添加生物质炭对旱地红壤中硝态氮水平运移的影响

[目的]探讨不同生物质炭施用量条件下旱地红壤中NO-3-N的含量及水平运移规律,为该地区的农田水分管理和环境保护提供科学依据。[方法]采用室内水平扩散率仪测定不同生物质炭施用量[C0(0t/hm~2,不施用生物质炭),C1(2.5t/hm~2),C2(5t/hm~2),C3(10t/hm~2),C4(20t/hm~2),C5(30t/hm~2)和C6(40t/hm~2)]条件下土壤中硝态氮水平运移速率和运移浓度。[结果]生物质炭施用对土壤中硝态氮的水平运移速率和水平运移浓度影响显著。随着生物质炭施用量的增加,硝态氮的水平运移速率和水平运移浓度呈先增加后降低的趋势,而土壤水扩散率呈逐渐降低趋势。C5(30t/hm~2)处理下硝态氮的水平运移速率和水平运移浓度均出现最大值,分别为0.67cm/min,165.52mg/kg。随着生物质炭施用量的继续增加,C6(40t/hm~2)处理的硝态氮的水平运移速率和水平运移浓度较C5(30t/hm~2)处理有所降低,硝态氮浓度最大值均出现在湿润峰峰面上。分析影响硝态氮水平运移规律的因素表明,生物质炭降低了土壤的容重、增加了土壤有机碳和孔隙度,从而导致了各处理硝态氮的水平运移规律发生了变化。[结论]生物质炭可以改善土壤的理化性状,促进硝态氮的水平运移,在利用生物质炭改良旱地红壤理化性状的同时,也要注意防止氮素流失对环境的影响,降低其对地表水的潜在污染风险。

Effects of Biochar Addition on Horizontal Transport of NO3--N in Upland Red Soil

[Objective] This experiment studied the effects of biochar addition on the content and horizontal transport of NO₃^--N in upland red soil in laboratory to provide scientific bases for water management and environmental protection in the fields.[Methods] Moisture diffusion rate meter was used to determine the horizontal transport velocity and concentration of NO₃^--N in soil at biochar addition rates of 0, 5, 10, 20, 30 and 40 t/hm².[Results] The horizontal transport velocity and concentration of NO₃^--N were significantly affected by biochar addition. A same trend, which performed an increase at first and then a decrease with the biochar application rate increased, was found in the horizontal transport velocity and concentration of NO₃^--N in soil and the diffusivity decreased with the increasing rate of biochar addition. When the application rate of biochar was 30 t/hm², the horizontal transport velocity and concentration of NO₃^--N in soil got the highest, which were 0.67 cm/min and 165.52 mg/kg, respectively. When the application rate of biochar was 40 t/hm², the horizontal transport velocity and concentration of NO₃^--N were lower than those of 30 t/hm². The transport concentration of NO₃^--N reached the maximum value at the surface of wet spearhead in all treatments, which existing on the interface between wet and dry soil. Biochar addition decreased the soil bulk density but increased the soil organic carbon content and total porosity so as to the horizontal transport of NO₃^--N in different treatments were changeable.[Conclusion] Biochar addition can improve the soil properties, and promote the horizontal transport of NO₃^--N in upland red soil. It is very important to pay attention to prevent the pollution of leaching loss of nitrogen and reduce the potential risk of surface water.