生物炭对某些高度风化的热带土壤和温带酸性土壤有改善土壤结构,减少营养元素淋失的作用,但关于温带干旱区的盐碱土的改良效果却很少报道。以新疆绿洲盐碱土为对象,研究玉米秸秆生物炭对氮淋溶的影响。采用室内土柱淋滤试验,土柱包含炭土比(W/W)0%、1%、5%和10%四个处理,模拟大气降雨,定期收集淋滤液,分析其中的氮素指标。结果显示,5%和10%添加比例分别减少了土壤氨态氮的淋失量31.14%和52.43%,1%的添加比例增加了铵态氮淋失。对比空白,10%处理的铵态氮、硝态氮和总氮减少淋失量分别达到52.43%、50.01%和33.83%,1%和5%处理土柱的硝态氮和总氮在试验10 d内(降雨量140 mm)就基本淋失完,而10%处理土柱则显得较为平缓,几乎到25 d(降雨量290 mm)时才基本淋失完。四个土柱的铵态氮的淋失都较为平缓。另外,生物炭可以减少土柱的溶液淋失量(20.95%),增加土壤持水能力。上述结果表明,生物炭施用于干旱区盐碱土能明显减少硝态氮和总氮淋失并延长其在土壤中的停留时间,增强土壤的持续供氮能力。
Biochar has been showed to improve soil structure and reduce nutrient leaching in highly weathered tropical soils and acidic temperate soils. However, there is little information available about the effect of biochar on temperate alkaline and/or saline soils in arid areas. In a laboratory study, ammonium and nitrate in soil leachate were monitored at different simulated precipitation after treatment with biochar. An alkaline soil was collected from Kashgar oasis, Xinjiang autonomous region. Bioehar was produced from corn stover at 550 ℃, and mixed thoroughly with the soil at 0%, 1.0%, 5.0% and 10.0%( W/W ) ratio. Compared with the control, applications of biochar at 5% and 10% reduced ammonium leaching by 31.14% and 52.43%, respectively, while biochar addition at 1% increased ammonium leaching by 85.95%. Accumulated leaching of ammonium-nitrogen increased with accumulated precipitation. The leaching losses of nitrate-nitrogen and total nitrogen were reduced by 24.79% and 38.19%, 50.01% and 16.13%, and 29.98% and 33.83% for 1.0%, 5.0% and 10.0% biochar additions, respectively, as compared with the control The leaching of nitrate-nitrogen and total nitrogen occurred most during the first three precipitation events or about the first 140 mm of precipitation, and phased out at about 190 mm precipitation in 0%, 1.0%, and 5.0% bioehar treatments. However, this phaseout was postponed at about 290 mm precipitationin in 10% biocbar treatment. The application of biochar also increased soil water-holding capacity by an average of 20.95%. These results indicate that biochar application in saline and/or alkaline soils in arid areas could significantly reduce the leaching losses of nitrogen and enhance soil water holding capacity.