Controlling effects of forest belts on non-point source pollution of agricultural lands in Taihu Lake area, China

Abstract

Taihu Lake area is one of the most developed areas in agricultural production. Application of fertilizers and pesticides in large quantities greatly aggravate environmental pollution of this area, and water pollution has worsened to an unbearable condition. Two sampling farms (respectively 1 hm²) under rape-rice rotation and wheat-rice rotation were selected as studied ecosystem and a 5-yr-old Poplar forest and 8-yr-old Metasequoia forest were chosen in the selected areas. By collecting samples of Nitrogen, Phosphorus in water, crops and underground of forest, the transfer and loss of N and P (main water pollutants) in faming ecosystem were studied, and the effects of forest belts on non-point source pollution of agricultural lands was analyzed. The results indicated that the transfer and loss of N and P vary with means of rotation, types of crops and the amount of fertilizer application. Buffering forest belts betweens farmlands and ditches can effectively stop and purify such elements as N and P in soil runoffs, thus controlling non-point source pollution of agricultural lands. When the width ratio of farmland to forest belt is 100 to 40, 50.05% losing N, 29.37% losing P can be absorbed by forest under rape-rice rotation and 30.98% N, 86.73% P can be absorbed by forest under wheat-rice rotation. When the width ratio of farmland to forest belt is 150 to 40, 33.37% losing N, 19.58% losing P can be absorbed by the forest under rape-rice rotation, and under wheat-rice rotation 20.65% lost N and 57.82% lost P can be absorbed. There is only some purification effect when the width ration of farmland to forest belt is 200 to 40. Based on model of buffering forest belts, the width ratio of farmland to forest is determined between 100 to 40 and 150 to 40, because it not only can purify water, but also occupy less farmland. It is suggested that Poplars, with the characteristics of fast-growing and high value, are suitable to be planted as shelter-forest in Taihu Lake Watershed.

Keywords

Agriculture / Non-point source pollution / Ultrophication / Nitrogen / Phosphorus / Forest belt / Sustainable development / S727.28 / S727.24 / A

References

[1] Liding Chen, bojie Fu Farm ecosystem management and control of non-point source pollution [J]. Chinese Journal of Environmental Science, 2000, 21(2): 98-100.

[2] Chansheng He, Bojie Fu, Liding Chen Non-point source pollution control and management [J]. Chinese Journal of Environmental Science, 1998, 19(5): 87-91.

[3] Haobo Jin Elementary discussion on water pollution prevention and control of Taihu Lake [J]. Environmental Protection, 1998, 4: 13-14.

[4] Xiangcan Jin, Chun Ye, Changzhou Yan et al. Comprehensive treatment plan for key-polluted regions of Taihu Kake[J] Research of Environmental Sciences, 1999, 12(5): 1-5.

[5] Wenxiang Liu Study on the use of artificial wet-land in agriculture non-point source pollution [J]. Research of Environmental Sciences, 1997, 10(4): 15-19.

[6] Lishan Ma, Minren Qian Pollution of nitrates and nitrites in the drainage area of the Taihu Lake and its assessment [J]. Chinese Journal of Environmental Science, 1987, 8(2): 60-64.

[7] Lishan Ma Nitrogen pollution from agricultural non-point sources and its control in water system of Taihu Lake [J]. Chinese Journal of Applied Ecology, 1992, 3(4): 346-354.

[8] Shuiming Zhang, Xingfa Ma, Zuqiang Wang Pollution by phosphorus in farmland drainage to the Taihu-Lake water system [J]. Chinese Journal of Environmental Science, 1993, 14(6): 24-29.