秸秆施入深度对土壤水分运移和水吸力变化的影响

为了研究秸秆还田下秸秆施入深度对土壤水分运移和水吸力变化的影响,通过室内模拟试验,对不同秸秆施入深度条件下土壤水分运移分布特性进行了模拟。玉米秸秆粉碎成<5 mm的小段且干燥放置,在秸秆施入深度内按干土重的1%配比均匀混施。设置无秸秆还田(CK)、秸秆施入深度15 cm(S15)、秸秆施入深度20 cm(S20)、秸秆施入深度25 cm(S25)、秸秆施入深度30 cm(S30)5个处理,并用微型张力计(T5)测定土壤水吸力值。结果表明:秸秆施入深度对土壤水分入渗特性有影响。随着秸秆施入深度的增加,土壤湿润锋运移距离和累积入渗量减小;秸秆施入深度对湿润锋运移影响较明显;相同入渗深度下,含有秸秆土层的含水量比不含有秸秆土层的含水量明显增加。秸秆施入深度对土壤水吸力有重要影响,土壤水吸力的变化反映了土层中水分的变化,不同土层深度下,土壤水吸力的变化趋势大致相同。不同秸秆施入深度,导致各处理在同一土层深度下,土壤水吸力峰值和达到峰值的时间出现差异,秸秆施入深度越深,土壤水吸力的峰值相对较大,达到峰值的时间相对较长。

Effect of Straw Application Depth on Soil Moisture Transport and Water Suction Changes

In order to study the effects of different straw application depths on soil water transport and water suction changes, the characteristics of soil water transport and distribution under different straw application depths were simulated by laboratory simulation test. Corn straw was crushed into small sections of less than 5 mm and stored in dry space. For the given application depth, straw was mixed with dry soil evenly with 1% application ratio. Five treatments were set up:no straw returning (CK), straw application depth of 15 cm (S15), straw application depth of 20 cm (S20), straw application depth of 25 cm(S25), straw application depth of 30 cm (S30). Soil water suction value was measured by micro-tensiometer(T5). The results showed that the application depth of straw had an effect on soil water infiltration characteristics. With the increase of straw application depth, the transport distance of wetting front and the cumulative water infiltration amount decreased. The influence of straw application depth on wetting front migration was obvious. At the same infiltration depth, the moisture content of soil layer containing straw increased significantly than that without straw layer. Straw application depth had an important impact on soil water suction, the changing trend of soil water suction values at different soil depth was roughly the same. Different straw application depth led to the difference of soil water suction peak and peak time under the same soil layer depth. The deeper straw application was applied, the greater the peak value of soil water suction and the longer the time to reach the peak value.