土壤水分入渗是降雨和灌溉水转变为土壤有效水的过程, 是降水、地表水、土壤水和地下水相互作用的环节, 是影响作物水分利用效率的重要因素。砂姜黑土黏粒含量高, 具有楔型结构等障碍因子, 水分入渗性能和持水能力较弱, 作物水分利用效率低。改良土体结构是提高土壤入渗与持水能力, 增加作物水分利用效率的重要途径。为研究施肥措施对砂姜黑土理化性质及水分入渗性能的影响, 设置不施肥对照(CK)、测土配方施肥(PF)、测土配方施肥+秸秆还田(PF+JG)和测土配方施肥+粉煤灰(PF+FMH) 4个试验处理, 进行小麦?玉米田间轮作试验。研究了土壤容重、颗粒组成、总孔隙度和有机质含量的变化规律, 分析了土壤水分入渗特征及其与土壤理化性质之间的关系。结果表明, PF+JG、PF+FMH处理使土壤有机质含量分别较CK和PF提高18.01%、8.92%和11.18%、2.61%, 土壤容重分别降低12.90%、11.29%和4.48%、2.98%, 土壤总孔隙度分别增加13.89%、5.87%和12.46%、4.56%, 土壤水分累积入渗量分别增加98.08%、90.39%和34.64%、29.41%。PF+JG(1.18×10-4 m·s-1)和PF+FMH(1.13×10-4 m·s-1)处理的土壤水分稳定入渗速率分别是CK(5.92×10-5 m·s-1)和PF(8.73×10-5 m·s-1)的1.99倍、1.91倍和1.35倍、1.29倍。土壤水分稳定入渗速率与有机质及总孔隙度显著正相关(P<0.01), 与土壤容重呈显著负相关(P<0.05)。该研究表明, 秸秆还田和粉煤灰处理, 可提高土壤有机质含量, 降低土壤容重, 增加土壤孔隙度, 提高土壤水分稳渗速率, 可为土壤水分入渗性能提升提供理论依据。
Infiltration is an important mechanism by which rain and irrigation water replenishes soil water to support plant growth. As a low-yield soil, the Shajiang black soil has high clay content with strong wedging structures. These structures hinder infiltration and water holding capacity of the soil. This implies that high percentage of water occurring on the soil surface is lost to evaporation or the water in the soil is lost to leaching, which either way results in low plant water use efficiency. Soil structure improvement was considered as the most effective strategy to increase water holding capacity and plant water use efficiency of Shajiang black soils. However, few approaches have been developed to ameliorate soil properties in the region. Returning crop straw to the soil is a recommended approach that is extensively used in China. However, the exact role of straw products after degradation in soil property improvement and water cycle has remained largely unknown. This study investigated how the addition of maize straw and coal fly ash to soils affected soil properties and water infiltration of Shajiang black soils. Using an in situ Lysimeter field device, the effects of fertilization practices on soil properties and soil water infiltration characteristics were investigated. The study used non-fertilization as the control (CK), and formulated fertilization (PF), formulated fertilization plus 7 500 kg·hm-2 straw returning (PF+JG) and formulated fertilization plus 7 500 kg·hm-2 coal fly ash application (PF+FMH) as the experimental treatments. Soil properties and water infiltration characteristics were determined using the double-ring infiltration method at the end of the 2-year field experiment. The results indicated that soil organic matter in PF+JG treatment increased by 18.01% and 11.18%, that in PF+FMH treatment increased by 8.92% and 2.61% over those in CK and PF treatments, respectively. Similarly, soil total porosity respectively increased by 13.89% and 12.46% in PF+JG treatment and by 5.87%, 4.56% in PF+FMH treatment over those in CK and PF treatments. But soil bulk density decreased by 12.90% and 4.48% in PF+JG treatment and by 11.29% and 2.98% in PF+FMH treatment over those in CK and PF treatments, respectively. Cumulative soil water infiltration respectively increased by 98.08% and 34.64% in PF+JG treatment and by 90.39% and 29.41% in PF+FMH treatment over those in CK and PF treatments, which was significant. Steady-state infiltration rates of PF+JG (1.18 × 10-4 m·s-1) and PF+FMH (1.13 × 10-4 m·s-1) treatments were 1.99 and 1.91 times higher than that of CK (5.92×10-5 m·s-1) and 1.35 and 1.29 times higher than that of PF (8.73 × 10-5 m·s-1), respectively. While significant positive correlations were noted between steady-state infiltration rate and soil organic matter content or total porosity (P < 0.01), steady-state infiltration rate was negatively correlated with soil bulk density (P < 0.05). The results suggested that the application of maize straw and coal fly ash was a useful alternative method for improving soil properties and increasing water infiltration capacity in Shajiang black soils.