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无锡市20年来施肥量不断增加,但氮、磷用量较多,钾肥使用较少。无锡市区、江阴市、宜兴市土壤氮、磷含量分别增长0.06～0.48gkg-1和0.06～0.17gkg-1,无锡市区稻田土壤速效钾含量基本没有变化,但江阴市、宜兴市速效钾含量明显降低。随着城镇化进程加快,1999年以来无锡农业生产结构产生较大变化,蔬菜等经济作物种植比例越来越大。典型区土壤养分输入-输出平衡的监测结果表明,单位面积菜地氮的盈余量是稻田的6倍以上,磷的盈余量是稻田的100倍以上,但菜地和稻田的钾素均不断亏缺。稻田土壤转变为菜地土壤后,土壤剖面0～50cm范围内发生明显的氮素和磷素积聚,土壤pH降低。通过释放多余的氮、磷,土壤可能对周围环境产生长期持续的不良影响。
In the past 20 years, the amount of fertilizers in Wuxi has been continuously increasing, but more nitrogen and phosphorus have been used and less potassium has been used. The content of soil nitrogen and phosphorus in Wuxi, Jiangyin and Yixing increased by 0.06-0.48gkg-1 and 0.06-0.17gkg-1, respectively. There was almost no change in available potassium in paddy soils in Wuxi city, but the contents of available potassium in Jiangyin and Yixing Significantly reduced content. With the acceleration of urbanization, the agricultural production structure in Wuxi has undergone major changes since 1999, and the proportion of cash crops such as vegetables is growing. The monitoring results of soil nutrient input-output balance in a typical area showed that the surplus nitrogen per unit area of vegetable garden was more than 6 times that of paddy field and the surplus of phosphorus was more than 100 times that of paddy field, but the potassium in vegetable field and paddy field continued to decrease lack. After paddy soil was changed to vegetable soil, obvious nitrogen and phosphorus accumulation occurred in 0-50 cm soil profile, soil pH decreased. By releasing excess nitrogen, phosphorus, the soil may have long-term, persistent, adverse effects on the environment.