Soil chemical properties and microbial biomass.pdf

Available online at 08) 502–508 /locate/geodermaGeoderma 144 (20Soil chemical properties and microbial biomass after 16 years of no-tillage farming on the Loess Plateau, China Qingjie Wang a,1, Yuhua Bai b,1, Huanwen Gao a, Jin He a, Hao Chen a, R.C. Chesney a, N.J. Kuhn c, Hongwen Li a,? a Department of Agricultural Engineering, China Agricultural University. P.O. Box 46, Beijing, 100083, China b College of Agriculture and Biotechnology, China Agricultural University, China c Institute of Geography and Environmental Change, University of Basel, Switzerland Received 28 August 2007; received in revised form 15 January 2008; accepted 16 January 2008 Available online 7 March 2008Abstract Data from a 16-year field experiment conducted in Shanxi, on the Chinese Loess Plateau, were used to compare the long-term effects of no- tillage with straw cover (NTSC) and traditional tillage with straw removal (TTSR) in a winter wheat (Triticum aestivum L.) monoculture. Long- term no-tillage with straw cover increased SOM by 21.7% and TN by 51.0% at 0–10 cm depth and available P by 97.3% at 0–5 cm depth compared to traditional tillage. Soil microbial biomass C and N increased by 135.3% and 104.4% with NTSC compared to TTSR for 0–10 cm depth, respectively. Under NTSC, the metabolic quotient (CO2 evolved per unit of MBC) decreased by 45.1% on average in the top 10 cm soil layer, which suggests that TTSR produced a microbial pool that was more metabolically active than under NTSC. Consequently, winter wheat yield was about 15.5% higher under NTSC than under TTSR. The data collected from our 16-year experiment show that NTSC is a more sustainable farming system which can improve soil chemical properties, microbial biomass and activity, and thus increase crop yield in the rainfed dryland farming areas of northern China. The soil processes responsible for the improved yields and soil quality, in particular soil organic matter, require further research. ? 2008 Elsevier B.V. All rights res