Physical Factors Influencing Soil Strength and Root Growth¹

Abstract

Soil compaction is a major factor which influences root growth and crop yields. Studies were conducted to determine the influence of different factors on mechanical impedance and to determine the influence of mechanical impedance and other soil factors on root growth. Regression models for dependent variables, soil strength and root growth, vs. the independent variables, soil type, soil depth, clay content, bulk density, voids, and water content were computed using the maximum R2 improvement by stepwise regression. The models for soil strength and root growth varied with soil type, soil depth, and/or clay content. The soils used were a Miles fine sandy loam, Udic Paleustalf and an Abilene clay loam, Pachic Argiustoll. Soil strength for both soils studied and at all depths was influenced by bulk density, voids, and clay content. The overall equational models accounted for 75% of the variability in soil strength and 76% of the variability in root growth. Root growth in both soils and at all depths was significantly influenced by soil strength, volumetric water content, voids, and clay content. The critical strength in bars, defined as the probe pressure at which root elongation stopped, was a function of % clay. The critical strength ranged from 60 to 70 bars in coarsetextured to 25 bars in clay soils. These data provide a better understanding of the influence of mechanical impedance on root growth, and a basis for determining the need for use of deep tillage to minimize the adverse effects of excessive soil strength or compaction.

Impact of Small-Scaled Differences in Micro-Aggregation on Physico-Chemical Parameters of Macroscopic Biopore Walls

“…Further possible explanations are the generally increasing water contents with depth at field condition (for Bt-2) or with increased water content caused by exudates (REW, Bt-1). Gerard et al (1982) computed regression models (stepwise) for both, root growth and soil strength, as dependent variables, using soil type, soil depth, clay content, bulk density, voids, and water content as independent variables. The considered soil types were a sandy loam and a clay loam.…”

Efeitos da integração lavoura-pecuária nas propriedades físicas do solo e características da cultura do milho

“…Em um Podzólico Vermelho-Amarelo franco-arenoso, Silva et al (2000) não observaram redução da produtividade do milho após a compactação pelo pisoteio animal, nos sistemas de preparo convencional e plantio direto, apesar de haver concentração das raízes na camada superficial do solo no plantio direto. Gerard et al (1982) afirmaram que a resistência do solo à penetração, considerada crítica ao crescimento das raízes, diminui com o aumento no teor de argila do solo. Portanto, em solos mais argilosos, o aumento da densidade do solo e da resistência do solo à penetração pode ser mais restritivo às raízes do que em solos arenosos.…”

SOIL WATER EXTRACTION PATTERN OF COCONUT (Cocos nucifera L.) IN RELATION TO SOIL COMPACTION

“…The high penetrometer readings of the Andigama series was due to the inherent nature of the soil profile. As reported by Vidhana Arachchi (1996) the high amount of clay particles accumulating in the sub-horizon, cemented with gravel particles formed a hard layer in the Andigama series of which bulk density was greater than 1.6 g/cm\ Gerard et al, (1982) also reported that soil strength in a Miles fine sandy loam, Udic Paleustalf, and in an abilene clay loam, Pachic Argiustoll, were influenced by bulk density, voids, and clay content in their soil profiles. Results also showed that soil resistance increased beyond the 100 cm depth in both soil profiles.…”