酸性硫酸盐土壤对柑桔枝生物炭改良的响应

Response of Acid Sulfate Soil to Amelioration by Citrus Branch Biochar

酸性硫酸盐土壤(ASS)作为华南地区典型低产田,其改良利用有重大意义。本研究通过盆栽试验,研究不同柑桔枝生物炭(BC)用量对ASS的改良效果。试验设5个处理,4个重复。分别为NPK(氮、磷、钾肥);NPK+0.5%BC(生物炭与干土质量比);NPK+1%BC;NPK+2%BC;NPK+4%BC。结果表明:生物炭的施入使土壤pH值和有机质同时提高且变化趋势较为一致。土壤总氮含量随着生物炭用量增加而升高,最多提高了15.1%,但其平均升幅降低。氨态氮从11.46 mg/kg降至0.96 mg/kg,硝态氮从8.37 mg/kg降至5.14 mg/kg。这在降低面源污染风险的同时可能导致作物生长高峰期供氮不足。产量的提高在4%BC出现了拐点,表明过量使用会造成减产。土壤细菌和放线菌数量持续增加,但真菌数量无显著相关性。本试验表明适量添加柑桔枝生物炭,能够改良ASS并获得较好的环境和农学效益。

Acid sulfate soil （ASS） is the typical type of low yield field in south China, its amelioration and utilization has great significance. A pot experiment was used to study the improvement effect of different citrus branch biochar application amounts on ASS. The experiment consisted of five treatments with four replicates, which were NPK, NPK＋0.5%BC （the rate of biochar and dry soil）, NPK＋ I%BC, NPK＋2%BC and NPK＋4% BC. The results indicated that with the application of biochar, soil pH and OM increased consistently. The total nitrogen （TN） elevated with the increase of biochar application amount, the maximum increase was 15.1%, but the average increasing rate decreased. The ammonia nitrogen decreased from 11.46 mg/kg to 0.96 mg/kg and the nitrate nitrogen decreased from 8.37 mg/kg to 5.14 mg/kg. Those were benefit to lower the risk of non-point source pollution but might cause insufficient nitrogen during peak-growth period. The increased yield had an inflection point in 4% biochar treatment, which showed that the overuse could cause the reduction of output. The amount of soil bacteria and actinomycetes increased gradually, but the amount of fungus had no significant correlation with biochar application amount. The results indicate that the appropriate application of citrus branch biochar can ameliorate ASS and has good environmental and agriculture benefits.