紫色土坡耕地耕层土壤质量诊断及调控途径研究

发布时间：2018-05-02 19:06

本文选题：坡耕地 + 土壤质量　；参考：《西南大学》2017年硕士论文

【摘要】：坡耕地作为我国重要的土地资源,是构成我国农业土地资源的主要部分,以坡耕地为利用方式的耕地面积占全国耕地面积的2/5,而坡耕地粮食产量占我国粮食总产量的1/5~1/3;紫色土主要分布于长江上游,约占长江上游总土地面积的18%,集中分布在四川省和云南省境内,这两省内的紫色土占全国总紫色土面积的75%以上。紫色土具有明显的高生产力性、快速风化性和强侵蚀性。紫色土坡耕地土层浅薄,多石质,基岩埋深较浅,仅40~100cm,土壤孔隙度高,土壤饱和导水率高,水力特性的空间变异性大。坡耕地土壤剖面构形特征、理化性状及耕性特征是影响坡耕地土壤质量的根本原因;了解坡耕地土壤质量变化及稳定性特征、建立坡耕地土壤质量评价的最小数据集、提出坡耕地土壤质量的优化途径是坡耕地土壤质量定量化评价以及坡耕地土壤质量提升的前提条件。本文以重庆合川、江西兴国、云南楚雄三个地点紫色土坡耕地为研究对象,野外实地调查与室内测试相结合,揭示了不同区域紫色土坡耕地的土壤剖面构型特征、分析了不同区域紫色土坡耕地土壤基本理化性状及耕性特征的差异性;采用室内环刀法分别测定了土壤入渗及水库特征,分析了不同区域紫色土坡耕地土壤入渗及保水性能;同时通过土壤干筛和湿筛、土壤崩解及水稳定性试验研究了不同区域紫色土坡耕地土壤稳定性和抗蚀性;采用主成分分析方法建立了紫色土坡耕地土壤质量评价指标的最小数据集(MDS),分析了不同区域土壤侵蚀对紫色土坡耕地土壤质量的影响;并通过资料查阅及数据调查结果,分析各区域紫色土坡耕地土壤质量评价指标的适宜性阈值,提出了基于DPSIR坡耕地合理耕层的优化途径;最后针对坡耕地水土保持措施—生物埂在次降雨干湿交替作用下土壤物理、力学特性特征进行了分析。主要结论如下:(1)农作物根系主要分布于表土层(约占整个作物根系的60%以上),在心土层有少量分布(占作物根系的20%左右),而底土层几乎没有农作物根系存在;不同地点土壤机械组成以砂粒含量和粉粒含量为主,且0—20 cm土壤粘粒(0.001 mm)含量显著高于20—40 cm和40—60 cm;土壤容重随坡耕地土层垂直深度变化表现为0—20 cm20—40 cm40—60 cm;3个地点坡耕地土壤总孔隙度、毛管孔隙度的随土壤垂直深度的变化规律均表现为耕作层(0—20 cm)心土层(20—40 cm)底土层(40—60 cm);重庆合川坡耕地耕层土壤物理质量较差,主要表现在土壤容重最高(1.43 g/cm3),土壤总孔隙度(45.97%)和毛管孔隙度(34.36%)最小;同一地点紫色土坡耕地土壤物理性质随垂直深度变化明显。从土壤质量角度看,坡耕地0—20 cm耕层土壤物理质量要优于20—40 cm心土层和40—60 cm底土层。(2)不同地点紫色土坡耕地土壤养分、耕性特征存在较大差异。不同地点紫色土坡耕地土壤全量养分和速效养分均存在较大差异,土壤有机质含量由高到低依次为云南楚雄(28.80g/kg)、江西兴国(9.03 g/kg)、重庆合川(8.80 g/kg);不同地点紫色土坡耕地土壤养分含量随土层深度变化存在显著差异,坡耕地0—20 cm土壤全氮含量高于20—40 cm和40—60 cm土层含量;坡耕地不同垂直层次土壤速效养分变化规律基本一致,速效养分主要在0—20 cm耕层富集,而20—40 cm和40—60 cm土层则无显著差异;不同地点紫色土坡耕地耕层土壤抗剪强度和土壤贯入阻力均表现为重庆合川云南楚雄江西兴国,且随土层垂直深度耕层土壤抗剪强度和土壤贯入阻力值增加;不同地点坡耕地耕层土壤抗剪强度依次为15.39、14.74、10.66kg/cm2,土壤贯入阻力则分别为424.83、252.50、188.87kPa,这说明重庆合川紫色土坡耕地耕层土壤可以较好抵抗降雨、耕作的剪切破坏能力以及耕作机械碾压能力。(3)不同地点紫色土坡耕地土壤累积入渗量表现为云南楚雄重庆合川江西兴国,耕层土壤入渗特征随垂直深度的变化规律保持一致,土壤入渗随着土层深度减小。Kostiakov模型适用于拟合不同地点紫色土坡耕地0~20cm土层土壤入渗过程;而20~40cm土层Horton模型适用于重庆合川和云南楚雄。紫色土坡耕地土壤水总库容的大小表现为云南楚雄(1052.52t/hm2)江西兴国(974.15 t/hm2)重庆合川(867.30 t/hm2);土壤水死库容的变化规律与土壤水总库容的变化规律一致;兴利库容大小依次为重庆合川(293.02 t/hm2)云南楚雄(291.89t/hm2)江西兴国(182.28 t/hm2);最大有效库容以云南楚雄(873.311 t/hm2)最大;坡耕地耕层土壤水库特征均表现为0—20 cm耕作层大于20—40 cm心土层和40—60 cm底土层。耕层土壤入渗性能与土壤容重呈负相关,而稳定入渗率和平均入渗率与土壤容重之间呈显著正相关,相关系数分别为0.540和0.525;土壤总孔隙度与稳定入渗率和平均入渗率之间呈极显著正相关,相关系数分别为0.604和0.635;土壤入渗性能与机械组成的相关性表现为,与1~0.05mm呈正相关,与0.05~0.001mm和0.001mm呈负相关。土壤库容与土壤容重呈负相关关系,相关系数在0.021~0.451之间,土壤水库特性与土壤含水率、土壤孔隙度、土壤有机质呈正相关关系。(4)不同地点紫色土坡耕地因土壤属性差异而表现出不同团聚体分布特征。0.25mm风干团聚体含量由大到小依次为重庆合川(97.716%)云南楚雄(94.430%)江西兴国(90.875%);紫色土坡耕地土壤0.25 mm水稳定性团聚体含量较风干团聚体含量明显降低,0.25mm水稳性团聚体含量具体表现为云南楚雄(86.118%)重庆合川(83.769%)江西兴国(65.805%);紫色土坡耕地耕层土壤团聚体结构破坏率表现为江西兴国(34.195%)重庆合川(16.231%)云南楚雄(13.882%);0~20cm土层0.25mm风干团聚体和水稳性团聚体含量小于20~40cm和40~60cm土层;不同地点紫色土坡耕地土壤风干团聚体分形维数,重庆合川介于1.79~2.38之间,江西兴国在2.01~2.30的范围内变化,云南楚雄数值在2.16~2.52之间;土壤团聚体稳定性指数表现为云南楚雄江西兴国重庆合川,同一地点不同土层的土壤团聚体稳定性指数总体表现为0~20cm20~40cm40~60cm,即0~20cm土层土壤结构性和稳定性相对较好,具有较强的土壤抗侵蚀能力。土壤团聚体几何平均直径(GMD)和平均重量直径(MWD)具有相同变化规律,具体表现为重庆合川(GMD:4.975,MWD:1.014)云南楚雄(GMD:3.977,MWD:1.012)江西兴国(GMD:2.808,MWD:1.008);不同地点紫色土坡耕地土壤团聚体最终破损率表现为江西兴国(86.667%)重庆合川(78.333%)云南楚雄(45.333%);耕层水稳定性指数数值大小表现为云南楚雄最大(0.686),重庆合川次之(0.550),江西兴国最小(0.211);在土壤含水量一定的情况下,抗剪强度随土壤所承受垂直压力的增加而线性增大;不同地点紫色土坡耕地所受垂直压力对抗剪强度的作用大小存在差异,以云南楚雄土壤抗剪强度增加幅度最大,增大幅度≥300;以重庆合川次之,增加幅度介于273~299之间;江西兴国随压力的增大增大幅度为130~299;随着含水率增加,土壤抗剪强度下降,含水率对抗剪强度的影响主要是降低土壤粘聚力,对内摩擦角的影响较小。(5)紫色土坡耕地耕层土壤质量评价的最小数据集(MDS)有土壤容重、田间持水量、土壤贯入阻力、土壤有机质、0.25mm水稳性团聚体含量、田面坡度6个指标。