Nutrient composition, uptake by weeds and rice under different crop establishment and weed management practices

Field study was conducted during the kharif, 2011 at Agronomy Research Farm, Central Research Station, Orissa University of Agriculture and Technology, Bhubaneswar to assess the nutrient concentration and uptake by weeds and crops under different crop establishment methods. Weedy check recorded highest nutrient content of weeds. Weedy check plot recorded the maximum N, P and K content of 0.83, 0.13 and 1.3% respectively. The removal of N,P and K (82.45,13.42 and 127.74 kg ha−1) was the highest in the same treatment and the lowest nutrient uptake by conoweeding N,P and K was 0.73, 0.13 and 1.25% and removal of N,P and K (kg ha−1) was 17.34, 3.11 and 29.44 respectively. The nutrient content of grain and straw of rice in conoweeding was maximum recording N, P and K of grain are 1.33, 0.37 and 1.26% respectively. The corresponding values for straw were 0.44, 0.10 and 1.82% respectively. The weedy check recorded the lower values of N, P and K content as compared with weed control treatments. Nutrient uptake of rice crop showed that maximum uptake of nutrient was recorded in SRI (62.72 and 25.13 kg ha−1 of N, 17.06 and 5.26 kg ha−1 of P and 13.04 and 101.11 kg h−1a of K in grain and straw respectively) it was followed by transplanting, drum seeding and line sowing. Minimum depletion of 47.34 kg of N, 11.18 kg ha−1 of P and 67.54 kg ha−1 of K was observed in weedy check taking the total values of grain and straw. The highest benefit: cost ratio were recorded in the SRI supplemented with conoweeder.