本文選題：坡耕地 + 土壤質(zhì)量��； 參考：《西南大學(xué)》2017年碩士論文

【摘要】：坡耕地作為我國(guó)重要的土地資源,是構(gòu)成我國(guó)農(nóng)業(yè)土地資源的主要部分,以坡耕地為利用方式的耕地面積占全國(guó)耕地面積的2/5,而坡耕地糧食產(chǎn)量占我國(guó)糧食總產(chǎn)量的1/5~1/3;紫色土主要分布于長(zhǎng)江上游,約占長(zhǎng)江上游總土地面積的18%,集中分布在四川省和云南省境內(nèi),這兩省內(nèi)的紫色土占全國(guó)總紫色土面積的75%以上。紫色土具有明顯的高生產(chǎn)力性、快速風(fēng)化性和強(qiáng)侵蝕性。紫色土坡耕地土層淺薄,多石質(zhì),基巖埋深較淺,僅40~100cm,土壤孔隙度高,土壤飽和導(dǎo)水率高,水力特性的空間變異性大。坡耕地土壤剖面構(gòu)形特征、理化性狀及耕性特征是影響坡耕地土壤質(zhì)量的根本原因;了解坡耕地土壤質(zhì)量變化及穩(wěn)定性特征、建立坡耕地土壤質(zhì)量評(píng)價(jià)的最小數(shù)據(jù)集、提出坡耕地土壤質(zhì)量的優(yōu)化途徑是坡耕地土壤質(zhì)量定量化評(píng)價(jià)以及坡耕地土壤質(zhì)量提升的前提條件。本文以重慶合川、江西興國(guó)、云南楚雄三個(gè)地點(diǎn)紫色土坡耕地為研究對(duì)象,野外實(shí)地調(diào)查與室內(nèi)測(cè)試相結(jié)合,揭示了不同區(qū)域紫色土坡耕地的土壤剖面構(gòu)型特征、分析了不同區(qū)域紫色土坡耕地土壤基本理化性狀及耕性特征的差異性;采用室內(nèi)環(huán)刀法分別測(cè)定了土壤入滲及水庫(kù)特征,分析了不同區(qū)域紫色土坡耕地土壤入滲及保水性能;同時(shí)通過(guò)土壤干篩和濕篩、土壤崩解及水穩(wěn)定性試驗(yàn)研究了不同區(qū)域紫色土坡耕地土壤穩(wěn)定性和抗蝕性;采用主成分分析方法建立了紫色土坡耕地土壤質(zhì)量評(píng)價(jià)指標(biāo)的最小數(shù)據(jù)集(MDS),分析了不同區(qū)域土壤侵蝕對(duì)紫色土坡耕地土壤質(zhì)量的影響;并通過(guò)資料查閱及數(shù)據(jù)調(diào)查結(jié)果,分析各區(qū)域紫色土坡耕地土壤質(zhì)量評(píng)價(jià)指標(biāo)的適宜性閾值,提出了基于DPSIR坡耕地合理耕層的優(yōu)化途徑;最后針對(duì)坡耕地水土保持措施—生物埂在次降雨干濕交替作用下土壤物理、力學(xué)特性特征進(jìn)行了分析。主要結(jié)論如下:(1)農(nóng)作物根系主要分布于表土層(約占整個(gè)作物根系的60%以上),在心土層有少量分布(占作物根系的20%左右),而底土層幾乎沒(méi)有農(nóng)作物根系存在;不同地點(diǎn)土壤機(jī)械組成以砂粒含量和粉粒含量為主,且0—20 cm土壤粘粒(0.001 mm)含量顯著高于20—40 cm和40—60 cm;土壤容重隨坡耕地土層垂直深度變化表現(xiàn)為0—20 cm20—40 cm40—60 cm;3個(gè)地點(diǎn)坡耕地土壤總孔隙度、毛管孔隙度的隨土壤垂直深度的變化規(guī)律均表現(xiàn)為耕作層(0—20 cm)心土層(20—40 cm)底土層(40—60 cm);重慶合川坡耕地耕層土壤物理質(zhì)量較差,主要表現(xiàn)在土壤容重最高(1.43 g/cm3),土壤總孔隙度(45.97%)和毛管孔隙度(34.36%)最小;同一地點(diǎn)紫色土坡耕地土壤物理性質(zhì)隨垂直深度變化明顯。