合理耕层适宜性阈值范围分别如下:有效土层厚度25~100cm之间、土壤容重介于1.15~1.45g/cm3范围、总孔隙度在46%~56%、田间持水量35%、有机质含量10g/kg;不同地点坡耕地耕层土壤耕性指标平均值均在适宜值范围,而20—40 cm和40—60 cm的评价指标数值超出耕性适宜范围而20—40cm和40—60cm的个别指标数值超出耕性适宜范围;耕性指标良好程度将直接关系到农作物产量高低,因此可在当地采取适当耕作措施(如一般22—24 cm以下深松、深土培肥等)进行坡耕地耕层土壤质量改良,如选择深松、有机肥培肥、秸秆还田等合适耕作措施,以实现对坡耕地耕层土壤质量有效改善;基于DPSIR的坡耕地耕层质量调控途径主要有四个,一是控制耕地总量动态平衡,保持坡耕地数量和质量可持续性;二是强化坡耕地农业生态环境建设,保护坡耕地生态环境安全;三是加大投入,确保坡耕地效益和质量安全;四为制定耕地保护标准,确保耕地保护的长效性。(6)坡耕地生物埂根系的空间分布在不同土层中存在差异,根径级越小的根系集中于土壤表层附近的位置,而深层次的土壤主要由较粗根径级的根系穿插生长。生物埂土壤容重、孔隙度特征、田间持水量随干湿作用时间变化差异显著。在次降雨前,各层次桑树生物埂土壤容重在1.19~1.38 g/cm3之间,且随土层深度增加而增大;在次降雨之后随干湿水平变化,土壤容重呈现先逐渐增大后减小的变化趋势;毛管孔隙和非毛管孔隙数量的变化主要发生在干湿作用第0天~第1天时间。土壤粘聚力和内摩擦角随着含水率的增加而呈近似线性衰减,相关系数分别为0.6820和0.7251;各层次土壤粘聚力和内摩擦角在干湿效应作用下呈先衰减后恢复的“V”型变化趋势;土壤粘聚力衰减程度依次为30~40cm(18.11Kpa)0~10cm(15.80Kpa)10~20 cm(15.28Kpa)20~30cm(6.99kpa),土壤内摩擦角以0~10cm层土壤衰减程度最大(14.69°),30~40cm的衰减程度最小(12.84°);在干湿循环过程中,土壤粘聚力和内摩擦角均有所恢复,但均未达到降雨前的水平,粘聚力恢复程度以30~40cm最大(14.24Kpa),20~30cm最小(0.99Kpa),内摩擦角恢复程度的顺序为0~10cm(13.33°)10~20cm(11.71°)20~30cm(11.02°)30~40cm(9.54°);桑树生物埂不同根系径级土体的粘聚力、内摩擦角和抗剪强度与根长密度和根表面积密度达到显著正相关,相关系数在0.301~0.793之间。
[Abstract]:As an important land resource in China, sloping arable land is the main part of the agricultural land resources in China. The cultivated area of slope farmland is 2/5 of the land area of the whole country, while the grain yield of the slope farmland accounts for 1/5~1/3 of the total grain output of our country, and the purple soil is mainly distributed in the upper reaches of the Yangtze River, accounting for about 18% of the total land area in the upper reaches of the Yangtze River. Concentrated in Sichuan and Yunnan Province, the purple soil in these two provinces accounts for more than 75% of the total purple soil area in the country. Purple soil has obvious high productivity, fast weathering and strong erosion. The soil layer of purple soil slope is shallow, multi stone, shallow, only 40~ 100cm, soil porosity is high, soil saturated water conductivity is high, water is high. The spatial variability of force characteristics is large. Soil profile characteristics, physicochemical properties and tillage characteristics are the fundamental causes of soil quality in sloping cultivated land, and the changes and stability characteristics of soil quality in sloping farmland are understood, and the minimum data set of soil quality evaluation of slope farmland is set up, and the optimization approach of soil quality of sloping cultivated land is the slope farmland soil The quantitative evaluation of soil quality and the precondition for improving the soil quality of sloping land. This paper takes the purple soil slope farmland of three locations in Hechuan, Jiangxi, Jiangxi and Chuxiong, Yunnan, as the research object. Field investigation and indoor test are combined to reveal the characteristics of soil profile configuration of purple soil ploughed land in different regions, and analyze the different regions. The difference of soil basic physicochemical properties and tillage characteristics in purple soil slope farmland, and the characteristics of soil infiltration and reservoir were measured by indoor ring knife method, and soil infiltration and water retention property of Purple Soil Sloping Farmland in different regions were analyzed, and