【作者】 张晓梅；

【导师】 何丙辉； 郝明德；

【作者基本信息】 西南大学 ， 水土保持与荒漠化防治， 2010， 硕士

【摘要】 黄土高原地区分布大面积的黄绵土,是世界范围内严重的水土流失区。研究该地区的黄绵土农耕地施肥对有机质和氮素流失影响规律,有利于提高农业生产中氮肥的有效的利用,达到农业在较少投入下能够得到较高的经济产量,为作物生长需要的养分量与减少环境污染之间建立平衡关系。本文采用室内人工模拟降雨,研究黄绵土4种施氮处理下产流过程中有机质和氮素流失特征,得出如下主要结论：1)不同施肥处理径流泥沙流失特征研究表明,施肥可以延长初始产流时间,与对照处理相比较,高肥、中肥、低肥延长的初始产流时间分别为对照的5.5倍、5.2倍、2.6倍,高肥处理延长的初始产流时间最长；不同处理径流量变化趋势基本相同即先迅速增大至最大值后趋于稳定,产流末期又急剧下降；而含沙量变化与径流量不同,降雨初期含沙量急剧下降,随后在整个径流过程中达到稳定。在对径流和泥沙累计流失过程回归分析后得出,不同施肥处理下,径流流失量与降雨时间存在显著的幂函数相关关系,而泥沙流失量与降雨时间存在显著的线性相关关系。与对照处理相比较,增施氮肥后可以不同程度减少径流和泥沙流失量。2)不同施肥处理下有机质流失特征研究表明,各种施肥处理泥沙中有机质含量变化总趋势相似,先急剧下降,在产流12min达到稳定含量之后略有波动但波动不大,对照处理有机质含量变化最不稳定；不同施肥处理有机质累计流失量曲线高低依次是：对照>低肥>中肥>高肥处理,高肥处理累计流失量最少；各处理有机质流失量与降雨时间存在y=a+bln(x)的对数回归方程相关关系。施肥不同有机质流失量不同,回归分析得出施肥量与有机质流失量之间存在T=97.2161e-0.004805q的指数函数关系。有机质在泥沙中存在富集现象,各种施肥处理下富集率大小依次是：对照>低肥>高肥>中肥,中肥处理富集率最低,施肥可以降低泥沙对有机质的富集作用,但其对降低有机质富集作用关系比较复杂,并非简单的正相关关系。3)不同施肥处理下全氮流失特征研究表明,不同施肥处理的全氮含量变化不同,在整个降雨过程中全氮含量变化是：高肥>中肥>低肥>对照;不同施肥处理全氮累计流失量变化与其含量变化不同,施肥后减少了全氮流失总量,与对照相比,高肥、中肥、低肥处理全氮减少量分别为对照的67.7%、45.6%、44.1%,且施肥处理与全氮流失量存在T=97.2161e-0.004805q指数函数相关关系。而全氮累计流失量与降雨时间也存在相关性,回归分析得出y=a+bLn(x)对数相关关系。全氮在泥沙中有富集现象,不同施肥处理对全氮富集作用与有机质相反,其中高肥处理富集率显著高于其他处理,而中肥和低肥处理富集率基本相同,对照处理富集率最低。增施氮肥可以减少全氮流失总量,但却加剧了全氮的富集作用。4)不同施肥处理下铵态氮、硝态氮流失特征表明,不同施肥处理径流中铵态氮和硝态氮浓度随降雨时间延长变化趋势基本相似：高肥、中肥、低肥处理先急剧下降到稳定浓度至降雨结束；径流中以硝态氮流失为主,铵态氮的流失极少；但二者流失量与降雨时间均存在显著的线性相关关系。泥沙中铵态氮含量变化趋势是先降低后又逐渐增大至最大值,降雨后期又减少至产流初期时的含量,而硝态氮含量变化趋势是先缓慢增加至最大,随降雨时间延长又略有下降；与径流相比泥沙中流失的铵态氮和硝态氮总量都比较小,但不同施肥处理硝态氮和铵态氮与降雨时间都存在显著对数函数关系。侵蚀过程过程中铵态氮和硝态氮流失总量中以硝态氮为主,且硝态氮主要源于径流中的流失。更多还原

