冬季施用鸡粪和生物炭对南方稻田土壤CO_2与CH_4排放的影响

Effect of chicken manure and biochar on CO_2 and CH_4 emission in paddy fields in South China

生物炭的利用近年来是农田土壤固碳减排研究中的热点。本研究通过在冬季稻田养鸡,结合生物炭添加,采用箱式法结合温室气体分析仪定量测定冬季稻田和双季稻期间土壤CO_2和CH_4排放通量,分别估算冬季稻田和双季稻期间土壤CO_2和CH_4排放总量,评估生物炭和鸡粪添加对土壤碳排放的影响。结果表明,鸡粪还田处理显著提高了土壤CO_2的排放,冬季稻田和水稻生育期排放量分别达9 935.39 kg·hm^(-2)和27 756.34kg·hm^(-2),比对照增加58.7倍(P<0.01)和56%(P<0.05);生物炭添加处理冬季稻田和水稻生育期CO_2累积排放量比对照高12.3倍(P<0.01)和41%(P<0.05)。鸡粪还田处理下冬季稻田和水稻生育期稻田的CH_4排放量均显著高于其他处理;而生物碳添加对冬季稻田CH_4排放无显著影响,但显著降低了水稻生育期稻田的CH_4排放。鸡粪还田配施生物炭处理也显著提高了稻田土壤CO_2的排放。冬季稻田时,鸡粪还田配施生物炭土壤CO_2累积排放量显著高于鸡粪还田处理;而水稻生育期时,鸡粪还田配施生物炭处理下土壤CO_2累积排放量显著低于鸡粪还田处理。鸡粪还田下添加生物碳可以降低因鸡粪还田引起的CH_4排放增加的效应。总之,鸡粪原位还田显著增加了冬季稻田和水稻生育期稻田的CO_2和CH_4排放;无论是冬季稻田还是水稻生育期,生物炭的添加都降低了土壤CH_4的排放,且生物炭添加后期有抑制土壤CO_2排放的作用。因此,从更长的时间尺度来看,生物炭施入土壤有利于土壤固碳减排。

The application of biochar to enhance soil carbon sequestration in farmlands is an increasingly investigated research to reverse the effects of climate change.There is little report on the effect of adding manure in situ in combination with biochar application to winter paddy fields on CO2and CH4emissions during winter fallow and growth period of double rice.To fully use winter fallow paddy fields and determine how biochar and chicken manure affected the emission of CO2and CH4,four treatments were set up― no fertilization(CK),chicken raised in the field and chicken manure addition(C),in situ chicken manure addition and biochar addition(CB),and biochar addition(B).The CO2and CH4fluxes and total emissions were determined in paddy fields using the chamber method along with Greenhouse Gas Analyzer during winter and the growth period of double cropping rice.The objective was to assess the effects of chicken manure in situ incorporation and biochar on soil carbon emission.The results showed that relationship between CO2flux under CK and B treatments and soil temperature at5cm soil depth fitted well the non-linear index model.Then CO2flux under C and CB treatments had no significant correlation with soil temperature at5cm soil depth,which meant that the in situ addition of chicken manure made it more sophisticated for soil to modulate CO2emission.The treatment of in situ addition of chicken manure significantly increased soil CO2emission in winter paddy fields and during rice growth period with respective emissions of9935.39kg·hm?2and27756.34kg·hm?2,which was58.7times(P<0.01)and56%(P<0.05)higher than that of CK.The cumulative CO2emissions in winter paddy fields and during rice growth period under biochar addition were12.3times(P<0.01)and41%(P<0.05)higher than that of CK during in winter paddy fields and during rice growth period.The emissions of CH4in winter paddy fields and during rice growth period under treatment of in situ addition of chicken manure were significantly higher than that under other treatments,while it was not significantly changed in winter paddy fields and significantly decreased during rice growth period under biochar addition treatments.Chicken manure in situ application in combination with biochar treatment also significantly improved CO2emission of paddy soils.Cumulative CO2emission under chicken manure in situ application along with biochar addition in winter paddy fields was significantly higher than that under chicken manure in situ application.Also during rice growth period,it was significantly lower than that under chicken manure return.This suggested that biochar addition inhibited soil CO2emission in the late period.The addition of biochar decreased soil CH4emission in both winter paddy field and rice growth stage.In short,the addition of exogenous organic carbon like chicken manure to soils increased carbon emission(both CO2and CH4),while the addition of biochar to soils increased carbon emission in the short-term and decreased CH4emission.Therefore,from the longer time view,biochar application to soils was beneficial to soil carbon sequestration,and might mitigate carbon emission caused by in situ application of chicken manure.