Direct and Residual effect of Organic and Inorganic sources of Nutrients on Maize (Zea mays)-Mustard(Brassica napus) Cropping sequence under Rainfed conditions

A study was conducted to evaluate the direct and residual effect of organic and inorganic sources of nutrients, alone and in combination on the yield of maize (Zea mays) and mustard (Brassica napus). The experiment was conducted for three years on sandy loam soil (Inceptisol) of kandi belt analyzing low in organic carbon (2.2 g kg⁻¹) and available N (150 kg ha⁻¹). Ten treatments were replicated four times in a randomized block design. The highest grain yield of maize (2646 kg ha⁻¹) was recorded with treatment receiving 100% NPK (60:40:20) coupled with 20 kg ha⁻¹ ZnS0₄ which was 94.4 ligher than control. Alternatively, residual effect of organics was pronounced leading to the highest mustard seed yield (1414 kg ha⁻¹) in the treatment receiving 101 FYM ha⁻¹ with 61.8% higher yield than control. The combined use of organics and inorganic fertilizers proved superior to inorganic fertilizers alone in influencing mustard seed yield. The lowest maize (1361 kg ha⁻¹) and mustard seed yield (874 kg ha⁻¹) was recorded in the control. The fertilizer applied to maize showed significant effect on nutrient uptake of mustard crop. The maximum N, P and K uptake (102.6, 21.4 and 105.0 kg ha⁻¹, respectively) was recorded in maize with the application of 100% recommended NPK through fertilizers + 20 kg Zn S0₄ ha while minimum in control. Consequently, mustard showed maximum N and P uptake (31.6 and 7.3 kg ha⁻¹ respectively) with the application of 50% recommended NPK through fertilizers + 50% N through FYM and maximum K (26.4 kg ha-⁻¹) with FYM. The organic carbon and available-N content showed significant increase of 3.0 g kg⁻¹ and 31 kg ha⁻¹ respectively in 10 t FYM ha⁻¹ treated plots.