Evaluation of Sesbania bispinosa leaves applied as a green manure supplement to inorganic fertilizers.
A pot experiment was conducted to study the effect of adding dried and ground leaves of sesbania (Sesbania bispinosa) at 0, 12, 24, 36 and 48 t/ha, to soil supplemented with 200 kg/ha N as ammonium sulfate and urea. Glazed pots (26.5×26.5 cm) were filled with sandy clay loam soil to which leaves and inorganic fertilizers were added. The sesbania leaves contained 2.8% nitrogen. Wheat was sown in Nov. 19 as a test crop. All the normal cultural practices were given to the crop, and 120 days after sowing the crop was harvested and the dry matter yield and N content of the plants recorded. Soil was sampled after wheat harvest and total NH4-, NO2- and NO3-N determined. The dry matter yield of wheat was significantly increased by the addition of sesbania leaves, with the increase being related to the increase in leaf doses. The 48 t/ha sesbania treatment gave yields about 66.2% higher than the control (0 t/ha) treatment. Sesbania leaves significantly increased the N content of plants, N uptake by the plants, and N content of the soil recorded after crop harvest. Sesbania application increased soil NO3-, NO2- and NH4-N proportionally to the dose applied. Nitrogen recovery from the soil was best at the 12 t/ha dose and decreased proportionally at higher doses. There was a 4.5% gain of soil N where N fertilizer alone was applied, but losses in proportion to the dose occurred when sesbania leaves were added.