黄土高原旱作覆膜玉米不同时期施氮效果及气态氮损失

发布时间：2018-06-23 12:14

本文选题：施氮时期 + ~(15)N去向　；参考：《中国科学院研究生院(教育部水土保持与生态环境研究中心)》2016年博士论文

【摘要】：在适宜时期施用氮肥既能满足作物对养分需求,又能获得较高的氮肥利用效率并减少氮损失及其带来的环境风险。黄土高原属于典型旱作农业区,玉米是该地区主要粮食作物之一。地膜覆盖技术因其具有增温保墒、大幅提高作物产量的作用,已在该地区被广泛应用。本研究以黄土高原旱作覆膜玉米为研究对象,采用大田试验与田间微区试验相结合的研究方法,利用15N示踪技术,连续3年对施入土壤中的肥料氮进行定向追踪,探索不同施氮时期对肥料氮去向及其残留效应的影响;并对土壤N2O、NH3排放进行连续同步监测,以期查明旱作覆膜玉米农田氮素气态损失对施氮时期的响应。通过对不同施氮时期处理的作物产量、养分利用及环境效应的综合评价,明确黄土高原旱作覆膜玉米适宜施氮时期,求证假设“在氮肥总施用量不变情况下,生育期分次施氮因作物吸收利用不同,其残留、后效及损失程度不同”真伪,为该地区制定有效氮肥管理措施提供理论参考。本研究主要获得以下结论:(1)分次施氮显著增加植株氮中来源于肥料氮的比例和数量,与单次和两次施氮相比,三次施氮也显著增加了植株氮中来源于土壤氮的数量,说明多次施氮对土壤氮库存在一定正激发效应。两次和三次施氮下15N肥料当季利用率分别为37.6%和39.1%,显著高于单次施氮(28.0%),而15N潜在损失率(11.2%和12.7%)显著低于单次施氮(22.2%),两次与三次施氮间无显著差异。与基施15N和吐丝期追施15N相比,作物对8叶期追施15N的利用率最高,损失率最低。当季作物收获后15N在0-200 cm土层的残留量占总施氮量的48.3%-51.3%,其中约50%残留在0-20 cm土层;分次施氮对土壤中当季残留15N总量无显著影响。(2)不同施氮时期处理土壤残留15N被第二季和第三季作物利用率分别为24.1%-32.3%和10.4%-11.0%,占15N肥料总施入量的12.1%-15.7%和5.4%-5.8%;氮肥分三次施入会显著增加第二季作物对残留15N的利用效率。三季作物对15N肥料叠加利用效率为47.6%-60.8%,分次施氮显著提高氮肥叠加利用率。第三季作物收获后15N在0-200 cm土壤中残留率及潜在损失率分别为15.0%-21.0%和18.2%-37.4%,分次施氮显著增加了肥料氮在土壤中的残留,并减少了其潜在损失。(3)氮肥分三次施入在玉米生育中后期降雨较多的情况下会显著增加N2O累积排放量以及单位产量N2O排放量。施肥与降雨耦合是N2O排放的主要驱动因子。由于在黄土高原地区玉米生长发育中后期(7-9月)常常伴有较强降雨,因此分三次施氮增加了N2O排放风险。旱作覆膜玉米不同时期施氮的NH3挥发损失率为6.2%-9.4%,分次施氮会显著降低肥料氮NH3挥发损失。与基肥氮(撒施后旋耕)相比,追肥氮(带状沟施覆土)的NH3挥发损失率更低。与单次施氮相比,将氮肥分两次施用能有效减少NH3挥发损失,又不会增加单位产量N2O排放。(4)分次施氮显著提高玉米产量,但两次与三次施氮间无显著差异。分次施氮会显著增加玉米成熟期地上部氮素累积量,尤其是分三次施氮能显著增加玉米吐丝后期地上部氮素累积。分次施氮显著提高氮肥表观利用率、氮肥农学利用率和氮肥偏生产力,在半膜覆盖下显著降低0-200 cm土壤硝态氮累积。全膜覆盖下不施氮、单次、分两次和三次施氮处理两年平均产量较半膜覆盖分别提高20.2%、10.3%、10.1%和10.5%。全膜覆盖显著增加玉米地上部干物质和氮素累积,尤其在生育初期表现更加明显。全膜覆盖下玉米收获后0-200 cm土壤硝态氮累积量显著高于半膜覆盖。施氮显著提高玉米水分利用效率,与单次施氮相比,分次施氮在生育期降水较少的年份更有利于提高水分利用率。全膜覆盖在生育期降水较多的年份对水分利用效率的增加更为显著。综上可见,将氮肥在播种前和8叶期按4:6的比例分两次施用既能获得较高产量与较高水氮利用效率,还可有效减少肥料氮的NH3挥发损失,且与单次施氮相比并未增加单位产量N2O排放量。因此,综合考虑作物产量、养分高效利用以及环境效应,分两次施氮更适合本地区旱作覆膜玉米生产。
[Abstract]:The application of nitrogen fertilizer in the suitable period can not only satisfy the nutrient demand of crops, but also obtain higher nitrogen use efficiency and reduce nitrogen loss and environmental risks. The Loess Plateau belongs to the typical dry farming area, and corn is one of the main grain crops in this area. This study has been widely used in this area. In this study, the mulched Maize in dry soil in the Loess Plateau was used as the research object. The field test and field micro area test were combined to study the fertilizer nitrogen in the soil for 3 years. The direction of fertilizer nitrogen direction and its residual effect in different nitrogen application periods were explored for 3 years. In order to find out the response of nitrogen gas loss to nitrogen application period in the dryland mulched corn farmland, the response of nitrogen gas loss to nitrogen application period in the dryland covered field was detected by continuous synchronous monitoring of the soil N2O and NH3 emission. In this study, the following conclusions were obtained: (1) the ratio of nitrogen fertilizer to fertilizer nitrogen was significantly increased in the nitrogen application of plant nitrogen. Compared with the single and two nitrogen application, the three nitrogen application also significantly increased the number of nitrogen in the plant nitrogen, indicating that there was a certain positive excitation effect on the soil nitrogen pool. The utilization rate of 15N fertilizer in the two and three nitrogen application periods was 37.6% and 39.1%, respectively, significantly higher than the single nitrogen application (28%), and the potential loss rate of 15N. (11.2% and 12.7%) was significantly lower than single nitrogen application (22.2%), and there was no significant difference between two and three nitrogen application. Compared with 15N and 15N, the utilization rate of 15N was the highest and the loss rate was the lowest. The residual amount of 15N in the 0-200 cm soil layer after crop harvest was 