Effect of Rice (Oryza sativa L.) Establishment Methods and Integrated Weed Management on Productivity and Soil Fertility in Eastern Himalayas, India

Field experiments in 2010 and 2011 was conducted during kharif season to evaluate the effect of integrated weed management practices on productivity, nutrient uptake, nutrient harvest index and residual soil fertility status in wetland rice crop ( Oryza sativa L., Ranjit) under different establishment methods. Wetland rice under SRI method gave significantly higher grain productivity (5.63 tha -1 ) at par with ICM method (5.58 tha -1 ).  However, significantly higher grain productivity of wetland rice was obtained with hand weeding twice at 20 and 40 DAT (5.89 tha -1 ) at par with butachlor 50 EC@1.5 kg a.i. ha -1 at 3 DAT + cono-weeding at 20 DAT (5.78 tha -1 ). Uptake of N, P and K was recorded higher in grain and straw with SRI method followed by ICM and CRC. Total mean uptake of N, P and K by wetland rice was recorded higher with SRI method (81.06, 21.76 and 42.02 kgha -1 , respectively) followed by ICM and CRC methods. Meanwhile, hand weeding twice at 20 and 40 DAT recorded significantly higher N, P and K uptake in grain and straw closely followed by butachlor 50 EC@1.5 kg a.i.ha-1 at 3 DAT + cono-weeding at 20 DAT. However, significantly higher mean value of NHI and PHI was recorded with CRC while, higher mean value of KHI was recorded with ICM (34.93%) followed by CRC and SRI. The highest NHI, PHI and KHI were recorded with cono-weeding twice at 20 and 40 DAT (79.80, 58.88 and 36.60%, respectively). The highest mean pH, OC and SMBC of 5.133, 0.58% and 172.78 µgg -1 soil, respectively, was recorded in SRI method followed by ICM and CRC.  However, the pH, OC, SMBC, available N, P and K in soil had left significantly higher with hand weeding twice at 20 and 40 DAT (264.22, 9.55 and 283.69 NPK kgha -1 , respectively) over control and in comparison with other treatments. Hence, integrated weed management in SRI with butachlor 50 EC @ 1.5 kg a.i.ha -1 + cono-weeding at 20 DAT and ICM with hand weeding twice at 20 and 40 DAT can be adopted to obtain higher productivity, nutrient uptake, nutrient harvest index and better soil health in wetland rice ecosystem of West Garo Hills district of Meghalaya, India as compared to CRC method.