Rice direct seeding: Experiences, challenges and opportunities

Rice is one of the most important food crops in the world, and staple for more than half of the global population. Looming water crisis, water-intensive nature of rice cultivation and escalating labour costs drive the search for alternative management methods to increase water productivity in rice cultivation. Direct seeded rice (DSR) has received much attention because of its low-input demand. It involves sowing pre-germinated seed into a puddled soil surface (wet seeding), standing water (water seeding) or dry seeding into a prepared seedbed (dry seeding). In Europe, Australia and the United States, DSR is highly mechanised. The development of early-maturing varieties and improved nutrient management techniques along with increased availability of chemical weed control methods has encouraged many farmers in the Philippines, Malaysia, Thailand and India to switch from transplanted to DSR culture. This shift should substantially reduce crop water requirements, soil organic-matter turnover, nutrient relations, carbon sequestering, weed biota and greenhouse-gas emissions. Still, weed infestation can cause large yield losses in DSR. In addition, recent incidences of blast disease, crop lodging, impaired kernel quality and stagnant yields across the years are major challenges in this regard. In this review, we discuss the experiences, potential advantages and problems associated with DSR, and suggest likely future patterns of changes in rice cultivation. (C) 2010 Elsevier B.V. All rights reserved.