不同生物炭用量对酸性菜地土硝化作用的影响

Effect of biochar on nitrification from vegetable-planting acid soil

采集了种植过蕹菜(60 d)的不同生物炭用量(0、2%、5%、10%干土重)的盆栽酸性菜地土,在60%土壤持水量和温度25℃培养条件下对土壤硝化作用进行了研究,并探讨了土壤硝化作用与土壤性质的关系.结果表明,通过Logistic修正模型(延滞期为0)拟合得出土壤NO-3-N随时间的变化为"S"型增长,与不施氮肥(CK)和施氮肥(NB0)处理相比,生物炭处理土壤NO-3-N累积量较高,生物炭提高土壤最大硝化速率(Kmax)同时减少达到最大硝化速率所需时间(t0)是其主要原因.Kmax与土壤pH、氨氧化细菌数量、NO-3-N、微生物生物量碳、氮,t0与微生物生物量氮、氨氧化细菌数量,最大硝化潜势(Np)与脲酶活性间显著相关.尽管生物炭提高Kmax,但却降低Np,生物炭对酸性菜地土硝化作用的影响以及NO-3-N淋失风险还需要进一步研究.

A laboratory soil incubation condition with moisture content 60% WHC and temperature 25 ℃ was applied to study the effect of biochar treatments( 0,2%,5%,10% dry soil weight) on nitrification with vegetable-planting acid soil collected from a pot experiment. The correlation between nitrification characteristics and soil properties were also studied. The results showed the type of'S'mode of time courses for NO-3-N accumulation with no delay step with the modified logistic model. Soil NO-3-N accumulation was higher with biochar treatments. Higher maximum nitrification rate( Kmax) and lower nitrification time( t0) were the important reasons for accelerated nitrification compared with CK and NB0 treatments. There were significant correlation between Kmaxand soil pH,population of ammonia oxidizing bacteria,NO-3-N,microbial biomass C,and microbial biomass N,between t0 and microbial biomass N,and ammonia oxidizing bacteria,as well as between the maximal nitrification potential( Np) and urease activity. The results indicated that biochar could accelerate Kmax,while Npdecreased with short planting pot soil. Further studies are needed to assess the effects of biochar on nitrification and its environmental implications through nitrate leaching and /or runoff for vegetable-planting acid soil.