# Soil Test Based Fertilizer Calibration for Common Bean (Phaseolus vulgaris L.) Varieties of the Southern Ethiopia

Authors: Mesfin Kassa; Tadesse Kifle
Journal: Applied and Environmental Soil Science
 (2023)

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## Abstract

Blended Nitrogen, Phosphorus, Sulfur, and Boron fertilizer calibration foxr optimum common bean (Phaseolus vulgaris L.) varieties yield was used to assess the effect of different rates of blended fertilizer on growth, yield and yield components, and nutrient use efficiency of common bean varieties and to identify economically feasible rates of blended fertilizer at Meskan District, Southern Ethiopia during 2020 crop season. The experiment had six treatment levels of blended fertilizer (0, 50, 100, 150, 200, and 250 kg·ha−1), and two common bean varieties were arranged in a randomized complete block design with three replications. Soil samples of the experimental plots were analyzed and used as blended fertilizer calibration to estimate soil nutrient supplies and recommend fertilizer. The results revealed that growth, yield, and yield components were highly significantly p≤0.05 affected by the main effect of varieties and application of blended NPSB rates. The interaction of varieties and blended fertilizer shown a significant p≤0.05 effect on all parameters. The partial budget analysis indicated that the highest net benefit of 67665 ETB ha−1 was obtained from the Nasir variety with the application of 100 kg·ha−1. Therefore, growing the Nasir variety with blended fertilizer rates of 100 kg·ha−1 is economically feasible for the studied soil type and different locations.


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## Body

## 1. Introduction

Low crop production is inappropriate soil fertility management [1]. The relatively low yield of common beans in Ethiopia including the study area is as a result of the low use of enhanced variety and low soil fertility status and poor management practice which are the major production constraints [2]; ATA [3]. Wossen [4] reported NPKSB nutrient ratios for common bean growth and yield. However, soil fertility mapping projects in Ethiopia recently reported the deficiency of K, S, Zn, B, and Cu in addition to N and P in major Ethiopian soils, and thus recommend the application of customized and balanced fertilizers [5]. Common bean N fertilizer requirement depends on soil fertility levels; for low soil nitrogen levels (below 34 kg N·ha−1) N fertilizer is generally recommended in order for deficiency symptoms not to manifest and for full development up to production, inorganic phosphorus fertilizer has a positive effect on the yield and yield components of common bean and sulfur is required in similar amount as that of phosphorus [6]. In Ethiopian soils, the deficiency of K, S, Zn, B, and Cu in addition to N and P have common bean recently reported by soil fertility mapping project, and thus recommend the application of customized and balanced fertilizers [11]. The fertilizer recommendation did not consider the existing soil nutrient supply and resulted in low crop yield response in the region [2]. To correct these nutrient deficiencies, farmers in the Gurage zone of the Southern Ethiopia have been using a uniform blanket application of 100 kg NPSB ha−1 for all legumes including common bean to increase crop yields and this did not consider soil fertility status and crop requirement. Therefore, this study was initiated with the following objectives to determine the effect of blended fertilizer on growth, yield, and yield components and on nutrient uptake and nutrient use efficiency of common bean varieties and to identify and suggest the economically feasible rates of NPSB fertilizer for common bean varieties production in the study area.


## 2. Materials and Methods

### 2.1. Description of the Study Site

The experiment was conducted at Dobo Tuto Kebele, Meskan District, Gurage Zone, Southern Ethiopia, during the 2020 rain season. It is located 135 km south of Addis Ababa at a latitude and longitude range of 7°.99′35″–8°.02′781″N and 38°.26′31′–38°.57′86″E, respectively (Figure1). The area has an elevation range of 1823–2000 meters above sea level. The mean annual rainfall is 1000–1200 mm with a bimodal pattern, which extends from February to April and June to September. The mean annual minimum and maximum temperatures are 10.3°C and 26°C, respectively (Figure 2).Figure 1
Map of the experimental site in Meskan District, Gurage Zone, Southern Ethiopia.Figure 2
Monthly mean annual rainfall and monthly minimum and maximum temperature of Meskan District.


### 2.2. Experiment Design and Treatments

The treatments were consisted of a factorial combination of six blended NPSB fertilizer rates (0, 50, 100, 150, 200, and 250 NPSB kg ha−1), and two varieties (awassa dume and Nasir) were evaluated in a factorial arrangement laid in a randomized complete block design with three replications. Each plot size was 2.4 × 3 m2, which contained six rows per plot and the four central rows were used for data collection, the spacing between rows and plants were 40 cm and 10 cm, respectively. Blended NPSB (19% N, 38% P2O5, 7% S, and 0.1% B) was used as sources of N, P, S, and B, respectively, for the study.


