太湖地区种植结构及农田氮磷流失负荷变化

太湖地区是我国农业最发达区域,近年来随着经济利益的驱动,太湖地区稻田改为果园、菜地、茶园现象突出,该地区种植结构的变化趋势和分布特征以及种植结构改变前后的氮(N)、磷(P)肥投入量、径流流失负荷量尚缺乏研究。本研究基于农业统计年鉴和文献调研数据,通过2002—2017年太湖地区主要城市(常州、无锡、苏州、湖州)果菜茶和水稻种植面积、N和P养分投入量、农田N和P流失负荷研究分析,为该地区农业面源污染防治和治理提供科学依据。得出如下结论:2002—2017年太湖地区果菜茶种植面积显著增加,尤其是果园(增加2.852×104hm2)和茶园(增加1.892×104hm2),而稻田种植面积下降显著(下降1.985×105hm2);2002—2010年间种植结构变化速率远高于2010—2017年,且果菜茶种植面积增加主要集中在武进、南浔、宜兴、苏州市区、长兴等临湖地区。2002—2017年太湖地区N、P肥投入量分别降低25.26%和9.59%, N流失量显著下降34.66%, P流失量仅下降1.84%。现今太湖地区稻田、果园、菜园和茶园的N流失负荷分别为10 200t、670 t和10 100 t、250 t, P流失负荷估算量分别为290 t、400 t、3 000 t和50 t。随着种植结构的改变,太湖地区稻田种植体系已不是农田N、P流失的最大来源,果菜茶来源的N、P流失总和已排在第一位,成为了目前农田N、P流失的优先控制对象。建议下一阶段太湖地区农业面源污染防治应侧重于优化果菜茶与水稻种植结构,同时强化P污染防治技术研究,最终实现太湖地区种植业的清洁可持续发展。

Changes in planting structure and nitrogen and phosphorus loss loads of farmland in Taihu Lake region

The Taihu Lake region is the most developed agricultural region in China. In recent years, driven by economic interests, the transformation of rice paddy into orchard, vegetable field and tea garden in Taihu Lake region has become prominent. The changes in the trend and distribution characteristics of planting structure, as well as the N and P fertilizer inputs and runoff loads (before and after the change in planting structure) are still not studied. Based on the Agricultural Statistical Yearbook and survey data of literatures, through the analysis on planting areas of rice paddy, orchard, vegetable field, and tea garden in major cities in Taihu region (Changzhou, Wuxi, Suzhou, and Huzhou) from 2002 to 2017, nutrient input and N and P loads in farmland were studied to provide scientific basis for prevention and treatment of agricultural non-point source pollution in the area. The main results were summarized as follows: from 2002 to 2017, the planting areas of orchard, vegetable field, and tea garden significantly increased; especially for orchard (increased by 2.852×10⁴ hm²) and tea garden (increased by 1.892×10⁴ hm²). However, the area of rice paddy was decreased by 1.985×10⁵ hm²; the change in rate of planting structure from 2002 to 2010 was much higher than that of 2010 to 2017. The increased planting areas of orchard, vegetable field, and tea garden were mainly concentrated in the lakeside districts, such as Wujin, Nanxun, Yixing, Suzhou urban area, and Changxing. The total N and P fertilizer inputs were decreased by 25.26% and 9.59%, respectively, from 2002 to 2017. The risk of total N runoff reduced significantly by 34.66%, while the total P loss amount remained stable (overall decline by 1.84%). In 2017, the estimated N loss loads from the sources of rice paddy, orchard, vegetable field, and tea garden were 10 200 t, 670 t, 10 100 t and 250 t respectively, and the P loss loads were 290 t, 400 t, 3 000 t and 50 t, respectively, in the Taihu Lake region. With the change in planting structure, rice paddy was no longer the largest source of N and P loss in the farmland, but the total N and P loss from orchard, vegetable field, and tea garden was the largest; these are currently the priority control objects of N and P loss in farmland of the Taihu Lake region. It is suggested that in the next stage, the prevention and control of agricultural non-point source pollution should focus on the optimization of planting structure, and strengthen research on the prevention and control technology of P pollution, in order to achieve clean and sustainable development of the planting industry in the Taihu Lake region.