Developments in conservation tillage in rainfed regions of North China

Dryland regions in northern China account for over 50% of the nation's total area, where farming development is constrained by adverse weather, topography and water resource conditions, low fertility soils, and poor soil management. Conservation tillage research and application in dryland regions of northern China has been developed since the 1970s. Demonstration and extension of conservation tillage practices is actively stimulated by the Chinese government since 2002, following the recognition of the increased rate of degradation of the environment due to erosion and water shortage in North China. This paper reviews the research conducted on conservation tillage in dryland regions of northern China, and discusses the problems faced with the introduction and application of conservation tillage practices. Most of the studies reported have shown positive results of soil and water conservation tillage practices. These practices generally involve a reduction in the number and intensity of operations compared to conventional tillage, with direct sowing or no-till as the strongest reduction. Crop yields and water use efficiency have increased (with up to 35%) following the implementation of reduced tillage practices. Under no-till, crop yields are equivalent to or higher than those from conventional tillage methods, especially in dry years. However, during wet years yields tend to be lower (10-15%) with no-till. Other benefits are an increased fallow water storage and reductions in water losses by evaporation. In order to fully exploit the advantages of conservation tillage, systems have to be adapted to regional characteristics. Farmers' adoption of conservation tillage is still limited. (c) 2006 Elsevier B.V. All rights reserved.