施用生物质炭对酸性茶园土壤氨挥发的影响

摘要

Ammonia (NH3) volatilization is a major reason for nitrogen loss in tea garden soils. Field experiment was carried out to study the effects of biochar on soil physiochemical properties and ammonia volatilization in acid tea gardens, which would provide scientific support for the appropriate application of biochar. Four treatments were included in the experiment, namely no N fertilizer (CK), N fertilizer (B0N1, 225 kg·hm-2), N fertilizer with 8 t·hm-2 biochar (B1N1) and N fertilizer with 16 t·hm-2 biochar (B2N1). The nitrogen was applied three times, namely top dressing in spring, top dressing in autumn and basal dressing in winter in the ratio of 3︰3︰4. Compared with the B0N1 (N-applying only), biochar treatments (B1N1 and B2N1) significantly increased soil pH and organic carbon content (P<0.05), while decreased soil bulk density (P<0.05). Moreover, the average soil NH4+-N and NO3--N concentrations in biochar treated soils were 5.34%-12.59% lower and 11.02%-36.54% higher than B0N1, indicating the nitrification was promoted. The total NH3-N volatilization losses in acid tea garden varied from 13.01 kg·hm-2 to 40.95 kg·hm-2 and the percentages of the losses relative to total amount of N-application ranged from 7.29 to 12.42%.NH3-N volatilization losses also varied significantly among applying stages, with the highest NH3-N volatilization loss in winter basal dressing. The NH3-N volatilization increased significantly with N application (P<0.05), but NH3-N volatilization in B1N1 and B2N1 were significantly decreased by 26.25% and 28.21% (P<0.05), respectively. In summary, the soil NH4+-N concentrations had a direct correlation with NH3 emission and the reduction of NH3-N volatilization in biochar treatments might be attributed to the decrease of NH4+-N concentrations in soils.%氨挥发是土壤氮素损失的主要因素之一.通过田间试验,研究了施用生物质炭对酸性茶园土壤理化性质及氨挥发的影响,以期为评价生物质炭在茶园土壤中的应用提供科学数据.试验设不施氮肥(对照CK)、单施氮肥(B0N1,225 kg·hm-2)、施8 t·hm-2生物质炭基础上增施氮肥(B1N1)、施16 t·hm-2生物质炭基础上增施氮肥(B2N1)4个处理,施氮量春季追肥、秋季追肥和冬季基肥比例为3︰3︰4,进行了为期1年的观测.结果表明,与B0N1处理相比,B1N1和B2N1处理显著提高了土壤pH值和有机碳含量(P<0.05),显著降低了土壤容重(P<0.05),全氮量变化不显著(P<0.05);与B0N1处理相比,B1N1和B2N1处理土壤铵态氮平均含量降低了5.34%~12.59%,硝态氮平均含量增加了11.02%~36.54%,促进硝化作用.酸性茶园土壤氨挥发量为13.01~40.95 kg·hm-2,氨挥发损失率为7.29%~12.42%,冬季基肥期氨挥发损失量最大;施氮显著增加土壤氨挥发量(P<0.05),增施生物质炭则显著降低了氨挥发量(P<0.05),降幅为26.25%~28.21%.土壤铵态氮浓度是影响氨挥发的最主要因素,施用生物质炭降低了土壤铵态氮浓度,从而抑制了氨挥发.