有机肥与无机肥配施对潮土N2O排放的影响

Effect of Organic Fertilizer and Inorganic Fertilizer Application on N2O Emissions from Fluvo-aquic Soil in the North China Plain

华北平原是我国重要的粮食主产区,由于土壤有机质含量低,增加氮肥用量并不能导致玉米产量持续增加.有机肥和无机肥配施被广泛认为是同时实现粮食增产和提高土壤有机质的双赢措施,但是有机肥和无机肥配施对华北平原农田N2O排放的影响尚不明确.本研究在华北平原潮土区,通过测定不同种类有机肥与无机肥配施后农田N2O排放通量和作物产量,旨在揭示不同种类有机肥及其用量对潮土N2O排放和作物产量的影响效应.田间试验共设置8个处理,分别为不施肥(CK)、化肥氮(NPK)、 40%牛粪氮+60%化肥氮(CM)、 40%鸡粪氮+60%化肥氮(FC)、 40%猪粪氮+60%化肥氮(FP)、 20%牛粪氮+80%化肥氮(1/2CM)、 20%鸡粪氮+80%化肥氮(1/2FC)和20%猪粪氮+80%化肥氮(1/2FP).整个玉米季N2O排放通量均与土壤WFPS显著正相关(P<0.05).除NPK处理外,玉米季N2O排放量与土壤可溶性有机碳(DOC)平均含量存在显著的线性关系.玉米季CK处理N2O排放量为0.50 kg·hm^-2,NPK处理增加到2.28 kg·hm^-2.相同用量不同种类有机肥处理,N2O排放未出现显著差异. 40%有机肥氮用量处理下N2O排放量与NPK处理无显著差异,而用量减少至20%后, 1/2CM、 1/2FC和1/2FP处理N2O排放量分别较CM、 FC和FP减少了33.6%、 43.7%和12.1%,其主要原因为易分解有机碳输入减少,土壤DOC含量降低,但玉米产量未出现显著差异.因此,从减少温室效应的角度,玉米季80%化肥氮配施20%有机肥氮为本地区农田施肥的较佳选择.

The North China Plain is an important grain production area in China. Due to the low content of soil organic carbon, increasing the application rate of nitrogen fertilizer would not lead to a continuous increase of maize yield at present. The combined application of organic fertilizer and inorganic fertilizer is widely regarded as a measure to simultaneously increase grain yield and soil organic carbon;however, the effect of organic fertilizer and inorganic fertilizer application on N2O emissions from farmland in the North China Plain is unclear. Here, N2O emissions and crop yields in cropland under the combined application of different types and rates of organic fertilizers plus inorganic N fertilizer were measured in the North China Plain. The field experiment included eight treatments: no N fertilizer(CK), inorganic fertilizer(NPK), 40% cow manure N plus 60% inorganic fertilizer N(CM), 40% chicken manure N plus 60% inorganic fertilizer N(FC), 40% pig manure N plus 60% inorganic fertilizer N(FP), 20% cow manure N plus 80% inorganic fertilizer N(1/2 CM), 20% chicken manure N plus 80% inorganic fertilizer N(1/2 FC), and 20% pig manure N plus 80% inorganic fertilizer N(1/2 FP). The N2O fluxes were significantly correlated with soil water-filled pore space during the maize season(P<0.05). There was a significant linear relationship between N2O fluxes and soil dissolved organic carbon content during the maize season in all treatments except the NPK treatment. In the maize season, N2O emission was 0.50 kg·hm^-2 under CK treatment, and increased to 2.28 kg·hm^-2 under NPK treatment. However, when the proportion of manure N to total N applied was reduced from 40% to 20%, N2O emissions were significantly reduced by 33.6%, 43.7%, and 12.1% under 1/2 CM, 1/2 FC, and 1/2 FP treatments, respectively. The difference in application rate of organic manure N did not significantly affect maize yield. The reduction of N2O emission at the low manure application rate compared with the high manure application rate was likely due to the decrease in dissolved organic carbon in soils.