the soil disintegration and water stability were studied by soil dry sieve and wet sieving, soil disintegration and water stability. The soil stability and corrosion resistance of sloping cultivated land, the minimum data set (MDS) of soil quality evaluation index of purple soil slope cultivated land were established by principal component analysis, and the influence of soil erosion on the soil quality of purple soil slope cultivated land in different regions was analyzed, and the soil purple soil slope farmland soil was analyzed through data inspection and data investigation results. The optimum threshold of the suitability of the quality evaluation index was put forward, and the optimization approach based on the rational plough layer on the slope farmland based on DPSIR was put forward. Finally, the soil physical characteristics and the mechanical characteristics of the slope farmland soil and water conservation measures under the alternate dry and wet alternate action were analyzed. The main conclusions are as follows: (1) the roots of the crops are mainly distributed in the surface soil layer (about the whole of the whole soil). More than 60% of the root of the crop (more than 60%) in the soil layer (about 20% of the root of the crop), and the bottom soil layer has almost no crop roots; the soil mechanical composition in different locations is mainly sand and powder content, and the 0 - 20 cm soil clay (0.001 mm) content is significantly higher than 20 - 40 cm and 40 to 60 cm; soil bulk density with slope farmland soil The variation of vertical depth of the layer is 0 - 20 CM20 - 40 cm40 - 60 cm; the soil total porosity and the variation of the capillary porosity with the vertical depth of the soil are all displayed in the cultivated layer (0 to 20 cm) soil layer (20 to 40 cm) bottom soil layer (40 - 60 cm), and the soil physical quality of the tilled soil in the sloping farmland in Chongqing is poor, mainly in soil. The soil bulk density is the highest (1.43 g/cm3), soil total porosity (45.97%) and capillary porosity (34.36%) are the smallest, and the soil physical properties of purple soil slope farmland in the same place change obviously with the vertical depth. From the point of view of soil quality, the physical quality of the 0 to 20 cm soil in sloping farmland is better than the 20 to 40 cm soil layer and 40 to 60 cm bottom soil. (2) different sites purple. There are great differences in soil nutrients and tillage characteristics of the cultivated land slope farmland. There are great differences in soil total nutrient and available nutrients in purple soil slope farmland at different locations. The organic matter content from high to low is in Yunnan Chuxiong (28.80g/kg), Jiangxi Xingguo (9.03 g/kg), and heavy Qing Hechuan (8.80 g/kg), and purple soil slope farmland in different locations is cultivated in different locations. There was a significant difference in the content of the soil depth. The total nitrogen content in the 0 - 20 cm soil of sloping farmland was higher than 20 - 40 cm and 40 - 60 cm soil layer; the soil available nutrients in different vertical layers of slope farmland were basically the same, the available nutrients were mainly enriched in the 0 - 20 cm plough layer, while the 