氮沉降背景下生物炭输入对土壤可溶性有机质和无机氮的影响

Effects of Biochar Application on Dissolved Organic Matter and Inorganic Nitrogen Contents of Soils under Nitrogen Deposition

利用盆栽试验探究氮沉降背景下生物炭输入对土壤可溶性有机质(DOM)和无机氮(NH_(4)^(+)-N、NO_(3)^(-)-N)含量的短期影响。氮沉降处理分别为0(对照)、40(低氮)和80 kg·N·hm^(-2)·a^(-1)(高氮),在每个氮沉降水平下生物炭施用量分别为0(对照)、12(低量)、36 t·hm^(-2)(高量),供试植物为杉木幼苗,试验进行18个月。结果表明,与对照相比,单独氮沉降处理使土壤pH下降了0.05~0.18个单位,而单独施用生物炭以及在氮沉降背景下施用生物炭处理后土壤pH则显著提高了0.26~0.91个单位(P<0.05)。单独氮沉降处理对土壤可溶性碳(DOC)含量和可溶性氮(DON)含量的影响并不明显,而单独施用生物炭以及在氮沉降背景下施用生物炭处理均显著提高了DOC(1~2倍)和DON(1~6倍)含量。同对照组比较,各处理下的土壤NH_(4)^(+)-N含量变化并不明显,高量施用生物炭处理显著提高了NO_(3)^(-)-N含量。因此,在杉木幼苗生长初期,施用适量的生物炭有利于缓解由氮沉降所引起的土壤酸化并维持DOM处于较高水平,这对亚热带人工林的可持续经营具有重要意义。

A pot experiment was conducted to investigate the short-term effects of biochar application on soil dissolved organic matter(DOM)and inorganic nitrogen(NH_(4)^(+)-N and NO_(3)^(-)-N)contents of Cunninghamia lanceolata seedlings under simulated nitrogen(N)deposition.N deposition treatments consisted of 0,40 and 80 kg·N·hm^(-2)·a^(-1),and biochar application rates were 0,12 and 36 t·hm^(-2) at each N deposition level,respectively.Compared with the control,the soil pH of separate N deposition decreased with 0.05~0.18 unit,however biochar applications(both separate biochar and biochar combined with N deposition)significantly increased with 0.26~0.91 unit(P<0.05)after 18 months.Separate N deposition had no significant effect on the soil DOC and DON contents,which were significantly increased to 1~2 times,while 1~6 times with BC applications.There was no significant change in soil NH_(4)^(+)-N content in other treatments in relative to the control.However,the higher application of biochar significantly increased NO_(3)^(-)-N content in soil.Therefore,biochar application would be benefit for alleviating soil acidification induced by increasing N deposition.Meanwhile it can maintain DOM at a higher level in the early stage of Cunninghamia lanceolata seedling growth,which is of great significance for the sustainable management of subtropical plantation.