Response of foliar application of iron and green manuring in dry direct-seeded andtransplanted rice (Oryza sativa)

摘要

Rice (Oryza sativa L.) production in northwest part of Indo-Gangetic Plains (NW-IGP) is critical for food security of India because this region contributes more than 40% of the rice procured by government of India for its buffer stock and distributionto public. Rice in this region is grown following the traditional system of puddled transplanted rice (PTR) and requires huge labour and large amount of water. Water and labour, however, are becoming increasingly scarce in the region raising the questions of environmental sustainability and sustainability of rice production systems. In NW-IGP, increasing use of groundwater for rice cultivation has led to declines in water table by 0.1 to 1.0 m/yr, resulting in water scarcity and increased cost for pumping water (Rodell etal. 2009). Implementation of the Mahatma Gandhi National Rural Employment Guarantee Act, introduced by the Indian government in 2005 (GOI2011), promising 100 days of paid work in people's home village, has been creating a labour scarcity in Punjab and Haryana which are the cereal bowl of north-west India. This suggests that alternatives to puddled transplanted rice are required to save water and increase crop and labour productivity. Dry seeding of rice with subsequent aerobic soil conditions eliminates the need of puddling and maintaining submerged soil conditions, thus reducing the overall water demand and providing opportunities for water and labour savings. Since the concept of dry direct seeding (DSR) under high input environment is new, relatively few insights exist for fertilizer N use for higher productivity in DSR. Alternate moist-dry soil conditions in DSR may stimulate nitrification-denitrification processes, resulting in a loss of nitrogen through N_2 and N_20.