CO2浓度升高对小麦秸秆性质、数量及其分解的影响

在江都FACE平台上观测了常N水平下大气CO2浓度升高对小麦秸秆数量和性质的影响,并利用稻季淹水培养试验研究了CO2浓度升高引起的小麦秸秆量和质的改变对其腐解和土壤微生物量碳的影响,结果表明:CO2浓度升高显著降低了麦秸中N含量,导致麦秸C/N和木质素/N比显著增加,但对麦秸其他生化组成——可溶物、半纤维素、纤维素、木质素和酚含量均无影响;CO2浓度升高引起的小麦秸秆性质改变对麦秸及其含C物质的分解均无显著影响,但显著减缓了含N物质的分解;若将收获的麦秸全部还田,CO2浓度升高引起的小麦秸秆量的增加也没有显著影响麦秸及其含C、N物质的分解。由于高CO2浓度导致的麦秸性质改变对土壤微生物量碳无显著影响,这也是CO2浓度升高引起麦秸性质变化幅度太小不足以影响麦秸及其含C物质分解的主要原因。

Effects of CO2-induced change on wheat straw quality, quantity and decomposition

The effect of CO2 enrichment on the quality and quantity of wheat straw,wheat straw decomposition and anaerobic soil microbial biomass activity was examined in rice season.Analysis shows that elevated CO2 significantly enhances C/N and lignin/N rations of wheat straw due primarily to decreased N content.However,elevated CO2 has no effect on biochemical compositions(soluble fractions,semi-cellulose,cellulose and lignin) and phenol content of wheat straw.Alteration of wheat straw quality caused by elevated CO2 has insignificant effect on wheat straw and wheat straw C decomposition, but rather significantly retardes wheat straw N decomposition.When all produced wheat straw under ambient and elevated CO2 are added to the soil,elevated CO2 alteration of wheat straw quantity has no obvious impact on subsequent wheat straw decomposition.Change in wheat straw quality from elevated CO2 insignificantly affects subsequent soil microbial biomass C.This implicitly explains any lack of effect of elevated CO2 on wheat straw quality,decomposition and C content.