### 2.3. Soil-Plant Samples and Analysis

Before planting, soil samples were taken randomly in a zigzag manner to a depth of 0–30 cm from 20 spots of the experimental field (Table1). The soil samples were composited to one sample and air-dried ground and sieved using 2 mm and 0.5 mm (for organic carbon). Then, the composite soil sample was analyzed for soil pH in water and was determined potentiometrically in a supernatant suspension of 1 : 2.5 soils: water ratio using a combined glass electrode pH meter [14]. Soil texture was determined by the Bouyoucos hydrometer method [15]. Soil organic carbon (SOC) was using the Walkley and Black method [16], total nitrogen (TN) was using the Kjeldahl method [17] available phosphorous (AP) was using the Olsen method [13], cation exchange capacity (CEC) was extracted by 1M ammonium acetate (pH 7) method [18], available sulfur (AS) was determined using the turbid metric method, and available boron (AB) was determined using the hot water method [19]. After harvesting the plant samples was collected, dried, processed, and analyzed for total N, P, S, and B contents were determined by wet acid digestion procedure as suggested [20].Table 1
Physicochemical properties of the study site’s soil before planting.
NoParameterUnitValuesClassificationReferences1.1Sand%401.2Silt%301.3Clay%30Textural classClay loamBouyoucas hydrometer method3pH6.8Slightly acidicHavlin et al. [11]4OC%2.70LowLondon [12]5TN%0.23ModerateHavlin et al. [11]6APmg kg−12.15Very lowOlsen et al. [13]7CECCmock−134.4HighLondon [12]8ASmg kg−16.0Very lowLondon [12]9ABmg kg−10.63Very lowLondon [12]


## 2.1. Description of the Study Site

The experiment was conducted at Dobo Tuto Kebele, Meskan District, Gurage Zone, Southern Ethiopia, during the 2020 rain season. It is located 135 km south of Addis Ababa at a latitude and longitude range of 7°.99′35″–8°.02′781″N and 38°.26′31′–38°.57′86″E, respectively (Figure1). The area has an elevation range of 1823–2000 meters above sea level. The mean annual rainfall is 1000–1200 mm with a bimodal pattern, which extends from February to April and June to September. The mean annual minimum and maximum temperatures are 10.3°C and 26°C, respectively (Figure 2).Figure 1
Map of the experimental site in Meskan District, Gurage Zone, Southern Ethiopia.Figure 2
Monthly mean annual rainfall and monthly minimum and maximum temperature of Meskan District.


## 2.2. Experiment Design and Treatments

The treatments were consisted of a factorial combination of six blended NPSB fertilizer rates (0, 50, 100, 150, 200, and 250 NPSB kg ha−1), and two varieties (awassa dume and Nasir) were evaluated in a factorial arrangement laid in a randomized complete block design with three replications. Each plot size was 2.4 × 3 m2, which contained six rows per plot and the four central rows were used for data collection, the spacing between rows and plants were 40 cm and 10 cm, respectively. Blended NPSB (19% N, 38% P2O5, 7% S, and 0.1% B) was used as sources of N, P, S, and B, respectively, for the study.


## 2.3. Soil-Plant Samples and Analysis

Before planting, soil samples were taken randomly in a zigzag manner to a depth of 0–30 cm from 20 spots of the experimental field (Table1). The soil samples were composited to one sample and air-dried ground and sieved using 2 mm and 0.5 mm (for organic carbon). Then, the composite soil sample was analyzed for soil pH in water and was determined potentiometrically in a supernatant suspension of 1 : 2.5 soils: water ratio using a combined glass electrode pH meter [14]. Soil texture was determined by the Bouyoucos hydrometer method [15]. Soil organic carbon (SOC) was using the Walkley and Black method [16], total nitrogen (TN) was using the Kjeldahl method [17] available phosphorous (AP) was using the Olsen method [13], cation exchange capacity (CEC) was extracted by 1M ammonium acetate (pH 7) method [18], available sulfur (AS) was determined using the turbid metric method, and available boron (AB) was determined using the hot water method [19]. After harvesting the plant samples was collected, dried, processed, and analyzed for total N, P, S, and B contents were determined by wet acid digestion procedure as suggested [20].Table 1
Physicochemical properties of the study site’s soil before planting.
NoParameterUnitValuesClassificationReferences1.1Sand%401.2Silt%301.3Clay%30Textural classClay loamBouyoucas hydrometer method3pH6.8Slightly acidicHavlin et al. [11]4OC%2.70LowLondon [12]5TN%0.23ModerateHavlin et al. [11]6APmg kg−12.15Very lowOlsen et al. [13]7CECCmock−134.4HighLondon [12]8ASmg kg−16.0Very lowLondon [12]9ABmg kg−10.63Very lowLondon [12]


## 3. Data Collection

An effect of blended NPSB rate was examined by measuring data on phenology, growth, yield, and yield component parameters.