20 - 40 cm and 40 - 60 cm soil layer had no significant difference. The shear strength and penetration resistance of the plough soil in the purple soil slope are all manifested in the Chongqing Hechuan Yunnan Chuxiong Jiangxi Xingguo, and the soil anti shear strength and soil penetration resistance value increases with the vertical depth of the soil layer, and the shear strength of the plough soil in different locations is 15.39,14.74,10.66kg/cm2, and the soil penetration resistance is divided. Not 424.83252.50188.87kPa, this shows that the plough soil in the purple soil slope of Hechuan, Chongqing, can resist the rainfall, the shear failure ability of the tillage and the rolling machine rolling capacity. (3) the cumulative infiltration of the purple soil slope farmland in different locations is shown in the Jiangxi Xingguo of Hechuan, Chuxiong, Chongqing, Hechuan, Jiangxi, and the infiltration characteristics of the plough soil are perpendicular to the vertical. The variation of depth is consistent. Soil infiltration with soil depth decreases with.Kostiakov model suitable for fitting the infiltration process of 0~20cm soil layer in purple soil slope cultivated land in different locations, while 20~40cm soil layer Horton model is suitable for Hechuan and Yunnan Chuxiong in Yunnan. The total capacity of soil water capacity in purple soil slope arable land is Yunnan Chuxiong (1052.) 52t/hm2) Jiangxi Xingguo (974.15 t/hm2) Chongqing Hechuan (867.30 t/hm2); the change law of soil water dead storage capacity is consistent with the change law of soil water total storage capacity, and the size of Xingli reservoir capacity is Chongqing Hechuan (293.02 t/hm2) Yunnan Chuxiong (291.89t/hm2) Jiangxi Xingguo (182.28 t/hm2), and the largest effective storage capacity is largest in Yunnan Chuxiong (873.311 t/hm2). The characteristics of the soil reservoir in the tilled soil of the sloping farmland all show that the 0 - 20 cm tillage layer is greater than the 20 - 40 cm soil layer and the 40 - 60 cm bottom soil layer. The infiltration performance of the tilth soil is negatively related to the soil bulk density, while the stable infiltration rate and the average infiltration rate are positively correlated with the soil bulk density, and the correlation coefficient is 0.540 and 0.525 respectively; the total soil porosity and stability are stable. There is a significant positive correlation between the entrant infiltration rate and the average infiltration rate, and the correlation coefficients are 0.604 and 0.635, respectively. The correlation between soil infiltration and mechanical composition shows that there is a positive correlation with 1~0.05mm, and negatively related to 0.05~0.001mm and 0.001mm. Soil storage capacity is negatively related to soil bulk density, the correlation coefficient is between 0.021~0.451 and soil water. The characteristics of the reservoir have a positive correlation with soil moisture, soil porosity and soil organic matter. (4) the distribution characteristics of different aggregates in the purple soil slope cultivated in different locations.0.25mm wind dry aggregate content from large to small in Hechuan, Chongqing (97.716%) Yunnan Chuxiong (94.430%) Jiangxi Xingguo (90.875%); purple soil slope tillage. The