玉米和大豆根系对滇中地区坡耕地红黏土抗剪强度的影响
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作者单位:

1.云南农业大学植物保护学院;2.云南农业大学机电工程学院;3.云南农业大学资源与环境学院

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基金项目:

国家自然科学基金(41461059)和云南省教育厅科学研究(2019J0178)


Effects of Maize and Soybean Roots on Topsoil Shear Strength of Red Clay on Sloping Farmland in Central Yunnan
Author:
Affiliation:

1.Yunnan Agricultural University;2.College of Resources and Environment, Yunnan Agricultural University

Fund Project:

National Natural Science Foundation of China (No. 41461059) and Scientific Research Fund of Yunnan Provincial Department of Education (No. 2019J0178)

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    摘要:

    水土流失是限制山区坡耕地持续利用的主要问题。为探讨农作物根系固土机理,本文采用无侧限压缩试验测定了素土、玉米和大豆成熟期根土复合体的抗剪强度和应力应变特性,WinRHIZO(Pro.2019)根系分析系统测定了根系构型特征,分析了根土复合体力学特性与根系特征参数间的关系。结果表明:①玉米和大豆根系能显著增强土体抗剪强度(P<0.01),其根土复合体强度相对素土分别提高了117.65%和71.91%;②两种农作物根土复合体黏聚力c与根长密度、根表面积密度、根体积密度、根重密度均呈极显著正相关(P<0.01),其中D≤1mm细根对黏聚力增量Δc的贡献大于其他径级根系;③根系构型性状中,玉米根分支数高于大豆45.44%且各径级根系分布更均匀,其根土复合体随含根量的增加在破坏时表现出弱应变硬化特征且裂缝拓展变缓,侧向变形减小。综上:农作物根系均能增强土体抗剪强度,但根系结构类型不同则对土体力学特性的影响不同,细根和分支数较多的玉米根系更能有效增强土体强度和约束变形,因此须根系玉米对表层土体的固持能力优于直根系大豆。坡耕地利用中,可以通过合理布局须根系农作物来防治水土流失。

    Abstract:

    【Objective】The area of sloping farmland in central Yunnan accounts for 61.14% of the total arable land area, and its sustainability is affected by serious soil erosion,so it is urgent to study the positive effects of the rational allocation of vegetation on the sloping land space on improving soil erosion and maintaining sustainable agricultural production.And 89.4% of the sloping farmland utilization in the province is planting crops, and maize and soybean are the main ones in summer. Previous studies have shown that the soil-fixing capacity of vegetation roots plays a significant role in soil and water conservation.This study was conducted to explore the soil-fixing effect of corn and soybean roots ,and provided a basis for the calculation of the soil-fixing ability of crop roots. It also provided a reference for the rational layout of crop planting to prevent soil erosion on slope farmland.【Method】In this study the field experiment was designed to have three treatments and a total of 9 experimental plots were set up, i.e.CK(Bare land) , MM(mono-maize)and SS (mono- soybean).The unconfined compression tests were used to determine the shear strength and stress-strain characteristics of rootless soil and root-soil composites of maize(Zea mays L.)and soybean(Glycine max L.)at mature stage. The WinRHIZO(Pro.2019) system was employed to analyze the root distribution and configuration characteristics. And then the relationship between shear strength and root parameters was studied.【Result】The results indicated that: ①Compared with rootless soil, the roots of maize and soybean could significantly enhance the shear strength of root-soil composite (P < 0.01), and the strength of the root-soil composites is increased by 117.65% and 71.91%, respectively;②The cohesion of two crop root-soil composites were significantly positively correlated with root length density, root surface area density, root volume density and root weight density (P <0.01). and the contribution of fine roots with D≤1mm to the cohesive force increment is greater than that of other diameter-level roots;③In the different root architecture traits, the number of root branches of maize is 45.44% higher than that of soybeans, and the root distribution of each diameter class is more even. The corn root-soil complex shows weak strain hardening characteristics when the root content increases. The crack propagation slows down and the lateral deformation decreases.【Conclusion】The root systems of the two crops could enhance the shear strength of the soil, but the different root structure types have different effects on the mechanical properties of the soil. The maize root system with more fine roots and more branches can effectively enhance the strength and restrain the deformation, so fibrous root maize is better than taproot soybeans in holding the surface soil. In the use of sloping farmland, it is possible to prevent soil erosion by rationally arranging fibrous root crops.

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张立芸,段青松,范茂攀,杨亚丽,程伟威,李永梅.玉米和大豆根系对滇中地区坡耕地红黏土抗剪强度的影响[J].土壤学报,DOI:10.11766/trxb202012140689,[待发表]
ZHANG Liyun, DUAN Qingsong, FAN Maopan, YANG Yali, CHENG Weiwei, LI Yongmei. Effects of Maize and Soybean Roots on Topsoil Shear Strength of Red Clay on Sloping Farmland in Central Yunnan[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202012140689,[In Press]

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