【作者】 张扬；

【导师】 吴发启； 张树兰；

【作者基本信息】 西北农林科技大学 ， 土地资源与空间信息技术， 2010， 硕士

【摘要】 陕西省渭北地区是世界苹果最佳适生区,但该区干旱少雨,水资源短缺且利用难度大,土壤水分成为苹果生产中的首要限制因子。苹果园土壤的水分特征对果树的生长状况有极大影响,而表层土壤的物理性质直接影响土壤在果树根系吸水范围的水分特征。本研究对渭北地区苹果园表层土壤的物理和水分性质进行了测定,分析其分布特点及不同层次的相关性和变异性,为研究黄土高原地区苹果园的土壤水分生态特征和运动规律服务,促进节水果业的发展和水资源的科学利用。通过对陕西省渭北地区12个区县的优质苹果示范园表层土壤的基本物理性质和水分特征进行测定,结合相关分析和方程拟合方法,分析了渭北地区不同苹果园土壤的物理结构性质和水分特性的空间分布与变化情况。取得以下主要结论:(1)渭北苹果园表层土壤的机械组成中粉粒含量较高,粘粒含量较低:安塞土样为砂质壤土,砂粒含量高达76.55%,其他土样为粉质壤土,粉粒含量普遍达到50%以上;大部分土样的粘粒含量低于10%。渭北果园土壤的容重变异较小,容重随土层深度的增加而变大,总孔隙度则逐渐降低。部分土样的总孔隙度变异较大,表现出差异性。(2)渭北苹果园表层土壤的结构较好,团聚体水稳性很强,适宜果树种植生产:不同土样的团聚体分布情况差别较大,总体上0.5～1mm中间粒径团聚体含量最高,随着土层深度的增加,不同粒径团聚体含量呈现不同程度的变化。表层土壤的平均重量直径范围在0.33～1.58mm之间。果园土壤的有机质和粘粒含量对土壤团聚体稳定性具有重要作用,团聚体稳定性随有机质含量的增加而显著增加。(3)渭北苹果园表层土壤水分特征曲线显示:渭北苹果园土壤的含水量在接近植物能有效利用的低水吸力范围内随土壤水吸力增加而显著减小。在水吸力较低的情况下(小于100kPa)水分特征曲线实测值与幂函数经验公式能较好拟合,相关程度较高,可作为土壤水吸力和含水量换算的参照,以及用于分析不同质地土壤的持水性和土壤水分的有效性,为合理有效地利用土壤水分和科学指导灌溉提供条件。(4)渭北苹果园表层土壤的持水、导水特征表明:随土层深度增加,果园土壤饱和含水量降低;土壤田间持水量的分布出现波动,反映出表层土壤水分特征的空间变异性极强;土壤饱和导水率出现一定波动,整体上小幅降低,在土壤剖面上表现出异质性。果园土壤有效含水量沿土壤剖面变化的规律性不强,安塞土壤水分有效性高,蒲城土壤低。土壤质地、容重、结构、有机质含量、温度等因素都对土壤水分运动产生影响。团聚体含量越多,容重越小,水分特征曲线在低吸力段越平缓。有机质的积累能改善土壤结构和孔隙状况,提高土壤导水性能,并有助于保持土壤水分,增加土壤含水量。更多还原

【Abstract】 Weibei region in Shaanxi Province is the world’s best suitable area for apple, but the area is drought, water shortage and difficult to use, therefore, soil water become the first limiting factor in apple production. Soil water characteristics of orchards have great impact on the growth of apple tree, while the physical properties of topsoil directly affect the soil water characteristics in the range of root. For this reason, the soil physical and water properties of apple orchards in Weibei region were determined to analyze the distribution and different levels of relevance and variability, service for the study of ecological characteristics of apple orchard and soil water movement law on the Loess Plateau region, promote the development of apple industry and the scientific use of water resources.Through determine the basic physical properties and water characteristics of topsoil in 12 demonstration apple garden in Weibei region of Shaanxi Province to analyze the soil physical structure and water features in different apple orchards by combination of correlation analysis and equation fitting method. Obtained the following main conclusions:(1) Topsoil in apple orchards is higher silt content and low clay content in mechanical composition: The soil in Ansai is sandy loam, the sand content of up to 76.55%, most of the other samples more than 50% silt content for the silty loam, the clay content of soil in most less than 10%. Soil bulk density have little variation and increased with soil depth. Total porosity decreased gradually. Part of the total porosity of soil samples varied greatly, Show differences.(2) The soil structure of apple orchards in Weibei region is good, water stable aggregates are suitable for the growth of apple trees: Different distribution of soil aggregates varies considerably, the aggregate content of diameter between 0.5mm to 1mm in the middle is the highest, with the increase of soil depth, different aggregate sizes varying in content. The mean weight diameter of topsoil is range between 0.33mm to 1.58mm. Soil organic matter and clay content have important role in aggregate stability, which increased significantly with the organic matter content increase.(3) Soil water characteristic curves of topsoil in apple orchards show: Soil water decreased significantly within the soil water suction increased under low water suction. In the case of low water suction (<100kPa), measured water characteristic curve equation with the power function can be well fited and correlation is high. Soil water suction and water content can be translated as a reference, and for the analysis of different soil texture and water holding capacity. Further more, provide the conditions for the rational and efficient use of soil water and scientific guidance for irrigation.(4) Soil water retention and hydraulic conductivity characteristics of topsoil in apple orchards show: With soil depth increase, saturated water content lower; fluctuations in the distribution of soil field capacity, reflecting the characteristics of topsoil water spatial variability; soil saturated hydraulic conductivity have certain fluctuations, the overall slightly lower in the soil profile showed heterogeneity. Soil effective water content change along the soil profile in law is not strong; Ansai soil has slightly high soil water availability while Pucheng soil is low. Soil texture, bulk density, structure, organic matter content, temperature and other factors are all have impact on soil water movement. The more aggregate content and smaller bulk density, the more gentle water retention curve at low suctions. The accumulation of organic matter can improve soil structure, porosity condition and soil hydraulic conductivity, and also help to maintain soil moisture and increase soil water content.更多还原