东北黑土区坡耕地斜坡垄作与顺坡垄作土壤侵蚀对比分析

斜坡垄作是东北黑土区最普遍的垄作方式之一,但当前关于斜坡垄作对坡耕地土壤侵蚀的影响鲜见报道。为此,基于室内模拟试验,设计2个降雨强度(50,100 mm/h)和2种垄作方式(斜坡垄作和顺坡垄作),分析东北黑土区坡耕地斜坡垄作与顺坡垄作坡面土壤侵蚀的差异。结果表明:(1)在50,100 mm/h降雨强度下,斜坡垄作断垄前坡面侵蚀速率分别是顺坡垄作的0.46%和0.35%;但在45 min的降雨过程中,由于斜坡垄作发生断垄现象,造成50,100 mm/h降雨强度下斜坡垄作坡面侵蚀速率分别是顺坡垄作的1.24,1.03倍。(2)斜坡垄作径流强度和侵蚀速率随降雨历时的变化均从断垄开始发生突变。在50,100 mm/h降雨强度下,随着降雨历时的变化,斜坡垄作断垄前的径流强度和侵蚀速率值均低于顺坡垄作,其平均径流强度分别为顺坡垄作的8.42%和3.75%;平均侵蚀速率分别为顺坡垄作的0.46%和0.35%;但斜坡垄作断垄后坡面径流和侵蚀速率明显增大,其平均径流强度分别为顺坡垄作的1.33,1.47倍,平均侵蚀速率分别是顺坡垄作的2.03,1.62倍。(3)在50,100 mm/h降雨强度下,斜坡垄作断垄前坡面径流量和侵蚀量存在极显著的线性关系(P<0.01),而断垄后两者的相关关系则不显著(P>0.05);而顺坡垄作在2种降雨强度下坡面径流量和侵蚀量存在极显著的线性关系。(4)在2种降雨强度下斜坡垄作坡面90%以上的径流泥沙均来自断垄后。因此,提高垄丘稳定性和防止断垄现象发生,是减少斜坡垄作坡面土壤侵蚀的关键所在。

Comparative Study on Hillslope Soil Erosion Between Sloping Ridge-tillage and Longitudinal Ridge-tillage in Chinese Mollisol Region

Sloping ridge-tillage is one of the most common ridge-tillage methods in Chinese Mollisol region. However, there are few studies related to the effects of sloping ridge-tillage on hillslope soil erosion. Thus, the indoor simulated rainfall experiments were conducted under 50 and 100 mm/h rainfall intensities with a typical slope of 5 degree (transforming from longitudinal ridge-tillage to contourridge-tillage) to analyze the differences in hillslope soil erosion between sloping ridge-tillage and longitudinal ridge-tillage system in Chinese Mollisol region. The results showed that: (1) Under 50 and 100 mm/h rainfall intensities, the erosion rates in sloping ridge-tillage before ridge failure were only 0.46% and 0.35% of the longitudinal ridge-tillage, respectively. However, during the 45-minute rainfall, once the ridge was failed, the erosion rates in sloping ridge-tillage were 1.24 and 1.03 times higher than that in longitudinal ridge-tillage under 50 and 100 mm/h rainfall intensities, respectively. (2) Both runoff and erosion rates suddenly changed with the rainfall time after ridge failure in sloping ridge-tillage system. Before ridge failure in sloping ridge-tillage system, both runoff and erosion rates were lower than those in longitudinal ridge-tillage under 50 and 100 mm/h rainfall intensities. The average runoff rate in sloping ridge-tillage were only 8.42% and 3.75% of that in longitudinal ridge-tillage under the two rainfall intensities, respectively; and the average erosion rates in the former were 0.46% and 0.35% of those in the latter,respectively.After ridge failure in sloping ridge-tillage system, the average runoff rate were 1.33 and 1.47 times higher than those in longitudinal ridge system, the average erosion rates in the former were 2.03 and 1.62 times higher than those in the later under 50 and 100 mm/h rainfall intensities, respectively.(3) Under the two rainfall intensities, there was a extremely significant linear relationship between runoff and erosion amount in sloping ridge-tillage (P<0.01), while the correlation was not significant after ridge failure (P>0.05). There was a extremely significant linear relationship between runoff and erosion amount in longitudinal ridge-tillage. (4) Under the two rainfall intensities, more than 90% of runoff and sediment generated after ridge failure in sloping ridge-tillage system. Therefore, the key approach for controlling soil erosion in sloping gridge-tillage is to improve the ridge stability and to prevent the ridge failure.