從土壤質(zhì)量角度看,坡耕地0—20 cm耕層土壤物理質(zhì)量要優(yōu)于20—40 cm心土層和40—60 cm底土層。(2)不同地點(diǎn)紫色土坡耕地土壤養(yǎng)分、耕性特征存在較大差異。不同地點(diǎn)紫色土坡耕地土壤全量養(yǎng)分和速效養(yǎng)分均存在較大差異,土壤有機(jī)質(zhì)含量由高到低依次為云南楚雄(28.80g/kg)、江西興國(guó)(9.03 g/kg)、重慶合川(8.80 g/kg);不同地點(diǎn)紫色土坡耕地土壤養(yǎng)分含量隨土層深度變化存在顯著差異,坡耕地0—20 cm土壤全氮含量高于20—40 cm和40—60 cm土層含量;坡耕地不同垂直層次土壤速效養(yǎng)分變化規(guī)律基本一致,速效養(yǎng)分主要在0—20 cm耕層富集,而20—40 cm和40—60 cm土層則無(wú)顯著差異;不同地點(diǎn)紫色土坡耕地耕層土壤抗剪強(qiáng)度和土壤貫入阻力均表現(xiàn)為重慶合川云南楚雄江西興國(guó),且隨土層垂直深度耕層土壤抗剪強(qiáng)度和土壤貫入阻力值增加;不同地點(diǎn)坡耕地耕層土壤抗剪強(qiáng)度依次為15.39、14.74、10.66kg/cm2,土壤貫入阻力則分別為424.83、252.50、188.87kPa,這說(shuō)明重慶合川紫色土坡耕地耕層土壤可以較好抵抗降雨、耕作的剪切破壞能力以及耕作機(jī)械碾壓能力。(3)不同地點(diǎn)紫色土坡耕地土壤累積入滲量表現(xiàn)為云南楚雄重慶合川江西興國(guó),耕層土壤入滲特征隨垂直深度的變化規(guī)律保持一致,土壤入滲隨著土層深度減小。Kostiakov模型適用于擬合不同地點(diǎn)紫色土坡耕地0~20cm土層土壤入滲過(guò)程;而20~40cm土層Horton模型適用于重慶合川和云南楚雄。紫色土坡耕地土壤水總庫(kù)容的大小表現(xiàn)為云南楚雄(1052.52t/hm2)江西興國(guó)(974.15 t/hm2)重慶合川(867.30 t/hm2);土壤水死庫(kù)容的變化規(guī)律與土壤水總庫(kù)容的變化規(guī)律一致;興利庫(kù)容大小依次為重慶合川(293.02 t/hm2)云南楚雄(291.89t/hm2)江西興國(guó)(182.28 t/hm2);最大有效庫(kù)容以云南楚雄(873.311 t/hm2)最大;坡耕地耕層土壤水庫(kù)特征均表現(xiàn)為0—20 cm耕作層大于20—40 cm心土層和40—60 cm底土層。耕層土壤入滲性能與土壤容重呈負(fù)相關(guān),而穩(wěn)定入滲率和平均入滲率與土壤容重之間呈顯著正相關(guān),相關(guān)系數(shù)分別為0.540和0.525;土壤總孔隙度與穩(wěn)定入滲率和平均入滲率之間呈極顯著正相關(guān),相關(guān)系數(shù)分別為0.604和0.635;土壤入滲性能與機(jī)械組成的相關(guān)性表現(xiàn)為,與1~0.05mm呈正相關(guān),與0.05~0.001mm和0.001mm呈負(fù)相關(guān)。土壤庫(kù)容與土壤容重呈負(fù)相關(guān)關(guān)系,相關(guān)系數(shù)在0.021~0.451之間,土壤水庫(kù)特性與土壤含水率、土壤孔隙度、土壤有機(jī)質(zhì)呈正相關(guān)關(guān)系。