施氮量对黄土高原旱地冬小麦产量和水分利用 效率影响的整合分析

【目的】明确氮肥在黄土高原地区不同种植条件下对冬小麦生产的影响及各条件下合理的施氮量。【方法】通过文献检索共获得82篇大田试验文献,包含355个独立研究的1 169组观测数据,采用整合分析比较氮肥在黄土高原不同区域、不同年均温、不同年降水量及不同耕层有机质含量下对冬小麦产量和水分利用效率的影响,并采用回归分析探究各分组产量和水分利用效率与施氮量间的关系。【结果】施氮整体上显著提高了黄土高原冬小麦产量和水分利用效率,相对增长率分别为66.09%和72.38%（P＜0.05）。施氮后西北部产量相对增长率（69.27%）高于东南部,水分利用效率增长率（65.53%）低于东南部;西北部在施氮量212 kg·hm ^-2时产量达到最高,东南部需多施15 kg·hm ^-2才能获得最高产量;西北部施氮232 kg·hm ^-2时水分利用效率最高,而东南部水分利用效率在施氮224 kg·hm ^-2时基本趋于稳定。施氮后年均温≤10℃地区产量和水分利用效率的相对增长率（79.12%,75.00%）均高于＞10℃地区;年均温＞10℃地区施氮189 kg·hm ^-2和187 kg·hm ^-2时产量和水分利用效率分别达到最高,而年均温≤10℃地区施氮225 kg·hm ^-2时产量才趋于最大,水分利用效率在施氮239 kg·hm ^-2时达到最高。施氮后在年均降水≤600 mm地区产量相对增长率（70.48%）更显著,而水分利用效率则在年均降水＞600 mm时更显著;年均降水≤600 mm地区在施氮量235 kg·hm ^-2和244 kg·hm ^-2时,产量和水分利用效率分别达到最高,年均降水＞600 mm地区实现高产的施氮量为250 kg·hm ^-2。施氮后耕层有机质含量≤12 g·kg ^-1条件下,产量和水分利用效率的相对增长率（78.24%, 86.55%）均高于＞12 g·kg ^-1条件,前者在施氮量226 kg·hm ^-2和212 kg·hm ^-2时产量和水分利用效率分别达到最高,而后者获得最高产量和最高水分利用效率的施氮量分别为163 kg·hm ^-2和175 kg·hm ^-2。【结论】在黄土高原,冬小麦在东南部和西北部获得高产的合理施氮量分别为227 kg·hm ^-2和212 kg·hm ^-2;年均温＞10℃地区合理施氮量为187 kg·hm ^-2,年均温≤10℃地区为239 kg·hm ^-2;年均降水＞600 mm地区合理施氮量为250 kg·hm ^-2,年均降水量≤600 mm地区为235 kg·hm ^-2;耕层有机质含量≤12 g·kg ^-1条件下的合理施氮量为226 kg·hm ^-2,高于12 g·kg ^-1时则为163 kg·hm ^-2。

A Meta-Analysis of the Effects of Nitrogen Application Rates on Yield and Water Use Efficiency of Winter Wheat in Dryland of Loess Plateau

【Objective】 The objective of this study was to clarify the effects of nitrogen fertilizer (N) on winter wheat yield and the optimum N level under different planting conditions in the Loess Plateau.【Method】A total of 82 field studies were obtained through literature retrieval. The effects of N on yield and water use efficiency of winter wheat in different regions, annual mean temperature, annual precipitation and plough layer organic matter content in the Loess Plateau were compared by meta-analysis. Regression analysis was used to explore the relationship between yield and N application rate, water use efficiency and N application rate in each group. 【Result】 Compared with no N application, N application improved the yield and water use efficiency of winter wheat in the Loess Plateau by 66.09% and 72.38%, respectively (P＜0.05). The effect of N on yield was more prominent in the northwest than that in the southeast, and the effect of N on water use efficiency was more prominent in the southeast than in northwest. The yield of northwest reached the highest when the N application rate was 212 kg·hm ^-2, and the highest yield could be obtained by applying another 15 kg N·hm ^-2in southeast. The water use efficiency reached maximum at 232 kg N·hm ^-2 in northwest, while at 224 kg·hm ^-2 in southeast. The effects of N on yield and water use efficiency of winter wheat were more prominent in areas with average annual temperature ≤10℃. At the area of average temperature ＞10℃, yield and water use efficiency reached the maximum when N rates were 189 kg·hm ^-2 and 187 kg·hm ^-2, respectively. However, at the area of average temperature ≤10℃, yield and water use efficiency reached the maximum when N rates were 225 kg·hm ^-2 and 239 kg·hm ^-2, respectively. The effect of N on yield was prominent in areas of annual average precipitation ≤ 600 mm, while the change rate of water use efficiency was prominent in areas with annual precipitation ＞600 mm. The yield and water use efficiency reached the highest at 235 kg N·hm ^-2 and 244 kg N·hm ^-2 application rates in areas with annual precipitation ＜600 mm, while 235 kg·hm ^-2 and 250 kg·hm ^-2 in the area with annual precipitation ＞600 mm. The effect of N on yield and water use efficiency was prominent when the organic matter content in plough layer was ≤12 g·kg ^-1. Under the condition of topsoil organic matter ＞12 g·kg ^-1, the yield and water use efficiency tended to be highest when the N application rates were 163 kg·hm ^-2 and 175 kg·hm ^-2. The optimum N application rate was 226 kg·hm ^-2 when the topsoil organic matter content ≤12 g·kg ^-1.【Conclusion】 The optimum N application rates for high yield of winter wheat in the southeast and northwest were 227 kg·hm ^-2 and 212 kg·hm ^-2, respectively. The optimum N application rate was 188 kg·hm ^-2 in the area with average annual temperature ＞10℃, and 225 kg·hm ^-2 when average annual temperature ≤10℃. In the area with annual average precipitation ＞600 mm, the optimum N application rate was 250 kg·hm ^-2, and 235 kg·hm ^-2 when annual average precipitation ≤600 mm. The optimum N application rate was 226 kg·hm ^-2 under the topsoil organic matter content ≤12 g·kg ^-1, and 163 kg·hm ^-2 when the topsoil organic matter content ＞12 g·kg ^-1.