生物质炭对土壤有机质活性的影响

为了解施用生物质炭对土壤碳组分的潜在影响,通过室内2年盆栽培养试验研究施用不同用量生物质炭对土壤有机碳积累、有机碳稳定性、微生物量碳和水溶性有机碳的影响,并与施用等碳量的小麦秸秆、酸洗生物质炭(去除生物质炭中的速效养分)及同时施用小麦秸秆与生物质炭的处理进行比较。结果表明,施用生物质炭可显著提高土壤有机碳的积累,增加土壤有机碳的氧化稳定性,降低土壤水溶性有机碳。施用生物质可在短时间内增加微生物量碳,但随着培养时间的增加,其微生物量碳逐渐下降,最终明显低于对照土壤(不施有机物料的处理)。土壤水溶性有机碳的下降可能与生物质炭对其吸附固定有关,而短时间内激发微生物量碳增加可能与施入生物质炭增加了土壤有效养分、改善土壤微生物生长环境有关。研究结果认为,长期单一施用生物质炭可能会引起土壤有机质生物活性的下降,但生物质炭与一般生物质有机肥配合施用可减免这些负影响。

Effects of Biochar’s Application on Active Organic Carbon Fractions in Soil

Biochar is a relatively stable carboncious material converted from organic waste.Application of biochar was thought to have an important role in sequestration of organic carbon in agricultural soils.However,limited information is available about the effect of biochar’s application on soil carbon fractions and soil carbon mineralization.Thus,a two-year observation experiment was designed to study the potential effect of biochar’s application on accumulation of carbon,stability of organic carbon,microbial biomass carbon,and dissolved organic carbon in soil.The effect of biochar’s application was compared with those of wheat stalk and acid-washed biochar with removal of available nutrients at equivalent carbon application rate.The results indicated that application of biochar could increase significantly the accumulation of organic carbon in soil,and improve the stability of soil organic carbon.However,application of biochar decreased content of dissolved organic carbon in the soil.At the beginning of incubation experiment,application of biochar to soil could increase microbial biomass carbon in soil.However,the increased effect declined gradually and finally disappeared with increasing incubation time.After six months of incubation,soil microbial biomass carbon in the soil amended with biochar was lower than that of the control soil.The decrease of dissolved organic carbon in the soil amended with biochar may be due to fixation of dissolved organic carbon by the added biochar.And increase of microbial biomass carbon in the soil amended with biochar at the beginning of incubation experiment may be responsed to the increase of available nutrients and modification of microbial environments induced by biochar.It was suggested that long-term application of biochar without any application of other organic materials may decrease activity of soil organic matter.Combinated application of both biochar and other organic materials may alleviate the negative effects on soil organic matter.