### 3.1. Efficiency Parameters

The actual uptakes of N, P, S, and B based on the potential supplies of N, P, S, and B were calculated using equations (1)–(4) as described in [21] as follows:(1)PE,kgkg−1=BYf−BYuNf−Nu,where PE is thephysiological efficiency, BYf is the biological yield (grain plus straw) of the fertilized pot (kg), BYu is the biological yield of the unfertilized plot (kg), Nf is the nutrient uptake (grain plus straw) of the fertilized plot, and Nu is the N uptake of the unfertilized plot (kg).(2)RE=TUa−TUa0Fra,where RE is the recovery fraction, TUa-average total nutrient uptake, kg ha−1 from treatments receiving a dose Fr (a) TUa0-average total nutrient uptake, kg ha−1, from the control treatments, Fra is the rate of fertilizer application (kg ha−1), and (a)-nutrient under consideration, namely, N, P, or K.(3)AE,kgkg−1=Gf−GuNf,where AE is the agronomic recovery, kg kg−1; Gf is the grain yield of the fertilized plot, kg; Gu is the grain yield of the control plot, kg; and Nf is the quantity of N, P, and K fertilizer applied, kg.Where EU: Utilization efficiency, Nutrient utilization efficiency is the product of physiological and apparent recovery efficiency. It can be calculated as follows:(4)EUkgha−1=PEXRE.


### 3.2. Efficiency of Soil Nutrient Was Calculated from Soil Test Value

Calculation of the important parameters (NR, Cs, and Cf) was computed following the formula as defined by [22] as follows:(5)NutrientrequirementNRkgq−1=TotaluptakeofnutrientKgha−1GrainyieldsKgha−1,PercentcontributionofavailableNutrientfromsoil%Cs=TotaluptakeofnutrientincontrolplotSoiltestvalueofthatnutrientincontrolplotx100,%Cf=Totaluptakeofnutrients–Soiltestvaluesofnutrientsx%Cs/100FertilizerdoseNPSBappliedkgha−1X100.


### 3.3. Fertilizer Requirement Equations

(6)FN=NRCf×100T−CsCf×SN,FP2O5=NRCf×100T−CsCf×2.29xSP,FS=NRCf×100T–CsCf×SS,FB=NRCf×100T–CsCf×SB,where (% Cf) is the percent contribution of nutrient from fertilizer, FN is the fertilizer nitrogen (kg N ha−1), FP2O5 is the fertilizer phosphorus (kg P2O5·ha−1), FS is the fertilizer sulfur, and FB is the fertilizer boron.T is the targeted yield (q ha−1), SN is the soil test value for available nitrogen (kg ha−1), SP is the soil test value for available phosphorus (kg ha−1), SS is the soil test value for available sulfur (kg ha−1), and SB is the soil test value for available boron (kg ha−1).


### 3.4. Economic Analysis

Economic analysis was performed using partial budget analysis following the procedure of CIMMYT [28].


### 3.5. Statistical Analysis

Agronomic data were subjected to analysis of variance (ANOVA) using SAS 9.0 version software [29]. Least significant differences (LSDs) were used for mean separation comparison at a probability 5%.


## 3.1. Efficiency Parameters

The actual uptakes of N, P, S, and B based on the potential supplies of N, P, S, and B were calculated using equations (1)–(4) as described in [21] as follows:(1)PE,kgkg−1=BYf−BYuNf−Nu,where PE is thephysiological efficiency, BYf is the biological yield (grain plus straw) of the fertilized pot (kg), BYu is the biological yield of the unfertilized plot (kg), Nf is the nutrient uptake (grain plus straw) of the fertilized plot, and Nu is the N uptake of the unfertilized plot (kg).(2)RE=TUa−TUa0Fra,where RE is the recovery fraction, TUa-average total nutrient uptake, kg ha−1 from treatments receiving a dose Fr (a) TUa0-average total nutrient uptake, kg ha−1, from the control treatments, Fra is the rate of fertilizer application (kg ha−1), and (a)-nutrient under consideration, namely, N, P, or K.(3)AE,kgkg−1=Gf−GuNf,where AE is the agronomic recovery, kg kg−1; Gf is the grain yield of the fertilized plot, kg; Gu is the grain yield of the control plot, kg; and Nf is the quantity of N, P, and K fertilizer applied, kg.Where EU: Utilization efficiency, Nutrient utilization efficiency is the product of physiological and apparent recovery efficiency. It can be calculated as follows:(4)EUkgha−1=PEXRE.


## 3.2. Efficiency of Soil Nutrient Was Calculated from Soil Test Value

Calculation of the important parameters (NR, Cs, and Cf) was computed following the formula as defined by [22] as follows:(5)NutrientrequirementNRkgq−1=TotaluptakeofnutrientKgha−1GrainyieldsKgha−1,PercentcontributionofavailableNutrientfromsoil%Cs=TotaluptakeofnutrientincontrolplotSoiltestvalueofthatnutrientincontrolplotx100,%Cf=Totaluptakeofnutrients–Soiltestvaluesofnutrientsx%Cs/100FertilizerdoseNPSBappliedkgha−1X100.


## 3.3. Fertilizer Requirement Equations

(6)FN=NRCf×100T−CsCf×SN,FP2O5=NRCf×100T−CsCf×2.29xSP,FS=NRCf×100T–CsCf×SS,FB=NRCf×100T–CsCf×SB,where (% Cf) is the percent contribution of nutrient from fertilizer, FN is the fertilizer nitrogen (kg N ha−1), FP2O5 is the fertilizer phosphorus (kg P2O5·ha−1), FS is the fertilizer sulfur, and FB is the fertilizer boron.T is the targeted yield (q ha−1), SN is the soil test value for available nitrogen (kg ha−1), SP is the soil test value for available phosphorus (kg ha−1), SS is the soil test value for available sulfur (kg ha−1), and SB is the soil test value for available boron (kg ha−1).