(4)不同地點(diǎn)紫色土坡耕地因土壤屬性差異而表現(xiàn)出不同團(tuán)聚體分布特征。0.25mm風(fēng)干團(tuán)聚體含量由大到小依次為重慶合川(97.716%)云南楚雄(94.430%)江西興國(guó)(90.875%);紫色土坡耕地土壤0.25 mm水穩(wěn)定性團(tuán)聚體含量較風(fēng)干團(tuán)聚體含量明顯降低,0.25mm水穩(wěn)性團(tuán)聚體含量具體表現(xiàn)為云南楚雄(86.118%)重慶合川(83.769%)江西興國(guó)(65.805%);紫色土坡耕地耕層土壤團(tuán)聚體結(jié)構(gòu)破壞率表現(xiàn)為江西興國(guó)(34.195%)重慶合川(16.231%)云南楚雄(13.882%);0~20cm土層0.25mm風(fēng)干團(tuán)聚體和水穩(wěn)性團(tuán)聚體含量小于20~40cm和40~60cm土層;不同地點(diǎn)紫色土坡耕地土壤風(fēng)干團(tuán)聚體分形維數(shù),重慶合川介于1.79~2.38之間,江西興國(guó)在2.01~2.30的范圍內(nèi)變化,云南楚雄數(shù)值在2.16~2.52之間;土壤團(tuán)聚體穩(wěn)定性指數(shù)表現(xiàn)為云南楚雄江西興國(guó)重慶合川,同一地點(diǎn)不同土層的土壤團(tuán)聚體穩(wěn)定性指數(shù)總體表現(xiàn)為0~20cm20~40cm40~60cm,即0~20cm土層土壤結(jié)構(gòu)性和穩(wěn)定性相對(duì)較好,具有較強(qiáng)的土壤抗侵蝕能力。土壤團(tuán)聚體幾何平均直徑(GMD)和平均重量直徑(MWD)具有相同變化規(guī)律,具體表現(xiàn)為重慶合川(GMD:4.975,MWD:1.014)云南楚雄(GMD:3.977,MWD:1.012)江西興國(guó)(GMD:2.808,MWD:1.008);不同地點(diǎn)紫色土坡耕地土壤團(tuán)聚體最終破損率表現(xiàn)為江西興國(guó)(86.667%)重慶合川(78.333%)云南楚雄(45.333%);耕層水穩(wěn)定性指數(shù)數(shù)值大小表現(xiàn)為云南楚雄最大(0.686),重慶合川次之(0.550),江西興國(guó)最小(0.211);在土壤含水量一定的情況下,抗剪強(qiáng)度隨土壤所承受垂直壓力的增加而線性增大;不同地點(diǎn)紫色土坡耕地所受垂直壓力對(duì)抗剪強(qiáng)度的作用大小存在差異,以云南楚雄土壤抗剪強(qiáng)度增加幅度最大,增大幅度≥300;以重慶合川次之,增加幅度介于273~299之間;江西興國(guó)隨壓力的增大增大幅度為130~299;隨著含水率增加,土壤抗剪強(qiáng)度下降,含水率對(duì)抗剪強(qiáng)度的影響主要是降低土壤粘聚力,對(duì)內(nèi)摩擦角的影響較小。(5)紫色土坡耕地耕層土壤質(zhì)量評(píng)價(jià)的最小數(shù)據(jù)集(MDS)有土壤容重、田間持水量、土壤貫入阻力、土壤有機(jī)質(zhì)、0.25mm水穩(wěn)性團(tuán)聚體含量、田面坡度6個(gè)指標(biāo)。