Effects of Straw Returning and Residue Cleaner on the Soil Moisture Content, Soil Temperature, and Maize Emergence Rate in China's Three Major Maize Producing Areas

Straw returning is of significant value for the sustainable development of agriculture, but it can easily cause the decrease of soil moisture content (SMC) and soil temperature (ST), leading to the serious reduction of maize emergence rate (MER). This paper focuses on the influence law and influence principle of straw returning amounts and residue cleaner on SMC, ST, and MER. This paper selected representative areas of China's three major maize-producing areas as test sites to take two-factor tests. Four levels were selected with straw returning amounts of 30%, 50%, 70%, and 100%. Three types of residue cleaners were selected: corrugated disc (CD), profiling residue cleaner (PRC), and rotary blade (RB). The test results show that the test factors have significant effects on the test indicators, and there is an interaction between the test factors. However, due to the large difference in annual average temperature, the influence of test factors on ST in different major maize producing areas is not the same. In order to obtain the optimal combination of factors in the three major maize producing areas, the nine regression models and the combination of factors corresponding to the extreme values were obtained through MATLAB. The following conclusions are drawn from the regression models: The maize emergence rate reached 91.7% when using PRC, and the amount of straw returning was 52% at the Jilin Maize Production Area. The maize emergence rate reached 94.7% when using CD, and the amount of straw returning was 67% at the Heilongjiang Maize Production Area. The maize emergence rate reached 91.4% when using CD, and the amount of straw returning was 68% at the Inner Mongolia Maize Production Area. This paper discussed the principle that test factors have a significant impact on test indicators. It is believed that, because the test factors can change the residual cover thickness (RCT) and soil compactness (SC), they have a significant impact on SMC and ST. In addition, it is believed because the test factors can change SMC, ST and the difficulty of cleaning operations, they have a significant impact on MER. At the same time, the basis for selecting straw returning amounts and rescue cleaner under different conditions is discussed. This paper can provide theoretical support and data reference for the sustainable development of agriculture in China's three major maize producing areas.