长期施肥对春玉米田土壤呼吸及碳平衡的影响研究

Effects of long-term fertilization on soil respirationand carbon balance in spring corn fields

为探讨不同施肥方式下农田碳平衡规律,研究农田排放到大气CO_2的"源"、"汇"特征,依托39 a肥料定位试验测定了秸秆和氮磷肥配施(SNP)、农家肥和氮磷肥配施(MNP)、单施农家肥(M)、氮磷肥配施(NP)、单施氮肥(N)和不施肥(CK)等6种不同施肥方式下西北黄土旱塬春玉米拔节期到成熟期的土壤呼吸。结果表明:长期不同施肥方式能够影响春玉米农田土壤CO_2排放,不同生育时期排放特征不同,呈先升高后下降趋势,即开花期达到排放高峰,SNP、MNP和M的CO_2排放通量分别达到3 650.54、2 980.50 mg·m^(-2)·h^(-1)和2 167.61 mg·m^(-2)·h^(-1),与CK相比,分别增加了340.32%、259.51%和161.45%。不同施肥处理间表现为SNP>MNP>M>NP>N>CK。整个测定时期内土壤CO_2平均排放速率表现为SNP>MNP>M>NP>N>CK,土壤呼吸中根系呼吸的贡献率波动在31%～77%之间。6种不同施肥处理农田土壤均表现为大气CO_2排放的"汇",不同施肥处理农田碳汇强弱不同,表现为SNP>M>MNP>NP>N>CK。

A field experiment was carried out to explore fertilization effects on soil CO 2 emission,relative contribution of root and soil respiration and carbon balance,and carbon respiration intensity during the period of spring corn jointing to maturity.The effects of different fertilizer applications:straw and chemical fertilizer(SNP),manure and chemical fertilizer(MNP),single manure(M),nitrogen and phosphorus fertilizer(NP),single nitrogen fertilizer(N),and no fertilizer(CK)on soil respiration were analyzed based on long-term fertilization experiment of 39 years.The results showed that soil CO2 emission was significantly affected by different fertilization techniques.It showed a considerable fluctuation with the growth stages,which was in hoisting until reached the peak in anthesis and dropping during the following period.The CO2 emission of SNP,MNP and N was 3 650.54,2 980.50 mg·m^-2·h^-1 and 2 167.61 mg·m^-2·h^-1,respectively.Compared with CK,the increases were 340.32% ,259.51% and 161.45% for SNP,MNP and N,respectively.The order of average soil CO2 emission rates were SNP>MNP>M>NP>N>CK.The contribution ratio of rhizosphere respiration to total soil CO2 emission was fluctuated from 31% to 77% .Therefore,soils were sinks of atmosphere CO2 under all fertilization,but impact intensity on the carbon sink varied and in an order of SNP>M>MNP>NP>N>CK.