><td>0.003</td><td>0.002</td><td>0.005</td><td>0.03</td><td>0.02</td><td>0.02</td><td>0.01</td></tr><tr><td>CV</td><td>0.35</td><td>0.41</td><td>0.32</td><td>0.20</td><td>2.809</td><td>1.686</td><td>1.406</td><td>2.677</td><td>6.63</td><td>9.63</td><td>9.26</td><td>14.24</td></tr><tr><td>Median</td><td>7.92</td><td>7.96</td><td>8.09</td><td>8.14</td><td>0.132</td><td>0.151</td><td>0.165</td><td>0.184</td><td>0.40</td><td>0.26</td><td>0.19</td><td>0.10</td></tr><tr><td>Standard Deviation</td><td>0.08</td><td>0.09</td><td>0.07</td><td>0.05</td><td>0.010</td><td>0.007</td><td>0.007</td><td>0.014</td><td>0.08</td><td>0.07</td><td>0.04</td><td>0.04</td></tr><tr><td>Sample Variance</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.00</td><td>0.000</td><td>0.000</td><td>0.000</td><td>0.000</td><td>0.01</td><td>0.00</td><td>0.00</td><td>0.00</td></tr><tr><td>Kurtosis</td><td>0.30</td><td>-1.28</td><td>2.14</td><td>-1.72</td><td>1.272</td><td>0.532</td><td>-1.960</td><td>-0.891</td><td>-0.30</td><td>3.05</td><td>3.92</td><td>-1.81</td></tr><tr><td>Skewness</td><td>0.27</td><td>0.06</td><td>-1.46</td><td>0.45</td><td>0.083</td><td>-0.107</td><td>0.638</td><td>0.828</td><td>1.04</td><td>-1.61</td><td>-1.91</td><td>-0.24</td></tr><tr><td>Range</td><td>0.25</td><td>0.25</td><td>0.22</td><td>0.12</td><td>0.036</td><td>0.024</td><td>0.016</td><td>0.036</td><td>0.23</td><td>0.21</td><td>0.13</td><td>0.09</td></tr><tr><td>Minimum</td><td>7.81</td><td>7.85</td><td>7.92</td><td>8.10</td><td>0.114</td><td>0.140</td><td>0.162</td><td>0.173</td><td>0.36</td><td>0.10</td><td>0.07</td><td>0.04</td></tr><tr><td>Maximum</td><td>8.06</td><td>8.10</td><td>8.14</td><td>8.22</td><td>0.150</td><td>0.164</td><td>0.178</td><td>0.209</td><td>0.59</td><td>0.31</td><td>0.20</td><td>0.13</td></tr><tr><td>Sum</td><td>63.37</td><td>63.80</td><td>64.59</td><td>65.21</td><td>1.056</td><td>1.220</td><td>1.347</td><td>1.503</td><td>3.54</td><td>1.94</td><td>1.35</td><td>0.72</td></tr><tr><td>Count</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.000</td><td>8.000</td><td>8.000</td><td>8.000</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td></tr></tbody></table>
<table><caption>Table 7: Descriptive statistical analysis of chemical properties (Available N) of soil in sugarcane growing areas of Samastipur</caption><thead><tr><th rowspan="2">Descriptive Stats</th><th colspan="4">Available N (kg ha<sup>-1</sup>)</th></tr><tr><th>0-30 cm</th><th>30-60 cm</th><th>60-90 cm</th><th>90-120 cm</th></tr></thead><tbody><tr><td>Mean</td><td>206.20</td><td>156.02</td><td>104.27</td><td>65.86</td></tr><tr><td>Standard Error</td><td>7.63</td><td>4.95</td><td>7.01</td><td>7.21</td></tr><tr><td>CV</td><td>3.70</td><td>3.17</td><td>6.72</td><td>10.95</td></tr><tr><td>Median</td><td>203.85</td><td>156.80</td><td>109.77</td><td>72.13</td></tr><tr><td>Standard Deviation</td><td>21.58</td><td>14.00</td><td>19.82</td><td>20.39</td></tr><tr><td>Sample Variance</td><td>465.69</td><td>196.05</td><td>392.70</td><td>415.91</td></tr><tr><td>Kurtosis</td><td>1.54</td><td>0.01</td><td>-0.18</td><td>-0.22</td></tr><tr><td>Skewness</td><td>0.14</td><td>-0.41</td><td>-0.95</td><td>-1.06</td></tr><tr><td>Range</td><td>75.26</td><td>43.91</td><td>56.45</td><td>56.45</td></tr><tr><td>Minimum</td><td>169.35</td><td>131.71</td><td>68.99</td><td>31.36</td></tr><tr><td>Maximum</td><td>244.61</td><td>175.62</td><td>125.44</td><td>87.81</td></tr><tr><td>Sum</td><td>1649.56</td><td>1248.15</td><td>834.19</td><td>526.85</td></tr><tr><td>Count</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td></tr></tbody></table>

## Nitrate- Nitrogen

In the selected villages the vertical distribution of nitrate has shown in the Fig.5. The range of Nitrate-nitrogen in 0-30 cm layer was 24.08 to 42.27 kg ha⁻¹, showing considerable variance. The mean value of nitrate- nitrogen in this depth was found to be 29.18 kg ha⁻¹ (table 8). The range of soil nitrate-nitrogen with increasing soil depth (30-60 cm) was 14.39- 22.18 kg ha⁻¹, with a mean value of 17.46 kg ha⁻¹. Similarly, in 60-90 cm depth the nitrate- nitrogen was varied from 12.14 to 15.08 kg ha⁻¹ with a mean value of 13.71 kg ha⁻¹. In 90-120 cm depth Nitrate- nitrogen content ranged between 10.16 to 12.90 kg ha⁻¹ with a mean of 11.53 kg ha⁻¹. In the village Rasulpur Dharha maximum nitrate- nitrogen (42.27 kg ha⁻¹) was found at 30 cm depth. At 120 cm depth of Jahangirpur South village minimum amount of nitrate- nitrogen (10.16 kg ha⁻¹) was recorded.

The deficiency of nitrogen in agricultural system is a global issue, and India is not an exception. By 2030 AD, there will be 1.5 billion people living in India, and in order to boost crop yield and provide for the bare necessities of such a big population,
a lot of fertilizers would need to be used. By "excessive, recurrent planting," farmers first deplete the soil, and then to maintain crop yields, they try to replenish the less-productive soil by applying an increasing quantity of nitrogen-based fertilizers to the area. Poor nitrogen recovery is a major concern for a variety of reasons: (i) nitrogen fertilizers are expensive because they require enormous amounts of non-renewable energy, specifically naphtha, natural gas, etc. (ii) it causes environmental issues, such as groundwater nitrate pollution, surface water eutrophication, and nitrous oxide emissions that cause global warming, ozone layer loss, ammonia emissions, fog generation, and acid rains. It is a crucial part of chlorophyll. As a result, nitrogen is spread out over a broader area of agricultural fields with other fertilizers. Since nitrate losses occur in heavily farmed areas, measuring leaching in ground water and build-up in soil layers under typical farming practises is of utmost importance.

