Covering farming pattern to improve soil physical properties and crop yield in wheat-maize cropping system

Soil physical properties and crop productivity are general affected by different management methods of farmland, such as different tillage systems and crop straw managements. The objective of this study were to measure physical properties of soil including soil water content, soil water storage, soil bulk density and soil porosity (capillary porosity and non-capillary porosity) under a long-term tillage and straw management experiment system in the North China Plain, and the crop productivity of a wheat-maize cropping system was also analyzed (2010-2012). The study was assessed on 10 year field study with a split-plot design, which involved two tillage methods of conventional tillage (C) and zero tillage (Z) and four levels of straw utilization systems at straw returning (P), stubble returning of 1m height (-1), stubble returning of 0.5 m height (-0.5) and straw removal (A). The innovation of this study investigated effects of 4 different stubble heights returning on soil physical properties and crop yields. The result showed that, the soil water content in the 0-40 cm soil layer under treatments of conventional tillage and zero tillage increased with the amounts of straw returning increasing, so straw returning could increase the soil water content, Z-0.5 was more than 15.95% to AZ. In comparison to the conventional tillage, no tillage method combination with straw could improve the soil moisture, so zero tillage could improve the soil water content. In 0-40 cm soil layer, amounts of straw returning affected variation of soil water storage in the two stages, in the planting stage of wheat, soil water storage under treatments of conventional tillage and zero tillage gradually reduced with the amounts of straw returning increasing, but in the maturating stage of wheat, soil water storage under treatments of conventional tillage and zero tillage gradually increased with the amounts of straw returning increasing. In the planting stage of wheat, tillage methods could significantly affected soil bulk density, the treatment of stubble 1 meter returning had the lower soil bulk density (p<0.05). However, soil bulk density could self-increasing with the times, eventually there was no significant difference of soil bulk density under treatments of conventional tillage and zero tillage in the maturating stage of wheat. Straw returning also increased the soil porosity, reduced the ratio of capillary porosity and non-capillary porosity in the planting stage of wheat. Zero tillage treatment without straw returning reduced wheat and maize yields, but the zero tillage method combination with straw could increase total yields of wheat and maize, and the best treatment to increase yields was 1 m stubble returning treatment, it increased 22.44% than zero tillage without straw returning. Therefore, the treatment of stubble 1 m returning had conducive to improve soil physical properties and crop productivity.