## 3.4. Economic Analysis

Economic analysis was performed using partial budget analysis following the procedure of CIMMYT [28].


## 3.5. Statistical Analysis

Agronomic data were subjected to analysis of variance (ANOVA) using SAS 9.0 version software [29]. Least significant differences (LSDs) were used for mean separation comparison at a probability 5%.


## 4. Results and Discussions

### 4.1. Effect of Blended Fertilizer on Yield and Yield Components of Common Bean

The analysis of variance indicated that the main effect of varieties and NPSB rates had a highly significant effect (p<0.05) on plant height (Table 2). The tallest plant height (97.96 cm) with the application of 100 kg·ha−1 NPSB rate, whereas the shortest plant height (79.6 cm) was recorded from 0 kg·ha−1 NPSB rate for the same variety (Table 2). The highest number of nodules per plant (39.2) and nodule dry weight (0.76 g) were recorded from variety awassa dume with application of 100 kg·ha−1 NPSB blended fertilizer, whereas the lowest nodules number (21) and nodule dry weight (0.20) were recorded from 0 kg·ha−1 by variety Nasir (Table 2). The highest number of primary branch per plant (4.6) was recorded for the Nasir variety with a blended fertilizer treatment (NPSB) of 100 kg·ha−1, while the minimum number of primary branch per plant (2.8) was from the awassa variety Dume (Table 2). The highest number of pods per plant (52.04) was obtained from the application of 100 kg·ha−1 blended NPSB fertilizer rate from Nasir, whereas the minimum number of pods per plant (39.65) was recorded from 0 kg ha·−1 NPSB fertilizer rates gave from awassa dume (Table 2). These results were consistent with the finding of Haleh et al. [30], Lake and Jemaludin [31] and, Turuko and Mohammed [28] reported yield and yield components statistically influenced by the application of NPSB application. The analysis of variance showed that the main effect of varieties and blended NPSB fertilizer rate had shown a highly significant (p≤0.01) effect at the same time the interaction of fertilizer application and varieties also had showed significant (p<0.01) effect on the above ground dry biomass. The highest above ground dry biomass yield (5358 kg·ha−1) gave at a fertilizer rate of 100 kg·ha−1 NPSB with variety awassa dume, whereas the lowest dry biomass yield (3918 kg·ha−1) was obtained from control with variety Nasir (Figures 3(a)–3(c)). The highest hundred seed weight (28) was recorded from the variety awassa dume, while the minimum seed weight (21) gave with control from the Nasir variety (Figures 4(a)–4(c)). The highest harvest index (36.2) with an application rate of 100 kg·ha−1 blended fertilizer, whereas the lowest record (24.06) was registered from 0 kg·ha−1 NPSB rate for the same variety (Tables 3–5). According to Girma [29] who found a significant increment in the biological yield of common bean with an increased rate of NP fertilizers from 0 kg P205·ha−1 and 69 kg P205·ha−1 (150 kg DAP) and Tesfaye [30] reported that 100 seed weight in common bean increased with increase in phosphorus fertilizer application (69 kg·ha−1).Table 2
Interaction effects of varieties and blended NPSB fertilizer rates on growth parameters of common bean at Meskan District in 2020 cropping season.
NSPB kg ha−1Number of primary branch per plantPlant height (cm)Number of nodules per plantNodule dry weight per plantNumber of pods per plantAwassa dumeNasirAwassa dumeNasirAwassa dumeNasirAwassa dumeNasirAwassa dumeNasir02.8fgh4.13bcd79.6ghi85.26efg26hij21klm0.24efg0.20ghi39.65fgh42.6ef503.2efg4.2bc81.9fgh90.26cde30def24.5ijk0.38cd0.22fgh41.73efg44.69d1003.6cde4.6a97.96a95.66bc39.2a27.46ghi0.76a0.28de43de52.04a1503.55cde4.6a97.66ab95.06bc38.5ab28.15fgh0.69b0.26def43.75de48.88c2003.51bdef.4.46b89.84cde92.8cd36.7abc28.73efg0.62bc0.26def44.81d49.70b2503.48def4.13bcd86.6def92.66cd34.9cde28.25fgh0.59bc0.24efg44.92d49.10bLSD (0.05)0.70.97.826.70.790.340.240.212.683.1CV7.685.657.375.14.115.16.266.22.302.7Figure 3
(a–d) Yield relation with uptakes of Nasir common bean variety.
(a)(b)(c)(d)Figure 4
(a–d) Yield relation with uptakes of awassa dume common bean variety.
(a)(b)(c)(d)Table 3
Interaction effects of varieties and blended NPSB fertilizer rates on biomass yield and grain yield of common bean at Meskan in 2020 cropping season.
NSPB (kg ha−1)Biomass yield (kg ha−1)Grain yield (kg ha−1)Harvest index (%)Awassa dumeNasirAwassa dumeNasirAwassa dumeNasir04458def4268efg1768ghi1852fgh27.13ghi24.06hij505111b4576cde2133def2045efg27.23ghi29.6fgh1005358a4988bc2312c2595a34.4b36.2a1505266b4957bc2304cd2422b33.66bc34.10b2005043bc4855c2264d2403b32.6cd31.6def2504952bc4837c2227de2375bc32.2cde31.2efgLSD (0.05)19.8720.926.927.8211.95.6CV4.846.16.97.213.232.7Table 4
Basic data for computing fertilizer dose for targeted yields of awassa dume common bean variety at Meskan District, Gurage zone, Southern Ethiopia.
S.NoTreatments NPSB (Kg ha−1)Nutrient requirement (Kg q−1)Contribution of available nutrient from soil (%)Contribution from applied fertilizer (%)NPSBNPSBNPSB03.001.140.900.467.693.130.964.38————502.660.960.790.501.170.020.330.2148.2874.1248.6050.391002.880.870.930.610.660.170.210.14100.88121.03101.59100.141502.880.980.900.550.440.220.130.08150.80104.73158.17103.462002.930.960.910.440.320.100.100.05207.2976.08204.29197.572502.600.950.860.400.230.100.070.03251.7469.93271.13294.17Table 5
Basic data for computing fertilizer dose for targeted yields of Nasir common bean variety at Meskan District, Gurage zone, Southern Ethiopia.
S.NoTreatments NPSB (Kg ha−1)Nutrient requirement (Kg q−1)Contribution of available nutrient from soil (%)Contribution from applied fertilizer (%)NPSBNPSBNPSB02.60.900.880.3574.312.920.913.51————502.670.841.010.360.880.010.340.1459.41290.1759.7950.01002.641.071.010.370.500.110.190.09131.89251.06135.4599,631502.250.931.000.450.230.120.090.07230.78101.02265.83149.392002.110.770.820.350.080.120.020.04620.5465.14676.14149.552502.110.740.840.280010.130.010.02407.3860.98704.90156.01


