Potassium (K) and magnesium (Mg) are essential plant macronutrients responsible for mitigation of biotic and abiotic stresses as well as enhancement in yield of maize. In rainfed maize, low productivity due to imbalanced use of fertilizers, erratic rainfall and periodic dry spells are major constraints. Hence, a field experiment was conducted in rainy season during 2015, 2016 and 2017 on an Inceptisol to optimize the levels of K and Mg in rainfed maize. The experiment consisted of four levels of K; control, K @20 kg ha⁻¹, K@30 kg ha⁻¹ and K 40 kg ha⁻¹ and four levels of Mg; control, Mg@15 kg ha⁻¹, Mg@30 kg ha⁻¹, and Mg@45 kg ha⁻¹. Application of K and Mg improved leaf area Index, chlorophyll content and relative water content in maize. Yield attributes of maize also improved significantly with application of K and Mg over control. Highest grain yield (3205 and 3169 kg ha⁻¹) was recorded with the application of 40 kg K ha⁻¹and 45 kg Mg ha⁻¹, respectively which was at par with 30 kg K ha⁻¹ (3103 kg ha⁻¹) and 30 kg Mg ha⁻¹ (3106 kg ha⁻¹), respectively. The highest net returns (US $347 ha⁻¹) and BC ratio (1.72) was recorded with 40 kg K ha⁻¹ while application of 30 kg Mg ha⁻¹ recorded highest net returns (US $332 ha⁻¹) and BC ratio (1.71). Application of 30 kg K ha⁻¹ and 30 kg Mg ha⁻¹ was found to be optimum to improve growth, yield and nutrient uptake in rainfed maize.

An experiment was conducted at Punjab Agricultural University, Ludhiana during 2014–15 and 2015–16, keeping four sowing dates {25th Oct (D₁), 10th Nov (D₂), 25th Nov (D₃) and 10th Dec (D₄)} in main plots and five irrigation schedules {irrigation at 15 (FC₁₅), 25 (FC₂₅), 35 (FC₃₅) and 45 (FC₄₅) % depletion of soil moisture from field capacity (FC) and a conventional practice} in sub plots. The objective of the study was to evaluate the performance of CERES-Wheat model for simulating yield and water use under varying planting and soil moisture regimes. The simulated and observed grain yield was higher in D₁, with irrigation applied at FC₁₅ as compared to all other sowing date and irrigation regime combinations. Simulated grain yield decreased by 19% with delay in sowing from 25th October to 10th December because of 8% reduction in simulated crop evapotranspiration. Simulated evapotranspiration decreased by 16%, wheat grain yield by 23% and water productivity by 15% in drip irrigation at 45% depletion from field capacity as compared to drip irrigation at 15% of field capacity. It was further revealed that the model performed well in simulating the phenology, water use and yield of wheat.