生物炭对塿土持水能力的影响

通过连续6年定位试验，探究较长时间施用生物炭对土壤保水作用的影响，以期为塿土区水土保持和土壤改良提供理论参考。田间试验于2011年开始，设4个生物炭施用梯度：对照，不施生物炭（B0）；5 t·hm^-2（B5）；10 t·hm^-2（B10）；20 t·hm^-2（B20）。在2017年测定了土壤含水量、土壤基础理化性质和水分累积蒸发量等。结果表明：生物炭能够显著减小土壤容重、增加土壤孔隙度、饱和含水量和田间持水量，且随着生物炭施入量的增加，各指标变化幅度也增大，B20与B0处理相比，土壤容重减少了8.28%，毛管孔隙度增加了20.17%，饱和含水量与田间持水量分别增加了22.17%和14.86%；生物炭显著增加了土壤团聚体稳定性，B20与B0处理相比，土壤水稳性团聚体含量增加了19.00%，团聚体破坏率和不稳定团粒指数分别降低了11.34%和9.61%；生物炭还可有效抑制土壤水分的蒸发，B10和B20处理的土壤累积蒸发量分别比B0处理减少了7.45%和10.18%。结合逐步回归分析与通径分析发现，生物炭对土壤结构的改良是其促进土壤持水能力的主要原因。土壤孔隙度和有机碳含量是影响土壤饱和含水量的主要因子，影响土壤毛管持水量的主要因子为有机碳含量和土壤毛管孔隙度，而毛管孔隙度与水稳性团聚体含量则解释了绝大部分土壤田间持水量的变化。研究表明生物炭施用可以显著改良土壤结构，提升塿土持水性能，增加干旱半干旱地区土壤的蓄水保墒能力。

Influences of biochar on soil water retention capacity in the Lou soil

The objective of this study was to investigate the influence of biochar application on soil water retention capacity of the Lou soil in a six-year field experiment since 2011. Four treaments of different biochar application rates were set in this study as follows: 0 (B0), 5 (B5), 10 (B10), and 20 (B20) t·hm^-2. In 2017, the soil moisture content, soil physical and chemical properties, and water cumulative evaporation content were measured. The results showed that the addition of biochar significantly decreased soil bulk density and increased soil porosity, saturation moisture content, and field water holding capacity. These parameters also had large range of variation. Compared with B0 treatment, the B20 treatment decreased soil bulk density by 8.28%, increased capillary porosity by 20.17%, increased saturation moisture content and field water holding capacity by 22.17% and 14.86%, respectively. Biochar significantly increased the stability of soil aggregates. Compared with B0 treatment, the B20 treatment increased the content of soil water stable aggregates by 19.00%, and the proportion of soil aggregate destruction and the unstable aggregate index decreased by 11.34% and 9.61%, respectively. Moreover, biochar effectively inhibited the evaporation of soil water, and the cumulative evaporation of B10 and B20 was 7.45% and 10.18% less than that of B0. Furthermore, through regression analysis and path analysis we found that the improvement of soil structure was the main reason why biochar enhance soil water retention. Soil porosity and organic carbon content were the main factors affecting soil saturation water content. The main factors affecting soil capillary water holding capacity were organic carbon content and soil capillary porosity. In addition, the capillary porosity and water stable aggregate content explained the most of the changes in soil field water holding capacity. The results indicated that biochar improved the soil water retention of the Lou soil, and increased the capacity of soil storage and water conservation in arid and semi-arid areas.