深松深度对砂姜黑土耕层特性、作物产量和水分利用效率的影响

研究深松深度对砂姜黑土耕层特性、作物产量和水分利用效率的影响,可为构建砂姜黑土合理耕层的耕作深度指标提供依据。本研究基于多年定位大田试验,采用大区对比设计,设置4个深松深度(30 cm、40 cm、50 cm、60 cm)处理,以旋耕(RT,平均耕作深度为15 cm)作为对照,研究不同深松深度对土壤紧实度、土壤三相比(R)值、作物根系形态、作物产量和水分利用效率的影响。研究结果表明,深松深度增加能显著降低土壤紧实度,使土壤的三相比(R)更加合理,进而促进作物根系生长。不同深松深度中,深松60 cm处理的土壤紧实度和三相比(R)值与对照相比降幅最大,深松40 cm处理的冬小麦根系生物量最大,深松50 cm处理的夏玉米根系生物量最大。深松不仅增加作物产量,还提高作物水分利用效率。深松30 cm处理的周年作物产量最高,比对照增产12.2%,但与深松40 cm处理差异不显著。深松50 cm处理的周年水分利用效率最高,但与深松30 cm和深松40 cm处理差异不显著。深松30 cm、40 cm和50 cm的周年水分利用效率比对照分别增加9.1%、8.8%和12.7%。因此,砂姜黑土适宜的深松深度为30~40 cm。

Effects of subsoiling depth on topsoil properties, crop yield and water use efficiency in Lime Concretion Black soil

Lime Concretion Black soil is widely distributed in the south of the Huang-Huai-Hai Plain with area of 3.7 million hm², which is one of the main middle-to-low-yielding soil types in the region. Currently, the long-term continuous farming system is made possible by using small-sized 4-wheel tractors. However, owing to the years of over exploitation and improper mechanical plough, the effective depth of topsoil has gradually decreased and the plow pan thickened. The problem of shallow, solid and little topsoil in the plough layer has limited the ability of storage and release of fertilizer and continuous increase in crop yield in the Lime Concretion Black soils. Subsoiling is one of the main technologies in conservation tillage and the area with sub-soling in China has exceeded 10 million hm². Studies have shown that subsoiling can improve soil properties in plough layer by reducing soil bulk density and penetration resistance, increasing soil porosity, hydraulic conductivity and infiltration rate, and creating more favorable soil environment for root growth and crop production than rotary tillage. However, most studies have been carried out only on the 30 cm depth of subsoiling and little research has been focused on the effects of different depths of subsoiling on soil characteristics, root growth, crop yield and water use efficiency under wheat-maize cropping system in Lime Concretion Black soils. The objective of this study was to determine the effects of the depth of subsoiling on topsoil properties, crop yield and water use efficiency and to build the basis for establishing suitable depth of subsoiling in Lime Concretion Black soils. To that end, a multi-year experiment with four depths of subsoiling30 cm (SS30), 40 cm (SS40), 50 cm (SS50) and 60 cm (SS60)] and rotary tillage (RT) as the control was carried out to study the effects of different depths of subsoiling on soil penetration resistance, soil three-phase (R) value, root growth, crop yield and water use efficiency. The results showed that increasing depth of subsoiling significantly reduced soil compaction, created more suitable soil three-phase (R) value and thus promoted crop root growth. In the four depths of subsoiling, decrease in soil penetration resistance and soil three-phase (R) value were the highest under SS60 treatment, root weight of winter wheat was the highest under SS40 treatment and root weight of summer maize the highest under SS50. Subsoiling not only increased crop yield, but also increased water use efficiency. Annual crop yield was the highest under SS30 treatment, 12.2% higher than that under RT. There was no significant difference in annual crop yield between SS30 and SS40 treatments. Annual water use efficiency was the highest under SS50 treatment, which was 12.7% higher than that under RT. Also there was no significant difference in annual crop yield among SS30, SS40 and SS50 treatments. Annual water use efficiency was respectively 9.1% and 8.8% higher under SS30 and SS40 treatments than that under RT. Therefore, subsoiling at the 30-40 cm depth was a suitable depth in Lime Concretion Black soils.