48.3%-51.3%, of which about 50% remained in 0-20 cm. The total amount of residual 15N in soil was not significantly affected in soil layer. (2) the utilization rate of soil residual 15N in second and third seasons was 24.1%-32.3% and 10.4%-11.0% respectively, which accounted for 12.1%-15.7% and 5.4%-5.8% in the total amount of 15N fertilizer, and the nitrogen fertilizer application was significantly increased by second season crops to the remaining 15N. The efficiency of utilization of 15N fertilizer in three season crops was 47.6%-60.8%, and nitrogen fertilizer application rate increased significantly. The residual rate and potential loss rate of 15N in 0-200 cm soil after third season crops were 15.0%-21.0% and 18.2%-37.4% respectively. The potential loss. (3) the cumulative emission of N2O and the N2O emissions per unit yield were significantly increased by the three nitrogen fertilizer application in the middle and late period of maize growth. The coupling of fertilization and rainfall is the main driving factor of N2O emission. The three nitrogen application increased the risk of N2O emission. The loss rate of NH3 volatilization loss was 6.2%-9.4% in different period of dry mulched maize, and secondary nitrogen application could significantly reduce the loss of fertilizer nitrogen NH3 volatilization. Compared with basal fertilizer nitrogen (after applying rotary tillage), the loss rate of NH3 volatilization was lower. Compared with the single nitrogen application, the nitrogen fertilizer was divided into two times. The application can effectively reduce the loss of NH3 volatilization and not increase the unit output N2O emissions. (4) nitrogen application significantly increases maize yield, but there is no significant difference between the two and the three nitrogen application. Nitrogen application can significantly increase the nitrogen accumulation in the upper part of the maturing period of maize, especially the three nitrogen application can significantly increase the nitrogen accumulation in the upper part of the later period of corn silk spinning. Nitrogen fertilizer application rate, nitrogen fertilizer utilization ratio and nitrogen fertilizer partial productivity significantly decreased nitrate nitrogen accumulation in 0-200 cm soil under semi film mulching. No nitrogen application under full film mulching, the average yield of single, two and three nitrogen treatments increased by 20.2%, 10.3%, 10.1% and 10.5%. full film cover respectively. The accumulation of dry matter and nitrogen in the upper part of maize increased significantly, especially at the early stage of growth. The accumulation of nitrate nitrogen in the 0-200 cm soil was significantly higher than that of half film mulching after the full film mulching. Nitrogen application significantly increased the water use efficiency of maize. Compared with the single nitrogen application, the nitrogen application was more favorable in the year of less precipitation. To improve the water use efficiency, the full film mulching increased the water use efficiency more significantly in the years of more precipitation in the growing period. It was found that the two application of nitrogen fertilizer at the ratio of 4:6 in the pre sowing and 8 leaf stages can not only obtain higher yield and higher water and nitrogen use efficiency, but also effectively reduce the loss of NH3 volatilization of fertilizer nitrogen, and a single time. Nitrogen application did not increase the N2O emissions per unit yield. Therefore, considering crop yield, nutrient efficient utilization and environmental effects, two nitrogen application is more suitable for the production of dryland mulched Maize in the region.
【学位授予单位】：中国科学院研究生院(教育部水土保持与生态环境研究中心)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S513

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