3种草本植物根系特征对土壤抗侵蚀性能影响

发布时间：2018-04-01 11:27

本文选题：草本植物　切入点：根系参数　出处：《华中农业大学》2017年硕士论文

【摘要】：南方红壤区是我国重要农业资源区,对我国农业经济发展有极其重要的作用。该区雨量丰沛,水热条件好,但过度的人为活动,使区域地表植被大面积破坏,加上地形复杂,降雨强度大而集中,水土流失严重,导致土层薄化,岩石裸露,耕地质量下降,耕地面积减少。植被恢复因其在减小土壤侵蚀方面效果显著,被认为是农业区最有效的防治水土流失的手段之一,植物根系在间接增强土壤抗侵蚀性能方面,如稳定土壤结构、提高土壤渗透性和抗剪强度等,以及直接增强土壤抗侵蚀性能方面,如对侵蚀动力机制方面的影响,均有重要作用。但是,由于根系所处环境的隐蔽性和取样的难度大,根系对土壤理化性质的影响及对抑制土壤侵蚀的相对贡献缺乏深入的研究。在深入分析现有资料和结合野外实地调查的基础上,选取本地区常见的3种草类(香根草(Vetiveria zizanioides(L.)Nash)、白三叶(Trifolium repens L.)和黑麦草(Lolium perenne L.))对本区域典型土壤(黄棕壤和棕红壤)抗侵蚀性能的影响,以及实地种植白三叶、黑麦草和其混合草样对黄棕壤抗侵蚀影响的季节性变化规律,采用原状土集中水流冲刷试验的方法,深入研究了植物根系对土壤抗侵蚀性能的增强效果,以期为本地区水土保持草类选择和水土流失防治提供理论支持和技术参考,研究结论如下:(1)根系存在可有效增强两种土壤抗侵蚀性能,黄棕壤和棕红壤增强效果均表现为:香根草白三叶黑麦草。但是同一植物根系对不同类型土壤抗侵蚀性能增强效果有差异,香根草对黄棕壤和棕红壤增强效果相同,白三叶对黄棕壤的增强效果大于棕红壤,而黑麦草对黄棕壤的增强效果小于棕红壤;(2)在根系参数,根长密度(RLD)、根重密度(RMD)、根面积比(RAR)、根系总面积(Stotal)、根系平均直径(Dmean)等因子中,RLD是影响土壤抗侵蚀性能的最重要的因子,可较好模拟两种土壤可蚀性变化,RMD和RAR也有重要作用,RSD随RLD、RAR呈指数下降,随RMD对数下降,均有显著的相关关系(P0.05);(3)全生长期,土壤容重呈先增大后略减小的趋势,而土壤孔隙随之产生相应变化,水稳性团聚体的MWD有缓慢增加的趋势。土壤抗侵蚀性能与土壤容重、孔隙度显著相关(P0.05),与0.25 mm和2 mm水稳性团聚体显著相关(P0.05),与其它径级团聚体相关性不好(P0.05),与根系RLD、RMD和RAR显著相关(P0.05);(4)植物根系对两种类型土壤抗侵蚀性能增强效应均可与RLD较好的通过WEPP模型模拟,RLD与两类土壤Dc的非线性回归方程相关系数R2在0.93以上,黄棕壤为:Dc=0.002exp(-0.036*RLD)(τ-1.145),棕红壤为:Dc=0.002exp(-0.040*RLD)(τ-1.562),临界剪切力黄棕壤棕红壤,说明该地区黄棕壤较棕红壤更容易被侵蚀;(5)同一剪切力下,各处泥沙含量随季节有减小趋势,不同种植密度间泥沙差异显著(20和30 g/m2除外)。在同一冲刷试验期内,前期泥沙含量增加较快,后期基本保持平衡或增加缓慢;(6)随种植密度增加,根系抗侵蚀作用增强,各样品可蚀性系数Kr随密度增加而减小,当密度超过20 g/m2时,Kr基本保持不变,说明植物根系适合的种植密度在10~20 g/m2之间。综上所述,植物根系均可对土壤物理性质产生影响而增强土壤抗侵蚀能力,湖北地区较适宜的根系发达的香根草,须根系草类较适宜种植密度为10~20 g/m2之间,合理选择合适草种和种植密度,以发挥最佳生态和经济效益。
[Abstract]:Southern red soil region is an important agricultural resource area in China, has an extremely important role in the development of agricultural economy in China. The area rainfall, good water and heat conditions, but excessive human activities, the regional surface vegetation destruction, with complex terrain, rainfall intensity and concentration, serious soil erosion, leading to soil thin, bare rock, the quality of cultivated land decreased, the decrease of cultivated land area. Vegetation restoration in reducing soil erosion because of its remarkable effect, is considered to be one of the most effective agricultural areas of soil erosion control measures, plant roots in indirectly enhance the soil anti erosion performance, such as the stability of soil structure, increase soil permeability and shear strength, and enhance the soil anti erosion ability, such as the impact of the erosion mechanism, has an important role. However, because of the root environment concealment and sampling is difficult to root Effect of soil physicochemical properties and inhibition of the relative contribution of soil erosion in the lack of in-depth research. In depth analysis of existing data and based on field surveys, select 3 kinds of local common grasses (Xiang Gencao (Vetiveria zizanioides (L.) Nash (Trifolium repens L.), white clover and ryegrass (Lolium perenne L.))) in this area of typical soils (yellow brown and Zong Hongrang) effect of anti erosion performance, and field planting white clover, seasonal variation and ryegrass mixed grass like anti erosion effect on yellow brown soil, the mining method of concentrated flow erosion test with undisturbed soil, in-depth study of the enhancing effect of plant roots on anti