Abstract
PurposeThe swelling characteristics and cracking of expansive clayey soils usually lead to their low yield, and as a result, large areas of expansive soils remain uncultivated and unproductive. There is a need for the development of simple, low-cost technologies which will bring these soils into production. The amendment of expansive clayey soils with agricultural waste products is a key goal for enhancing their production potential. Therefore, a study was conducted to evaluate the ameliorative effects of crop residues on the physiochemical and mechanical properties of expansive clayey soils.MethodIn this study, the potential soil amendments used include uncharred rice husk, rice husk biochar, uncharred sugarcane bagasse, and sugarcane bagasse biochar. The biochar was pyrolyzed at 450 °C. The amendments were applied into the soil at four applications rates: 0, 2, 5, and 10% by weight of soil (w/w), respectively. The mixture was then incubated in a glasshouse for 280 days.ResultsCharred and uncharred rice husk and sugarcane bagasse improved the physico-mechanical properties related to soil expansion. The liquid limit (LL), plastic limit (PL), plasticity (PI), coefficient of linier extensibility (COLEcore), volumetric shrinkage (VS), fissures’ dimensions, and crack area density (CAD) of the soil decreased with an increase in treatment application rate. On the contrary, saturated water content increased with an increase in dosage.Conclusions10% level of amendment application resulted in significantly improved soil properties than either 2% or 5% doses. Moreover, 2% level of amendment application is more preferable than 5% according to feasibility and economic point of view.
Highlights
Partially saturated fine-grained soils having high plasticity are very sensitive to changes in moisture content and show excessive volume changes (Sarkar et al 2012)
Based on the results of this study, it can be concluded that amendments such as charred and uncharred rice husk and sugarcane bagasse significantly improved the physiochemical as well as the mechanical properties of expansive clayey soil
The amendment materials used improved the desiccation cracking behavior of soil and decreased soil problems induced by desiccation cracking in expansive soil areas by reducing the values of consistency limits, COLEcore, volumetric shrinkage (VS), and crack area density (CAD)
Summary
Partially saturated fine-grained soils having high plasticity are very sensitive to changes in moisture content and show excessive volume changes (Sarkar et al 2012) Such soils are classified as expansive soils and they attribute their characteristics to the presence of swelling clay (smectite) minerals. Soil cracks may cause physical damage to plant roots, encourage the vertical movement and leaching of dissolved nutrients beyond root zone, provide extra surface for moisture loss, and they may even promote rill erosion. Because of all these problems caused by cracking, crop production on shrink–swell soils is limited (Wubie 2015)
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