干旱胁迫下水热因子变化对红壤坡耕地土壤CO2排放的影响OA

To analyze the impact of hydrothermal factor changes on soil CO₂ emissions under different tillage practices in red soil sloping farmland under drought stress,aiming to provide a scientific basis for accurately evaluating the effects of drought stress on soil carbon balance and carbon sink capacity.The trial established four typical cultivation treatments for red soil slopes:Conventional tillage(CT),Plastic mulch-covered conventional tillage(PM),Ridge-tillage(RT),and Downslope tillage(DT).Relative humidity(W)was adopted as the drought indicator to simulate drought stress scenarios during maize growth through the differences in thermal insulation and water retention performance of the various tillage practices,thereby investigating the response relationship between soil CO₂ emissions and hydrothermal factors under drought stress.Under mild drought stress,soil temperature exhibited fluctuating characteristics across all four tillage practices,while soil moisture content continuously decreased.Under mild drought stress,the soil moisture content and temperature for RT,DT,and CT practices showed the following order:RT>DT>CT for moisture,and CT>RT>DT for temperature.PM,due to its superior water retention capacity,did not experience drought stress;its soil temperature and moisture content were significantly higher than those of the other practices(p<0.05).During drought progression,soil CO₂ flux ranged between 60.53 and 224.67 mg/(m²·h),showing a decreasing trend as soil moisture content declined.The cumulative CO₂ emission under RT was reduced by 48.42%,40.66%,and 27.72%compared to PM,DT,and CT,respectively(p<0.05).Except for the flowering and grain-filling stage,all other maize growth stages experienced soil drought stress.Cumulative CO₂ emissions during the tasseling stage increased by 23.26%to 77.7%compared to those in the seedling stage(p<0.05).Drought stress exerts a significant inhibitory effect on soil CO₂ emissions in red soil sloping farmland.Soil moisture content is the key limiting factor for soil CO₂ emissions in this context.