Prospects for Permanent Beds for the Rice-Wheat System

Abstract

The ability of the rice–wheat (RW) system of the Indo-Gangetic Plains (IGP) to continue to meet the food needs of an increasing population is threatened by yield stagnation, resource sustainability, and environmental pollution. An important question is whether prolonged puddling and ponding for rice and the flat, poorly drained layouts required for ponding are inimical to high aggregate productivity and efficient resource use of the RW system. The evidence for the adverse effects of the puddled, flat layout on wheat productivity in the RW system, however, is scant, inconsistent, and inconclusive. It may depend on soil type and site-specific management, and needs more comprehensive investigation. Even so, issues of resource use warrant research on a radical redesign of the system, such as the use of permanent beds. Permanent raised beds may offer farmers significant advantages, such as reduced tillage, increased opportunity for crop diversification, mechanical weeding and placement of fertilizers, opportunities for relay cropping and intercropping, and water savings. Such a radical change in the system, however, will also have implications for a host of other production and environmental factors, including cultivar characteristics; irrigation and nutrient management; pest, disease, weed, and residue management; soil structure; deep drainage; groundwater depletion and pollution; and atmospheric pollution. At present, there seem to be good prospects for permanent beds to help address the sustainability constraints of the RW system, although overcoming them will require considerable investment in detailed research on all aspects of the system. The rice–wheat system in South and East Asia has developed quickly in the past three decades with the introduction of rice into traditional wheat areas (e.g., northwest India) and wheat into traditional rice areas (e.g., Bangladesh, eastern India, and Nepal). Consequently, wide variation exists in the growing conditions, principally in climate and soil properties, across the RW region that encompasses more than 13 Mha in the IGP of South Asia and a further 13 Mha in China (Timsina & 1 Copyright 2003. ASA–CSSA–SSSA, 677 S. Segoe Rd., Madison, WI 53711, USA. Improving the Productivity and Sustainability of Rice–Wheat Systems: Issues and Impacts. ASA Special Publication 65. Chapt09.qxd 1/8/03 4:00 PM Page 1