草地雀麦刈割对坡地水土流失的影响

Meadow Brome(Bromus riparius)Harvesting Effect on Surface Runoff and Soil Loss of Slope Land

在自然降雨条件下,选择25°坡地种植草地雀麦,建立径流试验小区,并在抽穗期进行刈割处理,研究刈割后草地雀麦生物学特性变化及其对坡地水土流失的影响.结果表明:坡地种植草地雀麦,水土流失防治效果显著,可使25°坡地地表年径流量与土壤侵蚀模数达到6 781.7 m3/km2和36.4 t/km2·a,保水、固土能力为93.0%和99.9%.草地雀麦抽穗期刈割,对其固土能力影响不大,仍可保持93.8%,但对其保水能力影响显著,一定程度上可以增加坡面径流流失,使保水能力降低到53.9%.草地雀麦覆盖对坡地土壤侵蚀影响显著,抽穗期刈割草地雀麦,短期内可使坡面覆盖度下降,土壤侵蚀增加,但随着草地雀麦不断再生,覆盖度快速增加,达到76.7%以后,刈割与无刈割坡地的土壤侵蚀量差异不显著.草地雀麦覆盖度与土壤入渗率对坡地地表径流流失均有一定影响,抽穗期刈割,可使草地雀麦覆盖度减小,0～30 cm土层地下生物量与无刈割坡地相比,减少33.4%,土壤入渗率相应降低,地表径流有所增加.

The experiment was conducted to study effect of meadow brome harvesting on surface runoff and soil loss of 25° slope land and its biological characteristics naturally under harvest and no harvest treatments on the heading stage.The effect was evident for meadow brome planting on the slope to prevent water and soil loss.And capabilities of water conservation and soil conservation of meadow brome were 93.0% and 99.9%,while yearly amount of surface runoff and soil erosion modulus were 6 781.7 m3/km2 and 36.4 t/km2·a.However,capability of water conservation of meadow brome descended to 53.9%,and then surface runoff loss had a certain increase when it was harvested on the heading stage,while capability of soil conversation had no obvious change with 93.8%.Otherwise,effect of meadow brome cover on soil loss of slope land was evident.The difference of soil loss was significant between harvest and no harvest treatments due to cover rate decrease and soil erosion increase in the month after harvest,but not after cover rate added to 76.7% with meadow brome regenerating.Meanwhile,amount of surface runoff of slope land was relative to cover rate of meadow brome and soil infiltration rate.Surface runoff improved with cover rate and soil infiltration rate after harvest on the heading stage descending due to underground biomass decreasing by 33.4% in the soil of 0~30 cm as compared with that of no harvest.