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En 2007, 2008 et 2009, on a réalisé dans le nord-est de la Chine des expériences par parcelle afin de comparer l’écoulement de surface, la perte de sol, la croissance des cultures, le rendement des cultures et les marges de rentabilité pour le soja et le maïs dans des conditions de gestion classique (GCL), de travail profond du sol (TPS) et de gestion de conservation (GCV).
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Mollisols (called black soil in China) are fertile and productive soils covering an area of 5,900,000 ha in northeastern China, but food production in the area is threatened by soil erosion. The objective of this study was to generate scientifically-based comparative information that can be used to help farmers improve their field management practices in order to reduce soil loss while at the same time decreasing input costs and increasing crop yields. Plot experiments to compare runoff, soil loss, crop growth, crop yield and economic margins for soybeans and corn under conventional management (CVM), deep-till management (DTM) and conservation management (CSM) were carried out in northeastern China in 2007, 2008, and 2009. Dry matter (measured aboveground) accumulation in DTM deep-till management was consistently higher than in CVM or CSM before early September, while the highest aboveground dry matter (DM) over all was obtained in CSM at maturity, which was 11.1% more than DTM or CVM. Compared to the conventional management, runoff in soybean in 2007 and 2008 was 71% and 98% less, respectively, under conservation management, and 12% less and 1% greater under deep tillage treatment. Similarly, sediment loss was 89%, 99%, and 97% less, respectively, under conservation management than under conventional management and 75% less, 72% greater, and 13% greater under deep tillage management than under conventional management. There was no significant difference in yield between deep-till management and conventional management in any year, but it was 19% (soybean, 2007) and 12.6% (soybean, 2008) higher under conservation management than under either of the other two treatments. Economic margin was 34%, and 27% higher under CSM than under CVM in 2007 and 2008 when the plots were cropped to soybean, respectively, but showed no significant difference between CVM and DTM in 2007 and 2008, or no significant difference between all treatments when corn was planted in 2009. It is apparent that conservation management can reduce soil loss, increase soybean yield and improve its profit margin on sloping fields in the black soil landscape of northeastern China.
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