The most crucial nutrient for plant growth in the soil is nitrogen, which is absorbed by plant roots as $NO_3^-$ and $NH_4^+$ from the soil. The most stable form of nitrogen (N) in soil is nitrate, which is often produced by the mineralization of organic materials or N fertilizers. Because of their high solubility, they can be leached

<table><caption>**Table 8: Descriptive statistical analysis of nitrate- nitrogen in soil in sugarcane growing areas of Samastipur**</caption><thead><tr><th rowspan="3">Descriptive Stats</th><th colspan="4">Nitrate-nitrogen (kg ha<sup>-1</sup>)</th></tr><tr><th colspan="4">Depth (cm)</th></tr><tr><th>0-30</th><th>30-60</th><th>60-90</th><th>90-120</th></tr></thead><tbody><tr><td>Mean</td><td>29.18</td><td>17.46</td><td>13.72</td><td>11.53</td></tr><tr><td>Standard Error</td><td>2.28</td><td>0.86</td><td>0.38</td><td>0.34</td></tr><tr><td>CV</td><td>7.81</td><td>4.94</td><td>2.78</td><td>2.95</td></tr><tr><td>Median</td><td>26.54</td><td>17.36</td><td>13.81</td><td>11.80</td></tr><tr><td>Standard Deviation</td><td>6.45</td><td>2.44</td><td>1.08</td><td>0.96</td></tr><tr><td>Sample Variance</td><td>41.60</td><td>5.94</td><td>1.17</td><td>0.93</td></tr><tr><td>Kurtosis</td><td>1.51</td><td>1.11</td><td>-1.65</td><td>-1.26</td></tr><tr><td>Skewness</td><td>1.46</td><td>0.91</td><td>-0.20</td><td>-0.21</td></tr><tr><td>Range</td><td>18.19</td><td>7.79</td><td>2.94</td><td>2.74</td></tr><tr><td>Minimum</td><td>24.08</td><td>14.39</td><td>12.14</td><td>10.16</td></tr><tr><td>Maximum</td><td>42.27</td><td>22.18</td><td>15.08</td><td>12.90</td></tr><tr><td>Sum</td><td>233.44</td><td>139.68</td><td>109.73</td><td>92.23</td></tr><tr><td>Count</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td></tr></tbody></table>
and cause aquifer pollution if there is water drainage. Health risks exist if this water is
used for human consumption and the nitrate concentration is greater than 10 mg L⁻¹.

<figure><img src="image_16.png" /></figure>

<figure><img src="image_17.png" /><figcaption>**Fig. 5: Vertical distribution of nitrate- nitrogen in the sugarcane growing areas of Samastipur**</figcaption></figure>

Applied nitrogen fertilizer accumulates in the soil after being taken up by the crops. The accumulated nitrogen in the form of nitrate can subsequently be washed away by rain or irrigation. Therefore, Soil profile assessment for the concentration of accumulated nitrate nitrogen is required to forecast nitrate leaching into ground water. In crops like sugarcane, where substantial volumes of N- fertilisation are utilised in vast areas with different aquifer sensitivity, studies of N- fertilizer losses due to leaching are highly relevant. Nitrate content in soil layers below the root zone indicates significant nitrate leaching through soil profile. Similar type of results of vertical distribution, leaching and accumulation of nitrate were obtained by Aparicio *et al.* (2008) and Martino *et al.* (2014).

Composition of Anions in Water

In December, 2021 water samples were collected from sugarcane-based cropping
system of Samastipur district (Table 1 and 2). The values for the anionic compositions of
CO3 2- + HCO3 - and SO4 2- in ground water and surface water presented in table 9 and 10,
respectively. Concentration of SO₄²⁻ was measured in ground water to assess the salinity issue, and CO₃²⁻ + HCO₃⁻ concentration was measured to assess the sodicity issue.

## Composition of Anions in Ground Water

The variation in CO₃²⁻ + HCO₃⁻ of groundwater samples those were collected from the sugarcane growing areas is shown in table 9. CO₃²⁻ + HCO₃⁻ was ranged between 2.81-4.87 meq L⁻¹ with a mean value of 4.02 meq L⁻¹. While the SO₄²⁻ concentration in the collected water samples varied from 0.19 to 0.18 meq L⁻¹ with an average value of 0.29 meq L⁻¹ (Table 9). The CO₃²⁻ + HCO₃⁻ content was highest in Rasulpur Dharha village, while maximum SO₄²⁻ was recorded in Rampur Rajawa village. Minimum CO₃²⁻ + HCO₃⁻ was found in Rohua while minimum SO₄²⁻ was detected in Jahangirpur South. The order of the concentration of anions found in ground water of sugarcane growing areas of Samastipur district was CO₃²⁻ + HCO₃⁻ > SO₄²⁻. The concentration of CO₃²⁻ + HCO₃⁻ in groundwater was may be due to the dissolution of carbonic acid and carbonate weathering in the aquifers (Kumar *et al.* 2009; Ramkumar *et al.* 2013). The change in SO₄²⁻ levels may result from sewage water discharged from various sources of contamination.
<table><caption>Table 9: Descriptive statistical analysis of chemical properties of ground water in sugarcane growing areas of Samastipur</caption><thead><tr><th>DESCRIPTIVE STATS</th><th>pH</th><th>EC (dS/m)</th><th>Ca<sup>2+</sup> + Mg<sup>2+</sup> (meq/L)</th><th>CO<sub>3</sub><sup>2-</sup> + HCO<sub>3</sub><sup>-</sup> (meq/L)</th><th>Na<sup>+</sup> (meq/L)</th><th>SO<sub>4</sub><sup>2-</sup> (meq/L)</th><th>SAR</th><th>RSC (meq/L)</th><th>Nitrate (mg/L)</th></tr></thead><tbody><tr><td>Mean</td><td>8.01</td><td>0.523</td><td>3.2</td><td>4.02</td><td>2.72</td><td>0.29</td><td>2.14</td><td>0.78</td><td>2.68</td></tr><tr><td>Standard Error</td><td>0.04</td><td>0.039</td><td>0.2</td><td>0.21</td><td>0.17</td><td>0.02</td><td>0.08</td><td>0.14</td><td>0.32</td></tr><tr><td>CV</td><td>0.45</td><td>7.551</td><td>6.2</td><td>5.19</td><td>6.32</td><td>8.12</td><td>3.74</td><td>18.14</td><td>12.03</td></tr><tr><td>Median</td><td>8.01</td><td>0.545</td><td>3.2</td><td>4.04</td><td>2.89</td><td>0.28</td><td>2.11</td><td>0.74</td><td>2.88</td></tr><tr><td>Standard Deviation</td><td>0.10</td><td>0.112</td><td>0.6</td><td>0.59</td><td>0.49</td><td>0.07</td><td>0.23</td><td>0.40</td><td>0.91</td></tr><tr><td>Sample Variance</td><td>0.01</td><td>0.012</td><td>0.3</td><td>0.35</td><td>0.24</td><td>0.00</td><td>0.05</td><td>0.16</td><td>0.83</td></tr><tr><td>Kurtosis</td><td>-1.18</td><td>-1.427</td><td>0.7</td><td>2.67</td><td>-0.66</td><td>-0.99</td><td>0.11</td><td>-1.14</td><td>0.36</td></tr><tr><td>Skewness</td><td>0.30</td><td>-0.461</td><td>0.8</td><td>-0.98</td><td>-0.99</td><td>0.14</td><td>0.86</td><td>0.32</td><td>0.43</td></tr><tr><td>Range</td><td>0.28</td><td>0.292</td><td>1.8</td><td>2.06</td><td>1.23</td><td>0.19</td><td>0.69</td><td>1.15</td><td>2.91</td></tr><tr><td>Minimum</td><td>7.89</td><td>0.347</td><td>2.5</td><td>2.81</td><td>1.95</td><td>0.19</td><td>1.85</td><td>0.27</td><td>1.42</td></tr><tr><td>Maximum</td><td>8.17</td><td>0.639</td><td>4.3</td><td>4.87</td><td>3.18</td><td>0.38</td><td>2.54</td><td>1.42</td><td>4.33</td></tr><tr><td>Sum</td><td>64.05</td><td>4.181</td><td>25.9</td><td>32.12</td><td>21.76</td><td>2.28</td><td>17.13</td><td>6.24</td><td>21.45</td></tr><tr><td>Count</td><td>8.00</td><td>8.000</td><td>8.0</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td></tr></tbody></table>
<table><caption>Table 10: Descriptive statistical analysis of chemical properties of surface water in sugarcane growing areas of Samastipur</caption><thead><tr><th>DESCRIPTIVE<br>STATS</th><th>pH</th><th>EC<br>(dS/m)</th><th>TDS<br>(mg/L)</th><th>Ca<sup>2+</sup> + Mg<sup>2+</sup><br>(meq/L)</th><th>CO<sub>3</sub><sup>2-</sup> + HCO<sub>3</sub><sup>-</sup><br>(meq/L)</th><th>Na<sup>+</sup><br>(meq/L)</th><th>SO<sub>4</sub><sup>2-</sup><br>(meq/L)</th><th>SAR</th><th>RSC<br>(meq/L)</th><th>Nitrate<br>(mg/L)</th></tr></thead><tbody><tr><td>Mean</td><td>7.00</td><td>0.750</td><td>766</td><td>3.2</td><td>3.77</td><td>3.59</td><td>0.53</td><td>2.01</td><td>0.54</td><td>7.92</td></tr><tr><td>Standard Error</td><td>0.03</td><td>0.035</td><td>31</td><td>0.2</td><td>0.12</td><td>0.13</td><td>0.03</td><td>0.06</td><td>0.05</td><td>0.68</td></tr><tr><td>CV</td><td>0.47</td><td>4.67</td><td>4.10</td><td>4.72</td><td>3.17</td><td>3.70</td><td>4.97</td><td>3.14</td><td>9.77</td><td>8.52</td></tr><tr><td>Median</td><td>7.01</td><td>0.779</td><td>769</td><td>3.2</td><td>3.84</td><td>3.49</td><td>0.54</td><td>1.95</td><td>0.62</td><td>7.59</td></tr><tr><td>Standard Deviation</td><td>0.09</td><td>0.099</td><td>89</td><td>0.4</td><td>0.34</td><td>0.38</td><td>0.07</td><td>0.18</td><td>0.15</td><td>1.91</td></tr><tr><td>Sample Variance</td><td>0.01</td><td>0.010</td><td>7904</td><td>0.2</td><td>0.11</td><td>0.14</td><td>0.01</td><td>0.03</td><td>0.02</td><td>3.65</td></tr><tr><td>Kurtosis</td><td>-1.82</td><td>-1.825</td><td>0</td><td>-1.1</td><td>-1.91</td><td>-1.64</td><td>-1.65</td><td>-0.09</td><td>0.16</td><td>-0.61</td></tr><tr><td>Skewness</td><td>-0.02</td><td>-0.244</td><td>0</td><td>0.4</td><td>-0.25</td><td>0.36</td><td>-0.06</td><td>0.66</td><td>-1.09</td><td>0.39</td></tr><tr><td>Range</td><td>0.24</td><td>0.256</td><td>277</td><td>1.2</td><td>0.82</td><td>0.99</td><td>0.20</td><td>0.54</td><td>0.43</td><td>5.61</td></tr><tr><td>Minimum</td><td>6.88</td><td>0.622</td><td>635</td><td>2.7</td><td>3.34</td><td>3.12</td><td>0.43</td><td>1.76</td><td>0.26</td><td>5.28</td></tr><tr><td>Maximum</td><td>7.12</td><td>0.878</td><td>912</td><td>3.9</td><td>4.16</td><td>4.11</td><td>0.63</td><td>2.30</td><td>0.69</td><td>10.89</td></tr><tr><td>Sum</td><td>56.02</td><td>6.000</td><td>6129</td><td>25.8</td><td>30.15</td><td>28.74</td><td>4.25</td><td>16.04</td><td>4.35</td><td>63.39</td></tr><tr><td>Count</td><td>8.00</td><td>8.000</td><td>8</td><td>8.0</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td><td>8.00</td></tr></tbody></table>
$SO_4^{2-}$ concentrations in groundwater could be caused by home sewage, landfill leachate, and agricultural runoff (Jalali 2005). Concentrations of $SO_4^{2-}$ ions are likely the result of weathering of sedimentary rocks containing sulphate and gypsum (Jeevanandam et al. 2006). The stomach may get irritated by greater $SO_4^{2-}$ concentrations when $Mg^{2+}$ and $Na^+$ are also present in drinking water supplies (Suthar et al. 2009). The amount of $SO_4^{2-}$ in groundwater samples collected from various locations in the Samastipur district were found to be within acceptable limits. The ground water of sugarcane-based cropping systems in Samastipur district was within the safe range for irrigation purposes when taking into account the tolerance or permissible limit of various anionic concentrations in ground water, FAO (1983). The outcome of these analyses for cations in groundwater is in line with the findings of Shulka, 2013.

