Nutrient Losses from Sloping Lands as Affected by Surface Mulching and Cultivation in Sichuan

IPNI-2009-CHN-SC17

03 Feb 2011

2010 Annual Interpretive Summary

Nutrient Losses from Sloping Lands as Affected by Methods of Surface Mulching and Cultivation in Sichuan, 2010

The objective of this project was to further evaluate effects of different methods of surface mulching and cultivation on corn yield and nutrient losses from Sichuan’s sloping farmlands during the summer rainy season. The three types of surface mulching included: a check (no mulching), wheat straw, and plastic film. The three methods of cultivation employed were flat, down-slope, and contour alley cultivation. The fertilizer rates were 225-150-150 kg N-P2O5-K2O/ha, which were based on current fertilizer recommendations.

Contour alley produced the highest corn yield, followed by flat cultivation with straw mulching. Mulching the soil with straw produced significantly higher corn yield than mulching with plastic film, which was opposite the results obtained in 2009, possibly due to higher drought–resistant capability of plastic film over straw under the season’s extreme weather conditions. In 2009, any methods that could conserve more soil moisture could produce more corn yield on this rain-fed sloping land. Mulching significantly reduced soil erosion compared to the treatments of bare land without mulching. Among the bare land treatments, the down-slope treatment caused the highest amount of runoff (181 mm), followed by the flat treatment (156 mm). The flat treatment suffered the worst soil erosion (7.2 t/ha) followed by the down-slope treatment (4.5 t/ha). With mulching, the soil losses were reduced to only 0.1 t/ha (contour) with straw to 0.9 to 1.0 t/ha with plastic film, reflecting the impact of straw mulching is better than that of plastic film if there is no drought during the growing season. Since the nutrient losses from the sloping lands were induced by the water loss and soil erosion, the quantity of N, P, and K losses was closely related to the quantity of soil and water losses. Thus, the down-slope and the flat treatments caused higher losses of N, P, and K, while mulching was particularly effective in blocking P loss.

This study indicates that rainfed sloping lands benefit greatly from contour cultivation + plastic mulching, which increased corn yield in a dry year. Contour cultivation + straw mulching performed best in a normal year. Sichuan-BFDP-09