Fertilizer Use on Different Upland Cropping Systems for Soil Conservation in Yunnan
IPNI-1997-CHN-YN9
09 Jan 2009
2008 Annual Interpretive Summary
Improving Topsoil Quality and Crop Productivity with Sloping Land Management Using Balanced Fertilization and Cash Crop Hedgerows in Yunnan, 2008
This trial continues to monitor the effect of balanced fertilization, contour cultivation, and hedgerow crops as soil conservation measures. In 2007/08, the objective was to determine the effect of different treatments on field slope changes. Productivity of soil suffering from different levels of soil erosion was assessed by simulation in a separate field trial using corn. The trial was composed of seven treatments which removed 0 (CK), 5, 10, or 15 cm of topsoil.
Improved practices continued to maintain higher corn yields than common farm practice (FP). The combination of FP and Chinese prickly ash (FP+A) hedgerows continued to lead to declining corn yields up to 8%, which indicates that significant benefit can only be obtained when correct farming practices are matched with correct nutrient management. Balanced fertilization produced the highest corn yields among all treatments, 5.6% higher than the BF+hedgerows (BF+H) treatment. The yield reduction from the BF+H (with smaller corn plants seen near hedgerows as evidence), can be attributed to hedgerow occupation of land and its competition for moisture and nutrients with corn. Regardless, as was shown in previous years, the BF+H treatment was more beneficial than the BF treatment alone. Thus, the adverse effect of hedgerows on the in-field corn crop can be at least partly overcome by proper fertilization to the hedgerow crops.
Soil productivity was directly proportional to topsoil thickness and it appeared to be most affected by the top 0 to 10 cm depth. Corn yield was reduced by 11.5% as the first 5 cm of topsoil was removed, which was further reduced by 10.8% as the second 5 cm was removed, and reduced by only another 1.8% as the third 5 cm was removed. Soil productivity, as indicated by soil analysis and corn yield, is highly correlated to soil organic matter, both ammonium and nitrate-N, and available soil P and K. Amending the soil with proper amounts of manure and mineral fertilizers could partially offset these yield losses, while adding topsoil alone could significantly increase yields. Both these results indicate the irreplaceable role which topsoil plays in field productivity. Yunnan-09