Study on shear strength of root-soil composite of Dolichos lablab and Medicago sativa in purple soil region

doi:10.11686/cyxb2022392

Abstract

Abstract:

To clarify the effects of plant root systems on soil shear strength in purple soil sloping farmland， Dolichos lablab and Medicago sativa were planted and sampled. Their root morphological traits， fiber contents and biomechanical traits were measured. The shear strengths of root-soil composites were measured simultaneously. Correlation analysis and multiple stepwise regression analysis were used to analyze the relation between root traits （including fiber content） and soil cohesion， and root traits and soil internal friction. It was found that： 1） Under 100， 200， 300， and 400 kPa vertical pressure， root-soil composite shear strengths of D. lablab and M. sativa were greater than CK by 1.18%-63.81% （P<0.05）. Similarly， the soil cohesion with plant roots was 141.30%-189.74% greater than CK. 2） For the dominant root diameter class ≤0.5 mm， root parameters were the same for D. lablab and M. sativa. For root diameter classes >0.5 mm and ≤1.0 mm， the root length density， root surface area density and root volume ratio of D. lablab were significantly greater than those of M. sativa. 3） Soil cohesion in the root-soil composite showed a significantly positive relationship with root length density （R²>0.710， P<0.01）， and could be predicted well by root length density and ultimate elongation in a linear regression equation. Generally， D. lablab was better than M. sativa for root enhancement of soil shear strength in purple soil sloping farmland.

Key words: soil erosion, root system, ultimate elongation, shear strength, soil cohesion

Yan WEI, You-bin LIU, Xiao-hong LIU, Yun CHEN, Zhe-hao YAN, Yi-zhi DU. Study on shear strength of root-soil composite of Dolichos lablab and Medicago sativa in purple soil region[J]. Acta Prataculturae Sinica, 2023, 32(8): 82-90.

