Effects of rice establishment methods on crop performance, water use, and mineral nitrogen
2002
Singh, A.K. | Choudhury, B.U. | Bouman, B.A.M.
To mitigate the increasing water scarcity in Asia, new ways of growing rice need to be developed that use less water than conventional lowland rice. An experiment was conducted in New Delhi, India, to evaluate the yield and water use of rice established by different methods: transplanting, wet seeding, and dry seeding with subsequent aerobic soil conditions on flat land and on raised beds. Transplanted rice yielded 5.5 t ha-1 and used 360 mm of water for wet-land preparation and 1,608 mm during crop growth. Compared with transplanted rice, dry-seeded rice on flat land and on raised beds reduced total water input during crop growth by 35-42% when the soil was kept near saturation, and by 47% and 51% when the soil dried out to 20 and 40 kPa moisture tension in the root zone, respectively. Most of the water saving were caused by reduced percolation losses. Moreover, no irrigation water was used during land preparation. However, the dry seeding of rice reduced yield by 23-41% on flat land and by 41-54% on raised beds compared with transplanted rice. There were no large differences in water productivity among treatments. In the topsoil, nitrogen occurred relatively more as ammonium under flooded transplanted and flooded wet-seeded conditions and as nitrate under dry-seeded aerobic conditions. The dry seeding and subsequent aerobic growing of rice face several potential yield-reducing factors that need to be studied further: micronutrient deficiency (iron), nematode and weed infestation, and proper cutivar development. When grown on raised beds, the variety needs to be able to compensate for the loss in cropped area (caused by the relatively large row spacing between the beds) by producing more productive tillers.
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