Monocropping systems have intensively exploited natural resources in recent decades, and the indiscriminate use of inorganic fertilizers, combined with agro-chemicals, has resulted in the deterioration of natural resources such as soil and water, resulting in the loss of soil fertility. Agroforestry is an ideal scientific strategy for eco-restoration of degraded areas and sustainable resource management when compared to mono cropping systems. It is a land management and farming strategy that aims to not only produce food from marginal agricultural land, but also to significantly improve the quality of the environment and soil. When compared to regular crop removal in a solo cropping system, leaf litters and their breakdown under tree-based vegetation favour nutrients enrichment. The adoption of an agroforestry system resulted in the accumulation of soil organic carbon, increased the availability of macronutrients and micronutrients, and improved the microenvironment for plant growth. As a result, pairing suitable tree species with agricultural crops can contribute in the maintenance or enhancement of soil fertility. Based on these findings, it is advised that farmers adopt agroforestry systems since they have enormous potential to improve soil fertility, leading to increased crop output and food security.

Soil phosphorous (P) can limit plant growth due to its fixation which stipulates the changes occuring due to imbalanced fertilization in pearl millet-wheat system. The study was aimed to identify the long-term effect of fertilizers and manures on availability of P due to changes in soil inorganic (Pi) and organic P (Po) pools at 0–15, 15–30, 30–60, and 60–90 cm. A sequential methodology was used to determine the effect of fertilizers and manures w.r.t. control (CK) on pools of P and their distribution in soil profile. Fertilizers and manures significantly increased the total and available P concentration. Labile (LOP) and moderately labile (MLOP) organic phosphorous concentrations significantly (P < .05) impacted throughout the soil profile. However, moderately and highly stable organic P pools (MSOP & HSOP) were significantly higher at surface soils. Integrating manures with fertilizers (NPKM) for 10 years increased the LOP and MLOP by 121.5 and 50.0%, while the concentration of MSOP and HSOP was higher under fertilizer treatments (NPK and BF_STCR) at surface soils. The P_i associated with Saloid-P, Aluminium-P, and Iron-P showed decreasing concentration, while calcium-phosphorous concentration increased at all soil depths. The increase in residual-P was more pronounced at lower depths. The proportion of Pi to the total P increased to 16.8% in fertilizer treatments at 30–60 and 60–90 cm soil, while Po proportions increased to 21.0% at 0–15 cm soil. Integrating manures with fertilizers could be a viable nutrient management practice of enhancing the Po and Pi and their availability to plants in sandy soils of Inceptisols.

Field experiments were conducted on Bt cotton to investigate soil test crop response under integrated plant nutrient system (STCR-IPNS) by following Ramamoorthy's inductive approach of fertility gradients in Inceptisols at Research Farm, Department of Soil Science, CCS Haryana Agricultural University, Hisar during 2011–12 and 2012–13. The experiments were carried out on well developed fertility gradients w.r.t. available N, P and K in the preceding season before sowing of Bt cotton having wide variability of N (105 to 175 kg ha⁻¹), P (10 to 32 kg ha⁻¹) and K (208 to 392 kg ha⁻¹). The nutrient requirement (NR), contribution of nutrients from soil (CS), fertilizer (CF) and farmyard manure (CFYM) were computed using the data on soil test values, fertilizer nutrients doses, uptake of nutrients and seed cotton yield obtained from the main fertility experiments for both the years. The nutrient requirement for producing one quintal of seed cotton was found to be 3.58, 1.20 and 3.50 of N, P₂O₅ and K₂O, respectively. The per cent contribution from soil and fertilizer were found to be 50.65 and 26.00 for N, 55.50 and 26.60 for P₂O₅ and 29.50 and 45.79 for K₂O, respectively. The per cent contribution from FYM was 3.70, 3.32 and 4.35 for N, P₂O₅ and K₂O, respectively. Making use of these parameters, the soil test based fertilizer prescription equations were developed under IPNS for desired yield targets of Bt cotton. The ready reckoner for making fertilizer recommendations for N, P₂O₅ and K₂O nutrients at varying soil test values in Bt cotton was prepared for attaining yield targets of 28, 30 and 32 q ha⁻¹.