## Composition of Anions in Surface Water

The variation in $CO_3^{2-}$ + $HCO_3^-$ of water samples those were collected from the sugarcane growing areas is shown in table 9. $CO_3^{2-}$ + $HCO_3^-$ ranged between 3.34- 4.16 meq L$^{-1}$ with a mean value of 3.77 meq L$^{-1}$ (Table 10). While the $SO_4^{2-}$ concentration in the collected water samples varied from 0.43 to 0.63 meq L$^{-1}$ with an average value of 0.53 meq L$^{-1}$ (Table 10). The $CO_3^{2-}$ + $HCO_3^-$ content was highest in the Rasulpur Dharha village, while maximum $SO_4^{2-}$ was recorded in the Chakthat West village. Minimum $CO_3^{2-}$ + $HCO_3^-$ was found in the village Rohua while minimum $SO_4^{2-}$ was detected in Jahangirpur South. The order of the concentration of anions found in surface water of sugarcane growing areas of Samastipur district was $CO_3^{2-}$ + $HCO_3^-$ > $SO_4^{2-}$.

## Composition of Cations in Water

One of the main alkali metal, $Na^+$ and the alkaline earth metals, $Ca^{2+}$ and $Mg^{2+}$, were investigated in water samples taken from the Samastipur district's sugarcane growing region. Table 9 & 10, contains information on the concentration of $Na^+$ and $Ca^{2+}$ + $Mg^{2+}$.

## Composition of Cations in Ground Water

The range of basic cations in ground water of different villages from sugarcane growing areas of Samastipur district were as follows: 3.12- 4.11 me L$^{-1}$ of $Na^+$, 2.7- 3.9 me L$^{-1}$ of $Ca^{2+}$ + $Mg^{2+}$ (Table 9). It was revealed from the data that basic cations were present in 100% ground water samples of Sugarcane cropping systems areas in Samastipur district. In all the water samples $Ca^{2+}$ + $Mg^{2+}$ concentration in ground water was comparatively higher than $Na^+$. The $Ca^{2+}$ + $Mg^{2+}$ content was highest in Rasulpur Dharha village, while maximum $Na^+$ was recorded in Jahangirpur South. The order of the
concentration of cations found in ground water of different villages from sugarcane growing areas of Samastipur district was (Ca²⁺ + Mg²⁺) > Na⁺. Clay minerals are the possible reasons for the presence of sodium, calcium, and magnesium. The basic cation concentrations in the groundwater (Ca²⁺ + Mg²⁺, and Na⁺) are below WHO standards. In particular, the calcium and magnesium ions found in groundwater come from the leaching of anhydrites, dolomites, gypsum, and limestone, while the calcium ions also come from the cation exchange process (Garrels, 1976). The weathering of sodium-bearing minerals and the dissolving of rock salts are two potential sources of sodium concentration in groundwater (Kumar et al., 2009).

## Composition of Cations in Surface Water

The range of basic cations in surface water of different villages from sugarcane growing areas of Samastipur district were as follows: 3.12- 4.11 me L⁻¹ of Na⁺, 2.7- 3.9 me L⁻¹ of Ca²⁺ + Mg²⁺ (Table 10). It was revealed from the data that basic cations were present in 100 % surface water samples of sugarcane cropping systems areas in Samastipur district. In all the surface water samples Na⁺ concentration in surface water was comparatively higher than Ca²⁺ + Mg²⁺. The Ca²⁺ + Mg²⁺ content (3.9 me L⁻¹) was highest in the village Rasulpur Dharha village, while maximum Na⁺ (4.11 me L⁻¹) was recorded in the village Jahangirpur South. The concentration of cations found in surface water from sugarcane growing areas of Samastipur district was Na⁺ > (Ca²⁺ + Mg²⁺).