erosion properties the soil, in order to provide theoretical support and technical reference for the selection of grass and soil erosion control of soil and water conservation in this region, the research conclusion is as follows: (1) the root can effectively enhance the two kinds of soil resistance Erosion, yellow brown soil and brown soil strengthening effect are as follows: the white clover ryegrass. Vetiver but the same plant roots in different types of soil anti erosion performance enhancement effect difference of vetiver yellow brown soil and brown red soil enhanced the same effect, enhance the effect of white clover on yellow brown soil and brown soil is greater than, less than the brown red soil ryegrass enhancement effect the yellow brown soil; (2) in root parameters, root length density (RLD), root weight density, root area ratio (RMD) (RAR), total root area (Stotal), average root diameter (Dmean) and other factors, RLD is the influence of the soil anti erosion ability is the most important factor, can simulate two kinds of soil erodibility changes, RMD and RAR also plays an important role in RSD with RLD, RAR decreased exponentially with the decline of RMD log, significantly correlated (P0.05); (3) the whole growth period, soil bulk density increases first and then slightly decreased, and soil pore Accompanied by the corresponding changes in water stable aggregates of MWD increased slowly. The soil anti erosion performance was significantly correlated with soil bulk density, porosity (P0.05), was significantly associated with 0.25 mm and 2 mm water stable aggregates (P0.05), and the other size aggregate correlation is not good (P0.05), and root RLD. RMD and RAR were significantly correlated (P0.05); (4) using WEPP model, two types of plant roots on soil anti erosion performance enhancement effect can be better with RLD, RLD and Dc of two kinds of soil nonlinear regression equation of the correlation coefficient of R2 in soil was above 0.93, Huang Zong (-0.036*RLD): Dc=0.002exp (-1.145). Brown red: Dc=0.002exp (-0.040*RLD) (-1.562), the critical shear stress of yellow brown brown red soil, yellow brown soil in this area is the brown red soil are more susceptible to erosion; (5) with a shear, sediment content throughout the season with the tendency of decrease of sediment differences between different planting densities significantly The (except 20 and 30 g/m2). In the test period of the same erosion, early sediment content increased rapidly, the late basic balance or increase slowly; (6) with the increase of planting density, the root of anti erosion is enhanced, the sample erodibility coefficient Kr decreases with the increase of density, when the density of more than 20 g/m2 when Kr remained unchanged, indicating the roots of plants suitable for planting density in 10~20 g/m2. In conclusion, plant roots can influence on soil physical properties and enhance the anti erosion ability of the soil in Hubei area, the suitable developed roots of vetiver, fibrous roots were suitable for planting grass density is 10~20 g/m2, select the appropriate and reasonable grass planting density, in order to play the best ecological and economic benefits.

【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157

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