# Nitrate Leaching and Threat of Ground Water Contamination in Maize Based Cropping System of Bihar

Ajeet Kumar, C.K. Jha

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Ajeet Kumar, C.K. Jha. Nitrate Leaching and Threat of Ground Water Contamination in Maize Based Cropping System of Bihar. Agriculture & Food: E-Newsletter, 2021, pp.144-147. hal-04936434

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# Nitrate Leaching and Threat of Ground Water Contamination in Maize Based Cropping System of Bihar

Article ID: 10848

Ajeet Kumar<fnref n="1" />, C. K. Jha<fnref n="1" />

## Abstract

Maize is the third most important crop following rice and wheat. The nitrogen and water are the two critical factors for ensuring maize production. To pursue high production, excessive nitrogen fertilizer (400 to 600 kg Nha⁻<fnref n="1" />) has been applied by the growers to the current rotation system, which exceeds the crop demands. The applied N fertilizer either absorbed by the crops or stored in the root zone, and lost by ammonia volatilization, nitrogen leaching, N₂O and N₂ emissions. The NO₃⁻ N accumulated in the root zone move downward by percolated soil water, and eventually enters the groundwater. The overuse of nitrogen fertilizer and flood irrigation caused severe nitrogen leaching and increases the risk of groundwater contamination with nitrate. Therefore, it is necessary to manage the water and nitrogen fertilizer to ensure optimum yield potential and the sustainable use of groundwater resources. The aim of the present status paper is to provide insight regarding nitrate contamination in groundwater. It is essential to develop strategies to control accumulation of NO3- in soil and their leaching from the soil and also maintain the yield potential of maize.

## Introduction

Bihar recent emergence as a maize powerhouse with farmers' harvesting yield comparable to Midwest US level. Maize (Zea mays L.) is the one of the most important cereals crop in the world agricultural economy both as food for human and feed for animals. The maize kernel is composed of approximately 72% starch, 10% protein, 5% oil, 2% sugar, and 1% ash with the remainder being water. The use of nitrogen fertilizer results in higher biomass and protein yield and increases the concentration of protein in the tissue. As the protein concentration of grain increases, zein makes up an increasing proportion of the protein. Nitrogen often affects the amino acid composition of the protein. In cereals, an abundant supply of nitrogen reduces the relative contribution of lysine and threonine, thus reducing the biological value of the protein. Increased nitrogen supply often leads to kernel integrity and strength, resulting in better milling properties of the grain. Nitrogen regulates the efficiency of the use of nutrients in the plant. The nitrogen affects various physiological and biochemical processes in plant cells. In proteins, alkaloids, nucleic acids, coenzymes and porphyrins, nitrogen is the main ingredient. The porphyrins are responsible for the inheritance, metabolic process and growth of plants. Porphyrins are the main component of cytochrome and chlorophyll. The protoplast of plant cells contains mainly nitrogen. It plays an essential role in the growth and development of the plant. The lack of nitrogen reduces the growth of the plants and lower yields. On the contrary, when optimum levels of nitrogen are used; higher yields are produced due to the larger leaf area of the plant. Nitrogen plays vital role in the development of the ear and kernel. Keeping in view the above facts the present status paper has been formulated to study on nitrate pollution in soil and extent of ground water pollution in maize based cropping system of North Bihar.

## Maize Yield Potential

The eastern region of Bihar is popularly known as the 'maize hub' where the maize is cultivated in around two lakh hectares of area. The importance of maize lies in its wide industrial uses besides serving as human food and animal feed and fodder. The demand for maize is growing due to its multiple uses for food, feed and industry sectors. The average annual maize production is around 22 lakh tonnes in Bihar which is steady positive

<footnote n="1">¹Assistant Professor-cum-Scientist, Department of Soil Science, Sugarcane Research Institute, DRPCAU, Pusa (Samastipur), Bihar.</footnote>
trend in production. The leading producer districts are Khagaria and Saharsa. After Karnataa and Madhya Pradesh, Bihar is the highest Maize Producer. Maize is grown throughout the year due to its photo-thermo insensitive character and highest genetic yield potential among the cereals. In Bihar, maize is grown in all season's viz., Kharif (Mansoon), Post mansoon Rabi (winter) and spring. During rabi and spring seasons a higher yield is achieved at farmers field under assured irrigation facilities. Around one-fourth of land under maize cultivation in Bihar is for summer maize which contributes about 28% of total maize produced in the state.