## Nitrate in Water of Samastipur District

One of the most crucial elements for ecosystem function is nitrogen (N), which also limits the productivity of many ecosystems worldwide. Approximately 99% of the world's nitrogen is present as stable atmospheric N₂, which cannot be used by ecosystems until it is changed into reactive nitrogen species like NH₃, NH₄⁺, NO₂⁻, and organic nitrogen. Reactive nitrogen fixation has been considerably increased by human activities due to the manufacturing of nitrogenous fertiliser, the growing of leguminous plants, and the burning of fossil fuels. Since there aren't many nitrogenous substances in the geological record, nitrogenous fertilisers, industrial effluents, and animal and human waste all contribute to the metabolic activity of nitrifying bacteria like Nitrosomonas and Nitrobacter, which causes nitrate to appear in ground water as well as surface water.
Nitrate in Ground Water of Samastipur District

Village- wise average nitrate- nitrogen concentration in ground water is annalysed.
The average nitrate concentration was 2.68 mg L⁻¹, with a range of 1.42 to 4.33 mg L⁻¹.
Chemical testing showed that none of the samples was found to have nitrate contents that
were higher than the permissible limit by World Health Organization drinking water
standards (WHO, 1984). Highest average nitrate level (4.33 mg L⁻¹) was found in
Rasulpur Dharha village while lowest average nitrate concentration in groundwater was
recorded in the Mahuli village. No ground water samples were detected for a nitrate value
less than 1 mg/L. 29.2% of the collected groundwater samples showed the nitrate
concentration between 1.0-2.0 mg L⁻¹ while maximum number of samples (37.5%) were in
the range between 2.0-3.0 mg L⁻¹. 16.7 % samples were recorded to be in the range of 3.0-
4.0 and 4.0- 5.0 mg L⁻¹ both.

The ground water resources contaminated with high levels of nitrate (>10 mg/l) are
an environmental hazard. Nitrate has been associated with agricultural operations due to
the overuse of nitrate fertilisers. However, there are additional nitrate sources connected to
urban growth that might raise groundwater nitrate levels. Recent studies have found that
some urban aquifers have nitrate concentrations that are comparable to or even greater
than the surrounding areas (Wakida and Lerner, 2005). The declining water quality due to
increasing N input are coastal eutrophication, acidification of freshwater lakes and
streams, and nitrate contamination in groundwater, all of which pose a threat to people and
other creatures. Human health is endangered by the nitrate contamination of groundwater.

According to epidemiological studies, drinking water with a high nitrate
concentration is typically associated with cancer and birth abnormalities, especially in
rural agricultural areas where shallow groundwater is frequently used for home water
supplies. Nitrate concentrations are frequently higher than the World Health
Organization's (WHO) limit contamination level (10 mg NO3⁻-N L⁻¹), particularly in
emerging developing nations. One of the most water-soluble anions is nitrate, which can
readily enter the groundwater system. It poses a significant risk to human health,
particularly for infants, as it can result in methemoglobinemia, popularly known as "blue
baby syndrome" a disorder. The environmental importance of nitrate leaching has
garnered a lot of attention (Gheysari et al., 2009), and it has been determined that high
amounts of N compounds applied to soils are the main causes of groundwater nitrate
contamination. In regions like the current study area under sugarcane growing area where
intense cropping has been conducted for a long period with extensive use of nitrogenous fertilisers, this issue is likely to be more severe (Burkart and Stoner, 2007). In the present study area, the most often used fertilisers are urea, ammonium nitrate and DAP. Raju *et al.* (2009) reported urea and ammonium nitrate as most nitrate contributing fertilizers to groundwater. The nitrogenous fertilisers are quickly transformed into a highly soluble nitrate form upon application to arable soils. When the amount of nitrate exceeds the immediate needs of the plants and the soil's ability to denitrify it, the excess nitrate drains out of the root zone of sugarcane by water percolating through the soil profile and eventually accumulates in groundwater making it potentially dangerous for drinking. My findings related to nitrate concentration in ground water is supported by the findings of Kundu and Mandal (2009) who studied nitrate contamination in West Bengal.

## Nitrate in Surface Water of Samastipur District

Village- wise average nitrate- nitrogen concentration in surface water of the sugarcane growing areas of Samastipur is shown in table 10. The average nitrate concentration was 7.48 mg L⁻¹, with a range of 5.28 to 10.89 mg L⁻¹. Highest nitrate level (10.89 mg L⁻¹) in surface water was found in the village Rampur Rajawa while lowest nitrate concentration in surface water was recorded in the Jahangirpur South village. No ground water samples were detected for a nitrate value less than 5 mg/L. 25 % of the collected surface water samples showed the nitrate concentration > 10.0 mg L⁻¹ while maximum number of samples (75%) were in the range between 5.0-10.0 mg L⁻¹. From the results it is clear that the average nitrate content in surface water is higher than ground water. The reason behind this maybe the direct washing out of nitrate from field to water body by irrigation water of rain water. The home sewage and landfill leachate also contribute to nitrate in surface water. High nitrate concentration in surface water causes eutrophications which reduce the O₂ level significantly and makes the water body unsuitable for aquatic animals such as fishes.

## Correlation of the soil properties with nitrate content in soils

The nitrate nitrogen in the soil, whether it is developed naturally as a result of nitrification or added through synthetic fertilizers, can either be digested and incorporated into higher plants, be lost through drainage, or escape in a gaseous state. Although some of the nitrate ions may be linked to the positive sites of the soil colloids (Hingston *et al.*, 1972), the majority are in the soil solution. Nitrate ions are negatively charged; therefore the negatively charged colloids that predominate in soils cannot adsorb them. As a result,
<figure><img src="image_18.png" /><figcaption>Fig. 6a: Frequency distribution of NO₃⁻-N content in groundwater</figcaption></figure>

<figure><img src="image_19.png" /><figcaption>Fig. 6b: Frequency distribution of NO₃⁻-N content in Surface Water</figcaption></figure>

<caption>Fig. 6: Frequency distribution of NO₃⁻-N content in water samples from sugarcane growing areas of Samastipur</caption>
they are liable to leaching readily and sink with the water. Soil bulk density, texture, EC, pH, availability of macronutrients like N, P₂O₅ and K₂O, as well as adsorbing components like organic matter etc., all affect the nitrate content in soil solution. Therefore, it is important to find out the correlation of nitrate with other soil physico-chemical properties.

The data on correlation of nitrate content in soils at different depths (0-30, 30-60, 60-90 & 90-120 cm) from the sugarcane growing areas with the physical and chemical properties of the soils of Samastipur district have been presented in Table 11. It was revealed from the data that the NO₃⁻-N content had significant positive correlation with silt content at all the four depths. Nitrate is also positively correlated with EC at 30 cm depths. It had also positive correlation with organic carbon and available nitrogen at 30 cm depth of the soils. Mineralization and decomposition of organic matter release nitrate in soil through the process of nitrification. As organic carbon functions as a source of nitrate in soil, the increment in organic carbon increases the nitrate- nitrogen content in soil and thus they are positively correlated (r=0.505*). The NO₃⁻ content of the soil showed also positive correlation with electrical conductivity (r= 0.519* at 30 cm & 0.520* at 120 cm); the total ions released are related with the electrical conductivity values. With increasing nitrate content, electrical conductivity of soil also increases thus; they are significantly as well as positively correlated. A major part of plant available nitrogen is nitrate. Thus, with increasing available nitrogen content nitrate also increases in with and that's why they are significantly positively correlated at 30 cm depth (r= 0.701**) (Table 11).

