氮磷等比与以磷定氮条件下玉米的最大施肥量研究

以前的研究已认识到种植玉米的土壤具有平衡与不平衡的土壤养分供应类型,因而其高产施肥需要相应的养分配比。本研究以养分平衡供应的山西石灰性褐土为对象,按照同步增加氮磷用量和以磷定氮等两种施肥量确定方法设置氮磷施肥量,探讨高产玉米的最大施肥量和最佳施肥比例。研究表明,氮磷等比施肥下玉米最大施氮量较以磷定氮增大46 kg hm-2,产量增加738 kg hm-2;而玉米最佳施氮量较以磷定氮增加39 kg hm-2,产量增加723 kg hm-2。氮磷等比施肥下最佳施氮量氮素的增产效益极大。试验说明氮磷施用比例是影响玉米最大施氮量及其肥效的重要因素。在供试的氮磷养分平衡供应条件下同步增加氮磷用量可以得到两者统一的玉米高产最佳施肥量点。本研究提出,根据土壤养分平衡供应特征调整施肥养分比例可能是作物高产施肥且提高肥料利用率的途径。

MAXIMUM FERTILIZATION RATES FOR CORN WITH FIXED N/P RATIO OR WITH N RATE VARYING WITH P RATE

It has been proved that there are two types of corn-growing soils,balanced or unbalanced in soil nutrient supply.Therefore it is necessary to recommend proper nutrient ratios to achieve high yield of corn.A field experiment was carried out on calcareous drab soil,which is balanced in nutrient supply,in Shanxi to explore maximum fertilization rate and optimal fertilization ratio for high yield of corn.N and P application rates were set in two ways,with fixed N/P ratio or with N rate varying with P rate.Results show that in the treatment with fixed N/P ratio,the maximum N application rate was 235.4 kg hm-2,the highest corn yield 10 213 kg hm-2,the optimum N application rate as 207.1 kg hm-2,its corresponding yield 10 163 kg hm-2,46 kg hm-2,738 kg hm-2,39 kg hm-2 and 723 kg hm-2 higher respectively than in the other,showing every additional kilogram of N could bring about an additional yield of 18.5 kg.The experiment demonstrated that N/P ratio of fertilization is the most important factor affecting maximum N rate and economic benefits.Through increasing N and P application rates while keeping them at a fixed ratio an optimal fertilization rate could be obtained.