Integrated Nutrient Management Studies for Higher Productivity of French Bean (Phaseolus vulgaris L.) in Calcareous Soil of Bihar, India

French bean (Phaseolus vulgaris L.), is one of the most important and widely cultivated legume crops on the globe (Anonymous, 2017; Anonymous, 2020). The crop thrives well in diverse environments of the world ranging from tropical to temperate regions (Mongi et al., 2016). It is a short duration and highly relished vegetables in North India (Anonymous, 2020).
       
French bean is consumed in various forms such as green vegetable, green shelled, or dry as pulses (Lyngdoh et al., 2018). It is an excellent source of protein and is cooked fresh or processed as frozen (Sachan and Krishna, 2020). Hundred grams of green pods contain approximately 1.7 g protein, 4.5 g carbohydrates, 221 I.U. vitamin A, 11 mg vitamin C and 50 mg of calcium (Gopalakrishnan, 2007; Kanwar et al., 2020).
       
Over the decade, the pressure on legume production has increased significantly, leading to the extensive use of chemical fertilizers (Datt et al., 2013; Sachan and Krishna, 2021). Excessive use of chemical fertilizers in French bean increases the chances of residual toxicity in the harvested produce which not only affects the human health but also hampers export of the harvested beans (Anonymous, 2021; Sachan and Krishna, 2020). 
       
Apart from human health the excessive use of chemical fertilizer in field deteriorates the soil health (Ramana et al., 2010; Kanwar et al., 2020). The solution of such an alarming issue probably lies in use of organic manures either solely or in combination with the chemical fertilizers (Sachan and Krishna, 2020).
       
Considering the fact that organic manures heal the soil attributes and with slow release of nutrients (Chauhan et al., 2010) compared to that of quick availability by inorganic fertilizers, an integrated approach by combination of both the component of chemical fertilizer with organic manure can be a possible solution to this (Datt et al., 2013; Kanwar et al., 2020).
       
Among the highly efficient organic manures ‘Farmyard Manure’ and ‘Vermicompost’ found to be best in improving production and quality of beans while retaining the soil health (Patel et al., 2017; Sachan and Krishna, 2020). This approach can play an important role in French bean cultivation, especially in calcareous soil regions (Kumar et al., 2014) such as in Bihar, India where retaining soil properties is equally important to achieve sustainable production of French bean (Ramana et al., 2010; Sachan and Krishna, 2020). Keeping this in view, an experiment was conducted to determine the effect of integrated nutrient management on growth and yield parameter of French bean in calcareous soil of Bihar, India.

The experiment was conducted during Rabi 2017-18 and 2018-19 at the Vegetable Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur situated at 25.98^o N latitude and 85.68^o E longitude with an altitude of 52.0 m above the mean sea level. The soil of the experimental field is deep and comes under the soil order Entisols, loamy sand in texture, whitish-brown in color and alkaline in reaction. This is due to presence of excess free CaCO3 (23.62%) in surface soil. A commercial French bean variety ‘Arka Suvidha’ was collected from ICAR-Indian Institute of Horticultural Research (IIHR), Bengaluru for trial during the course of investigation. The experiment comprises of eight treatments and was laid out in randomized block design with three replications (Table 1).
 

       
The pH of the experimental field was 7.94 to 8.12, EC 0.46 to 0.53 dSm^-1, CEC [c mol (p+) kg^-1] 11.26 to 13.14 and organic carbon was 0.36%. The N status of the experimental field were low (184 to 206 kg ha^-1), low in available P (18.40 to 20.14 kg ha-1) and medium in available K status (143.2 to 157.4 kg ha^-1). 
       
With context to treatment, the well decomposed FYM, Vermicompost and NPK fertilizer (urea, SSP and MOP) were procured from ‘Vegetable Research Farm of RPCAU, Pusa and were incorporated thoroughly in the soil at the time of field preparation as per the treatment layout (Table 1). The full dose of phosphorus and potash and ½ dose of nitrogen were applied at the time of sowing, whereas, half dose of nitrogen was applied as split dose one month after sowing. The source of nitrogen, phosphorus and potash were urea, SSP and MOP, respectively.
       
The healthy and bold seeds were sown at the spacing of 45 cm × 15 cm. All cultural operations and irrigations were carried out as per crop requirement and recommended schedule.
       
Observations on various growth and yield attributes were recorded from five random healthy plants of each treatment. The experimental data recorded were subjected to statistical analysis using analysis of variance technique suggested by Panse and Sukhhatme (1984) and analysed using statistical software of ICAR-Indian Agricultural Statistics Research Institute, New Delhi. Further, the benefit cost ratio was calculated by using the mean value of yield data.

Growth parameters
 
‘Plant height (cm) at harvest’, ‘Number of primary branches per plant’ and ‘Number of leaves per plant’
 
On the basis of two years pooled data, our results revealed that the various growth parameters increased significantly over control by the application of various organic and inorganic fertilizers (Table 2). This increase in growth attributes might be due to the enhanced photosynthetic activity, cell division, elongation and differentiation through the applied NPK in form of inorganic fertilizer and combination with organic manure (Metkari and Dhok, 2011), resulting in higher increment of growth attributes (Jagdale et al., 2005; Chauhan et al., 2010).
 

