太湖地区高产水稻土经济极点施肥:一种农田N、P养分负荷的田间控制技术

我国农业中化肥施用过多而利用率极低,过量N、P养分由农田向水系的迁移损失是农业非点源污染的重要问题.本研究选择太湖地区高产水稻土(乌栅土),进行了不同施肥量及其养分配比的肥料试验.结果表明,供试土壤的基础肥力相当于6.75t/hm²产量,总施肥量(N+P)为300kg/hm²时达到土壤的极点产量(9.79t/hm²);但发现施肥量(N+P)240kg/hm²时产量仍可达9.69t/hm²,此时养分的产量效应最大.为此,笔者提出一种经济极点施肥模式(化肥N+P 240kg/hm²,N:P:K比为3:2:0或1:1:0),可以减少30%的N、P施用量.这可以进一步发展为环境安全的减肥-轮肥新技术,从而有利于控制N、P的农业非点源污染.

Minimum Application Rates for High-Yielding Rice Production System in the Taihu Lake Region as a Field Measure for Controlling N and P Agricultural Loading

Excess application with the poor efficiency of fertilizers is one of the major problems confronting the sustainable agricultural development. Whereas, loss of N and P nutrients from farmlands to surface waters is considered as one of the major sources inducing eutrophication. In order to work out a minimum fertilizer application rate for both keeping conventional yield and reducing nutrient loading of non point source pollution, an experiment of formulated fertilization scheme on rice at different rates and nutrient ratios by incorporating the soil supply potential was conducted in a paddy soil Wunitu in Kunshan City, Suzhou. The soil nutrient can supply a yield at 6.75 t/hm2 at least for one cropping season. Among the fertilization treatments, a maximum yield of 9.79 t/hm2 was obtained at fertilization (N + P) rate of 300 kg/hm2kg N and P at a ratio of N to P being 3:2 or 1:1. However, with much lower fertilization (N + P) rate at 240 kg/hm2 with the same ratio a high yield of 9.69 t/hm2 was reached. The fertilizer efficiency of the later was 3 times as that of the former rate. Thus, a economical and environmentally sound mode of fertilization in such paddy soils as total N and P 240 kg/hm2, with N:P:Kratio being 3:2:0 or 1:1:0 was developed. Further study would be directed to a innovation of combination of reducing fertilization rate with rotated fertilization for alternative crops.