合理耕層適宜性閾值范圍分別如下:有效土層厚度25~100cm之間、土壤容重介于1.15~1.45g/cm3范圍、總孔隙度在46%~56%、田間持水量35%、有機(jī)質(zhì)含量10g/kg;不同地點(diǎn)坡耕地耕層土壤耕性指標(biāo)平均值均在適宜值范圍,而20—40 cm和40—60 cm的評(píng)價(jià)指標(biāo)數(shù)值超出耕性適宜范圍而20—40cm和40—60cm的個(gè)別指標(biāo)數(shù)值超出耕性適宜范圍;耕性指標(biāo)良好程度將直接關(guān)系到農(nóng)作物產(chǎn)量高低,因此可在當(dāng)?shù)夭扇∵m當(dāng)耕作措施(如一般22—24 cm以下深松、深土培肥等)進(jìn)行坡耕地耕層土壤質(zhì)量改良,如選擇深松、有機(jī)肥培肥、秸稈還田等合適耕作措施,以實(shí)現(xiàn)對(duì)坡耕地耕層土壤質(zhì)量有效改善;基于DPSIR的坡耕地耕層質(zhì)量調(diào)控途徑主要有四個(gè),一是控制耕地總量動(dòng)態(tài)平衡,保持坡耕地?cái)?shù)量和質(zhì)量可持續(xù)性;二是強(qiáng)化坡耕地農(nóng)業(yè)生態(tài)環(huán)境建設(shè),保護(hù)坡耕地生態(tài)環(huán)境安全;三是加大投入,確保坡耕地效益和質(zhì)量安全;四為制定耕地保護(hù)標(biāo)準(zhǔn),確保耕地保護(hù)的長(zhǎng)效性。(6)坡耕地生物埂根系的空間分布在不同土層中存在差異,根徑級(jí)越小的根系集中于土壤表層附近的位置,而深層次的土壤主要由較粗根徑級(jí)的根系穿插生長(zhǎng)。生物埂土壤容重、孔隙度特征、田間持水量隨干濕作用時(shí)間變化差異顯著。在次降雨前,各層次桑樹(shù)生物埂土壤容重在1.19~1.38 g/cm3之間,且隨土層深度增加而增大;在次降雨之后隨干濕水平變化,土壤容重呈現(xiàn)先逐漸增大后減小的變化趨勢(shì);毛管孔隙和非毛管孔隙數(shù)量的變化主要發(fā)生在干濕作用第0天~第1天時(shí)間。土壤粘聚力和內(nèi)摩擦角隨著含水率的增加而呈近似線性衰減,相關(guān)系數(shù)分別為0.6820和0.7251;各層次土壤粘聚力和內(nèi)摩擦角在干濕效應(yīng)作用下呈先衰減后恢復(fù)的“V”型變化趨勢(shì);土壤粘聚力衰減程度依次為30~40cm(18.11Kpa)0~10cm(15.80Kpa)10~20 cm(15.28Kpa)20~30cm(6.99kpa),土壤內(nèi)摩擦角以0~10cm層土壤衰減程度最大(14.69°),30~40cm的衰減程度最小(12.84°);在干濕循環(huán)過(guò)程中,土壤粘聚力和內(nèi)摩擦角均有所恢復(fù),但均未達(dá)到降雨前的水平,粘聚力恢復(fù)程度以30~40cm最大(14.24Kpa),20~30cm最小(0.99Kpa),內(nèi)摩擦角恢復(fù)程度的順序?yàn)?~10cm(13.33°)10~20cm(11.71°)20~30cm(11.02°)30~40cm(9.54°);桑樹(shù)生物埂不同根系徑級(jí)土體的粘聚力、內(nèi)摩擦角和抗剪強(qiáng)度與根長(zhǎng)密度和根表面積密度達(dá)到顯著正相關(guān),相關(guān)系數(shù)在0.301~0.793之間。
[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.

【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：S151.9

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