       
Among the treatments, application of ‘75% NPK through inorganic + 25% N through Vermicompost (T3)’ was recorded the best as it exhibited the highest plant height (34.04 cm), maximum numbers of primary branches (6.85) and maximum number of leaves (32.46) remaining statistically at par with the treatment ‘75% NPK through inorganic + 25% N through FYM (T2)’ and were significantly superior over control (T8) which exhibited the minimum plant height (22.80 cm), numbers of primary branches (3.83) and number of leaves (24.19). While comparing in terms of percentage growth, the treatment T3 recorded 49.30%, 78.85% and 34.19% increase in plant height, numbers of primary branches and number of leaves respectively over control (T8).
       
The increased growth with substitution of 50% N by organic manures might be due to the fact that organic manures release of nutrients slowly (Sharma et al., 2015), which resulting in enhanced nutrient use efficiency (Verma et al., 2015; Mohanty et al., 2017) and micro-nutrients availability (Nawalgatti et al., 2009; Shubhashree et al., 2011). 
 
Yield parameters
 
‘Pod length (cm)’, ‘Pod circumference (cm)’, ‘Average fresh weight of pod (g)’ and ‘No. of seeds /pod’
 
The results revealed occurrence of significant increase in various yield attributes over control by the application of organic and inorganic fertilizers except ‘average fresh weight of pod’ (Table 3).
 

       
Among the treatments, the treatment level ‘75% NPK through inorganic + 25% N through Vermicompost (T3)’ exhibited the highest ‘pod length’ (3.09 cm), ‘pod circumference’ (3.13 cm), ‘no. of seeds /pod’ (7.54) and ‘no. of pods/plant’ (20.46) which was at par with the treatment level ‘75% NPK through inorganic + 25% N through FYM (T2)’. The minimum values of yield attributes i.e. ‘pod length’ (8.48 cm), ‘pod circumference’ (2.32 cm), ‘no. of seeds/pod’ (5.69) and ‘no. of pods/plant’ (11.22) were recorded in control. The exhibited higher yield of treatment comprising of inorganic fertilizers in combination with organic manures may be due to the increased availability and uptake of macro and micro nutrients by the plant, resulting in higher rate of physiological (Barcchiya and Kushwah, 2017) and anabolic processes (Sen et al., 2006; Ramana et al., 2010).
       
The percentage comparison reflects that treatment level III i.e. ‘75% NPK through inorganic + 25% N through Vermicompost (T3)’ recorded and increase of 33.09%, 34.91%, 32.51% and 82.35% of ‘pod length’, ‘pod circumference’, ‘no. of seeds/pod’ and ‘no. of pods/plant’ respectively over the control (T8) plant.
       
In context to yield, the maximum yield (95.61 q/ha) was recorded with 75% NPK through inorganic + 25% N through Vermicompost (T3) showing 125.39% and 35.17% increase over T8 (Control) and T1 (RDF) respectively, while the minimum yield (42.42 q/ha) was recorded with control (T8) where no fertilizer or compost was applied. However, no statistical difference was found between yield of treatment level III (95.61 q/ha) i.e. ‘75% NPK through inorganic + 25% N through Vermicompost (T3)’ and treatment level II (90.11 q/ha) i.e. ‘75% NPK through inorganic + 25% N through FYM (T2)’. Further, the treatment level III (75% NPK through inorganic + 25% N through Vermicompost), treatment level II (75% NPK through inorganic + 25% N through FYM), treatment level V (50% NPK through inorganic + 50% N through Vermicompost) and treatment level IV (50% NPK through inorganic + 50% N through FYM) were at par with each other. The data on ‘average fresh weight of pod (g) indicated that there was no significant difference between the treatments for this attribute, which reflect that the treatments doesn’t have any adverse effect on the ‘Average fresh weight of pod’ (Manivannan et al., 2009; Barcchiya and Kushwah, 2017).
       
From an over view on our findings of growth and yield attributes, our results revealed that fertilizer requirement of French bean when met through 50-75% NPK through inorganic + 25-50% N through organic sources from either through Vermicompost or FYM, resulted in better yield and productivity (Table 3). This might be due to the ability of organic source to influence both the growth as well as yield attribute compared to that of sole application of (100% NPK) through inorganic source. This positive influence might be due the the favourable soil condition developed by the application of organic manure (Sharma et al., 2015; Bhathal and Kumar, 2016) which thereby positively influencing the economic traits such as growth (Chauhan et al., 2010; Mohanty et al., 2017) and yield attributes (Das et al., 2011; Ramana et al., 2011).
 
Benefit cost ratio
 
The data on economics of various treatments (Table 4) revealed that the maximum benefit-cost ratio (2.16) was recorded in treatment T3 i.e. 75% NPK through inorganic + 25% N through Vermicompost, which was followed by benefit-cost ratio 2.03 of treatment level II (75% NPK through inorganic + 25% N through FYM). The differences in benefit cost ratio defines and reflects the practical utility of the treatment level of integrated nutrient management (Ramana et al., 2010; Sachan and Krishna, 2020).
 

It can be concluded from the study that application of inorganic fertilizers when combined with organic sources of manures resulted in better growth and yield of French bean in calcareous soil of Bihar, India. It is noted that the application of 75% NPK through inorganic + 25% N through Vermicompost resulted in best yield (95.61 q/ha) and highest benefit-cost ratio (2.16).

The authors acknowledge ICAR-Indian Institute of Vegetable Research, Varanasi, India for providing the financial assistance and facilities to carry out this study under All India Coordinated Research Project on Vegetable Crops.