【作者】 杜臻杰；

【导师】 陈效民；

【作者基本信息】 南京农业大学 ， 土壤学， 2009， 硕士

【摘要】 红壤是我国南方的主要土壤类型之一,其面积广大,约占全国土地总面积的22.7%,对我国的粮食生产起着重要作用。由于红壤特殊的性质和不合理的施肥,引起了土壤酸化和氮、磷的污染,导致红壤地区生态环境的恶化。因此,如何科学、合理的开发利用红壤资源,走可持续发展道路,是我国土壤学科的研究热点。本文选择了湖南祁阳低山丘陵区典型红壤为供试土壤,定点监测了该区不同时期、不同施肥处理的硝态氮、铵态氮和速效磷等土壤养分和水分的含量,分析了这些速效养分和水分在土壤中的运移机理、时空变异和水肥耦合状况,并利用地统计学对其进行了插值处理,试图为红壤地区科学施肥、合理利用水肥资源、走农业可持续发展道路提供科学依据。本文的主要研究结果如下：(1)用水分扩散装置测定了供试红壤4个土壤发生层N03--N的含量及水平运移状况,结果表明：硝态氮水平运移速率随土壤含水量增加而相应增加,呈指数曲线变化；随运移距离增加而迅速减小,呈幂函数曲线变化。硝态氮水平运移速率与运移距离均有很好的相关性。硝态氮水平运移浓度与土壤含水量密切相关,随含水量的增加而减少,并呈幂函数曲线变化。硝态氮水平运移浓度还受到土壤水分扩散率的影响,随土壤水扩散率的升高而下降,并呈对数曲线变化。硝态氮浓度最大值出现在湿润锋(土壤干湿交界面上)。(2)在2007年3月到2009年3月期间,对供试红壤四个处理小区各土层中N03--N和NH4+-N含量的时间变化和剖面中垂直变化进行了研究。结果表明：各处理小区土壤表层中N03--N和NH4+-N的含量较高,而底层普遍较低,其中2007年5月份单施氮小区土壤淀积层(32-42cm)N03--N和土壤表层(0-25cm)NH4+-N的含量均达到最高,分别为248.34 mg·kg-1和127：24mg·kg-1,这是由于4、5月份为冬小麦的拔节-开花期,所需养分激增,大量追肥所致。N03--N和NH4+-N的含量在NPK小区和NP小区各土层中呈极显著直线线性正相关关系,而在单施N小区和空白小区的表现不一；各小区土壤中NO3--N和NH4+-N的含量与有机质含量呈正相关的指数曲线变化。(3)在2007年3月到2009年3月期间,对供试红壤四个处理小区各土层中速效磷含量的时间变化和剖面中的垂直变化进行了研究。结果表明：各处理小区土壤中速效磷的含量均在表层中较高,而底层普遍较低；每年的3月份、5月份和11月份速效磷含量较高,其他月份相对较低。其中在2007年3月份氮磷配施处理表层土壤的含量最高,达121.87 mg·kg-1。土壤有机质、团粒结构以及pH值均是影响土壤速效磷含量的重要因子,其中有机质和速效磷含量间呈显著正相关(P<0.05),红壤有机质含量较低,所以生产中应增加有机肥的施用量；CK小区各层土壤团聚体与速效磷含量呈指数曲线变化。(4)采用经典统计学与地统计学相结合的方法,对湖南地区典型红壤旱地进行网格法布点分层(0-20cm、20-40cm)取样,研究了田间尺度下土壤水分、有机质和氮素的空间变异特征。结果表明：土壤全氮和有机质含量随深度的增加而减小,而硝态氮含量随深度的增加呈增大的趋势。这是由于硝态氮易随着水分向下层迁移。两个土层硝态氮的变异系数(41.96%-62.08%)远高于全氮和有机质的变异系数(5.88%-18.82%)；各变量半方差变异函数的CO／(CO+C)均大于0.25而小于0.75,属于中等和弱空间自相关,这表明全氮、硝态氮、有机质和土壤含水量在研究区具有一定的空间结构且有较相近的空间相关距离。土壤全氮、有机质之间以及硝态氮与土壤水分之间均有极显著的相关性(P<0.01,n=96)。(5)对供试红壤氮磷钾(NPK)、氮磷(NP)、氮(N)、空白(CK)和有机肥氮磷钾配施(NPKOM)小区中硝态氮、铵态氮、速效磷三种速效养分与土壤水分的耦合作用进行了研究,结果表明：未施有机肥的氮磷钾(NPK)、氮磷(NP)、氮(N)、空白(CK)四个小区土壤中NO3--N、NH4+-N和速效磷与土壤含水量均呈极显著相关关系(n=112,P<0.01)；有机肥与氮磷钾配施小区(NPKOM)土壤中NO3--N、NH4+-N和速效磷三种速效养分与土壤水分也呈极显著的负相关性(n=40；P<0.01)。可见,研究区土壤水分和速效养分存在着较好的耦合作用；而增施有机肥可以改善土壤的团粒结构和理化性质,更有利于水肥的耦合作用。更多还原