CropSyst simulation model was tested during the rainy seasons of 2007 and 2008 and the winter seasons of 200708 and 200809 at New Delhi, to study the long and wide-spread adoptability of pearlmillet [Pennisetum glaucum (L.) R.Br. emend. Stuntz.]chickpea (Cicer arietinum L.) cropping system by comparison of simulated and observed variables. The observed variables collected from the experimental data were used to study the ef- fect of nitrogen (N) levels in pearlmillet and water levels in chickpea for pearlmillet chickpea crop rotation. The calibration, validation and sensitivity analysis of CropSyst model was utilized to quantify and verify the interactive effect of different water and N treatments on the productivity of pearlmilletchickpea crop rotation using measure- ments from field experiments. Results showed that CropSyst model performed well at lower levels of N treatments (60 kg/ha) whereas at higher levels of N treatments (90 kg/ha) the predicted values were lower than the observed values. The model also responded well to limited level of irrigation in pearlmillet, but in chickpea irrigation did not have a significant influence on biomass yield as predicted by the model. The model was tested for accuracy in de- termination of the crop parameters by conducting sensitivity analysis of the model, which depicted that crop pa- rameters, viz. light to above-ground biomass conversion, specific leaf area, phenological degree-days, base tem- perature, stem/leaf partition coefficient needs more accuracy during its calibration and validation. Also, the root mean square error (RMSE) for biomass and grain yield was found to be 1.97 and 0.36 t/ha, being 5 and 7% of the observed mean, respectively, in pearlmillet whereas for chickpea it was 0.40 and 0.17 t/ha which, in turn, was 8 and 6% respectively. These low values of RMSE indicates that the CropSyst model is highly accurate in predicting grain yield and above-ground biomass of pearlmilletchickpea crop rotation.

A field experiment was conducted at Research Farm of CCS Haryana Agricultural University, Hisar during kharif 2018 to refine the pre-existing fertilizer prescription equations of nitrogen (N), phosphorus (P₂O₅) and potassium (K₂O) for Bt. cotton hybrids and its validation was done at different locations of semi-arid regions of Haryana with the aim to balance the use of fertilizers for higher productivity and better soil health during kharif 2019 and 2020. Using the experimental data, the basic parameters viz. nutrient requirement (NR), per cent contribution of nutrients from soil (CS), fertilizers (CF) and farmyard manure (CFYM) towards total nutrient uptake by Bt. cotton were computed based on soil test crop response (STCR) targeted yield approach. The nutrient required to produce one quintal of seed cotton yield was 1.68, 0.8 and 1.18 kg N, P₂O₅ and K₂O, respectively. It was observed that 27.89, 45.21 and 6.24% of N, P₂O₅ and K₂O, respectively were contributed from the soil in achieving the desired yield targets while it was 11.25, 20.79 and 78.73% for N, P₂O₅ and K₂O, respectively from fertilizers. These basic parameters were used in generating the refined fertilizer prescription integrated plant nutrient system (IPNS) based equations for Bt. cotton. Based on these fertilizer prescription equations, the ready reckoners were formulated for desired yield targets of 2.8, 3.0 and 3.2 t ha⁻¹ at varying soil test values of N, P₂O₅ and K₂O, respectively. The ready reckoner of Bt. cotton at different yield targets showed the extent of saving the fertilizers under IPNS as compared to that of general recommended dose of fertilizers (175:60:60 kg ha⁻¹::N:P₂O₅: K₂O). Validation of fertilizer prescription equation of Bt. cotton at different locations of Haryana showed the highest mean seed cotton yield in STCR-IPNS 3.2 which decreased in the following order: STCR-IPNS 3.2 > STCR 3.2 > STCR-IPNS 2.8 > STCR 2.8 > GRD >FP > control. The response to fertilizer application also followed the same trend. The maximum variation of 30.0% was observed under STCR-IPNS 3.2 treatment while an increase of 28.0% in seed cotton yield was observed in STCR 3.2 treatment over the farmer's practice. The balanced fertilization due to STCR approach resulted an increase in B:C up to 14.40 Rs/Re ranging from 12.49 to 14.40 Rs/Re under different STCR and STCR-IPNS treatments in Bt. cotton. The results clearly revealed that the STCR based fertilizer recommendations for 3.2 t ha⁻¹ yield targets under irrigated conditions in cotton growing area of Haryana proved superior over generalized recommended dose due to higher productivity, response and benefit to farmers.