## Correlation of the soil properties with nitrate content in groundwater

The correlation between average nitrate content in ground water of each village with different physicochemical properties of soil of that village were analysed. In fig 7 the correlation of clay (%) and silt (%) with nitrate content in groundwater is shown. From the figure we can easily conclude that nitrate in groundwater is inversely correlated (r= -0.754*) with the clay content in soil while it is positively correlated with silt (r= 0.755*) content in soil. The reason behind inverse relationship of nitrate with clay content may be high clay levels creating impedance that prevented NO₃⁻ laden water from moving downward through soil profiles to the aquifers below. Nitrate may be adsorbed on the silt fractions of soil and thus silt prevents nitrate leaching into aquifers. Similar type of correlation was reported by Kundu and Mandal (2009). Nitrate in ground water in significantly positively correlated with nitrate nitrogen (kg ha⁻¹) content in soil (r=0.909*).
<table><caption>Table 11: Correlation-coefficient among soil properties and nitrate content (kg ha⁻¹) in soils (0-30 cm) of sugarcane growing area of Samastipur</caption><thead><tr><th></th><th>Sand (%)</th><th>Silt (%)</th><th>Clay (%)</th><th>B.D. (Mg m<sup>-3</sup>)</th><th>pH</th><th>EC (dS m<sup>-1</sup>)</th><th>Organic Carbon (%)</th><th>Available N (kg ha<sup>-1</sup>)</th><th>Available P<sub>2</sub>O<sub>5</sub> (kg ha<sup>-1</sup>)</th><th>Available K<sub>2</sub>O (kg ha<sup>-1</sup>)</th><th>Nitrate- nitrogen (kg ha<sup>-1</sup>)</th></tr></thead><tbody><tr><td>Sand (%)</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Silt (%)</td><td>-0.368<sup>NS</sup></td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Clay (%)</td><td>-0.556*</td><td>-0.568*</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>B.D. (Mg m<sup>-3</sup>)</td><td>0.564*</td><td>-0.450<sup>NS</sup></td><td>-0.097<sup>NS</sup></td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>pH</td><td>-0.072<sup>NS</sup></td><td>0.089<sup>NS</sup></td><td>-0.016<sup>NS</sup></td><td>0.128<sup>NS</sup></td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>EC (dS m<sup>-1</sup>)</td><td>-0.270<sup>NS</sup></td><td>0.512*</td><td>-0.219<sup>NS</sup></td><td>-0.495<sup>NS</sup></td><td>0.094<sup>NS</sup></td><td>1</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Organic carbon (%)</td><td>-0.056<sup>NS</sup></td><td>0.443<sup>NS</sup></td><td>-0.347<sup>NS</sup></td><td>-0.610*</td><td>-0.322<sup>NS</sup></td><td>0.450<sup>NS</sup></td><td>1</td><td></td><td></td><td></td><td></td></tr><tr><td>Available N (kg ha<sup>-1</sup>)</td><td>-0.075<sup>NS</sup></td><td>0.617*</td><td>-0.484<sup>NS</sup></td><td>-0.096<sup>NS</sup></td><td>-0.193<sup>NS</sup></td><td>0.245<sup>NS</sup></td><td>0.523*</td><td>1</td><td></td><td></td><td></td></tr><tr><td>Available P<sub>2</sub>O<sub>5</sub> (kg ha<sup>-1</sup>)</td><td>0.114<sup>NS</sup></td><td>0.427<sup>NS</sup></td><td>-0.483<sup>NS</sup></td><td>0.133<sup>NS</sup></td><td>0.689**</td><td>0.141<sup>NS</sup></td><td>-0.106<sup>NS</sup></td><td>0.236<sup>NS</sup></td><td>1</td><td></td><td></td></tr><tr><td>Available K<sub>2</sub>O (kg ha<sup>-1</sup>)</td><td>0.085<sup>NS</sup></td><td>0.020<sup>NS</sup></td><td>-0.092<sup>NS</sup></td><td>0.045<sup>NS</sup></td><td>-0.355<sup>NS</sup></td><td>0.043<sup>NS</sup></td><td>0.196<sup>NS</sup></td><td>0.371<sup>NS</sup></td><td>-0.102<sup>NS</sup></td><td>1</td><td></td></tr><tr><td>Nitrate-nitrogen (kg ha<sup>-1</sup>)</td><td>-0.448<sup>NS</sup></td><td>0.726**</td><td>-0.253<sup>NS</sup></td><td>-0.273<sup>NS</sup></td><td>-0.202<sup>NS</sup></td><td>0.519*</td><td>0.505*</td><td>0.701**</td><td>0.010<sup>NS</sup></td><td>0.207<sup>NS</sup></td><td>1</td></tr></tbody></table>
<figure><img src="image_20.png" /><figcaption>Fig.7a: Correlation of nitrate (ppm) in water with clay (%) in soil</figcaption></figure>

<figure><img src="image_21.png" /><figcaption>Fig. 7b: Correlation of nitrate (ppm) in water with sand (%) in soil</figcaption></figure>

<caption>Fig. 7: Correlation of Clay and Sand percent in soil with nitrate concentration (ppm) in ground water</caption>
<figure><img src="image_22.png" /><figcaption>Fig.8a: Correlation between Nitrate in ground water and nitrate in soil (0-30cm)</figcaption></figure>

<figure><img src="image_23.png" /><figcaption>Fig.8b: Correlation between Nitrate in ground water and available N in soil (0-30cm)</figcaption></figure>

<caption>Fig. 8: Correlation between Nitrate (ppm) in ground water and chemical properties of soil</caption>
Correlation between nitrate content in ground water and nitrogen application in soil

Table 12 shows the average N- application rate in soil of sugarcane growing areas of Samastipur district. Villages with N- application rate more than 200 kg ha⁻¹ was recorded to have relatively more nitrate content in groundwater.

<table><caption>Table 12: Average N- fertilization rate (kg ha⁻¹) in the sugarcane growing areas of Samastipur district</caption><thead><tr><td>SL. No</td><td>Name of the village</td><td>Average N- application rate (kg ha⁻¹)</td></tr></thead><tbody><tr><td>1</td><td>Rasulpur Dharha</td><td>246.68</td></tr><tr><td>2</td><td>Shasan</td><td>208.45</td></tr><tr><td>3</td><td>Mahuli</td><td>188.93</td></tr><tr><td>4</td><td>Chakthat West</td><td>195.53</td></tr><tr><td>5</td><td>Jahangirpur South</td><td>184.25</td></tr><tr><td>6</td><td>Rampur Rajawa</td><td>214.23</td></tr><tr><td>7</td><td>Jagarnathpur</td><td>206.80</td></tr><tr><td>8</td><td>Rohua</td><td>176.83</td></tr></tbody></table>

Fig 9 shows the relationship of nitrate content in ground water with the N- fertilization rate in soil. The nitrate content in ground water was positively correlated (R²=0.811) with the N- application rate in soil. With increasing rate of N fertilization nitrate content in GW increases. Similar result was reported by Kundu and Mandal (2009).

<figure><img src="image_24.png" /><figcaption>Fig. 9: Correlation between nitrate content in ground water and nitrogen application rate</figcaption></figure>
## Summary

The present technical bulletin was aimed to estimate the effects of intensive N-fertilization on nitrate leaching in soil, nitrate contamination in ground water and quality of sugarcane. Different physic-chemical properties of soil, chemical properties of water and quality parameters of sugarcane juice were analysed. Total 16 sites were selected from 8 villages in the study area. 64 soil samples were collected from 4 different depths (0-30, 30-60, 60-90 and 90-120 cm) and 16 sugarcane samples were collected from each sampling site. From each village 3 ground water samples and 1 surface water samples were collected. All the samples were analysed for different properties by following standard protocols. The main findings about soil, water and sugarcane quality are summarised below:

1. Soils from all the 8 selected villages in sugarcane growing area of Samastipur were varied widely in their physic-chemical properties.

