中国小麦季氮素养分循环与平衡特征

Nitrogen cycling and balance for wheat in China

通过汇总2000—2011年文献数据以及国际植物营养研究所实测试验数据,研究了华北、长江中下游和西北地区小麦季经过土壤界面的氮素输入和输出各项养分循环参数,分析并评估了3大区域的氮素养分平衡状况.结果表明:华北、长江中下游和西北地区小麦季氮肥平均施入量分别为170、183和150 kg N·hm-2,上季作物秸秆氮素还田量分别为74.6、15.2和8.1 kg N·hm-2,种子带入量分别为4.9、4.2和3.5 kg N·hm-2.华北地区来自非共生固氮、大气沉降和灌溉水氮素养分输入量分别为15、12.9和9.9 kg N·hm-2,长江中下游地区分别为15、14.5和5.8 kg N·hm-2,西北地区分别为15、9.4和7.7 kg N·hm-2.小麦收获时华北、长江中下游和西北地区地上部作物吸收的氮分别为174.3、144.4和122.3 kg N·hm-2,华北地区通过氨挥发、N2O排放和淋溶损失的氮素分别为19.9、2.6和11.8 kg N·hm-2,长江中下游地区分别为9.4、2.4和15.5 kg N·hm-2,西北地区小麦季氨挥发和N2O排放量分别为3.4和0.7 kg N·hm-2,不计淋溶损失的氮素.由此计算的小麦季氮素养分平衡结果显示,华北、长江中下游和西北地区的氮素养分均表现为盈余,盈余量分别为78.7、66.0和67.3 kg N·hm-2,超出了养分允许平衡盈亏率,应适当调整氮肥投入,避免氮肥的不科学施用带来的负面环境影响.

Abstract： In this study, the input and output parameters of N for wheat production were collected from published literatures and International Plant Nutrition Institute in the period of 2000 to 2011 to evaluate N cycling and balances in North China, the middle and lower reaches of Yangtze River and Northwest China. The results showed that the N fertilizer application rates for each region were 170, 183 and 150 kg N ·hm^-2, the amounts of N from the previous crop were 74.6, 15.2 and 8.1 kg N·hm^-2, and from seeds were 4.9, 4.2 and 3.5 kg N ·hm^-2, respectively. The N inputs from symbiotic fixation, atmospheric deposition and irrigation water in North China were 15, 12.9 and 9.9 kg N ·hm^-2, and in the middle and lower reaches of Yangtze River were 15, 14.5 and 5.8 kg N·hm^-2, and in Northwest China were 15, 9.4 and 7.7 kg N ·hm^-2, respectively. The amounts of N uptake by aboveground plant at harvest time in North China, the middle and lower reaches of Yangtze River and Northwest China were 174.3, 144.4 and 122.3 kg N ·hm^-2, respec- tively, and the rates of ammonia volatilization, N20 emission and N leaching in North China were 19.9, 2.6 and 11.8 kg N ·hm^-2, in the middle and lower reaches of Yangtze River were 9.4, 2.4 and 15.5 kg N ·hm^-2, and in Northwest China were 3.4, 0.7 and 0 kg N ·hm^-2, respectively. Asa result, the N balances in these three regions were all showing surpluses by 78.7, 66.0 and 67.3 kg N ·hm^-2. It is therefore necessary to adjust the N fertilizer application rates in these three regions to avoid the negative impacts on the environment.