## Maize Hub in Bihar

In Bihar, Maize is grown in almost all the districts of all the three agro-climatic zones of Bihar. But Zone-II is major maize producing area. In area, Khagaria occupies first rank followed by Samastipur and in production; Katihar is at the top followed by Madhepura, Khagaria, Muzaffarpur, Araria and Samastipur. Productivity is highest in Katihar (6510 kg/ha) followed by Madhepura (5285/kg/ha) Saharsa (4636 kg/ha) Araria (4272 kg/ha) Supaul (4096 kg/ha), Vaishali (4067 kg/ha) and Muzaffarpur (3935 kg/ha). Zone-wise data reflects, 0.27-million-hectare area under maize in zone-II with a production of 12.05 million tonnes. The productivity is 4397 kg/ha in zone-II which is known for its Rabi maize production while in zone-I area under maize is 0.33 million hectare and production 9.72 million tonnes. Zone-III have only 0.10 million hectares under maize (mainly kharif maize) with a production of 3.01 million tonnes. The area, production and productivity of maize in the state of Bihar are increasing.

## Fate of N-Fertilizer in Soil

Application rates of nitrogenous fertilizer by the local farmers in this area often exceed crop requirements, resulting in high accumulation of nitrate in the soil. The impact of downstream nutrient export from agricultural lands continues to be of much more concern. Nitrate-nitrogen (NO3-N) is particularly troublesome as it leaches through the soil into subsurface drainage or groundwater, which ultimately leads to surface waters. Permeable soils make the region susceptible to groundwater pollution by NO3-N, which is applied to fields in large amounts as fertilizer. Nitrate that has accumulated in soils is highly prone to leaching, which is directly threatening the quality of groundwater.

<figure><img src="image_2.png" /><figcaption>Agro-climatic Zones of Bihar</figcaption></figure>

<figure><img src="image_3.png" /><figcaption>Heavy applied nitrogenous crop</figcaption></figure>
The nitrogen and water are the two critical factors for ensuring maize production. To pursue high production, excessive N fertilizer (400–600 kg N ha⁻¹) has been applied to the current rotation system, which exceeds the crop demands of 200 to 300 kg N ha⁻¹ (Zhang *et al.*, 2011). Overall, the applied N fertilizer would be absorbed by the crops, stored in the root zone, and lost by ammonia volatilization, N leaching, N₂O and N₂ emissions. The soil, with a semi-arid and semi-humid monsoon climate has relatively stable nitrification and mineralization potential, which makes it easy to accumulate nitrate-nitrogen in the root zone. The NO₃⁻ N accumulated in the root zone would move downward continuously carried by percolated soil water, and eventually enter the groundwater. Therefore, the overuse of N fertilizer and flood irrigation has caused severe N leaching (15–55% N fertilizer applied) and increases the risk of groundwater contamination (Sun *et al.* 2018). Because of the aforementioned critical situation, it is necessary to manage the water and nitrogen fertilizer to ensure optimum yield potential and the sustainable use of groundwater resources. To decrease the water input and limit the groundwater withdrawal under the maize based cropping system, it is essential to investigate the effects of different irrigation type/schedules on the performance of crops. Nitrate from soils can leach into groundwater following heavy rainfall or irrigation, contaminating drinking water (Liu, 2015).

## Use of N-Fertilizer

The range of recommended dose of nitrogen for maize cultivation in Bihar is 100-150 kg Nha⁻¹ and the recommended dose of fertilizers for different seasons of maize growing in Bihar is as follows: Rabi maize:150:75:50 (NPK); Kharif Maize: 120:60:150 (NPK); Spring Maize: 100:40:30 (NPK). Nitrogen fertilizers are used in crop production to obtain high yields but overdose of fertilizers is problematic. The low efficiencies of nitrogen utilization ranging from 30 to 40% (Ju et al., 2009). In general, nitrate accumulations occur in soil when nitrogen fertilizer is oversupplied especially under intensive cropping viz. double or triple cropping regions (Zhou et al., 2016). In order to meet the demands of higher crop yields, the agricultural production has been intensified.

## N-Fertilizer and Ground Water Pollution

Groundwater contamination with NO₃⁻ N has vital concern, especially in intensive maize production area of Bihar. Nitrogen fertilization is the major source of nitrogen input in this area, with high consumption rate of fertilizers. The NO₃⁻ N is highly mobile in the soil and poses a health risk to the residing population of the area. The concentration of NO₃⁻ N in drinking water reaches its critical levels. The safe limits as decided by the Bureau of Indian standards (45 mgL⁻¹) and World Health Organization (50 mgL⁻¹). The World Health Organization and the European Community (Council of European Communities, 1980) set a limit of 50 mg NO₃⁻ L⁻¹ (11 mg NO₃⁻ N L⁻¹) in potable water. The US Environmental Protection Agency (USEPA, 1995) and the Canadian Water Quality Branch (Water Quality Branch, 1995) set a limit of 44 mg NO₃⁻ L⁻¹ (10 mg NO₃⁻ N L⁻¹) as the maximum safe level in drinking water. Drinking water in these plains exclusively comes from ground water and therefore, keeping its NO₃⁻ N below the maximum contaminant level is important. High NO₃⁻ in groundwater poses a direct threat to human health (World Health Organization (WHO, 2011). The risk of nitrate leaching to groundwater can be assessed from NO₃⁻ accumulation in the soil. As the concentration of NO₃⁻ in groundwater responds slowly to changes in agricultural practices and is subject to weather events (Wick *et al.*, 2012), soil residual NO₃⁻ has been used as an alternative indicator for the risk of NO₃⁻ leaching. Yadav (1997) determined that 68% of applied fertilizer nitrogen accumulated in the soil as NO₃⁻, from which 20% entered the groundwater; therefore, controlling groundwater nitrate contamination is important for safe water supply.

