冬小麦对铵态氮和硝态氮的响应

在陕西省永寿县和河南省洛阳市分别设置了11和7处大田试验,分5层采集0~100 cm土壤样品并测定其起始硝态氮含量。永寿试验设7个处理,分别为不施氮,硝态氮、铵态氮品种、硝态氮与铵态氮2∶1组合各2个处理;洛阳试验设6个处理(硝态氮肥只有1个品种),施氮处理均施N 150 kg hm-2,研究小麦对铵态氮和硝态氮肥响应的差异及其与不同深度土层硝态氮累积量的关系。试验表明,同一形态不同氮肥品种之间的增产差异显著低于不同形态之间的差异。比较不同形态氮肥的小麦产量、增产量和增产率的平均值,硝态氮肥最高,硝态氮、铵态氮组合次之,铵态氮最低。氮肥增产量和增产率随土壤累积硝态氮量增加而显著下降;累积量越低,氮肥增产效果越突出,硝态氮的效果也越显著。由此可见,土壤累积的硝态氮量是决定氮肥肥效的主要因子,也是决定不同形态氮素效果的主要因子。只有在硝态氮累积量低的土壤上,氮肥才能充分发挥作用,硝态氮也才能表现出明显的优势。

Responses of winter wheat to ammonium and nitrate nitrogen

11 and 7 field experiments were conducted in Yongshou County, Shaanxi Province and Luoyang, Henan Province, respectively and 5 layers of soil were sampled in 20 cm increment to 100 cm soil depth for each experiment field to study the difference of wheat responses to nitrate and ammonium N and the relation of its responses to nitrate N cumulative in different soil layers. Each of the experiments included control (without N fertilization), two sorts of nitrate N (calcium nitrate and sodium nitrate), two sorts of ammonium N (ammonium chloride and ammonium sulfate), and two combinations of nitrate to ammonium N in a ratio of 2:1 with total N input of 150 kg per ha as basal fertilizers. Results showed that the difference in yield increase of two sorts of N fertilizers in either ammonium or nitrate form or the two combinations was much less than the two forms. Using averages of yield, yield increase in amount (kg/ha) and yield increase in percentage of the same form of N fertilizer for comparison, we found that nitrate N was the highest in yield and yield increase, followed by the combination, while the ammonium N was the lowest. The cumulative nitrate N at different soil layers was linearly correlated with wheat yields for control and ammonium N application while no such a correlation was found with nitrate N or combinations of the two N forms. The yield increase amount and percentage were significantly declined with the increase of cumulative nitrate N amount in soil profile. The lower the nitrate N amount cumulative in soil profile, the higher the N fertilizer effect, and the better the nitrate N superiority. From such results, we could conclude that the cumulative nitrate in soil profile was the decisive factor that did not only determine the N fertilizer effect, but the nitrate superiority as well. Only under the condition with low nitrate N cumulative in soil profile, could the N fertilizer play its role, and nitrate N show its superiority.