确定合理施氮量是获得较高目标产量、维持土壤氮肥力和降低施氮引起环境污染的关键。自一个世纪前氮肥发明和施用以来，尽管已经开展了上百年的研究，但尚未找到令人满意能够在田块尺度上方便的确定合理施氮量方法。本文在前期提出的作物理论施氮量概念和方法基础上，进一步推导出在考虑其他来源氮素输入情况下，根据百千克收获物需氮量确定理论施氮量的计算式。结果表明，在确定了百千克收获物需氮量（N100，kg）后，推荐施氮量（Nfert，N kg hm-2）是目标产量（Y，kg hm-2）的唯一函数，即理论施氮量Nfert ≈ Y/100×N100。综合各种文献报道结果，在当前生产条件和产量水平下，小麦、玉米、水稻的百千克收获物需氮量分别取值为2.8、2.3和2.4 kg。应用大量文献报道的田间试验结果，对理论施氮量和经济最佳施氮量进行了比较。在绝大多数情况下，两者非常接近。但东北的小麦、玉米和水稻的理论施氮量远高于区域氮肥推荐量。主要原因是氮素矿化作用大于固持作用，作物利用了部分土壤矿化氮，土壤有机氮处于消耗状态。结合理论施氮量，本文详细解析了近年来我国建立的推荐施氮量方法的科学基础、推荐结果及适用性。认为将我国大面积生产中过量和不足施氮调节到合理施氮量范围，是当前和今后一段时期的紧迫任务。理论施氮量从长期维持高产稳产、土壤氮素平衡和低环境风险考虑，即可满足这种实际需求。推广技术员和农户能够根据自己地块的目标产量用口算确定出施氮量，简便易行。
Determining reasonable nitrogen (N) fertilizer rate is the key point for getting higher target yield, maintaining soil N fertility and reducing environmental pollution. Since N fertilizer invention and application a century ago, although it had been carried out more than hundred of years’ researches, people didn’t find the satisfied methods that could determine the reasonable N application rate on the field scale. Based on the previous concept and method of theoretical N rate (TNR) and on the conditions of considering other sources of nitrogen inputs, this paper further deduce the calculation of TNR according to the N requirement per hundred kilograms (kg) of grain. The results showed that, after determining the N requirement per hundred kg of grain (N100), the TNR (Nfert, N kg hm-2) is the only function of target yield (Y, kg hm-2) as: Nfert ≈ Y/100×N100. After integrating the results from all kinds of literatures, the N requirement per hundred kilograms of wheat, maize and rice was 2.8, 2.3 and 2.4 kg, respectively, under current production conditions and yield levels. Comparing the TNR with economic optimum N rate (EONR) from a large number of field experiments’ results on the literatures, in most case, the two rates are very close in other regions of China except for the northeast China. The TNR of wheat, maize and rice in the northeast region is much higher than the regional N recommended rate (RNRR). The main reason is that the soil N mineralization is greater than immobilization during growth period, which means the crops utilizing part of soil mineralized N and soil organic N is depleted. Combining with the TNR, this paper also analyzed the scientific basis, recommendation results and applicability of other N recommendation methods established in recent years in China in details. The paper recognized that to adjust the excessive and deficient N application rates to the reasonable scope is the urgent task nowadays and in the future, and the TNR could meet this actual demand by maintaining high and stable target yield, soil N balance and low environmental risk. It is very convenient for extension technicians and farmers to determine the reasonable N application rate according to the target yield of their own field.
巨晓棠.理论施氮量的改进及验证——兼论确定作物氮肥推荐量的方法[J].土壤学报,2015,52(2):249-261. DOI:10.11766/trxb201410250536 Ju Xiaotang. Improvement and validation of theoretical N rate (TNR)— Discussing the methods for N fertilizer recommendation[J]. Acta Pedologica Sinica,2015,52(2):249-261.复制