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| DOI：10.13522/j.cnki.ggps.2019390 |
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| The Effects of Biochar Amendment on Hydraulic Properties of Red and Paddy Soils in Southern China |
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CHEN Jiao, WU Fengping, WANG Hui, TAN Shuai, HU Chuanwang
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College of Water Resources and Civil Engineering, Hunan Agricultural University, Changsha 410128, China
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| Abstract: |
| 【Background】Biochar has been widely used to improve the properties of red and paddy soils in south China, but most work focused on the chemical and biochemical properties while the change in soil physical properties due to biochar addition had been largely overlooked.【Objective】The purpose of this work is to investigate how hydraulic properties of the red and paddy soils changed following biochar amendment.【Method】Soil samples were taken from red and paddy soils amended with biochar at rate (weight/weight) of 0 (CK), 0.1%, 0.5%, 1%, 3% and 5%, and their water retention curves were measured using the centrifuge method. From these water retention curves, we calculated pore-size distribution and unsaturated hydraulic conductivity of each soil sample.【Result】With biochar addition increasing, the water holding capacity of the paddy soil increased while that of the red soil increased first followed by a decline when the biochar addition exceeded 3%; on average, the water holding capacity of the red soil was higher than that of paddy soil. As the biochar addition increased, the volumetric fraction of effective pores in the red soil increased while that of the paddy soil gradually decreased. The unsaturated hydraulic conductivity and water diffusivity of both red and paddy soils decreased monotonically with the increase in biochar addition (P<0.05). Biochar addition impacted the unsaturated hydraulic conductivity and diffusivity of the red soil more significantly than on that of the paddy soil. The porosity of both red and paddy soils increased with soil carbon, while there was no noticeable change in other parameters in the van Genuchten formula used to fit the water retention curves.【Conclusion】Amending the red and paddy soil with biochar could improve their water holding capacity and hydraulic conductivity at both saturated and unsaturated conditions. |
| Key words: biochar amendment; soil; the BC model; unsaturated hydraulic conductivity; water diffusivity |
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