WEED DYNAMICS AND YIELD OF WHEAT IN LONG TERM SOIL FERTILITY EXPERIMENT UNDER RICE-RICE-WHEAT CROPPING SYSTEM

A long-term soil fertility experiment under rice-rice-wheat system was conducted to evaluate the long term effects ofinorganic fertilizer and manure applications on weed dynamics and grain yield of wheat during winter season of2018-19. The experiment was laid out in randomized complete block design with nine treatments replicated threetimes. Treatments were applied as: T1- no nutrients added, T2- N added; T3- N and P added; T4- N and K added;T5- NPK added at recommended rate for all crops. Similarly, T6- only N added in rice and NPK in wheat atrecommended rate; T7- half N; T8- half NP of recommended rate for both crops; and T9- farmyard manure (FYM)@10 t ha-1for all crops in rotation.The data revealed that the use of recommended fertilizer dose of 100:40:30N:P2O5:K20 kg ha-1 gave significantly (P≤0.05) higher wheat yield of 2383 kg ha-1followed by Farm Yard Manure(FYM) @10 t ha-1 of 2193 kg ha-1. Considerably, lower grain yield was obtained from treatments that did notreceive phosphorus as compared to treatments that received NPK (T5), T6 and FYM (T9).It was also observed eightweed species (Chenopodium album, Cynodon daactylon, Anagalis arvensis, Solanum nigrum, Medicago denticulate,Vicia sativa, Lathyrus vestitus and Cyperus rotandus) from six families (Amaranthaceae, Poaceae, Primulaceae,Solanaceae, Fabaceae and Cyperaceae) were recorded in the experimental field. Similarly, application of FYM@10 t ha-1 followed by recommended fertilizer dose recorded higher weed density and dry weed weight withcompared to any of N,P2O5 and K2O or all omitted treatments.