施氮对橡胶林土壤氮素淋洗损失及碳排放影响的研究

发布时间：2018-02-04 23:33

本文关键词： 橡胶林施氮硝态氮产生与累积硝态氮淋洗土壤呼吸　出处：《海南大学》2017年硕士论文　论文类型：学位论文

【摘要】：合理的施用氮肥是保证橡胶树增产、稳产的重要措施。热带季风气候条件下的橡胶林,具有高温、高湿和强降雨的气候特征。这种独特的气候条件下,硝态氮淋洗可能是其氮素损失的重要途径。明确橡胶林生态系统施氮后氮素损失过程、通量以及对土壤呼吸的影响,对于氮肥优化管理和调控,培育土壤有机碳氮库,提高土壤肥力具有重要意义。采用大田试验的研究手段,研究了4种施氮水平下(不施氮,NO;低氮,100kgNha~(-1),Ncon;中氮,230kgNha~(-1),配施有机肥30kgNha~(-1),Nbal;高氮,400kgNha~(-1),N400)海南橡胶林土壤硝态氮的产生、累积、移动和淋失过程及土壤呼吸的碳排放速率和通量。结果表明:1、尿素施入酸性砖红壤后,在很短时间内即能完成水解。施肥后第2天土壤pH和铵态氮含量基本达到峰值,之后随着土壤硝化作用的进行,铵态氮含量迅速降低后逐渐稳定,硝态氮含量随之升高。田间条件下,酸性砖红壤硝化过程受施氮量、土壤pH、土壤温度、土壤湿度影响较大。土壤净硝化速率与施氮量呈显著正相关关系(r=0.724*,P0.05)。2、旱季,硝态氮主要在0-100 cm 土体内累积,淋失出根层土壤剖面的硝态氮浓度较低;集中降雨后,淋失出根层土壤剖面的硝态氮浓度迅速增加。氮肥表施后,4个处理硝态氮年淋失量介于1.77-35.52 kgNha~(-1),其中N400硝态氮淋失率8.44%,显著高于其他处理。3、氮肥穴施后,各施氮处理产生少量铵态氮淋洗,年淋洗通量0.26-0.88 kg N ha~(-1),N400显著高于其他处理;不同处理硝态氮年淋失通量介于0.11-3.73 kg N ha~(-1),氮素年淋失总量 0.15-4.61 kg N ha~(-1),其中 N400NbalNcon=NO。干旱气候条件下,其氮素淋失量偏低,另外渗漏计法可能低估了其氮素淋洗通量。4、橡胶林土壤呼吸的碳排放速率具有明显的季节变化特征,全年呈多峰型曲线。与不施氮处理相比,较低的施氮水平并没有显著影响土壤呼吸。继续增施氮肥则显著地促进了橡胶林土壤呼吸,激发了土壤的碳排放。与N400和Ncon相比,Nbal化肥配施有机肥并没有引起土壤碳排放的显著增加。
[Abstract]:The rational application of nitrogen fertilizer is an important measure to ensure the increase of yield and stable yield of rubber trees. The rubber forest under tropical monsoon climate has the climatic characteristics of high temperature, high humidity and strong rainfall. Nitrate leaching may be an important way of nitrogen loss. The process of nitrogen loss, flux and effect on soil respiration after nitrogen application in rubber forest ecosystem were determined, and the optimal management and regulation of nitrogen fertilizer were also discussed. It is of great significance to cultivate soil organic carbon and nitrogen pool and improve soil fertility. Low nitrogen (100 kg) Nhaka-1 (Nconn); The medium nitrogen content was 230kg Nhafen ~ (-1), and the organic fertilizer was 30 kg ~ (-1) ~ (-1). The production, accumulation, movement and leaching process of nitrate nitrogen and the carbon emission rate and flux of soil respiration in Hainan rubber forest were studied. After urea was applied to acid latosol, hydrolysis could be completed in a very short time. The soil pH and ammonium nitrogen content reached the peak on the 2nd day after fertilization, and then with the soil nitrification. Ammonium nitrogen content decreased rapidly and then gradually stabilized, and nitrate nitrogen content increased. Under field conditions, the nitrification process of acid latosol was subjected to nitrogen application, soil pH, and soil temperature. The effect of soil moisture was significant. There was a significant positive correlation between the rate of net nitrification and the amount of nitrogen applied in the dry season. The nitrate nitrogen accumulated mainly in 0-100 cm soil, and the nitrate concentration in the soil profile was lower than that in the root soil profile. After concentrated rainfall, the nitrate concentration in the soil profile increased rapidly. After the application of nitrogen fertilizer, the annual leaching amount of nitrate nitrogen in the four treatments ranged from 1.77-35.52 kg Nhajian-1). The leaching rate of N400 nitrate nitrogen was 8.44%, which was significantly higher than that of other treatments. The annual leaching flux of 0.26-0.88 kg / a was significantly higher than that of other treatments. The annual leaching flux of nitrate was between 0.11-3.73 kg / a and 0.15-4.61 kg / year. The nitrogen leaching loss of N400NbalNconNo.was low in arid climate, and the leaching flux of N400NbalNconNo.was probably underestimated by leakage method. The carbon emission rate of soil respiration in rubber forest showed obvious seasonal variation, and showed a multi-peak curve throughout the year, compared with the treatment without nitrogen application. Low nitrogen application level had no significant effect on soil respiration, but continued application of nitrogen fertilizer significantly promoted soil respiration and stimulated soil carbon emissions. Compared with N400 and Ncon. Nbal fertilizer combined with organic fertilizer did not cause a significant increase in soil carbon emissions.
【学位授予单位】：海南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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