Figures/Tables 8

References 32

1	Chen Y， He B H， Lian C X， et al. Root system distribution characteristics of three herbs and their effects on soil composition and nutrients in the ‘Purple Soil’ region. Acta Prataculturae Sinica， 2015， 24（10）： 99-107.
	谌芸，何丙辉，练彩霞，等. 紫色土区3种草本植物根系特征及改土培肥效应. 草业学报， 2015， 24（10）： 99-107.
2	Ding W B， He W J， Shi D M， et al. Effect of drying-wetting condition on attenuation-recovery of soil shear strength of bio-embankment on sloping farmland comprising purple soil. Acta Prataculturae Sinica， 2017， 26（6）： 56-67.
	丁文斌，何文健，史东梅，等. 干湿作用对紫色土坡耕地生物埂土壤抗剪强度衰减-恢复效应. 草业学报， 2017， 26（6）： 56-67.
3	Lin C， Tu S， Huang J， et al. The effect of plant hedgerows on the spatial distribution of soil erosion and soil fertility on sloping farmland in the purple-soil area of China. Soil & Tillage Research， 2009， 105（2）： 307-312.
4	Li J， Wang X， Jia H X， et al. Ecological restoration with shrub roots for slope reinforcement in a shallow landslide-prone region. Acta Ecologica Sinica， 2019， 39（14）： 5117-5126.
	李佳，汪霞，贾海霞，等. 浅层滑坡多发区典型灌木根系对边坡土体抗剪强度的影响. 生态学报， 2019， 39（14）： 5117-5126.
5	Fan C C， Tsai M H. Spatial distribution of plant root forces in root-permeated soils subject to shear. Soil & Tillage Research， 2016， 156： 1-15.
6	Xia Z Y， Liu Q， Xu W N， et al. Characteristics of interface friction between Indigofera amblyantha root system and soil. Journal of Soil and Water Conservation， 2018， 32（1）： 128-134.
	夏振尧，刘琦，许文年，等. 多花木蓝根系与土体界面摩阻特征. 水土保持学报， 2018， 32（1）： 128-134.
7	Wang R Z， Chen Y， Li T， et al. Root distribution characteristics of Vetiveria zizanioides and Digitaria sanguinalis and their effects on the anti-erodibility of purple soil in slopelands. Acta Prataculturae Sinica， 2017， 26（7）： 45-54.
	王润泽，谌芸，李铁，等. 香根草和马唐的根系特征及对坡地紫色土抗侵蚀性的影响. 草业学报， 2017， 26（7）： 45-54.
8	Liu Y B， Hu X S， Yu D M， et al. Distribution characteristics of combined herb and shrub roots in loess area of Xining basin and their effect on enhancing soil shear strength. Journal of Engineering Geology， 2020， 28（3）： 471-481.
	刘亚斌，胡夏嵩，余冬梅，等. 西宁盆地黄土区草本和灌木组合根系分布特征及其增强土体抗剪强度效应. 工程地质学报， 2020， 28（3）： 471-481.
9	Pollen N. Temporal and spatial variability in root reinforcement of streambanks： Accounting for soil shear strength and moisture. Catena， 2007， 69（3）： 197-205.
10	Zhao J L， Li G F， Hu W， et al. Experiment research on rainforest trees tap root resistance slide effect in the shallow landslide. Chinese Journal of Rock Mechanics and Engineering， 2017， 36（S1）： 3663-3669.
	赵记领，李光范，胡伟，等. 雨林乔木直根根土复合体的抗剪强度试验研究. 岩石力学与工程学报， 2017， 36（S1）： 3663-3669.
11	Zhang C B， Zhou X， Jiang J， et al. Root moisture content influence on root tensile tests of herbaceous plants. Catena， 2019， 172： 140-147.
12	Li Z Y， Ouyang M， Xiao H B， et al. Improvement of slope soil consolidation capacity of plant root system based on regulation of root architecture. Rock and Soil Mechanics， 2021， 42（12）： 3271-3280， 3290.
	李珍玉，欧阳淼，肖宏彬，等. 基于根系构型的调控提高植物边坡根系固土能力. 岩土力学， 2021， 42（12）： 3271-3280， 3290.
13	Li Y P， Wang Y Q， Wang Y J， et al. Effects of Vitex negundo root properties on soil resistance caused by pull-out forces at different positions around the stem. Catena， 2017， 158： 148-160.
14	Zhang C B， Chen L H， Jiang J. Why fine tree roots are stronger than thicker roots： The role of cellulose and lignin in relation to slope stability. Geomorphology， 2014， 206（206）： 196-202.
15	Tang H， Chen Y， Liu X H， et al. Study on the mechanic features of root and root-soil matrix of Dolichos lablab L.hedgerows on the slopes of the karst area. Acta Ecologica Sinica， 2019， 39（16）： 6114-6125.
	唐菡，谌芸，刘枭宏，等. 喀斯特坡地拉巴豆地埂篱根及根-土复合体力学特性. 生态学报， 2019， 39（16）： 6114-6125.
16	Ghestem M， Ceylon G， Bernard A， et al. Influence of plant root system morphology and architectural traits on soil shear resistance. Plant & Soil， 2014， 377（1/2）： 43-61.
17	Li J X， He B H， Chen Y， et al. Root characteristics of Cynodon dactylis and Trifolium repens and their effect on shear performance of purple soil in barren hillside. Transactions of the Chinese Society of Agricultural Engineering， 2013， 29（10）： 144-152.
	李建兴，何丙辉，谌芸，等. 不同护坡草本植物的根系分布特征及其对土壤抗剪强度的影响. 农业工程学报， 2013， 29（10）： 144-152.
18	Su X， Zhou Z， Liu J， et al. The role of root traits of climax community species to shear strength in the Loess Hilly Region， China. Soil & Tillage Research， 2022， 221： 105417.
19	Zhang C B， Chen L H， Liu Y P， et al. Triaxial compression test of soil-root composites to evaluate influence of roots on soil shear strength. Ecological Engineering， 2010， 36（1）： 19-26.
20	Liu X H. The effects of terrace hedgerows roots on the erodibility of the root-soil complex in the purple soil area. Chongqing： Southwest University， 2021.
	刘枭宏. 紫色土区地埂篱根系对根-土复合体抗侵蚀性能的影响. 重庆：西南大学， 2021.
21	Lateh H， Avani N， Bibalani G H. Tensile strength and root distribution of Acacia mangium and Macaranga tanarius at spatial variation （Case study： East-West highway， Malaysia）. International Journal of Biosciences， 2015， 6（7）： 18-28.
22	Institute of Soil Physics， Nanjing Soil Research Institute， Chinese Academy of Sciences. Physical properties of soil. Beijing： Beijing Science Press， 1978.
	中国科学院南京土壤研究所土壤物理研究室. 土壤物理性质测定法. 北京：科学出版社， 1978.
23	Qiang J J， Yan Z H， Chen Y， et al. Factors affecting the shear strength of root-soil complexes from three types of grass hedgerows in a karst area. Acta Prataculturae Sinica， 2020， 29（12）： 27-37.
	强娇娇，颜哲豪，谌芸，等. 喀斯特区3种草篱根-土复合体抗剪性能及其影响因素. 草业学报， 2020， 29（12）： 27-37.
24	Li H S. Experimental principle and techniques for plant physiology and biochemistry. Beijing： Higher Education Press， 2000.
	李合生. 植物生理生化实验原理和技术. 北京：高等教育出版社， 2000.
25	Baets S D， Poesen J， Reubens B， et al. Root tensile strength and root distribution of typical Mediterranean plant species and their contribution to soil shear strength. Plant and Soil， 2008， 305（1/2）： 207-226.
26	Liu Y B， Hu X S， Yu D M， et al. Influence of the roots of mixed-planting species on the shear strength of saline loess soil. Journal of Mountain Science， 2021， 18（3）： 806-818.
27	Liu X H， Chen Y， Yan Z H， et al. The effects of grass hedgerow roots on shear strength and scouring resistance of root-soil complexes in the purple soil region. Acta Prataculturae Sinica， 2021， 30（11）： 98-107.
	刘枭宏，谌芸，颜哲豪，等. 紫色土区草篱根系对其根-土复合体抗剪和抗冲性能的影响. 草业学报， 2021， 30（11）： 98-107.
28	Mao Z J， Zhang J G， Bi Y L， et al. Numerical analysis of protection time effect on planting alfalfa in loess slope with shallow failure. Transactions of the Chinese Society of Agricultural Engineering， 2022， 38（15）： 72-83.
	毛正君，张瑾鸽，毕银丽，等. 紫花苜蓿对黄土边坡浅层破坏防护时间效应的数值分析. 农业工程学报， 2022， 38（15）： 72-83.
29	Li Q， Liu G B， Zhang Z， et al. Effect of root architecture on structural stability and erodibility of topsoils during concentrated flow in hilly Loess Plateau. Chinese Geographical Science， 2015， 25： 757-764.
30	Matti C， Bischetti G B， Gentile F. Biotechnical characteristics of root systems of typical Mediterranean species. Plant and Soil， 2005， 278（1/2）： 23-32.
31	Feng S Y， Wang J G， Wen H， et al. Soil shear strength of collapsing erosion area in south Jiangxi of China relative to position of the soil and its influencing factors. Acta Pedologica Sinica， 2020， 57（1）： 71-83.
	冯舒悦，王军光，文慧，等. 赣南崩岗侵蚀区不同部位土壤抗剪强度及影响因素研究. 土壤学报， 2020， 57（1）： 71-83.
32	Gonzalez-Ollauri A， Mickovski S B. Plant-soil reinforcement response under different soil hydrological regimes. Geoderma， 2017， 285： 141-150.

