Effects of carbon-based materials on water-heat-salt dynamics in purple soil under high temperature conditions

WEN Feng; QIU Chenyu; XIAO Ran; LIANG Tao; MA Lihua

doi:10.13522/j.cnki.ggps.2025243

Abstract：[Objective]Purple soil in Southwest China is characterized by low water-holding capacity and high susceptibility to drought and temperature fluctuations.This paper experimentally investigates the effect of applying carbon-based materials on soil water-heat-salt dynamics and their associated responses to temperature variation.[Method]The experiment was conducted in pots under both normal and high-temperature conditions,each with four treatments:control(CK),application of compound fertilizer(NPK),biochar(BC),and hydrothermal carbon(HC).During the experiment,we measured the changes in soil water-holding capacity,soil temperature,and soil salinity for each treatment.[Result]①Compared with CK,the addition of biochar and hydrothermal carbon increased both macro-and micro-pores in the soil,whereas compound fertilizer had no significant effect on soil pore structure.②Applying carbon-based materials significantly enhanced soil water-holding capacity,with biochar showing the most pronounced improvement.Under high-temperature condition,compared with CK,amending soil with NPK,BC,and HC increased saturated soil water content by 5.46％,74.06％and 14.93％,respectively.③In addition,BC and HC treatments significantly increased soil electrical conductivity(EC)and mitigated the adverse effects of high temperature on the interaction and coupled migration of soil water and salt.[Conclusion]Applying carbon-based materials,particularly biochar,optimizes soil pore structure and regulates water-heat-salt interactions,thereby effectively improving soil water-holding capacity and enhancing the buffering capacity of soil against temperature stress.This is an effective strategy for mitigating the detrimental effects of summer drought on soil properties and improving water use efficiency in sloped purple soil farmland in Southern China.