东北黑土区农田土壤风蚀的影响因素及其数量关系

为明确东北黑土区农田土壤风蚀的主要影响因素,通过室内模拟试验,对比分析了黑土在不同风速(5~14m/s)、土壤含水量(2%~11%)以及秸秆覆盖率(0~80%)下的风蚀速率差异,进而分析了风蚀速率与各因素之间的数量关系。结果表明,黑土起沙风速略大于5m/s,其风蚀速率随风速增大呈指数增加,风速14m/s(含水量2%)时的风蚀速率比8m/s时增加了11.6~42.7倍。黑土风蚀速率随土壤含水量升高呈先增加后降低趋势;在土壤含水量小于5%时随含水量升高而逐渐增加,至含水量5%时达到峰值并逐渐降低,至含水量11%时接近零。秸秆覆盖显著降低了黑土风蚀速率,二者成近似指数函数关系;秸秆覆盖率20%(含水量2%)时的风蚀速率比无覆盖减少了72.6%~92.3%,但秸秆覆盖率由20%增加至80%(含水量2%)后风蚀速率仅降低了0.02~1.20g/(m2·s),幅度有限。研究表明,风速、土壤含水量以及秸秆覆盖率均可显著影响东北黑土区农田土壤风蚀速率,其权重依次为风速土壤含水量秸秆覆盖率。

Influencing Factors of Wind Erosion and Their Quantitative Relationships with Erosion Rate in Black Soil Area of Northeast China

In order to identify the influencing factors of wind erosion in black soil area of Northeast China,the wind erosion rates of black soil under different wind speeds (5～14 m/s),soil water contents (2％～11％),and straw coverage rates (0 ～ 80％) were measured through a series of simulated wind experiments.Subsequently,the relationships between the wind erosion rate of black soil and the factors were quantitatively analyzed.The results showed that the black soil began to be eroded when the wind speed was slightly greater than 5 m/s,and wind erosion rate of black soil increased exponentially with increasing wind speed.The wind erosion rate under 14 m/s of wind speed (at 2％ of soil water content) was 11.6～42.7 times higher than that under 8 m/ s of wind speed.Moreover,the wind erosion rate of black soil increased with the increasing of soil water content when the soil water content was less than 5 ％,while it decreased with the increasing of soil water content when the soil water content was between 5 ％ and 11％.Especially,the wind erosion rate of black soil was close to zero when the soil water content exceeded 11％.In addition,the wind erosion rate of black soil was significantly reduced by straw cover and an exponential relationship was found between them.For instance,the wind erosion rate of black soil with 20％ of straw coverage (at 2％ of soil water content) was 72.6％～92.3％ lower than that of bare land.However,wind erosion rate was only decreased by 0.02～1.20 g/(m2 · s) when the straw coverage increased from 20％ to 80％ (at 2％ of soil water content).In conclusion,wind erosion rate of black soil was significantly affected by wind speed,soil water content,and straw coverage rate in Northeast of China in this study,and their importance in decreasing wind erosion listed in the order of wind speed＞soil water content＞straw coverage rate.