## Nitrate and Human Health

Nitrate concentration in drinking water starts affecting the health of the populace at levels in the range of 100 to 200 mg/L nitrate nitrogen. Nitrate pollution is most dangerous that causes harmful effects on the human health and animals. High Nitrate concentrations causes, Methemoglobinemia or "blue baby" disease that eventually leads to developing an intestinal cancer. Actually, Blood contains hemoglobin, which carries oxygen. When nitrate is present, hemoglobin can be converted to methemoglobin, which cannot carry oxygen. In the blood of adults, certain enzymes continually convert methemoglobin back to hemoglobin, and methemoglobin
levels normally do not exceed 1%, while infants have lower levels of these enzymes, and their methemoglobin level is usually rise upto 1% to 2 % which is fatal of infants.

## Impact of Other Nitrogen Sources

The use of manure, crop type, climatic factors and soil properties, affect soil nitrate accumulation and leaching. It is need of time to make water quality legislation for Nitrates Directive to control $NO_3^-$ contamination. The level of nitrate accumulation in soils has become a hazard to potable water. About 90% of the farming community of Bihar is frequently using groundwater for drinking purposes as well as for irrigation purposes also.

## Conclusion

Bihar state has challenge in feeding its ever-growing population. Therefore, it needs strategies to enhance fertilizer and water use efficiency, reduce $NO_3^-$ leaching and contamination of ground water vis-a vis without compromising yield potential of maize and degradation of the soil. The quantification the nitrate uptake by maize, nitrate leaching in soil profile and contamination of nitrate in ground water, under maize based cropping system in Corn Belt of Bihar is essentially to be accomplished so that general populace of the area may get rid of the nitrate problems.

## References

1. Council of European Communities. (1980). Relating to the quality of water intended for human consumption. Official J. Eur. Commun. (L229): 11-29.

2. Ju, X.T., Xing, G.X., Chen, X.P., Zhang, S.L., Zhang, L.J., Liu, X.J., Cui, Z.L., Yin, B., Christie, P., Zhu, Z.L., Zhang, F.S., (2009) Reducing environmental risk by improving N management in intensive Chinese agricultural systems. Proc. Natl. Acad. Sci. U. S. A. 106, 3041-3046.

3. Liu, H.B., (2015) Establishment and Application of monitoring technology on nonpoint pollution from arable land. Science Press, Beijing (in Chinese with English abstract).

4. Sun, M.; Huo, Z.; Zheng, Y.; Dai, X.; Feng, S.; Mao, X. (2018) Quantifying long-term responses of crop yield and nitrate leaching in an intensive farmland using agro-eco-environmental model. Sci. Total Environ, 613-614, 1003-1012.

5. US Environmental Protection Agency (USEPA). (1995) Drinking-water regulations and health advisories. office of water, US Environmental Protection Agency, Washington, DC. 11pp.

6. Water Quality Branch. (1995) Canadian water quality guidelines. Inland Waters Directorate, Ottawa, Ont., Canada.

7. Wick, K., Heumesser, C., Schmid, E., (2012) Groundwater nitrate contamination: factors and indicators. J. Environ. Manage. 111, 178-186.

8. World Health Organization (WHO), (2011) Water safety and quality. (Accessed 9 August 2017). http://www.who.int/water_sanitation_health/water-quality/en/.

9. Yadav, S.N., (1997) Formulation and estimation of nitrate-nitrogen leaching from corn cultivation. J. Environ. Qual. 26, 808-814.

10. Zhang, X.; Chen, S.; Sun, H.; Shao, L.; Wang, Y. (2011) Changes in evapotranspiration over irrigated winter wheat and maize in North China Plain over three decades. Agric. Water Management. 98, 1097-1104.

11. Zhou, J.Y., Gu, B.J., Schlesinger, W.H., Ju, X.T., (2016) Significant accumulation of nitrate in Chinese semi-humid croplands. Sci. Rep. 6, 1-8.