### 4.2. Nutrient Use Efficiency

Variation in agronomic use efficiency appeared to result from differences between varieties and levels of NPSB fertilizer. Among NPSB application, the Nasir variety interacted with 100 kg·ha−1 NPSB level being observed with the greatest agronomic efficiency which reached 7.43 kg·kg−1 whereas, the awassa dume variety interacted with 250 kg·ha−1 NPSB level was low agronomic efficiency which reached 1.84 kg·kg−1. As results indicated in (Table 6), the highest nutrient recovery efficiency (38.2%) was revealed with Nasir variety by fertilizer rate 100 kg·ha−1, and the lowest nutrient recovery efficiency (3.67%) and (4.15%) was found from a fertilizer rate 250 kg·ha−1 with awassa dume and Nasir varieties, respectively (Figures 3(a)–3(d) and 4(a)–4(d)). The highest physiological nutrient use efficiency (6.74 kg·kg−1) was recorded from the Nasir variety by a fertilizer rate of 100 kg·ha−1. Since overhead findings, it was manifested that higher application of nutrient has resulted in more nutrient uptake (Figures 4(a)–4(d)). In line with this result, Malakouti [31] reported that the NPK fertilizer can increase fertilizer use efficiency and grain yield for different crops. Likewise, Jones et al. [32] stated that macronutrients and micronutrients of the grain yields of common bean were also increased [31].Table 6
Effect of blended fertilizer rates on nutrient use efficiency of common bean varieties.
Treatment kg ha−1Nutrient use efficiencyAwassa dumaNasirAE (kg kg−1)RE (%)PE (kg kg−1)AE (kg kg−1)RE (%)PE (kg kg−1)00.00.00.00.00.00.0505.3b12.32f3.47efg3.86c29.98c1.95fgh1005.44b34.35b4.36cd7.43a38.32a5.57b1503.57cd15.87e4.37cd3.8c20.88d5.68b2002.48ef10.4g4.14def2.76de8.49h5.43bc2501.84fgh3.67ij4.24cde2.09efg4.15i6.4aMean3.1112.773.433.3216.974.17LSD (0.05)0.435.60.120.460.420.58CV5.096.085.040.925.070.18


### 4.3. Validation of the Fertilizer Requirement Equation

A confirmation study was leaded on the farmers’ field for one year to verify the routine of the equation. In the confirmation study, six treatments including the soil-test based of NPSB rates, 98% of the soil test-based P rate, 93% of the soil test-based S rate, 61% of the soil test-based B, and NPSB recommendations (100 kg NPSB kg ha−1) were evaluated on the grain yield of common bean verities. The data for calculating the fertilizer dose for the target yields of the awassa dume and Nasir varieties are shown in Tables 4 and 5. The application of NPSB blend fertilizer has a beneficial result of improving soil fertility and higher fertilizer use efficiency at 250 kg·ha−1 in both cases. For soil fertility management, it is necessary to select appropriate yield targets and apply fertilizers that produce the highest yields of awassa dume (2312 kg·ha−1) and Nasir (2995 kg·ha−1) at 100 kg NPSB ha−1. Consistent with Tedesse and Dechassa [33] reported that the nutrient requirements of the common bean are high yielding.