2. Soil health and soil quality greatly depend on the organic carbon content in soil. The average organic carbon content in most of the villages were in low range except two villages, Rasulpur Dharha and Jagarnathpur. Although, highest organic carbon (0.59 %) was recorded at 30 cm depth in the village Rasulpur Dharha while, lowest organic carbon (0.04 %) was reported at 120 cm depth in Shasan.

3. The outcome revealed that with increment of soil depth, the available nitrogen decreased. Although all the villages were reported to have low N content at all the 4 depths at 90 & 120 cm depths the available N content was very low. In the village Rasulpur Dharha maximum available nitrogen (244.61 kg ha⁻¹) was found at 30 cm depth. At 120 cm depth of Rampur Rajawa village minimum amount of available nitrogen (31.36 kg ha⁻¹) was recorded.

4. Nitrate- nitrogen content at 30 cm depth was found to be highest among all the four depths. It was decreasing with increasing depths. Nitrate content in soil layers below the soil solum indicates significant nitrate leaching through soil profile. In the village Rasulpur Dharha maximum nitrate- nitrogen (42.27 kg ha⁻¹) was found at 30 cm depth. At 120 cm depth of Jahangirpur South village minimum amount of nitrate- nitrogen (10.16 kg ha⁻¹) was recorded.

5. The groundwater samples have shown pH values ranging from 7.89 to 8.17 with a mean value of 8.01. The highest pH (8.17) was recorded in the village Rohua while
the lowest pH was reported to be 7.89 in the ground water of Rampur Rajawa village. The pH of Samastipur districts mostly varied around 8 i.e., the water samples were slightly alkaline in nature.

6. The Surface water samples have shown pH values ranging from 6.88 to 7.12 with a mean value of 7.00. The highest pH (7.12) was recorded in the village Rasulpur Dharha while the lowest pH was reported to be 6.88 in the surface water of Shasan village. The pH of surface water in Samastipur districts mostly varied around 7 i.e, the water samples were slightly acidic to neutral in nature.

7. The average value of EC of collected water samples was 0.523 while they showed a range of 0.347 to 0.639 dS m⁻¹. The highest EC (0.639 dS m⁻¹) was recorded in the village Rampur Rajawa while the lowest EC was reported to be 0.347 dS m⁻¹ in the ground water of Shasan village. As any of the collected samples did not exceed the safe limit of 1 dSm⁻¹, there is no severity of sodicity or salinity problems for drinking purpose.

8. The average value of EC of collected surface water samples was 0.750 while they showed a range of 0.622 to 0.878 dS m⁻¹. The highest EC (0.878 dS m⁻¹) was recorded in the village Rohua while the lowest EC was reported to be 0.622 dS m⁻¹ in the surface water of Jagarnathpur village.

9. The CO₃²⁻ + HCO₃⁻ and SO₄²⁻ concentration in the collected ground water samples were within safe limit. The CO₃²⁻ + HCO₃⁻ content was highest in Rasulpur Dharha village, while maximum SO₄²⁻ was recorded in Rampur Rajawa village. Minimum CO₃²⁻ + HCO₃⁻ was found in Rohua while minimum SO₄²⁻ was detected in Jahangirpur South. The order of the concentration of anions found in ground water of sugarcane growing areas of Samastipur district was CO₃²⁻ + HCO₃⁻ > SO₄²⁻.

10. In surface water the CO₃²⁻ + HCO₃⁻ content was highest in the Rasulpur Dharha village, while maximum SO₄²⁻ was recorded in the Chakthat West village. Minimum CO₃²⁻ + HCO₃⁻ was found in the village Rohua while minimum SO₄²⁻ was detected in Jahangirpur South. The order of the concentration of anions found in surface water of sugarcane growing areas of Samastipur district was CO₃²⁻ + HCO₃⁻ > SO₄²⁻.
11. It was revealed from the data that basic cations were present in 100% ground water samples of Sugarcane cropping systems areas in Samastipur district. In all the water samples Ca²⁺ + Mg²⁺ concentration in ground water was comparatively higher than Na⁺. The Ca²⁺ + Mg²⁺ content was highest in Rasulpur Dharha village, while maximum Na⁺ was recorded in Jahangirpur South (fig 4.3). The order of the concentration of cations found in ground water of different villages from sugarcane growing areas of Samastipur district was (Ca²⁺ + Mg²⁺) > Na⁺.

12. In surface water of the study area the Ca²⁺ + Mg²⁺ content (3.9 me L⁻¹) was highest in the village Rasulpur Dharha village, while maximum Na⁺ (4.11 me L⁻¹) was recorded in the village Jahangirpur South. The order of the concentration of cations found in surface water of different villages from sugarcane growing areas of Samastipur district was Na⁺ > (Ca²⁺ + Mg²⁺).

13. The average nitrate concentration was 2.68 mg L⁻¹. Chemical testing showed that none of the samples was found to have nitrate contents that were higher than the permissible limit by World Health Organization drinking water standards. Highest average nitrate level (4.33 mg L⁻¹) was found in Rasulpur Dharha village while lowest average nitrate concentration in groundwater was recorded in the Mahuli village. 29.2% of the collected groundwater samples showed the nitrate concentration between 1.0-2.0 mg L⁻¹ while maximum number of samples (37.5%) were in the range between 2.0-3.0 mg L⁻¹. 16.7% samples were recorded to be in the range of 3.0-4.0 and 4.0- 5.0 mg L⁻¹ both.

14. Highest nitrate level (10.89 mg L⁻¹) in surface water was found in the village Rampur Rajawa while lowest nitrate concentration in surface water was recorded in the Jahangirpur South village. No ground water samples were detected for a nitrate value less than 5 mg/L. 25% of the collected surface water samples showed the nitrate concentration > 10.0 mg L⁻¹ while maximum number of samples (75%) were in the range between 5.0-10.0 mg L⁻¹.

15. It was revealed from the data that the NO₃⁻-N content had significant positive correlation with silt content at all the four depths. Nitrate is also positively correlated with EC (r= 0.519* at 30 cm & 0.520* at 120 cm) at 30 cm and 120 cm depths. It had also positive correlation with OC (r=0.505*) and available nitrogen (r= 0.701**) at 30 cm depth of the soils.
16. From the observations we can easily conclude that nitrate in groundwater is inversely correlated ($R^2$= 0.569) with the clay content in soil while it is positively correlated with silt ($R^2$= 0.571) content in soil.

17. Data revealed the nitrate content in groundwater was positively correlated ($R^2$=0.811) with the N - application rate in soil. With increasing rate of N fertilization nitrate content in groundwater increases.

**Conclusions:**

From the outcome of the current research work, following conclusions drawn:

1. The mean nitrate (kg ha⁻¹) content in different depths were varied significantly and it decreases with increasing depth. Nitrate (kg ha⁻¹) content in soil layers below the root zone indicates significant nitrate leaching through soil profile.

2. In spite of intensive cultivation of sugarcane with excess fertilization, the nitrate (ppm) content in groundwater of the Samastipur district is under the permissible limits as per WHO standards.

3. The nitrate content in soil was significantly and positively correlated with EC, OC and available-N content.

4. The nitrate (ppm) concentration in groundwater of different villages were significantly and positively correlated with silt (%), nitrate (kg ha⁻¹) and available-N (kg ha⁻¹) content in soil while significant negative correlation existed between nitrate (ppm) in water and clay (%) in soil.

5. Higher nitrate concentration in ground water was recorded from the villages with higher N - fertilization in sugarcane cultivation.

