Impact of Topsoil Removal on Crop Performance/Productivity and Its Restoration with Soil Amendments in Chinese Mollisols.

Farmland soil erosion affects crop productivity. Field experiments were conducted from 2005 to 2006 on a typical Chinese Mollisols at a farm in Hailun, Heilongjiang, China, to determine the impact of topsoil removal on corn and soybean yield, and possible effectiveness of soil amendments for restoring the productivity of eroded soils. The simulated erosion levels were established in the autumn of 2004 by removing up to 30 cm of top soil in 5-cm and 10-cm depth increments. The two soil amendments were: NPK chemical fertilizer at the normal farm rate and chemical fertilizer plus cattle manure. Above ground dry matter was substantially reduced at later stage of vegetative growth, while root dry weight reduction was observed earlier. Plant height at harvest and photosynthetic rates during reproductive stages were also reduced. The 5 cm and 10 cm topsoil removal reduced soybean and corn yield slightly, while 20 cm and 30 cm topsoil removal reduced yield significantly. Corn was more sensitive to topsoil removal than soybean. Addition of cattle manure with chemical fertilizer restored crop yield in the slightly eroded soil (5 cm topsoil removal). The effect of erosion on crop productivity is complicated and addition of cattle manure was an excellent amendment to restore productivity through an enhanced effect on the photosynthetic rate. The use of chemical fertilizers with cattle manure for improving crop yields on eroded soils is very important in the region of Chinese Mollisols.