有机肥施用、土壤有效铜和氮素对稻田甲烷排放的影响

Methane Emission from Paddy Soils as Influenced by Application of Organic Manure,Soil Available Copper and Nitrogen

基于2000年18个水稻土的室外盆栽试验研究结果犤8犦,2001年水稻生长季对其中10个供试土壤继续进行盆栽试验研究,试验处理为化肥(对照)和化肥-小麦秸秆混施。结果表明,无论施用秸秆与否,不同土壤间CH4排放具有很大的差异。对照土壤CH4排放的季节性平均通量为0.89～5.92mg·m-2·h-1,施用秸秆大大促进CH4的排放,其增加幅度为2.0～8.3倍。单因素相关分析表明,对照土壤的CH4排放与水层铵态氮和土壤有效态铜含量呈显著负相关,相关系数分别为-0.6953和-0.8654。秸秆施用条件下,CH4排放与水层铵态氮呈弱负相关(r=-0.5605)、与有效态铜含量呈显著负相关(r=-0.7966)。进一步分析表明,施用小麦秸秆并未增加土壤水溶性有机碳含量。对照土壤的CH4排放随水溶性有机碳(DOC)的减少而线性递减(r=0.9030),而不同土壤的水溶性有机碳含量与有效态铜含量呈显著负相关(r=-0.8439)。这说明土壤有效态铜可能对水稻根系分泌物产生络合作用,因而减少了产CH4基质的供应。

Based on an outdoor pot experiment w ith 18paddy soils conducted in 2000d uring rice growing season 8 ,ten out of the 18soils were selected to further perfo rman outdoor pot experiment in 2001r ice growing season.Two treatments w ere designed as mineral fertilization(MF )and mineral fertilizer +wheat straw incorporation(MF +WS ).Seasonal average rate of CH 4 emission fromthe MF treatment ranged from0.89to 5.92mg ·m -2 ·h -1 .Incorporation of wheat straw enhan ced considerably CH 4 emission,some 2.0～8.3times higher than that from the MF treatment.Seasonal average of CH 4 emission was found to negatively correlateNH 4+ -N concentration in the floodwater,yielding the correlation coefficient s of -0.6953  and -0.5605for the treatments of MF a nd MF +WS,respectively.Negative correlation of the seasonal average emis sion against available copper concentration in the soils was also observed.The correlation coefficient was,respectively,-0.8654  and -0.7966  for the treatments of MF and MF +WS.A further investigation indicated that wheat straw incorporation di d not enhance the concentration of di ssolved organic carbon(DOC)in the soils.Methane emission fromt he MF treatment was positively assoc iated with the DOCconcentration(r=0.9030  ).Moreover,the DOC concentration correlated negatively to the available copper concentration,suggesting t hat a higher concentration of available copper chelate more roo t exudation and yield carbon -copper compound,facilitating reduction o f the availability of methanogenic substrates in the soil.