【Abstract】 Red soil, as a principal soil type in the south of China with large area distributed in many provinces, plays a significant function in agriculture production. Due to the special property of red soil and unreasonable fertilization, its environment has been deteriorated in this region. Exploiting red soil resource reasonably should be essential measures for agricultural sustainable development, which is also hotspot of soil science in China. In this paper, experiment of field and experimental simulation were taken to study the spatial variability of soil water content, soil nutrient, the transportation of nitrate and coupling of soil water-nutrients in typical red soil in Hunan Province. The results were as follows:(1) Horizontal migration and content of NO3-N in four natural occurring layers of the red soil in the hills of Qiyang, Hunan province were measured by water diffusion device. The transport velocities of nitrate-N was increased with the soil moisture content, presenting typical index relation. While it decreased rapidly with transport distance of nitrate-N, presenting power relation. There is a significant relationship between the horizontal transport velocity of nitrate-N and the distance of the tracer source. Nitrate-N transport concentration decreased with increase of the soil moisture content, presenting power curve. The transport concentration was also influenced by the soil moisture diffusivity, and decreased with increase of the diffusivity, presenting logarithmic curve. Transport concentration of Nitrate-N reach maximum value at the surface of wet spearhead, which is the interface of wet and dry soil.(2) Nitrate and ammonium contents varied with months in soil profile, which was studied in different treatments in dry land of the red soil during two years. The results indicated that nitrate and ammonium contents were high in surface soil layer in every treatment and low in bottom layer. Both nitrate and ammonium reached the highest contents of 248.34 mg·kg-1 and 127.24 mg·kg-1 in May 2007 in N treatment plot. Due to winter wheat required more nutrients in jointing-flowering stage in April and May, more fertilization was applied for crops. Significant differences were found between November and May and other months by SPSS 16.0. The nitrate and ammonium had significant relationship with straight line between NPK and NP plots. There were diverse relations in different months in N and blank plots. The nitrate and ammonium contents had a sharp relationship with soil organic matter in every treatment and changed with exponential function.(3) Available phosphorus content varied with seasons and soil profile, which were studied in different treatments during two years. The results indicated that available phosphorus content of each treatments were higher in surface soil layer and lower in bottom layer. Available phosphorus reached highest content in surface soil layer of NP plot in March 2007, which was 121.87 mg·kg-1. Organic matter, aggregates structure and pH value were important influencing factors, available phosphorus had a sharp positive relation with soil organic matter. The correlation coefficient was 0.8768. Soil aggregates and available phosphorus had significant relationship in CK plot and changed with exponential function..(4) The space variability of soil water content and soil nutrients at the depths of 0-20 cm,20-40cm in the red soil region of Hunan Province was examined by traditional statistics and geoststistics methods. Total N content and organic matter were both reduce while the depths increased, but NO3--N content was increased with the depth increased. Coefficient of variation (41.96%-62.08%) of NO3--N content in study soil profiles far higher than the coefficient of variation total N content and organic matter (5.88%-18.82%). All semi-variable functions of the variance variation CO/(CO+C) ranged from 0.25 to 0.75, it indicated they have middle and weak correlation space and similar distance spatial structure. The total N and organic matter contents had a sharp positive relation, so did NO3--N and soil water content.(5) Nitrate-N, ammonium-N and available phosphorus coupling with soil moisture in NPK, NP, N, CK and NPKOM plots under long-term fertilization of red soil were studied. The results indicated that NO3--N、NH4+-N and available phosphorus had a significant relation with soil moisture in NPK, NP, N, CK plots(n=112, P<0.01).There also existed a significant relationship between soil water and fertilizer in NPKOM plot(n=40; P＜0.01). It can be concluded that available nutrient had a great coupling affected with soil moisture. More organic fertilizer can not only improve soil aggregates structure and basic character, but also be propitious to the effect of water and soil coupling.更多还原