Effects of biochar produced from different temperatures on nutrients retention capability in a slopeland rural soil

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Slopeland farming mainly relies on large amounts of fertilizers and plowing on conventional farming, causing soil acidification and severe degradation. In tropical and subtropical regions, organic matter decomposes rapidly and excessively. Under heavy rainfall, overdose nutrients are easily lost, leading to the occurrence of environmental hazards such as mud and sand disasters and water pollution downstream. Biochar has been considered as a soil properties that can effectively improve soil properties. Thus, the application of biochar on sloping farmland during erosion occurs to erosion, runoff and the effect of leaching and its effect on soil nutrient retention capacity need to be further explored. In this study, woodchip biochar (WB),pyrolized under different temperatures (0°C, 300°C and 600°C), were applied to an infertile sandy cultivated soil at application rates of 1 % and 2 % (w/w). Incubation experiment was conducted for 100 days consecutively. At the end of the incubation, a simulated rainfall (50 mm hr-1) was performed to evaluate the hydrological properties and nutrient retention capacity of biochar-treated soils. The results of this study showed that the application of woodchip biochar could significantly reduce soil porosity by 2.9–7.5 %, and increase soil aggregate size and hydraulic conductivity by 1.7–3.8 % and 58.9-124%. As for chemical properties, the application of biochar increased soil organic matter, total nitrogen and soil pH by 17–75 %, 27–66 % and 12–33 %. Post-incubation, simulated rainfall was conducted for 2 hours. The results from of treatments sawdust (W), lowly temperatures pyrolized woodchip biochar (LWB), and high temperatures pyrolized woodchip biochar (HWB) showed a significant increase in the initial soil moisture content, water holdng content and rainfall infiltration, significantly reduced runoff and soil losses. After 30 minutes of rainfall, the soil moisture content and infiltration have gradually tended to be in equilibrium. Additionally, the addition of sawdust treatment significantly reduces the losses of TN, NH4+–N and Bray–1 P in runoffs. Furthermore, the addition of biochar can significantly reduce the losses of SOC, TN, NH4+–N and Bray-1 P, and Exc. K by erosion, runoff and through infiltration. In conclusion, the addition of biochar could effectively improve the retention capacity of nutrients in tropical sandy soil.