6. The nitrate in the surface water may be used as substitute for nitrogen fertilizer if irrigation is applied during a period that the crop needs nitrogen.
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Hingston, F.J., Posner, A.M. and Qrick, J.P. (1972). Anion adsorption by goethite and gibbsite.I. The role of the proton in determining adsorption envelopes. *J. Soil Sci.*, **23**:177-92.

Jalali, M. (2005). Nitrates leaching from agricultural land in Hamadan, western Iran. *Journal of Agriculture, Ecosystems and environment*, **110**:210-218.

Jeevanandam, M., Kannan, R., Srinivasalu, S., and Rammohan, V. (2006). Hydrogeochemistry and groundwater quality assessment of lower part of the Ponnaiyar River Basin, Cuddalore district, South India. *Environmental Monitoring and Assessment*, **132**(1), 263-274

Kumar A., C.K. Jha and Kumari Sunita (2022) Study on feasibility of growing oil palm (*Elaeis guineensis*) under alluvial plain of Bihar. *Environment and ecology*. 40 (2): 238–245, April–June 2022. https://hal.science/hal-04676953.

Kumar Ajeet and Jha C. K. (2021) Sugarcane: Crop of the Future. *Agriculture & Food: E-Newsletter*. Volume: 3 Issue: 6 June 2021, Page: 61-63, Article ID: 11020,. E-ISSN: 2581-8317. [hal-04934993](https://hal-04934993).

Kumar Ajeet, A.K. Singh, C.K. Jha, S.K. Sinha, S.K. Thakur, S.K. Meena, S.P. Singh, Minnatullah and K. Sunita (2021) Use of pressmud for sugarcane farming and sustaining soil health. *Agriblossom*. 1 (12): 34-39, July 2021, [hal-04935095](https://hal-04935095).
Kumar Ajeet, Anil Kumar Singh, S. K. Thakur, Sunita Kumari Meena and Ashish Rai (2022) Sugarcane is champion crop for carbon sequestration, 2 (10): 17-21. AGRIBLOSSOM, [hal-04935282].

Kumar Ajeet, C.K. Jha, S.P. Singh and Kumari Sunita (2021) Diagnosing nutrient deficiency symptoms in Maize. Agriculture & Food: E-Newsletter; Volume: 3, Issue: 6, June 2021, Page: 466-468, Article ID: 11161,. E-ISSN: 2581-8317, [hal-04935029].

Kumar, A. ., Singh, S. K. ., Meena, S. K. ., Sinha, S. ., Rana, L. ., Kumari, A. ., Singh, A.K ., & Kumar, A. . (2024). Human Health Risk Assessment of Nitrate-Contaminated Groundwater in North East Alluvial Plains of India. **In Book**: Geography, Earth Science and Environment: Vol. 2, Page No.: 1-26. Geography, Earth Science and Environment: Research Highlights Vol. 2, 1-26. https://doi.org/10.9734/bpi/geserh/v2/1424

Kumar, A. Nath, T. and Raha, P. (2010a). Nitrate levels in groundwater of Varanasi district of Uttar Pradesh, India, *Journal of Eco-friendly Agriculture*, **5**(2):120-123.

Kumar, A., Singh, S. K., Meena, S. K., Sinha, S. K., Rana, L., Singh, A. K., Kumar, A., Singh, H., & Paswan, S. (2025). A Comprehensive Review on Impact of Intensive Use of Nitrogenous Fertilizer on Nitrate Contamination in Groundwater under Sugarcane Based Cropping System in Indo-Gangetic Plains of India. International Journal of Environment and Climate Change, 15(2), 286-300. https://doi.org/10.9734/ijecc/2025/v15i24727.

Kumar, Ajeet (2015) Spatial Distribution of Macro and Micro Nutrients in soils of Saharsa district of Bihar. *An Asian Journal of Soil Science* (An International Refereed Research Journal). 10 (2): 276-282, (December, 2015). https://hal.science/hal-04676717.

Kumar, Ajeet and Choudhary, A. (2016) Constraints to cabbage (*Brassica oleracea* var. *capitata* L.) production in peri-urban area of Saharsa district in Bihar. *An Asian Journal of Soil Science* (An International Refereed Research Journal). **11 (2): 297-306**. https://hal.science/hal-04676725.

Kumar, Ajeet and Maurya, B.R. (2006). Efficacy of phosphate solubilising fungi on acidity and solubilisation of tricalcium phosphate in broth. *Plant archive*, **6 (1):** 309-311. https://www.cabidigitallibrary.org/doi/full/10.5555/20063144666
Kumar, Ajeet and Mukul Kumar (2017) Effect of different levels of phosphorus on the yield and yield components of maize under agro-climatic zone- II of Bihar. *International Journal of Agricultural Sciences*. 13 (2): 266-270. https://hal.science/hal-04676729

Kumar, Ajeet and Paswan, D. (2014) Response of biofertilizers on biomass partitioning pattern and yield of pea (Pisum sativum L.). *An Asian Journal of Soil Science* (An International Refereed Research Journal). 9 (2): 221-225 https://hal.science/hal-04676705.

Kumar, Ajeet and Paswan, D. (2015) Response of pea (Pisum sativum L.) to Rhizobium inoculation and nitrogen application in soils of North East Alluvial plains of Bihar. *An Asian Journal of Soil Science* (An International Refereed Research Journal). 10 (2): 252-258. https://hal.science/hal-04676715.

Kumar, Ajeet., Chattopadhyay, S. and Meena, S.K. (2023) Soil Fertility Assessment of Sugarcane Growing Villages in Samastipur District of Bihar. *Environment and Ecology*. 41 (2): 759-764, April-June 2023. ISSN 0970-0420. https://hal.science/hal-04676939.

Kumar, Ajeet., Choudhary A., and Kumar Mukul (2018) Impact of climate change and their mitigation for better sugarcane production-A Review; *International Journal of Agricultural Sciences*. 14 (2): 431-441. ISSN: 0973-130X; e ISSN: 0976-5670; Sl. No.:1187; NAAS Journal ID: I 146; https://hal.science/hal-04676732;

Kumar, Ajeet., Choudhary, C.S., Paswan, D., Kumar, B. and Arun, A. (2014) Sustainable Way for Enhancing Phosphorus Efficiency in Agricultural Soils through Phosphate Solubilizing Microbes – A Review. *An Asian Journal of Soil Science* (An International Refereed Research Journal). 9 (2): 300-310 https://hal.science/hal-04676707.

Kumar, Ajeet., Paswan, D., Choudhary, C.S., Kumar, B. and Arun, A. (2014) Ameliorating the effects of climate change through organic agriculture system -A Review. *An Asian Journal of Soil Science*. 9 (2): 318-324 (2014). http://researchjournal.co.in/online/AJSS/AJSS%209(2)/9_318-324_A.pdf
Kumar, Ajeet., Paswan, D., Choudhary, C.S., Kumar, B. and Arun, A. (2014) Ameliorating the effects of climate change through organic agriculture system -A Review. *An Asian Journal of Soil Science* (An International Refereed Research Journal). 9 (2): 318-324 (2014).
[http://researchjournal.co.in/online/AJSS/AJSS%209(2)/9_318-324_A.pdf](http://researchjournal.co.in/online/AJSS/AJSS%209(2)/9_318-324_A.pdf)

Kumar, Ajeet., Rai, A.K. and De, N. (2015) Influence of FYM and irrigation frequency on yield, vitamin and mineral contents of organic Cabbage (*Bracica oleracea*.var capitata). *An Asian Journal of Soil Science* (An International Refereed Research Journal). **10 (2): 215-221.** [https://hal.science/hal-04676713](https://hal.science/hal-04676713).

Kumar, Ajeet., Singh, S. K., Meena, S.K., Sinha, S.K. and Rana L (2024) Groundwater contamination with nitrate and human health risk assessment of North East alluvial plains of Bihar. *International Journal of Environment and Climate Change, 14*(3), 17-31. [https://doi.org/10.9734/ijecc/2024/v14i34016](https://doi.org/10.9734/ijecc/2024/v14i34016); [https://hal.science/hal-04484961](https://hal.science/hal-04484961).

