施肥对夏玉米季紫色土N_2O排放及反硝化作用的影响

EFFECTS OF FERTILIZATION ON N_2O EMISSION AND DENITRIFICATION IN PURPLE SOIL DURING SUMMER MAIZE SEASON IN THE SICHUAN BASIN

采用原状土柱-乙炔抑制培养法研究了施肥对紫色土玉米生长季土壤N2O排放通量和反硝化作用的影响。结果表明:玉米季施肥显著增加土壤N2O排放和反硝化损失,同时,各施肥处理间N2O排放与反硝化损失量差异显著。猪厩肥、猪厩肥配施氮磷钾肥、氮肥、氮磷钾肥和秸秆配施氮磷钾肥等处理的土壤N2O排放量分别为3.01、2.86、2.51、2.19和1.88 kg hm-2,分别占当季氮肥施用量的1.63%、1.53%、1.30%、1.09%和0.88%,反硝化损失量分别为6.74、6.11、5.23、4.69和4.12 kg hm-2,分别占当季氮肥施用量的3.97%、3.55%、2.97%、2.61%和2.23%,不施肥土壤的N2O排放量和反硝化损失量仅为0.56和0.78 kg hm-2。施肥是紫色土玉米生长前期(2周内)土壤N2O排放和反硝化速率出现高峰的主要驱动因子,土壤铵态氮和硝态氮含量是影响土壤N2O排放、土壤硝化和反硝化作用的限制因子,土壤含水量是重要影响因子,降雨是主要促发因素。土壤N2O排放量与反硝化损失量的比值介于0.45～0.72之间,土壤反硝化损失量极显著高于土壤N2O排放量,说明土壤反硝化作用是紫色土玉米生长季氮肥损失的重要途径。

The culture method of undisturbed soil cores-acetylene inhibitor was used in order to study effects of ferti- lization on N2O emission fluxes and denitrification rates during summer corn growing season in purple soil in the hilly area of the central Sichuan Basin. Results show that during the season, N loss through N2O emission and denitrifieation was significantly higher in purple soil with fertilization than without fertilization. Significant differences were observed between different fertilization treatments. The N2O emission flux in Treatment OM （pig manure） , OMNPK （pig manure with NPK fertilizer）, N （pure N fertilizer）, NPK （fertilizer NPK）, and RSDNPK （crop residues returned with NPK fertilizer） was 3.01, 2.86, 2.51, 2.19 and 1.88 kg hm-2, respectively, accounting for 1.63%, 1.53%, 1.30%, 1.09% and 0.88% , respectively, of the total fertilizer nitrogen applied to the crop. The N loss through denitrification in those treatments were 6.74, 6. 11, 5.23,4.69 and 4.12 kg hm-2 , respectively, accounting for 3.97% , 3.55% , 2.97% , 2.61% and 2.23% , respectively of the fertilizer N applied during the season. The N loss through N2O emission and denitrification in Treatment CK （no fertilization） was 0.56 and 0.78 kg hm-2, respectively, only. Fertilization was obviously the main driving force of peak emergence of soil N2O emission and denitrification in the early growth stage of corn （2 weeks） in purple soil. Inorganic N （ammonium and nitrate） content was the limiting factor of soil N2O emission, nitrification and denitrification. Soil moisture driven by rainfall was an important influencing factor. The ratio of N losses through N2O emission and denitrifieation ranged from 0.45 to 0. 72. Soil N loss was significantly higher through denitrification than through N2O emissions, which implies that the soil denitrification was the main pathway of fertilizer N loss during the maize growing season in the hilly area of purple soils.