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Clarifying the characteristics of annual yield, distribution and utilization of climatic resources, and establishing rational quantitative indexes of annual climatic resources distribution for different cropping systems are helpful to provide theoretical basis for further improving annual yield and resource use efficiency in the Yellow-Huaihe-Haihe Rivers plain. In this study, the experiment was conducted from 2011 to 2015 at Xinxiang, Henan province to analyze the grain yield, biomass, dry matter production energy, and distribution and utilization efficiency of climatic resources under four cropping systems, namely winter wheat–summer maize, winter wheat–summer soybean, double maize and one–season spring maize. There were no differences in the annual grain yield, total biomass, and dry matter production energy between the winter wheat–summer maize and double maize cropping systems, but they were significantly higher than those of the winter wheat–summer soybean and one-season spring maize cropping systems, with an average increase of 45.4%–61.5%, 37.3%–71.3%, and 35.77%–70.7%, respectively. The annual radiation production efficiency, radiation use efficiency of grain and total biomass for double maize and one-season spring maize cropping systems were significantly higher than those of the winter wheat–summer maize and winter wheat–summer soybean cropping systems, with an average increase of 11.8%–66.7% in the annual radiation production efficiency, and 0.13–0.42 and 0.18–0.69 percentage points increase in the radiation use efficiency of grain and total biomass, respectively. The accumulative temperature distribution rate for two seasons of winter wheat–summer maize was 45.6% and 54.4%, respectively, while those of double maize was 51.4% and 48.6%, respectively. The accumulative temperature ratio between two seasons was of winter wheat–summer maize 0.8, while that of double maize was 1.1. Considering both yield and resource use efficiency, winter wheat–summer maize and double maize cropping systems can be used to optimize the layout of planting patterns and support the sustainable development of agricultural production in the Yellow-Huaihe-Haihe Rivers plain. Furthermore, clarifying the accumulated temperature distribution rate and the accumulated temperature ratio between two seasons is helpful to optimize climate resource distribution, and further improve the yield potential and the resources use efficiency of double cropping system in the Yellow- Huaihe-Haihe Rivers plain.

The characterization of soil physicochemical properties and the resulting soil enzyme activity changes are crucial for understanding the effects of various tillage and straw management techniques on crop grain yield. In 2018&ndash, 2019, we conducted a field micro&ndash, plot experiment to determine the effects of tillage depth and straw management on the soil physicochemical properties, enzyme activity, and maize grain yield. Six treatments were employed, including straw removal (CK), straw mixed with (SM), and straw buried (SB) into the soil under tillage depths of 10 (D10) and 30 cm (D30). The results demonstrated that SM and SB significantly increased the soil nitrate (NO3&ndash, &ndash, N) content and decreased the ammonium (NH4+&ndash, N) content in the 0&ndash, 20 cm soil layer in 2018 relative to CK. SM had greater soil urease (URE) and acid phosphatase (APH) activities in the 0&ndash, 20 cm soil layer, and SB improved the soil APH activity at the 30&ndash, 40 cm depth in both seasons. D30 obtained a lower penetration resistance in the 10&ndash, 40 cm soil profile and higher soil organic carbon (SOC) and soil total nitrogen (STN) contents at the 30&ndash, 40 cm soil depth relative to D10. The soil enzyme activity was positively related to the soil nutrient content and negatively related to the soil penetration resistance in the 0&ndash, 20 cm soil layer, particularly in D30. Compared with CK, the grain yield was higher by 2.48&ndash, 17.51% for SM and 7.48&ndash, 24.46% for SB in 2018 and 2019, respectively. The structural equation model analysis suggested that the tillage depth mainly affected the soil penetration resistance (PR) and pH, however, straw management dominantly influenced the soil mineral N levels, leading to other soil property changes and crop production results. In conclusion, straw incorporation with deeper plow tillage might be an optimal straw return approach for soil quality improvement and sustainable maize production in northeast China.