Abstract
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 2018–2019, we conducted a field micro–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––N) content and decreased the ammonium (NH4+–N) content in the 0–20 cm soil layer in 2018 relative to CK. SM had greater soil urease (URE) and acid phosphatase (APH) activities in the 0–20 cm soil layer, and SB improved the soil APH activity at the 30–40 cm depth in both seasons. D30 obtained a lower penetration resistance in the 10–40 cm soil profile and higher soil organic carbon (SOC) and soil total nitrogen (STN) contents at the 30–40 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 0–20 cm soil layer, particularly in D30. Compared with CK, the grain yield was higher by 2.48–17.51% for SM and 7.48–24.46% 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.
Highlights
Soil degradation is recognized as a severe 21st century issue worldwide in the global agroecosystem [1]
In terms of the soil penetration resistance (PR) and pH, the analysis of variance (ANOVA) results demonstrated that the tillage depth demonstrated significant differences in the PR, but the tillage depth and straw treatments were found with completely opposite trends for the soil pH, as well as their interaction effects on the PR and soil pH in both seasons (Table 1)
Under the depths of 10 (D10) treatments, compared with the CK treatment, the soil pH at the 0–10 cm depth was decreased under the straw mixed with (SM) treatment in 2018, and the soil PR in the 10–20 cm layer was increased under the straw buried (SB) treatment in 2019 (Table 2)
Summary
Soil degradation is recognized as a severe 21st century issue worldwide in the global agroecosystem [1]. Increased soil degradation threatens agricultural production and the food supply for the growing human population in developing countries and areas [2,3]. The organic residues derived from crop straw are considered as the greatest source of soil organic matter in the agroecosystem [4]. Large quantities of crop straw were produced in China accompanied by constant increased crop yield, which was approximately 1.04 billion tons in 2015, accounting for one–third of the global production [5]. The government proposed returning crop straw to the field soil to practice conservation agriculture. Finding an efficient approach for straw return is an urgent issue to achieve the goal of improving soil quality [6]
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