根径 Root diameter	植物种类 Plant species	根长密度 Root length density （cm·cm^-3）	根表面积密度 Root surface density （cm²·cm^-3）	根体积比 Root volume ratio （cm³·cm^-3）	根尖数 Root tips	纤维素 Cellulose （%）	半纤维素 Lignin （%）	木质素 Hemicellulose （%）
Ⅰ	拉巴豆D. lablab	2.74±1.30Aa	0.17±0.07Aa	0.11±0.04Ab	1055±723Aa	36.81±0.85Aa	26.61±1.84Aa	21.36±0.10Aa
Ⅰ	紫花苜蓿M. sativa	2.84±2.83Aa	0.15±0.14Aa	0.09±0.08Aa	1523±469Aa	31.69±0.49Aa	24.06±0.08Aa	21.15±0.25Aa
Ⅱ	拉巴豆D. lablab	0.62±0.30Ab	0.13±0.07Aa	0.23±0.12Aa	21±8Ab	35.05±2.01Aab	24.64±1.44Aa	22.11±2.59Aa
Ⅱ	紫花苜蓿M. sativa	0.38±0.29Bb	0.08±0.06Bab	0.15±0.11Ba	17±5Ab	34.17±2.48Aa	25.29±1.03Aa	23.35±2.86Aa
Ⅲ	拉巴豆D. lablab	0.11±0.07Ab	0.04±0.02Ab	0.13±0.07Ab	4±2Ab	32.46±0.36Bb	24.50±0.93Aa	21.53±1.56Aa
Ⅲ	紫花苜蓿M. sativa	0.11±0.07Ab	0.04±0.03Ab	0.13±0.09Aa	3±1Ab	37.03±1.35Aa	26.12±0.15Aa	21.58±0.28Aa
Ⅳ	拉巴豆D. lablab	0.04±0.02Ab	0.02±0.01Ab	0.09±0.06Ab	1±1Ab	35.08±0.26Aa	27.37±1.07Aa	24.37±3.02Aa
Ⅳ	紫花苜蓿M. sativa	0.06±0.06Ab	0.04±0.03Ab	0.15±0.14Aa	1±1Ab	35.58±1.66Aa	25.06±0.72Aa	23.26±1.02Aa

