Soil water repellency characteristic curves for selected agricultural soils with different ranges in total organic carbon in Murang’a, Kenya.

Abstract

Soil water repellency (SWR) is a temporary property of the soil that changes the functionality of the soil across a soil-specific range in soil moisture content (W). The severity and persistence of soil water repellency in agricultural soils is important in understanding and predicting its effects on the soil hydrological processes to optimize plant growth. Therefore, this study aimed at characterizing the persistence of SWR using Water Drop Penetration Time (WDPT) test; evaluating the SWR curve as a function of gravimetric water content from the WDPT results and finally developing relationships between SWR parameters i.e. Total SWR (SWRAREA) and critical moisture content (Wc) and soil properties (Total Organic Carbon, Sand, Silt, Clay) to understand the persistence of SWR and its effect on water flow. The degree of SWR as a function of soil moisture content was measured and monitored from oven-dry conditions to the water content at which the soils turned hydrophilic (Wc). SWRAREA was calculated as the trapezoidal area under the SWR-w curve. A total of 37% of the soils investigated were water repellent. The soils investigated expressed wide range in clay (10-40%) and TOC (0.67-6.08%). The SWR-w curves were either single or double peaked. SWRAREA ranged from 8.38second/%W to 24.91 seconds/% W. TOC was the most important soil property in explaining SWRAREA and Wc. Inclusion of Clay and silt in the Multiple Linear Regression (MLR) expression of SWRAREA significantly improved the prediction of SWRAREA to 85%. Further, an upper limit critical water content was derived from the simple relationship between the Wc and TOC, which could be applied to improve irrigation practices of agricultural soils of Murang’a County in Kenya. It is however advisable to develop soil type specific models for Wc as a function of TOC when more comprehensive data is available for each soil type. VOLUME 22 NUMBER 1, 23 Downloads

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Published 13-02-2023 How to Cite NDOLO, M., Home, P., & Messo, J. (2023). Soil water repellency characteristic curves for selected agricultural soils with different ranges in total organic carbon in Murang’a, Kenya. JOURNAL OF AGRICULTURE, SCIENCE AND TECHNOLOGY, 22(1), 37–59. https://doi.org/10.4314/jagst.v22i1.5 Issue Vol. 22 No. 1 (2023): JOURNAL OF AGRICULTURE, SCIENCE AND TECHNOLOGY Section Regular Submission 0 Crossref 0 Google Scholar Information

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