content of soil 0.25 mm water stability aggregate content is lower than that of wind dry aggregate, and the content of 0.25mm water stable aggregate is concretely represented by Chuxiong (86.118%) Chongqing Hechuan (83.769%) Jiangxi Xingguo (65.805%), and the broken rate of soil aggregate structure in the plough layer of purple soil slope farmland is the cloud of Jiangxi Xingguo (34.195%) Chongqing Hechuan (16.231%) cloud. South Chuxiong (13.882%); the content of 0.25mm wind dry aggregate and water stable aggregate in 0~20cm soil layer is less than 20~40cm and 40~60cm soil layer; the fractal dimension of soil air dry aggregates in purple soil slope farmland in different locations, Hechuan in Chongqing is between 1.79~2.38, Jiangxi Xingguo in the range of 2.01~2.30, Chuxiong value of Yunnan between 2.16~2.52 and soil agglomeration. The stability index of body stability is in Chongqing Hechuan, Jiangxi, Chuxiong, Yunnan. The soil aggregate stability index of different soil layers in the same site is 0~20cm20~40cm40~60cm, that is, the soil structure and stability of 0~20cm soil layer is relatively good, and has strong soil erosion resistance. The geometric mean diameter of soil aggregate (GMD) is both peaceful and heavy. MWD (GMD:4.975, MWD:1.014), Yunnan Chuxiong (GMD:3.977, MWD:1.012) Jiangxi Xingguo (GMD:2.808, MWD:1.008), the final breakage rate of soil aggregates in purple soil slope cultivated land in different locations is Jiangxi Xingguo (86.667%) Chongqing Hechuan (78.333%) Yunnan Chuxiong (45.333%); plough water stability is stable. The numerical value of the qualitative index is the largest (0.686) in Yunnan Chuxiong (0.686), Chongqing (0.550) in Chongqing (0.550), and the youngest in Xingguo (0.211) in Jiangxi; the shear strength increases linearly with the increase of the vertical pressure of soil under the condition of soil water content, and the effect of vertical pressure on shear strength of the purple soil sloping farmland at different locations exists. The difference is that the increase in shear strength of soil in Chuxiong of Yunnan is the largest, the increase amplitude is more than 300; in Chongqing Aikawa Jinno, the increase range is between the range of 130~299 and the increase of Jiangxi Xingguo with the pressure; with the increase of water content, the shear strength of soil decreases, and the influence of water content against shear strength is mainly to reduce soil cohesive force, The influence of internal friction angle is small. (5) the minimum data set (MDS) of the soil quality evaluation of purple soil sloping cultivated land has soil bulk density, field water holding capacity, soil penetration resistance, soil organic matter, 0.25mm water stable aggregate content and field surface slope 6 indexes. The reasonable threshold range of reasonable plough layer is as follows: effective soil thickness 25~100cm, soil The soil bulk density is in the range of 1.15~1.45g/cm3, the total porosity is 46%~56%, the field water holding capacity is 35%, the organic matter content is 10g/kg, the average value of the tillage soil tillage index of the sloping farmland in different locations are in the suitable range, while the evaluation index values of 20 to 40 cm and 40 to 60 cm are beyond the ploughing