INFLUENCE OF TILLAGE, NUTRIENT AND WEED MANAGEMENT ON CHEMICAL PROPERTIES OF SANDY-LOAM SOIL AND YIELD OF SOYBEAN

Abstract

Adoption of crop management practices that are directed at achieving a self-sustaining system for soil protection is critical to sustainable crop productions. The influence of four tillage depths (T₁ = Disc plough and disc harrow at 25 cm depth, T₂ = Disc plough at 20 cm depth, T₃ = Double tillage pass of disc harrow (DDH) at 15 cm depth, T₄ =Single pass of disc harrow at 10 cm depth),three nutrient applications (N₁ = No nutrient application (Control),N₂= Farm Yard Manure (FYM) at 0.5 ton/hectare (applied during tillage operation) + 50 kg/hectare of Superphosphate applied 4 weeks after sowing, N₃ = FYM at 1 ton/hectare (applied during tillage operation) + 75 kg/hectare of Superphosphate applied 4 Weeks After Planting) and four levels of weed management (W₁ = No weeding as control, W₂ = 3 litres of pre-emergence at planting + Post-emergence (Fusillade forte) at 2.5 litres (0.14 kg/ha) of post emergence at 3WAP,W₃ = 3 litres of pre-emergence + 3 litres (0.17kg/ha) of post emergence at 5WAP,W₄= 3 litres of pre-emergence + 4 litres (0.23 kg/ha)of post emergence at 7WAP were used for the production soybean in 2018 and 2019 planting seasons. The results showed that tillage systems between 10-15 cm depth of cut favour availability and retention of soil nutrients within the tap root of soybean as in the case of T₃ (DDH at 15 cm) that recorded the highest mean values of Soil Organic Matter (SOM) (1.77), Soil Organic Carbon (SOC) (1.40), total N (0.41%), available P of 4.82 ppm and exchangeable K of 0.22 C mol/Kg. In terms of nutrient application, N₃ had the highest SOM (1.90), Mg²⁺ (1.99), Ca²⁺ (1.28), Total N (0.41), available P (4.48) and exchangeable K (1.32) during harvesting time. T₃ (DDH at 15 cm) had the highest mean values of pod/plant (74.78), 1000 seed weight (134.83g) and highest mean value of grain yield of 2.43 tons/ha, however, it was not significantly different from yield 0f 2.35 tons/ha obtained in T₁ (Disc plough and disc harrow at 25 cm depth).Weed management practices did not significantly influence soil chemical properties soil pH, soil organic matter, soil organic carbon, Magnesium, Nitrogen and others chemical properties analysed for the soil were uniformly distributed among the treatment at p≤0.05. It is important that soybean farmers adopt management practices that are directed at achieving a self-sustaining system of the soil. Hence, tillage depth at 15 cm and minimum application of compost poultry manure are recommended for a sustainable soybean production.