Continuous rotary tillage has resulted in several issues, including a thin tillage layer with low soil organic carbon (SOC) and soil compaction, impeding crop root development and resulting in low crop yields, especially in clay soils. Although deep tillage can increase crop yields by loosening the soil structure and expanding the tillage layer it is rarely applied in soils with high clay contents (such as lime concretion black soil) because of its high energy consumption and low economic benefit. This study aimed at investigating the modified tillage practice with lower energy consumption (combining rotary and deep tillage to return crop straw into different depths among different years) in the higher crop yield on a clay soil. We conducted a 5-year (2017–2021) field experiment in a lime concretion black soil with high clay content. The experiment included four treatments: conventional tillage (CT) to return crop straw into the 15-cm layer without and with fertilizer addition, modified tillage (MT) to return crop straw into different depths (i.e., 35 cm in 2017, 20 cm in 2018, 10 cm in 2019, and 20 cm in 2020) with fertilizer addition, and MT combined with fertilizer and activator addition. We investigated the crop yields, soil physicochemical properties, and microbial communities at the topsoil (0–15 cm) and subsoil (15–30 cm) layers. Compared with CT, MT increased maize () and wheat () yields by 9.8 % and 11.4 %, respectively, by enhancing the SOC content and improving the soil physical properties of the subsoil (i.e., aggregate stability, macroaggregate proportion, soil porosity, and the proportion of large and small pores). We suggest a scientific tillage practice for future attempts to increase SOC sequestration and promote crop productivity in agricultural soils, especially those with a high clay content.

中文翻译：

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结合旋耕和深耕，通过改善土壤物理结构和积累底土有机碳来提高作物产量


连续旋耕导致了一些问题，包括土壤有机碳（SOC）低的耕作层薄和土壤板结，阻碍作物根系发育并导致作物产量低，特别是在粘土中。深耕虽然可以通过松动土壤结构、扩大耕层来提高作物产量，但由于能耗高、经济效益低，在粘土含量高的土壤（如石灰结核黑土）中很少应用。本研究旨在研究在粘土上提高作物产量的、能耗较低的改良耕作方法（结合旋耕和深耕，在不同年份将农作物秸秆还田到不同深度）。我们在粘土含量高的石灰结核黑土上进行了为期 5 年（2017-2021）的田间试验。试验包括四种处理：常规耕作（CT）将农作物秸秆还田至15厘米层，不加肥和加肥；改良耕作（MT）将农作物秸秆还田至不同深度（即2017年为35厘米，2017年为20厘米）。 2018年、2019年10厘米、2020年20厘米）添加肥料，以及MT结合肥料和活化剂添加。我们调查了表土（0-15 厘米）和下土（15-30 厘米）层的作物产量、土壤理化性质和微生物群落。与 CT 相比，MT 通过提高 SOC 含量和改善底土的土壤物理性质（即团聚体稳定性、大团聚体比​​例、土壤孔隙度和大毛孔和小毛孔的比例）。 我们建议未来尝试采用科学的耕作方法来增加土壤有机碳固存并提高农业土壤（特别是粘土含量高的土壤）的作物生产力。