根径 Root diameter	植物种类 Plant species	根长密度 Root length density （cm·cm^-3）	根表面积密度 Root surface density （cm²·cm^-3）	根体积比 Root volume ratio （cm³·cm^-3）	根尖数 Root tips	纤维素 Cellulose （%）	半纤维素 Lignin （%）	木质素 Hemicellulose （%）
Ⅰ	拉巴豆D. lablab	2.74±1.30Aa	0.17±0.07Aa	0.11±0.04Ab	1055±723Aa	36.81±0.85Aa	26.61±1.84Aa	21.36±0.10Aa
Ⅰ	紫花苜蓿M. sativa	2.84±2.83Aa	0.15±0.14Aa	0.09±0.08Aa	1523±469Aa	31.69±0.49Aa	24.06±0.08Aa	21.15±0.25Aa
Ⅱ	拉巴豆D. lablab	0.62±0.30Ab	0.13±0.07Aa	0.23±0.12Aa	21±8Ab	35.05±2.01Aab	24.64±1.44Aa	22.11±2.59Aa
Ⅱ	紫花苜蓿M. sativa	0.38±0.29Bb	0.08±0.06Bab	0.15±0.11Ba	17±5Ab	34.17±2.48Aa	25.29±1.03Aa	23.35±2.86Aa
Ⅲ	拉巴豆D. lablab	0.11±0.07Ab	0.04±0.02Ab	0.13±0.07Ab	4±2Ab	32.46±0.36Bb	24.50±0.93Aa	21.53±1.56Aa
Ⅲ	紫花苜蓿M. sativa	0.11±0.07Ab	0.04±0.03Ab	0.13±0.09Aa	3±1Ab	37.03±1.35Aa	26.12±0.15Aa	21.58±0.28Aa
Ⅳ	拉巴豆D. lablab	0.04±0.02Ab	0.02±0.01Ab	0.09±0.06Ab	1±1Ab	35.08±0.26Aa	27.37±1.07Aa	24.37±3.02Aa
Ⅳ	紫花苜蓿M. sativa	0.06±0.06Ab	0.04±0.03Ab	0.15±0.14Aa	1±1Ab	35.58±1.66Aa	25.06±0.72Aa	23.26±1.02Aa

