长江三角洲地区竹林经营中的氮磷流失负荷概算

通过分析长江三角洲地区竹林集约经营面积、竹林施肥情况及氮(N)、磷(P)流失率,对该区竹林经营中因施肥产生的N、P流失量进行了概算.结果表明,长江三角洲地区竹林中每年N、P流失量分别为3795～6067t、828～1104t.其中,浙江省竹林地的N、P流失量分别为3573～5713 t、779～1039 t,均占总流失量的94%.从单位面积上的流失量来看,浙江省竹林地N流失负荷(9.8～15.6kg/hm2)显著低于该省农田N流失负荷(57.4 kg,hm2),而P流失负荷(2.1～2.8 kg/hm2)稍高于农田(1.7 kg/hm2) .在部分高度集约经营地区,竹林地每年的N、P流失更高.这些竹林地主要位于水源上游或河湖两岸,流失的N、P进入水体后,将对水体造成污染,降低水质,加速下游水体的富营养化.

Estimation of Nitrogen and Phosphorus Losses from Bamboo Forest in Yangtze River Delta

Losses of nitrogen and phosphorus from bamboo forest in Yangtze River Delta were estimated on the basis of analysing intensive cultivation area, fertilization, and fertilizer loss rate. The results showed that annual loss of nitrogen and phosphorus amounted to 3795 ~ 6067 t and 828 ~ 104 t, respectively, in which, those from Zhejiang Province were 3573 ~ 5713 t N and 779 ~ 1039 t P, accounting for 94% of the total loss. The loss of nitrogen from bamboo forest (9.8 ~ 15.6 kg/hm2) was much lower than that from farmland (57.4 kg/hm2) in Zhejiang Province. However, the loss of phosphorus from bamboo forest (2.1 ~ 2.8 kg/hm2) was higher than that from farmland (1.7 kg/hm2). In some intensive cultivation area of bamboo, the annual loss of nitrogen and phosphorus amounted to 162.9 ~ 195.5 and 7.4 kg/hm2, respectively. Since bamboo forests usually grow upriver or on the river or lake banks, the loss of N and P could directly increase the risk of water pollution.