Amitava Rakshit

Site-Specific Nutrient Management (SSNM): A Unique Approach Towards Maintaining Soil Health

Agricultural production in India has increased from ~50 Mt in 1950 to ~251 Mt in 2011–2012 by the intensive use of external inputs. The negative nutrient balance due to the imbalanced fertilization to the tune of ~8–10 Mt is reported, resulting in nutrient mining, stagnation and/or deceleration in productivity and soil health decline. The indispensable role of geo-informatics (RS, GPS and GIS) aided site-specific nutrient management (SSNM) for efficient use of resources and nutrients is suggested for achieving the projected food production target ~300 Mt by 2025. Towards the better response of SSNM over blanket fertilizer recommendation in terms of nutrient use efficiency (NUE), productivity and profitability is reported and discussed under Indian context. Long-term pooled data across several locations in India revealed an increase in yield of rice and wheat crops by ~12 and 17% and profitability by ~14 and 13%, respectively as an outcome of SSNM. Web based farmers’ advisory launched recently in the state of West Bengal is reported. The development of such dissemination mechanisms that consolidates the complex and knowledge-intensive SSNM information into simple delivery system is suggested for rapid implementation by the farmers towards maintaining soil health and ensuring future generation food security.

Determination of Soil Water Stress Coefficient by different Methods for Computing Crop Transpiration Under Bed Planted Pigeon Pea

To achieve the potential crop yield, time and amount of irrigation required for a particular crop under field condition should be quantified. Since soil water stress occurs after few days of irrigation, it affects root water uptake and hence transpiration rate. This stress effect can be quantified by soil water stress coefficient (Ks). Whenever, total available water (TAW) and readily available water (RAW) data are available, a simple Ks calculation can be done. To present a more realistic scenario, Ks can also be computed from simulated root water uptake (RWU) using HYDRUS-2D model. To check the reliability of model, our study was conducted under permanent raised bed with residue (PBB+R) and conventional tillage (CT) system in a pigeonpea (Cajanus cajan (L.) Millsp.)-wheat (Triticum aestivum) cropping system with the objective to compare actual measured transpiration rate with those simulated from model and calculated from FAO method. Soil water balance simulated (100-125 DAS) from HYDRUS-2D model showed higher cumulative root water uptake (CRWU) (1.72 cm), lower cumulative evaporation (CE) (0.34 cm) and higher soil water retention in PBB+R than in CT. Ks calculated from both the methods showed that under low soil moisture condition in root zone, Ks significantly reduced RWU whereas when root zone is sufficiently wet, Ks have very negligible effect. Model simulated actual transpiration rates were comparable with observed values whereas values computed from FAO method showed substantial deviation. Thus Ks obtained from model output showed the better soil moisture stress condition of the profile as it takes into account root growth parameters, radiation interception and crop canopy conditions. So, this model may be adopted for evaluating different management practices in terms of improvement in soil water use.

Herbicides, Nitrogen-Scheduling and –Rates Effects on Economics of Wheat (Triticum aestivum L.)

A field experiments was conducted during winter seasons of 2010–11 and 2011–12 at Agricultural Research Farm, Banaras Hindu University, Varanasi to study the effect of herbicide mixtures and differential rate of nitrogen application of economics of wheat under Indo-Gangetic Plains of eastern Uttar Pradesh. The experiment was laid out in factorial randomized complete block design and replicated thrice, having three factors. First factor comprised of three herbicides viz. weedy check, sulfosulfuron + metsulfuron [32 g ha−1] and carfentrazone [10 g ha−1] + fenoxaprop-p-ethyl [100 g ha−1], whereas, second and third factors comprised of two nitrogen rates (120 kg N ha−1 and 160 kg N ha−1) and three times of nitrogen application (50% basal + 50% CRI, 50% basal + 25% CRI + 25% flowering and 33.3% basal + 33.3% CRI + 33.3% flowering), respectively. Significantly highest grass return, net return and benefit cost ratio were observed with application of sulfosulfuron + metsulfuron [32 g ha−1]. Increasing nitrogen level from 120 to 160 kg ha−1 significantly increased the economic return. Application of nitrogen in three split (50% basal + 25% CRI + 25% flowering) proved significantly in term of grass return, net return and benefit cost ratio over other split application of nitrogen.

An economics of rice cultivation through appropriate management of zinc under northern gangetic alluvial plain

A field experiment was conducted to study the economics of rice cultivation through appropriate management of zinc at Agricultural Research Farm of Institute of Agricultural Sciences, Banaras Hindu University during the two consecutive kharif (rainy) seasons of 2010 and 2011. The experiment was laid out in randomized block design with three rice varieties (HUR-105, HUBR 2–1 and PHB-71) and seven zinc treatments. The hybrid PHB 71 showed the highest gross return of 78007 and 79570, but HUR 105 recorded maximum net return of 46886 and 48180 and B: C ratio 2.58 and 2.63 in year 2010 and 2011, respectively. Amongst the zinc treatments, application of Zn (EDTA) 0.25 kg ha-1 at basal + Zn (EDTA) 0.05% sprays at maximum tillering stage resulted in maximum gross return of 87211 and 88531), net return of 57572 and 58892 and B: C ratio 2.94 and 2.99 and was found economically feasible during both the years of experimentation.