不同覆被下红壤坡地地表径流及其养分流失特征

Surface runoff and nutrient loss from red-soil slope-lands under different land use types

通过对南方红壤坡地农作区、茶园、柑橘园、退化区和恢复区5种不同利用方式所产生的地表径流量的全年连续观测及其径流水中养分含量分析,结果表明:覆被植物群落类型单一化和农事耕作都能增加地表径流量、次数和增加养分流失,5种类型地表径流量不论是月平均径流量还是年总径流量,其大小关系为农作区*>茶园*>柑橘园>退化区>恢复区*,产流次数也是恢复区最少,其余4种类型基本一致;径流水中总P、K+、Ca2+、Mg2+和SO42-流失量以农作区达到最大,茶园和柑橘园次之,然后是退化区和,恢复区的径流各养分流失量最少,耕作区的总P、K+、Ca2+、Mg2+和SO42-流失量大于非耕作区,覆被植物群落类型少的总P、K+、Ca2+、Mg2+和SO42-流失量大于覆被植物群落类型复杂。综合考虑,红壤坡地用来耕作可以加剧水土和土壤养分流失,自然植被对红壤坡地保持水土和养分效果最佳,如果种植经济价值较高的果林和药、茶、草等需采用复种方式,避免单一种植和减少人工扰动,以便维持坡地土壤利用的可持续性。

Through the continuous observation of the amount and nutrient content of surface water runoff under 5-different land use types, which were crop land, tea land, orange land, degeneration land, restoration land, the study of surface runoff and nutrient loss under different vegetations of red sloping lands in south China were carried. The results showed that： single vegetation and fanning could not only increase the nutrient loss but also the degree and times of surface runoff. Either monthly average or yearly gross amount of runoff flow under 5 vegetation types followed a sort order： crop land^＊ 〉 tea land^＊ 〉 orange land 〉 degeneration land 〉 restoration land^＊. The restoration land had the fewest times of runoff generated by rainfall, the other while the other 4 treatments were the same. The maximum loss of P, K^＋, Ca^2＋, Mg^2＋ and SO4^2＋ in the runoff water was from fanning land, second was tea land, and then the orange, degeneration and restoration land. Contrast cultivated land to natural vegetation or single vegetation to multiplied vegetation land, the former had a larger nutrient loss amount. To sum up, utilization of farm would intensify the soil erosion and soil-nutrient loss; vegetation with stable structure and species diversity would be helpful to the soil-water conservation. Considering economically, multiplied planting of fruit tree, medical herb, tea bush and grass would be the best land use type for red-soil slope region.