Effects of tillage and residue management on soil quality in a wheat-maize cropping system

To determine reasonable cultivation mode for dryland farming practice,the effects of tillage and residue management on soil properties were compared in a winter wheat-summer maize cropping system. This experiment was conducted during the seven consecutive years of 2002—2009 in Guanzhong plain of Shaanxi province.Treatments included 8 factorial combinations of four tillage practices: subsoiling tillage( ST),rotary tillage( RT),no tillage( NT),conventional tillage( CT),and maize residue( with or without) management. Soil samples were collected after wheat harvest in June 2009 and maize harvest in October 2009. The highest soil bulk density in the0 ~ 10 cm soil layer after maize harvest was observed under NT,followed by that for CT and RT,and the lowest value was observed under ST. Compared with maize residue removed treatment(- r),soil bulk density in the 0 ~10 cm soil layer under residue retained treatment( + r) was significantly decreased by 2. 33%. Multivariate analyses were used to select appropriate soil quality indicators. The results showed that the three soil property groups( i.e. soil nutrient group,soil organic matter and environment group,enzymatic activity group) responded more to tillage practice than to residue management. CT resulted in the poorest soil quality in both seasons. The residual effects of ST and RT on soil quality were found in maize season. Additionally,scores for soil organic matter and nu-trient factor under ST and RT were higher in both seasons,but the opposite occurred in NT. Based on soil quality,crop yield and economic benefit,the practice of the subsoiling rotary tillage plus residue retained to wheat combined with no tillage plus high stubble mulching to maize can be promoted in such dryland regions.