### 4.4. Partial Budget Analysis

The result of the data showed that the maximum and minimum gross benefit was obtained 70065 and 47736 ETB (Ethiopia Birr ha−1) from a fertilizer rates 100 kg·ha−1 and 0 kg·ha−1 from Nassir and Hawssa Dume varieties, respectively. The highest net benefit 67665 ETB was recorded from a treatment treated by a fertilizer rate of 100 kg·ha−1 with the Nasir variety and the lowest net benefit 47736 ETB was received with a rate of 0 kg·ha−1 from the awassa dume variety. At the same time, the maximum rate of return (8.66%) was obtained with a fertilizer rate of 50 kg·ha−1 in the awassa dume variety (Table 7) and (13.65%) with a fertilizer rate of 100 kg·ha−1 with Nasir variety (Table 8).Table 7
Marginal analysis of common bean variety as influenced by blended fertilizer rates.
Treatments (kg ha−1)VarietiesUnadjusted yield (kg ha−1)Adjusted yield (kg ha−1)GB (ETB ha−1)TVC (ETB ha−1)NB (ETB ha−1)MRR (%)0Awassa dume17681591.2047736047736050Awassa dume21331919.7575911200563918.66100Awassa dume23122080.8624242400600243.633150Awassa dume23042073.662208360058608−1.42200Awassa dume22642037.661128480056328−2.28250Awassa dume22272004.360129600054129−2.20Table 8
Marginal analysis of common bean variety as influenced by blended fertilizer rates.
Treatments kgVarietiesUnadjusted yield (kg ha−1)Adjusted yield (kg ha−1)GB (ETB ha−1)TVC (ETB ha−1)NB (ETB ha−1)MRR (%)0Nassir18521666.850004050004050Nassir20451840.5552151200540154.01100Nassir25952335.57006524006766513.65150Nassir24222179.865394360061794−5.871200Nassir24032162.764881480060081−1.713250Nassir23752137.564125600058125−1.96GB: gross benefit, TVC: total variable cost, NB: net benefit, and MRR: marginal rate of return.


