水循环对太湖地区稻田生态系统中养分平衡的影响

EFFECTS OF HYDROLOGICAL CYCLE ON THE BALANCE OF NUTRIENTS IN RICE ECOSYSTEMS IN THE TAI LAKE REGION

本研究在太湖地区常熟、无锡和武进三县(市)设立试验点,同时研究小麦—水稻两熟轮作制中水循环过程的降雨、灌溉、外排、渗漏四途径对N、P、K、Ca、Mg,S六种营养元素的迁移量;水循环输入、输出途径对于土壤养分库中上述六种元素容量变化的贡献;水循环输入、输出途径对于稻田生态系统各养分总输入、总输出的贡献。结果表明,水循环对六种营养元素迁移量大小顺序为:Ca>Mg、S>K>N>P;水循环对土壤养分库容量影响最强烈的元素是Ca、Mg,使之出现了较大程度的亏损,而对钾,氮,磷的影响较小,尤以磷素为甚;水循环对稻田生态系统中Ca、Mg、S三元素的输入贡献率为50％——88％,输出贡献率为73——94％,主导着该三元素的循环。

This paper deals with the effects of hydrological transfers, i.e., precipitation, irrigation, leaching and surface runoff, on the balance of nitrogen, phosphorus, potassium, calcium, magnesium and sulphur in the rice field ecosystm, cropped with wheat-rice rotation, in the Tai Lake region of Jiangsu Province. The results show-edi a. the sequence of the quantities of the nutrients transfered by hydrological pathway was in the order of Ca, Mg, S,K,N, and P.b.the capacities of calcium and magnesium in the soil nutrient pool were very significantly influenced by hydrological transfers, which resulted in the negative balance for these two elements, w-hile the effect on the capacities of nitrogen and potassium was rather small, the least effect was found in that of phosphorus, c. the contributions of hydrological input to the total input of calcium, magnesium and sulphur ranged from 50% to 88%) on the other hand, the.output contributions were from 73% to 94%. It could be concluded that hydrological transfers played a predominant role in the cycling of these three elements.