Corn-Soybean Rotation with 9-Year Continuous Cattle Manure Addition Restores Farmland Productivity of Artificially Eroded Mollisols in Northeast China.

Corn-soybean rotation with 9-year continuous cattle manure addition restores farmland productivity of artificially eroded Mollisols in Northeast China

Keqin Zhou¹, Yueyu Sui¹, Xingyi Zhang¹, Jian Jin¹, Weiwei Zhang¹, Guanghua Wang¹, S.J. Herbert², Xiaobing Liu^1,3*

¹Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroeology, Chinese Academy of Sciences, Harbin, 150081, China

²Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, USA

³ Southern University Agricultural Research & Extension Center, Baton Rouge, LA, 70813, USA

*Corresponding author: liuxb@iga.ac.cn

Abstract: Soil erosion has been recognized as a major agricultural problem in the Mollisol region of Northeast China where sloping farmland accounts for 2/3 of the total cultivated area. This study was conducted to ascertain the effects of simulated erosion on soil productivity and methods for its amendment. Field experiments were conducted from 2005 to 2013 on a Mollisol farm field with 5% steepness. Five simulated-erosion levels were established in the autumn of 2004 by removing up to 30cm of top soil in 5-cm and 10-cm depth increments. The plots were cropped in corn-soybean or soybean-corn rotations with two soil amendments. The two soil amendments were: nitrogen, phosphorus, potassium (NPK) chemical fertilizer at the normal farm rate for each crop, and NPK chemical fertilizer plus cattle manure. Greatest yield decline was observed in the first year of the 30-cm topsoil removal for corn with 40.9% grain yield, and 31.8% grain yield for soybean compared to non-eroded treatment for chemical fertilizer alone. The negative impact of loss of topsoil depth on yield reduction was gradually alleviated with crop rotation. Compared to non-eroded plots, the average grain yield during 9 years on the chemical fertilizer treatment fell 5.1%, 5.9%, 12.3% and 18.6% for soybean, and 8.6%, 10.0%, 14.4% and 25.1% for corn with 5-cm, 10-cm, 20-cm and 30-cm topsoil removal treatment respectively. In contrast, the grain yield with the addition of manure treatment fell 0.01%, 3.4%, and 5.1% for soybean, and 0.75%, 4.7%, and 10.8% for corn with 10-cm, 20-cm and 30-cm topsoil removal treatment respectively, while grain yield was slightly increased by 2.5% for soybean and 1.4% for corn at the 5-cm topsoil removal treatment. Addition of cattle manure with crop rotation and chemical fertilizer had significant yield-enhancement effect, especially in the first to the sixth-year of the treatment. As the depth of topsoil removal increased, the average residual effect (2005–2013) of manure increased, e.g., on the 5 cm removal, the residual effect (over the equivalent cut with chemical fertilizer treatment) for soybean was 8.0%, and increased to 16.7% for the 30 cm removal depth, while the respective effect was 11.0% and 19.1% for corn. Based on the yield data from the 9-year growing periods, 1-cm topsoil loss reduced 14.0 kg/ha for soybean and 69.1 kg/ha for corn with chemical fertilizer alone under crop rotation, while1-cm topsoil loss reduced 9.1 kg/ha for soybean and 48.4 kg/ha for corn with addition of cattle manure plus chemical fertilizer under a similar crop rotation. Additionally, for non-eroded plots, a yield-enhancing effect from manure addition was significant 3 out of 9-years for soybean, and 2 out of 9-years for corn. 100 grain weight reduction was the common reason leading to the yield decline for corn and soybean, while shortened cob length for corn and reduced productive pod number for soybean also contributed to the yield reduction caused by topsoil removal. The integrated use of chemical fertilizers with cattle manure under a corn-soybean rotation is an excellent option for restoring the eroded soil productivity in Chinese Mollisols.

Keywords: Soil erosion; topsoil depth; yield reduction; crop rotation; cattle manure; soybean; corn; Black soil;