Kumar, S.K., Rammohan, V., Sahayam, J.D. and Jeevanandam, M. (2009) Assessment of groundwater quality and hydrogeochemistry of Manimukha River basin, Tamil Nadu, India. *Environmental Monitoring and Assessments*. **159**, 341-351.

Kundu, M.C. and Mandal, B. (2009). Nitrate enrichment in groundwater from long – term intensive agriculture: its mechanistic pathways and prediction through modelling. *Environ. Sci. Technol.*, **43**, 5837–5843.

Lapworth, D.J., Krishan, G., MacDonald, A.M. and Rao, M.S. (2017). Groundwater quality in the alluvial aquifer system of northwest India: New evidence of the extent of anthropogenic and geogenic contamination. *Sci Total Environ.*, 599-600:1433-1444.

Mandal, K.G., Kundu, D.K., Singh, R., Kumar, A., Rout, R., Padhi, J., Majhi, P., Sahoo, D.K., 2013. Cropping practices, soil properties, pedotransfer functions and organic carbon storage at Kuanria canal command area in India. *Springerplus* **2**, 1–14

Martino, San, Liliana and Lavado, Raul S. Lavado. (2014). Soil Nitrate Profiles and the Risk of Nitrate Leaching in Sweet Cherry Orchards Subjected to Different Management Schemes. *International Journal of Fruit Science*. 14.

Maurya, B.R. and Kumar, Ajeet (2006) Comparative performance of *Aspergillus niger*
isolates of different habitats on solubilisation of tricalcium phosphate in broth and
their impact on yield attributes of wheat (Triticum aestivum L.) *International Journal of Agricultural Sciences*. **2(2):** 581-583.

[http://www.connectjournals.com/file_html_pdf/414102H_2_581-583_a.pdf](http://www.connectjournals.com/file_html_pdf/414102H_2_581-583_a.pdf)

Maurya, B.R; and Kumar, Ajeet (2006). Effect of phosphate solubilising fungi on phosphorus solubilization, growth and acquisition of phosphorus by Wheat. *Annals of Plant and Soil Research.* **8 (1):** 51-53.

Mishra, Antaryami & Pattnaik, Trupti & Das, D. & Das, Mira. (2015). Vertical Distribution of Available Plant Nutrients in Soils of Mid Central Valley at Odisha Zone, India. *American Journal of Experimental Agriculture.* **7.** 214-221.

Paswan, D., Arun, A., Kumar, Ajeet and Choudhary, C.S. (2014) Effect of NPK uptake at different growth stages of wheat (Triticum aestivum L.) for yield maximization. *An Asian Journal of Soil Science.* **9 (2):** 265-270. [https://hal.science/hal-04676702](https://hal.science/hal-04676702).

Raju, N. Janardhana, Prahlad, R. and Dey, S. (2009). Ground water quality in the lower Varuna River basin, Varanasi district, Uttar Pradesh. Jour. Geol. Soc. India, **73**: 178-192.

Ramkumar, T., Venkatramanan, S., Anithamary, I. and Ibrahim, S.M.S. (2013) Evaluation of hydrogeochemical parameters and qualityassessment of the groundwater in Kottur blocks, Tiruvarur district,Tamilnadu, India. *Arabian Journal of Geoscience.* **6, 101–108.**

Reddy, A. G. S., Kumar, N.K., Rao, D.S. and Rao, S.S. (2009). Assessment of nitrate contamination due to groundwater pollution in north eastern part of Anantapur district, A.P. India, *Environ Monit Assess*, **148**: 463-476.

Rekha Rashmi, Kumari Usha and Kumar Ajeet (2019) Nutritional aspect of Type-2 Diabetes mellitus. *Bulletin of Pure and Applied Sciences, Vol.38A (Zoology), No.2, P.126-131.* [https://hal.science/hal-04676737](https://hal.science/hal-04676737)

Rekha Rashmi, Kumari Usha and Kumar Ajeet (2020) Effect of Living Environment on Health: A Prospective Study. *Bulletin of Pure and Applied Sciences, Vol.39A (Zoology), No.1, P.46-52.* [www.bpasjournals.com](http://www.bpasjournals.com). [https://hal.science/hal-04676740](https://hal.science/hal-04676740).

S.K. Singh, S.S. Prasad and Ajeet Kumar (2021) Dhan ki kheti me hone wale siksham poshak tatwo ki kami ke lakshan evam uska prabandhan. Krishak Prashokshan
pustika, Pg. 64-69. Published by: TCA, Dholi, DRPCAU, Pusa, ISBN: 978-81-954358-0-7. https://hal.science/hal-04881390.

Shulka, R.R. (2013). Ground water information booklet, Central Ground water Board Ministry of Water Resources (Govt. of India).

Singh, B. and Craswell, E. (2021). Fertilizers and nitrate pollution of surface and ground water: an increasingly pervasive global problem. *SN Appl. Sci.* **3**, 518.

Singh, S. K., Tagung, T., Kashiwar, S. R., Kumar, Ajeet., Tiwari, S., Singh, A. K., and Singh, K. K. (2023). Assessment of Soil Fertility Status in Paroo and Saraiyan Blocks of Muzaffarpur District of Bihar Using GPS and GIS. *International Journal of Plant & Soil Science*, **35**(17), 89–101.
https://doi.org/10.9734/ijpss/2023/v35i173187.

Singh, S. K., Tagung, T., Kumar, Ajeet., Singh, K. K., Tiwari, S., Kashiwar, S. R., Kumar, A., Kumari, S., & Singh, Y. B. (2024). Geospatial Analysis of Soil Fertility in Muzaffarpur District, Bihar, India: Integrating GPS and GIS Technologies. Journal of Advances in Biology & Biotechnology, **27**(7), 1083–1093.
https://doi.org/10.9734/jabb/2024/v27i71067.

Singh, Y.V., S. Goswami, S.K. Singh, A. Kumar, P.K. Bhartiya, and Kajal Singh. 2025. "Impact of Nutrient Management Technologies on Soil Physico-Chemical Properties, Yield and Economics of Mustard under Irrigated Condition of Chandauli District, Uttar Pradesh, India". *International Journal of Plant & Soil Science* **37** (2):78-83. https://doi.org/10.9734/ijpss/2025/v37i25306.

Suthar, S., Bishnoi, P., Singh, S., Mutiyar, P. K., Nema, A. K. and Patil, N. S., (2009) Nitrate contamination in groundwater of some rural areas of Rajasthan, *India. J. Hazard. Mater*, **171**: 189-199

USEPA (1985). Health effects criteria document for nitrate/nitrite. USEPA criteria and standards division, office of drinking water, Washington, DC.

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Vinod, P.N., Chandramouli, P.N. and Koch, M. (2015). Estimation of Nitrate Leaching in Groundwater in an Agriculturally Used Area in the State Karnataka, India, Using Existing Model and GIS. *Aquatic Procedia*, **4**: 1047–1053.

Wakida, F. and Lerner, D.N. (2005). Non-agricultural sources of groundwater nitrate: a review and case study. *Water Res.*, **39**, 3-16.

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WHO (2011). Guidelines for Drinking-Water Quality, 4th ed., World Health Organization: Geneva, Switzerland, 398–403.

Wick, K., Heumesser, C., and Schmid, E. (2012). Groundwater nitrate contamination: factors and indicators. *Journal of environmental management*, **111**(3): 178–186.

Wongsanit J, Teartisup P, Kerdsueb P, Tharnpoophasiam P, Worakhunpiset S. (2015) Contamination of nitrate in groundwater and its potential human health: a case study of lower Mae Klong River basin, Thailand. *Environ Sci. Pollut. Res Int. Aug; 22*(15):11504-12.

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