秸秆还田配施氮肥对麦田氮素平衡和籽粒产量的影响

Effect of Combination of Maize Straw and N Application on N Balance and Grain Yield of Wheat

为明确秸秆还田配施不同水平氮肥下麦田的氮素平衡状况,在夏玉米秸秆全部还田的基础上设置了不同的氮肥处理,测定了小麦植株全N含量、土壤硝态氮含量、氮肥氨挥发量和籽粒产量,分析了麦田不同土层硝态氮含量和积累量的变化趋势以及施氮量对氮素利用效率和麦田氮素平衡的影响。结果表明,小麦植株氮含量、植株氮素总积累量、籽粒产量均随施氮量的增加而显著增加;施加氮肥使氮素养分利用率、氮肥偏生产力显著降低。与播种时期土壤硝态氮含量相比,成熟期硝态氮含量降低,且施氮处理下土壤硝态氮含量、硝态氮积累量高于不施氮处理;硝态氮积累量主要分布在麦田土壤表层,与施氮量成正相关关系。施氮量为0、160、220、280kg·hm^(-2)时,硝态氮淋失量分别为5.04、13.10、17.10、37.26kg·hm^(-2)。氮肥的氨挥发速率在施肥后第一天达到最高,随后逐渐降低,遇到降雨或灌溉迅速降低至不施氮处理的氨挥发水平,氮肥氨挥发量与施氮量及时间存在正相关关系。160、220、280kg·hm^(-2)施氮量处理下,氮肥氨挥发量分别为0.65、0.77、1.01kg·hm^(-2)。从麦田氮素平衡来看,不施氮肥处理耗竭土壤氮素资源;施氮量为160kg·hm^(-2)时,有消耗土壤氮的风险;施氮量为220kg·hm^(-2)时,氮素投入与氮素输出保持平衡;施氮量为280kg·hm^(-2)时,有大量氮素损失到环境中的风险。为有效控制氮素淋溶和氨挥发损失,兼顾产量和节约生产成本,该区推荐施氮量为220kg·hm^(-2)。

In order to clarify the N balance of wheat field under different N fertilizer levels with straw return,a field experiment was carried out in Henan province from 2015 to 2016. Four N levels were set up on the basis of all the maize stalks return,and the contents of total N of plant,soil NO^--N and NHs-N volatilization were determined,respectively. The changing trend of NOs-N content, NOs-N accumulation in different soil layers and the effects of N application on ammonia volatilization of N fer- tilizer,N use efficiency and N balance were analyzed. The results showed that N content,N accumula- tion,and grain yield of wheat were significantly increased with the increase of N fertilization rate. The N use efficiency and partial productivity of N fertilizer were significantly decreased with the increase of N application rate. NOs-N content of the soil at the mature stage showed lower than that before so- wing,and NO3--N content and accumulation under N application treatments were higher than that without N application. There was a positive correlation between NOg-N accumulation and N applica-tion level,and NO;--N was mainly accumulated in topsoil at mature stage. The leaching loss oi Nt - N under the treatment of 0,160,220, and 280 kg hm-2 N were 5. 04, 13. 10, 17. 10, and 37. 26 kg hm-2 ,respectively. Ammonia volatilization rate of N fertilizer reached the highest level on the first day after fertilization,and decreased gradually. Ammonia volatilization rate of N application were rapidly reduced to the ammonia volatilization rate of no N application after precipitation or irrigated. There was a positive correlation between the accumulation o{ ammonia volatilization and N application rates and times. The accumulation of ammonia volatilization of N fertilizer under the treatments of 160,220 and 280 kg hm-2 N were 0. 65,0.77,and 1.01 kg hm-2,respectively. Referring to N bal- ance of wheat field, soil N resources was depleted under the treatment of none N application. There was a risk of consumption of soil N under the treatment of 160 kg hm-2. N input was equal to N output under the treatment of 220 kg hm-2 ,and there is a risk of lots of N losses to the environment under the treatment of 280 kg hm-2. The recommended N application rate was 220 kg hm-2 in or- der to control N leaching and ammonia volatilization loss effectively,and to balance the yield and sav- ing production cost.