Influences of biochar on soil water retention capacity in the Lou soil
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DOI:10.7606/j.issn.1000-7601.2019.06.37
Key Words: biochar  Lou soil  bulk density  soil porosity  soil aggregates  soil moisture constant  water evaporation  soil water retention
Author NameAffiliation
DAI Zhen College of Agronomy, Northwest A&F University, Yangling, Shaanxi 712100, China 
LI Wei College of Agronomy, Northwest A&F University, Yangling, Shaanxi 712100, China 
HAN Juan College of Agronomy, Northwest A&F University, Yangling, Shaanxi 712100, China 
WEN Xiaoxia College of Agronomy, Northwest A&F University, Yangling, Shaanxi 712100, China 
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Abstract:
      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.