Effects of straw and manure management on soil and crop performance in North China Plain

The North China Plain (NCP) is one of the most intensively farmed agricultural regions in China, and the annual double-cropping system of winter wheat and summer maize produces a large quantity of straw. A field experiment was carried out from 2010 to 2016 to assess the effects of straw and manure management on crop performance, soil physical and chemical characteristics. Four management practices were tested: (1) all the straw from the annual double-cropping system was returned to the soil directly (as a control, WMs); (2) maize straw was removed as yellow silage and winter wheat straw was maintained (Ws); (3) manure produced from dairy farms was added to Ws (Ws + M); (4) extra manure was added to WMs (WMs + M). The results showed that the soil bulk density and soil aggregates were not significantly different among the four treatments. The soil nutrient contents and organic matter (OM) increased continuously under the four treatments. The results indicated that with at least one season of straw returning to the field would maintain an improved soil nutrient contents. The increase rate for organic matter, P and K for the treatments with manure addition was higher than that for the treatments without manure application. Both biomass and grain yield of summer maize were improved with the continuous addition of manure. Although the biomass of winter wheat was improved with manure addition, the grain yield of winter wheat was not affected due to the reduction in the harvest index, which might be related to the shortened grain-filling duration. No significant difference in water use efficiency was found among the four treatments for winter wheat or maize. The improved soil nutrient and organic matter contents affected the production of the two crops differently in this annual double-cropping system. The larger increase in organic matter contents using maize straw changed manure through animal feeding would benefit the grain production of summer maize as well as the soil carbon sequestration.