9Elcio L B, Miriam K, Amaldo C F, et al. Soil enzymeactivities under long-term tillage and crop rotation systems insubtropical agro-ecosystems[J]. Brazilian Journal of Microbiology, 2004, 35(4): 300-306.
10Busscher W J, Bauer P J, Frederick J R. Deep tillage management for high strength southeastern USA Coastal Plain soils[J]. Soil and Tillage Research, 2005, 85(1): 178- 185.