Comprehensive analysis of emissions and global warming effects of greenhouse gases in winter-wheat fields in the high-yield agro-region of North China Plain

Comprehensive studies on greenhouse gas emissions and the related global warming potential (GWP) under different agricultural management practices had the benefits of mitigated greenhouse gas emissions, reduced GWP and strengthened theoretical basis for measurements of greenhouse gas emissions. Based on experiment with four agricultural management patterns (T1: conventional pattern; T2: high-yield and high-efficiency pattern; T3: super-high-yield pattern; T4: super-high-yield, high-efficiency and soil fertility improvement pattern), N₂O, CO₂ and CH₄ fluxes in winter-wheat fields were monitored from October 2009 to September 2011 using the static chamber method and the gas chromatographic technique. Total greenhouse gas emissions and GWP were then accordingly estimated. The results indicated that the winter-wheat field was the sources of N₂O and CO₂, but the sink of CH₄. The effects of the different agricultural management patterns on the different greenhouse gas sources and sinks were different. High N application and sufficient irrigation increased the CO₂ and N₂O in the soil and strengthened the characteristics of soil as the emission source of CO₂ and N₂O. Meanwhile, CH₄ oxidation in soils was restrained and soil characteristics as CH4 sink decreased. The carbon equivalent of emitted greenhouse gases in treatments T1, T2, T3 and T4 in 2009-2010 were respectively 8 880 kg(CO₂)·hm^-2, 8 372 kg(CO₂)·hm^-2, 9 600 kg(CO₂)·hm^-2 and 9 318 kg(CO₂)·hm^-2; and 13 395 kg(CO₂)·hm^-2, 12 904 kg(CO₂)·hm^-2, 13 933 kg(CO₂)·hm^-2 and 13 189 kg(CO₂)·hm^-2 in 2010-2011. Differences in greenhouse gas emissions among different treatments were caused by different fertilization and irrigation managements. Straw return or non-return largely led to the differences in greenhouse gas emissions between 2009-2010 and 2010-2011. GWP was relatively low while yield and input-output ratio relatively high in T2. Treatment T2 was therefore considered the optimal management mode for winter-wheat cultivation in the North China Plain.