生物炭用量与粒径对紫色土水分入渗及再分布特征的影响

Effects of Rate and Particle Size of Biochar on Water Infiltration and Redistribution Characteristics of Purple Soil

为探究生物炭用量和粒径对紫色土入渗过程与持水性能的影响,采用室内一维土柱模拟试验,设置4种生物炭用量(0%,1%,3%,5%)和3种粒径(0~0.25,0.25~0.5,0.5~1 mm),其中0%施用量为对照处理(CK).结果显示:添加不同用量和粒径的生物炭均延长了湿润锋达到土柱底部的时间,相同粒径条件下湿润锋运移深度和累积入渗量随生物炭施用量的增加而降低(p<0.05),3%施用量时较小粒径(0.25~0.5 mm)的生物炭对水分入渗的抑制作用优于大粒径(0.5~1 mm),湿润锋运移深度随入渗时间的变化规律符合幂函数.生物炭可以改变土壤剖面含水率的分布趋势,增强紫色土的持水能力,整体增效为:5%>3%>1%>CK,0~0.25 mm>0.25~0.5 mm>0.5~1 mm>CK.入渗结束24 h时,施用生物炭处理下各土层土壤含水率均比CK高,其中土层10~30 cm中施炭处理的含水率明显增大(p<0.05),各处理土壤平均含水率较CK增加了6.48%~13.51%.Kostiakov模型对添加生物炭后紫色土的水分入渗过程的拟合程度优于Philip模型,R 2>0.89.本研究揭示了施用生物炭后土壤水分入渗与再分布的变化规律,可为应用生物炭改良紫色土区土壤水分运动过程提供科学依据.

In order to investigate the effects of the rate and particle size of biochar on the infiltration process and water retention of purple soil,a one-dimensional soil column simulation experiment was conducted under the condition of water accumulation.Biochar derived from rice straw was applied to soil in 4 application rates(0%,1%,3%and 5%)and 3 particle sizes(0-0.25,0.25-0.5 and 0.5-1 mm).The 0%application rate was used as the control(CK).The results showed that the addition of biochar with different rate and particle size delayed the time of wetting front reached the bottom of soil column.With the same particle size of biochar,the depth of wetting front migration and cumulative infiltration volume decreased with the increase of the application rate of biochar(p<0.05).The inhibition effect of small particle size biochar(0.25-0.5 mm)on water infiltration was better than that of large particle size biochar(0.5-1 mm)at 3%of application.The variation of wetting front migration depth with infiltration time demonstrated a power function relationship.Meanwhile,biochar can change the distribution of soil moisture content and enhance the water holding capacity of purple soil.The overall effect was 5%>3%>1%>CK,0-0.25 mm>0.25-0.5 mm>0.5-1 mm>CK.At 24 h after infiltration,the soil moisture content of each soil layer treated with biochar was higher than that of control,of which the moisture content of 10-30 cm layer of soil treated with biochar was significantly increased(p<0.05),the average soil moisture content of each treatment increased by 6.48%-13.51%compared with control.The fitting degree of Kostiakov model to the water infiltration process of purple soil after adding biochar is better than that of Philip model,R 2>0.89.This study revealed the change regulation of soil water infiltration and redistribution after the application of biochar,which can provide a scientific basis for the application of biochar to improve soil water movement in purple soil area.