Improving maize productivity and conserving soil on sloping land in Yunnan province, P.R. China

Abstract

Yunnan province is 94% mountainous and maize is one of the major arable crops grown in uplands areas. Increasing the productivity of maize crops on sloping land in the province is an important priority to improve rural incomes and reduce cultivation pressures on the more fragile, marginal land. At present, few soil conservation techniques are employed with maize cultivation to reduce erosion. This field-based study investigated the effectiveness of cultivation practices designed to improve productivity, while maintaining or enhancing soil conservation. This investigation was carried out in Wang Jia Catchment, selected as a representative area of fragile slopes in Yunnan province. Five cultivation treatments, including the use of contour planting, straw and polythene mulches, were selected for evaluation and established on replicated field plots in 1998 and 1999. Crop growth parameters, soil temperature and soil moisture were measured during the growing season and yield was determined at harvest. Straw mulch with contour planting retained soil moisture and was associated with lower soil temperatures. Polythene mulch improved soil moisture retention when the polythene was applied after irrigation and increased soil temperatures by up to 4 C. The changes were associated with increases in green leaf area index, green leaf area duration and crop yield, which was increased by up to 51.6% compared to unmulched plots. The effectiveness of theses mulches in reducing runoff and erosion has been evaluated in parallel erosion plot studies (Barton, 1999; Milne, 2001). It is concluded that a cultivation technique combining contour planting with early irrigation and polythene and straw mulches would be the most effective for increasing productivity and improving soil conservation on sloping land in Yunnan province.