【Abstract】 Loessial Soil is widely distributed in the Plateau Loess, which suffered from severe soil erosion in the worldwide. Studying on soil nutrient loss is one of the most important way for the region to reduce its soil and water loss, increase agricultural production, improve the ecological environment, and increase income of farmers on the Loess Plateau. Studying on effects of fertilization treatments on nitrogen and organic matter loss in loessial soil, is beneficial to improving efficient use of nitrogen fertilizer in agricultural production, obtaining higher economic yield with less investment in agriculture field, and balancing relationship between crop nutrient needs and the reduction of environmental pollution. Based on simulation rainfall condition, this paper mainly study on characteristics of nitrogen and organic matter loss by runoff period under four kinds of nitrogen treatments., and the main conclusions are as follows:(1) The characteristics of runoff and sediment loss under different fertilization treatments showed that, fertilization can extend the initial runoff time, comparing with the CK, the initial runoff lag time of high nitrogen、medium nitrogen and low nitrogen were 5.5 times,5.2 times and 2.6 times respectively, that was, the initial runoff lag time of high nitrogen is the longest; under different fertilization treatments the runoff had the same variation trend which increased to the maximum initially, and then kept stabilize, but fell sharply at last; on the other hand, the variation trend of sediment concentration was different,which initially fell sharply, then sediment concentration was stable in remain runoff process. Furthermore, according to regression analysis of runoff and sediment accumulated loss, we found that there was a significant power function correlation between the runoff and rainfall time, while the significant linear correlation between sediment loss and rainfall time under different fertilization treatment. Comparing with the CK, increased application of nitrogen fertilizer can reduce runoff and sediment loss at varying degrees.(2) The characteristics of loss organic matter under different fertilization treatments showed that, the total variation trend of organic matter content under different fertilization treatments was similar, which sharply decreased at first, then reached the steady value when runoff time was 12 min, then, had little fluctuation; organic matter followed curves under different fertilization treatments were:: CK>low nitrogen>medium nitrogen>high nitrogen, and loss of high nitrogen was the least; However, the relationship between organic matter loss content and rainfall time under different treatments can be described by the regression equation:y= a+b Ln (x). Different fertilization had different organic matter total loss, according to regression analysis, the relationship between fertilization and organic matter loss can be described by the exponential function:T=97.2161e-0004805q.Organic matter has enrichment effect in sediment, enrichment rates under different fertilization treatments were: CK>low nitrogen>high nitrogen>medium nitrogen, and medium nitrogen had the lowest enrichment rate. So fertilization can reduce the enrichment of sediment on organic matter, but its relationship with lowering organic matter enrichment were not simple positive correlation.3) The characteristics of total nitrogen loss under different fertilization treatments showed that, the variation of the concentration of total nitrogen loss was different under different fertilization treatments, during the whole process of the rainfall, the content of total nitrogen were all follow the order of:high nitrogen> medium nitrogen>low nitrogen>CK. However, the variation of the cumulative total nitrogen loss was different from the variation of the content. Compared to the CK, the total quantity of the total nitrogen loss decreased after fertilization, which were separately 67.7%, 45.6% and 44.1%. The relationship between fertilization and total nitrogen can be described by the loss exponential equation:T=97.2161e-0004805q. Besides, there was also a correlation ship between total nitrogen loss content and rainfall time under different treatments, the logarithm correlation function of which was y= a+b Ln(x). Total nitrogen has enrichment effect in sediment, but the effect of different fertilization treatments was negative to organic matter. Furthermore, the enrichment rate of high nitrogen was significantly higher than others, while the enrichment rates of medium and low nitrogen were almost the same and that of the CK was the lowest, increased application of nitrogen fertilizer could decrease the concentration, but enhance the enrichment effect of total nitrogen.4) The characteristics of ammonium and nitrate nitrogen under different fertilization treatments showed that, the concentration of ammonium and nitrate nitrogen in the runoff under different fertilization treatments prolonged with the duration of rainfall simulation. The concentration of high nitrogen、medium nitrogen and low nitrogen decreased sharply and then went to a steady value till the end of the rainfall event. The main loss in the runoff was nitrate nitrogen, and the amount of ammonium nitrogen was little. However, there were significant linear relation between the loss of both type of nitrogen and rainfall time. The varying trend of ammonium nitrogen in sediment was decreasing to the lowest and then increasing gradually to the highest, and, at last decreasing to the primary concentration as the beginning of the runoff. While the varying trend of the nitrate nitrogen was increasing slowly to the highest, then decreasing with the rainfall time lasting. Compared to the loss of ammonium and nitrate nitrogen in the runoff, that in sediment was smaller, but both the ammonium and nitrate nitrogen under different fertilization treatments had significant logarithm relationship with rainfall time. According to regression analysis, During soil erosion process, loss style of nitrogen was mainly nitrate nitrogen which was mainly in runoff.更多还原