菜-稻轮作对菜田氮、磷利用特性和富集状况的影响

菜田氮、磷污染治理的最佳途径是提高化肥利用率.本研究开展了四季豆(Phaseolus vulgaris)-瓢瓜(Lagenaria sicerariae)-早稻轮作中不同氮、磷肥用量的3年定位田间试验.结果表明,经济施肥量为四季豆N 155kg/hm2和P2O579 kg/hm2、瓢瓜N 247 kg/hm2和P2O5 130 kg,/hm2,早稻不施肥.取得最佳经济效益的施肥处理,净增收比其他氮、磷水平提高1.6％～46.8％,氮肥利用率从四季豆和瓢瓜连作的45.1％提高到四季豆-瓢瓜-早稻轮作的65.6％,磷肥利用率则从17.9％提高到26.5％.四季豆-瓢瓜-早稻轮作的土壤硝态氮和有效磷含量分别为四季豆和瓢瓜连作的27.5％和87.0％,为基础土壤硝态氮和有效磷含量的63.7％和93.9％.养分吸收特性分析表明,四季豆的氮、磷最大吸收速率分别是早稻的25.1倍和2.5倍,瓢瓜则分别是早稻的18.4倍和1.2倍；四季豆的氮、磷最大吸收量分别是早稻的1.7倍和2.2倍,瓢瓜则分别是早稻的2.5倍和1.9倍.因此,菜-稻轮作体系利用了蔬菜和水稻在氮、磷吸收强度上的差异,较蔬菜连作促进了氮、磷高效利用,从而削减菜田过高的氮、磷富集,降低了土壤氮、磷流失潜力.

Effect of vegetable-paddy rice rotation system on N and P utilzation characters and their enrichments in vegetable fields

  Increasing chemical fertilizer recovery is the best method of controlling N and P non point pollution in vegetable fields. A 3-year orientation field experiment was carried out in kidney bean (Phaseolus vulgaris)-gourd ladle melon (Lagenaria sicerariae)-early rice rotating system in Pinghe County. The results show that the economic application rates of N and P for kidney bean are N 155 kg/ha and P₂O₅ 79 kg/ha, and N 247 kg/ha and P₂O₅ 130 kg/ha for gourd ladle melon，but no fertilization for early rice in the rotating system. Under the optimum benefit treatment, the net income is increased by 1.6%-46.8% compared with other application rates of N or P. In the treatment, the N fertilizer recovery is increased from 45.1% in the kidney bean-gourd ladle melon continuous cropping to 65.6% in the kidney bean-gourd ladle melon-paddy rice rotation, and the P fertilizer recovery is increased from 17.9% to 26.5%. The soil nitrate N and available P contents in the kidney bean-gourd ladle melon-early rice rotation are about 27.5% and 87.0% of those in the kidney bean-gourd ladle melon continuous cropping when the gourd ladle melon and paddy rice are harvested respectively, and are about 63.7% and 93.9% of those in base soils. Under the balanced fertilization, the nutritive peculiarity analysis shows that maximum uptake rates of N and P of kidney bean are 25.1 and 2.5 times of those of early rice, and are 18.4 and 1.2 times of those of gourd ladle melon respectively. The maximum uptake amounts of N and P of kidney bean are 1.7 and 2.2 times of those of early rice, and are 2.5 and 1.9 times of those of gourd ladle melon. The N and P uptakes are different in vegetable and rice, compared with vegetable continuous cropping system, the recoveries of N and P are enhanced in the vegetable-paddy rice rotating system, and the exorbitant enrichments and runoff amounts of N and P are reduced.