生物炭对草甸黑土物理性质及雨后水分动态变化的影响

为探明生物炭对草甸黑土物理性质及雨后水分动态变化的影响,在大豆全生育期生长条件下,研究了东北黑土区草甸黑土5种生物炭添加量(0、25、50、75、100 t/hm2)下土壤物理性质(包括:土壤水分特征曲线、土壤含水率常数、土壤水分扩散率)和单次降雨土壤含水率变化特征,分析了生物炭对黑土区草甸黑土耕层土壤持水能力及雨后水分动态变化的影响。结果表明,施用生物炭能降低土壤残余含水率,增加土壤饱和含水率和田间持水量,其中对残余含水率的影响最显著,100 t/hm~2生物炭处理使残余含水率最多降低27.6%;施用生物炭能明显降低土壤水分扩散率,随生物炭添加量的增加依次比对照组减少34.8%、37.5%、71.4%和58.9%;在单次降雨过程中,施用生物炭能减小土壤含水率的变化幅度,使土壤含水率在降雨之后更快地由迅速下降期进入缓慢下降期,并能明显提高缓慢下降期对应的土壤含水率;施用生物炭可以提高大豆产量,以75 t/hm~2生物炭处理最高。研究结果可为黑土区农业水土资源高效利用与保护提供理论依据。

Influences of Biochar on Physical Properties of Meadow Black Soil and Dynamic Changes of Soil Water after Individual Rainfall

The effects of biochar which was made of crop straw on physical properties of meadow black soil and dynamic changes of soil water after individual rainfall were studied. The experiments were conducted by field pilots which were located at the sloping farm-land with three degrees of land slope gradient of Hongxing State Farm, Heilongjiang Province in 2015, and soybean, the main crop type of study area, was selected as experimental crop. Five levels of biochar were set, as 0t/hm, 25t/hm, 50t/hm, 75t/hm and 100t/hm of biochar were put in the field pilots, which were represented by CK, C1, C2, C3 and C4, respectively. During the whole growth period of soybean, the soil physicochemical properties were investigated, including soil water characteristic curve, soil water diffusivity, soil bulk density, rate of soil porosity, organic matter content of soil, saturated soil water content, field water capacity and characteristics of soil water after individual rainfall. Soil water characteristic curve was measured by centrifuge, soil water diffusivity was tested by horizontal vitreous soil column, and soil water contents were measured by TDR field soil water measurement system in situ. The results showed that biochar could remarkably reduce soil bulk density and decrease soil water diffusivity of meadow black soil in the black soil area. The residual soil water content could be declined by 27.6% by treatment of C4. With the increase of biochar quantitative level, soil water diffusivities of C1, C2, C3 and C4 were decreased by 34.8%, 37.5%, 71.4% and 58.9%, respectively. Additionally, it could give a rise to the saturated soil water content, field capacity and soybean yield, and the treatment with 75t/hm biochar got the highest yield. During an individual rainfall, with the use of biochar, the variation amplitude of soil water content tended to fall. This helped to accelerate the process of soil water content changing from rapid declining stage to slow declining stage, meanwhile, it increased the soil water content in the slow declining stage obviously. The research results can provide theoretical foundation for efficient utilization and protection of soil and water resources in agriculture in the black soil region.