根径级别 Root diameter class	植物种类 Plant species	抗拉强度 Tensile strength （MPa）	极限延伸率 Ultimate elongation （%）	弹性模量 Elastic modulus （MPa）	平均根直径 Mean root diameter （mm）	样本数 Number
Ⅰ	拉巴豆D. lablab	52.07±7.52Aa	6.24±1.41Aab	864.68±153.45Ba	0.26	14
Ⅰ	紫花苜蓿M. sativa	47.69±16.38Aa	3.67±1.50Ab	1538.11±740.75Aa	0.39	10
Ⅱ	拉巴豆D. lablab	38.88±6.85Ab	5.31±1.84Ab	839.82±325.14Aa	0.67	17
Ⅱ	紫花苜蓿M. sativa	36.86±3.83Ab	7.13±2.55Aab	607.52±271.76Bb	0.87	19
Ⅲ	拉巴豆D. lablab	24.60±7.57Ac	9.61±2.56Aa	289.75±152.79Ab	1.36	20
Ⅲ	紫花苜蓿M. sativa	20.41±4.02Bc	11.09±3.67Aa	195.03±43.06Bb	1.22	20
Ⅳ	拉巴豆D. lablab	13.94±5.37Ad	9.22±2.29Aa	170.38±89.79Ab	1.62	14
Ⅳ	紫花苜蓿M.sativa	12.07±3.02Ac	11.52±3.85Aa	123.57±64.04Bb	1.79	17

根径级别 Root diameter class	植物种类 Plant species	抗拉强度 Tensile strength （MPa）	极限延伸率 Ultimate elongation （%）	弹性模量 Elastic modulus （MPa）	平均根直径 Mean root diameter （mm）	样本数 Number
Ⅰ	拉巴豆D. lablab	52.07±7.52Aa	6.24±1.41Aab	864.68±153.45Ba	0.26	14
Ⅰ	紫花苜蓿M. sativa	47.69±16.38Aa	3.67±1.50Ab	1538.11±740.75Aa	0.39	10
Ⅱ	拉巴豆D. lablab	38.88±6.85Ab	5.31±1.84Ab	839.82±325.14Aa	0.67	17
Ⅱ	紫花苜蓿M. sativa	36.86±3.83Ab	7.13±2.55Aab	607.52±271.76Bb	0.87	19
Ⅲ	拉巴豆D. lablab	24.60±7.57Ac	9.61±2.56Aa	289.75±152.79Ab	1.36	20
Ⅲ	紫花苜蓿M. sativa	20.41±4.02Bc	11.09±3.67Aa	195.03±43.06Bb	1.22	20
Ⅳ	拉巴豆D. lablab	13.94±5.37Ad	9.22±2.29Aa	170.38±89.79Ab	1.62	14
Ⅳ	紫花苜蓿M.sativa	12.07±3.02Ac	11.52±3.85Aa	123.57±64.04Bb	1.79	17

指标 Indicators	拉巴豆D. lablab		紫花苜蓿M. sativa
指标 Indicators	黏聚力 Cohesion	内摩擦角 Internal friction angle	黏聚力 Cohesion	内摩擦角 Internal friction angle
根长密度Root length density	0.715**	-0.025	0.949**	-0.579*
根表面积密度Root surface density	0.729**	-0.037	0.575	-0.563
根体积比Root volume ratio	0.400	-0.034	-0.174	-0.031
根尖数Root tips	0.651*	0.228	0.590*	-0.276
纤维素Cellulose	-0.424	0.116	0.120	-0.046
半纤维素Hemicellulose	0.066	0.420	0.723*	-0.476
木质素Lignin	0.720*	0.292	0.390	-0.353
抗拉强度Tensile strength	0.381	-0.327	-0.183	0.200
极限延伸率Ultimate elongation	-0.673*	0.562	-0.878**	0.529