## 4.1. Effect of Blended Fertilizer on Yield and Yield Components of Common Bean

The analysis of variance indicated that the main effect of varieties and NPSB rates had a highly significant effect (p<0.05) on plant height (Table 2). The tallest plant height (97.96 cm) with the application of 100 kg·ha−1 NPSB rate, whereas the shortest plant height (79.6 cm) was recorded from 0 kg·ha−1 NPSB rate for the same variety (Table 2). The highest number of nodules per plant (39.2) and nodule dry weight (0.76 g) were recorded from variety awassa dume with application of 100 kg·ha−1 NPSB blended fertilizer, whereas the lowest nodules number (21) and nodule dry weight (0.20) were recorded from 0 kg·ha−1 by variety Nasir (Table 2). The highest number of primary branch per plant (4.6) was recorded for the Nasir variety with a blended fertilizer treatment (NPSB) of 100 kg·ha−1, while the minimum number of primary branch per plant (2.8) was from the awassa variety Dume (Table 2). The highest number of pods per plant (52.04) was obtained from the application of 100 kg·ha−1 blended NPSB fertilizer rate from Nasir, whereas the minimum number of pods per plant (39.65) was recorded from 0 kg ha·−1 NPSB fertilizer rates gave from awassa dume (Table 2). These results were consistent with the finding of Haleh et al. [30], Lake and Jemaludin [31] and, Turuko and Mohammed [28] reported yield and yield components statistically influenced by the application of NPSB application. The analysis of variance showed that the main effect of varieties and blended NPSB fertilizer rate had shown a highly significant (p≤0.01) effect at the same time the interaction of fertilizer application and varieties also had showed significant (p<0.01) effect on the above ground dry biomass. The highest above ground dry biomass yield (5358 kg·ha−1) gave at a fertilizer rate of 100 kg·ha−1 NPSB with variety awassa dume, whereas the lowest dry biomass yield (3918 kg·ha−1) was obtained from control with variety Nasir (Figures 3(a)–3(c)). The highest hundred seed weight (28) was recorded from the variety awassa dume, while the minimum seed weight (21) gave with control from the Nasir variety (Figures 4(a)–4(c)). The highest harvest index (36.2) with an application rate of 100 kg·ha−1 blended fertilizer, whereas the lowest record (24.06) was registered from 0 kg·ha−1 NPSB rate for the same variety (Tables 3–5). According to Girma [29] who found a significant increment in the biological yield of common bean with an increased rate of NP fertilizers from 0 kg P205·ha−1 and 69 kg P205·ha−1 (150 kg DAP) and Tesfaye [30] reported that 100 seed weight in common bean increased with increase in phosphorus fertilizer application (69 kg·ha−1).Table 2
Interaction effects of varieties and blended NPSB fertilizer rates on growth parameters of common bean at Meskan District in 2020 cropping season.
NSPB kg ha−1Number of primary branch per plantPlant height (cm)Number of nodules per plantNodule dry weight per plantNumber of pods per plantAwassa dumeNasirAwassa dumeNasirAwassa dumeNasirAwassa dumeNasirAwassa dumeNasir02.8fgh4.13bcd79.6ghi85.26efg26hij21klm0.24efg0.20ghi39.65fgh42.6ef503.2efg4.2bc81.9fgh90.26cde30def24.5ijk0.38cd0.22fgh41.73efg44.69d1003.6cde4.6a97.96a95.66bc39.2a27.46ghi0.76a0.28de43de52.04a1503.55cde4.6a97.66ab95.06bc38.5ab28.15fgh0.69b0.26def43.75de48.88c2003.51bdef.4.46b89.84cde92.8cd36.7abc28.73efg0.62bc0.26def44.81d49.70b2503.48def4.13bcd86.6def92.66cd34.9cde28.25fgh0.59bc0.24efg44.92d49.10bLSD (0.05)0.70.97.826.70.790.340.240.212.683.1CV7.685.657.375.14.115.16.266.22.302.7Figure 3
(a–d) Yield relation with uptakes of Nasir common bean variety.
(a)(b)(c)(d)Figure 4
(a–d) Yield relation with uptakes of awassa dume common bean variety.
(a)(b)(c)(d)Table 3
Interaction effects of varieties and blended NPSB fertilizer rates on biomass yield and grain yield of common bean at Meskan in 2020 cropping season.
NSPB (kg ha−1)Biomass yield (kg ha−1)Grain yield (kg ha−1)Harvest index (%)Awassa dumeNasirAwassa dumeNasirAwassa dumeNasir04458def4268efg1768ghi1852fgh27.13ghi24.06hij505111b4576cde2133def2045efg27.23ghi29.6fgh1005358a4988bc2312c2595a34.4b36.2a1505266b4957bc2304cd2422b33.66bc34.10b2005043bc4855c2264d2403b32.6cd31.6def2504952bc4837c2227de2375bc32.2cde31.2efgLSD (0.05)19.8720.926.927.8211.95.6CV4.846.16.97.213.232.7Table 4
Basic data for computing fertilizer dose for targeted yields of awassa dume common bean variety at Meskan District, Gurage zone, Southern Ethiopia.
S.NoTreatments NPSB (Kg ha−1)Nutrient requirement (Kg q−1)Contribution of available nutrient from soil (%)Contribution from applied fertilizer (%)NPSBNPSBNPSB03.001.140.900.467.693.130.964.38————502.660.960.790.501.170.020.330.2148.2874.1248.6050.391002.880.870.930.610.660.170.210.14100.88121.03101.59100.141502.880.980.900.550.440.220.130.08150.80104.73158.17103.462002.930.960.910.440.320.100.100.05207.2976.08204.29197.572502.600.950.860.400.230.100.070.03251.7469.93271.13294.17Table 5
Basic data for computing fertilizer dose for targeted yields of Nasir common bean variety at Meskan District, Gurage zone, Southern Ethiopia.
S.NoTreatments NPSB (Kg ha−1)Nutrient requirement (Kg q−1)Contribution of available nutrient from soil (%)Contribution from applied fertilizer (%)NPSBNPSBNPSB02.60.900.880.3574.312.920.913.51————502.670.841.010.360.880.010.340.1459.41290.1759.7950.01002.641.071.010.370.500.110.190.09131.89251.06135.4599,631502.250.931.000.450.230.120.090.07230.78101.02265.83149.392002.110.770.820.350.080.120.020.04620.5465.14676.14149.552502.110.740.840.280010.130.010.02407.3860.98704.90156.01


## 4.2. Nutrient Use Efficiency

Variation in agronomic use efficiency appeared to result from differences between varieties and levels of NPSB fertilizer. Among NPSB application, the Nasir variety interacted with 100 kg·ha−1 NPSB level being observed with the greatest agronomic efficiency which reached 7.43 kg·kg−1 whereas, the awassa dume variety interacted with 250 kg·ha−1 NPSB level was low agronomic efficiency which reached 1.84 kg·kg−1. As results indicated in (Table 6), the highest nutrient recovery efficiency (38.2%) was revealed with Nasir variety by fertilizer rate 100 kg·ha−1, and the lowest nutrient recovery efficiency (3.67%) and (4.15%) was found from a fertilizer rate 250 kg·ha−1 with awassa dume and Nasir varieties, respectively (Figures 3(a)–3(d) and 4(a)–4(d)). The highest physiological nutrient use efficiency (6.74 kg·kg−1) was recorded from the Nasir variety by a fertilizer rate of 100 kg·ha−1. Since overhead findings, it was manifested that higher application of nutrient has resulted in more nutrient uptake (Figures 4(a)–4(d)). In line with this result, Malakouti [31] reported that the NPK fertilizer can increase fertilizer use efficiency and grain yield for different crops. Likewise, Jones et al. [32] stated that macronutrients and micronutrients of the grain yields of common bean were also increased [31].Table 6
Effect of blended fertilizer rates on nutrient use efficiency of common bean varieties.
Treatment kg ha−1Nutrient use efficiencyAwassa dumaNasirAE (kg kg−1)RE (%)PE (kg kg−1)AE (kg kg−1)RE (%)PE (kg kg−1)00.00.00.00.00.00.0505.3b12.32f3.47efg3.86c29.98c1.95fgh1005.44b34.35b4.36cd7.43a38.32a5.57b1503.57cd15.87e4.37cd3.8c20.88d5.68b2002.48ef10.4g4.14def2.76de8.49h5.43bc2501.84fgh3.67ij4.24cde2.09efg4.15i6.4aMean3.1112.773.433.3216.974.17LSD (0.05)0.435.60.120.460.420.58CV5.096.085.040.925.070.18