suitability and the individual index values of 20 to 40cm and 40 to 60cm are exceeded. The good tillage range, the good degree of the tillage index will be directly related to the crop yield, so it is possible to adopt appropriate tillage measures (such as the deep loosening below 22 to 24 cm, deep soil cultivation, etc.) to improve the soil quality of the tilled soil on the slope farmland, such as the selection of the appropriate tillage measures, such as the selection of deep pine, the organic manure and the straw returning to the field, so as to realize the slope tillage. The quality of soil in the topsoil is improved effectively; there are four main ways to control the quality of the plough layer based on DPSIR, one is to control the dynamic balance of the total amount of cultivated land, keep the quantity and quality of the sloping arable land, and the two is to strengthen the construction of the agricultural ecological environment in the slope farmland and protect the ecological environment of the sloping arable land, and the three is to increase the investment and ensure the efficiency of the slope farmland. And quality safety; four to establish the protection standard of cultivated land, to ensure the long-term efficiency of cultivated land protection. (6) the spatial distribution of the root system of slope farmland is different in different soil layers, the lower root diameter of the root system is concentrated near the surface of the soil surface, and the deep soil is mainly composed of the roots of the coarser root diameter. Heavy, porosity characteristics, the field water holding capacity varies significantly with the dry and wet time. Before the secondary rainfall, the soil bulk density of the mulberry tree species is between 1.19~1.38 and g/cm3, and increases with the depth of the soil layer. The variation of the number of non capillary pores occurs mainly in zeroth days to first days of dry and wet effect. The cohesive force and internal friction angle of soil are approximately linearly attenuated with the increase of water content, and the correlation coefficients are 0.6820 and 0.7251, respectively. The cohesion and internal friction angle of soil at all levels are first attenuated and then recovered "V" type under the action of dry and wet effect. The decreasing degree of soil cohesive force is 30~40cm (18.11Kpa) 0~10cm (15.80Kpa) 10~20 cm (15.28Kpa) 20~30cm (6.99kpa), the soil friction angle is the maximum attenuation (14.69 degrees) in the 0~10cm layer, and the least attenuation of 30~40cm (12.84 degrees). In the dry and wet cycle, the cohesive force and the internal friction angle of soil are all restored, but they are not reached. The level of cohesion before rainfall is 30~40cm (14.24Kpa), 20~30cm minimum (0.99Kpa), and the order of internal friction angle recovery is 0~10cm (13.33) 10~20cm (11.71) 20~30cm (11.02) 30~40cm (9.54 degree), and the cohesive force, internal friction angle and shear strength, root length density and root surface area of different root diameter grade soil of mulberry tree biological ridge The density was significantly positively correlated, and the correlation coefficient was between 0.301~0.793.

【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S151.9

【参考文献】