1.Yunnan Agricultural University;2.College of Resources and Environment, Yunnan Agricultural University
National Natural Science Foundation of China (No. 41461059) and Scientific Research Fund of Yunnan Provincial Department of Education (No. 2019J0178)
【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.
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]