## 4.3. Validation of the Fertilizer Requirement Equation

A confirmation study was leaded on the farmers’ field for one year to verify the routine of the equation. In the confirmation study, six treatments including the soil-test based of NPSB rates, 98% of the soil test-based P rate, 93% of the soil test-based S rate, 61% of the soil test-based B, and NPSB recommendations (100 kg NPSB kg ha−1) were evaluated on the grain yield of common bean verities. The data for calculating the fertilizer dose for the target yields of the awassa dume and Nasir varieties are shown in Tables 4 and 5. The application of NPSB blend fertilizer has a beneficial result of improving soil fertility and higher fertilizer use efficiency at 250 kg·ha−1 in both cases. For soil fertility management, it is necessary to select appropriate yield targets and apply fertilizers that produce the highest yields of awassa dume (2312 kg·ha−1) and Nasir (2995 kg·ha−1) at 100 kg NPSB ha−1. Consistent with Tedesse and Dechassa [33] reported that the nutrient requirements of the common bean are high yielding.


## 4.4. Partial Budget Analysis

The result of the data showed that the maximum and minimum gross benefit was obtained 70065 and 47736 ETB (Ethiopia Birr ha−1) from a fertilizer rates 100 kg·ha−1 and 0 kg·ha−1 from Nassir and Hawssa Dume varieties, respectively. The highest net benefit 67665 ETB was recorded from a treatment treated by a fertilizer rate of 100 kg·ha−1 with the Nasir variety and the lowest net benefit 47736 ETB was received with a rate of 0 kg·ha−1 from the awassa dume variety. At the same time, the maximum rate of return (8.66%) was obtained with a fertilizer rate of 50 kg·ha−1 in the awassa dume variety (Table 7) and (13.65%) with a fertilizer rate of 100 kg·ha−1 with Nasir variety (Table 8).Table 7
Marginal analysis of common bean variety as influenced by blended fertilizer rates.
Treatments (kg ha−1)VarietiesUnadjusted yield (kg ha−1)Adjusted yield (kg ha−1)GB (ETB ha−1)TVC (ETB ha−1)NB (ETB ha−1)MRR (%)0Awassa dume17681591.2047736047736050Awassa dume21331919.7575911200563918.66100Awassa dume23122080.8624242400600243.633150Awassa dume23042073.662208360058608−1.42200Awassa dume22642037.661128480056328−2.28250Awassa dume22272004.360129600054129−2.20Table 8
Marginal analysis of common bean variety as influenced by blended fertilizer rates.
Treatments kgVarietiesUnadjusted yield (kg ha−1)Adjusted yield (kg ha−1)GB (ETB ha−1)TVC (ETB ha−1)NB (ETB ha−1)MRR (%)0Nassir18521666.850004050004050Nassir20451840.5552151200540154.01100Nassir25952335.57006524006766513.65150Nassir24222179.865394360061794−5.871200Nassir24032162.764881480060081−1.713250Nassir23752137.564125600058125−1.96GB: gross benefit, TVC: total variable cost, NB: net benefit, and MRR: marginal rate of return.


## 5. Conclusion

Low use of fertilizer and crop nutrient imbalance are the major constraint in realizing the high productivity of all cultivated crops in the study area. Thus, the study was conducted to assess the effect of different levels of blended NPSB fertilizer on growth, yield, and yield components, and use efficiency of common bean varieties. Treatments consisted of two common bean varieties with six blended NPSB fertilizer rates (0, 50, 100, 150, 200, and 250 kg·ha−1) applied in RCBD with three replicates.The result of the experiment revealed that the interaction of varieties and NPSB fertilization had showed a significant (p≤0.01) effect on plant height, nodule number, nodule dry weight, number of primary branches, number of pods per plant, biomass yield, grain yield, and harvest index. The partial budget analysis indicated that the highest net benefit (67665 ETB ha−1) was obtained from variety Nasir with the application of 100 kg·ha−1 NPSB, whereas the lowest was from variety awassa dume (47736 ETB ha−1) with no fertilizer application. Thus, it can be inferred that the application of 100 kg·ha−1 NPSB with variety Nasir was found to be higher and can be used for common bean production in the study area. However, the result of the study must be validated and approved in different agroecologies to give a comprehensive recommendation for a wide range of common bean production.



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*Source: 9102273-2023-02-23.xml*