Impacts Of Different Farming Measures On The Emissions Of Greenhouse Gases And Carbon Footprint For Maize From Brown Soil

In order to study the impacts of different farming measures on N2O and CO2 emission for maize production and the carbon footprint during whole maize growth season, the field experiment was conducted in middle and lower reaches of Liaohe Plain in 2014 and 2015. Five farming measures, including the non-nitrogenous fertilizer control (CK), the regular fertilization (F), the pyridine coated urea (FP), regular fertilization and biochar (FC), and regular fertilization and straw semi-farm return (FS) were taken in the test. CO2 and N2O flux and cumulative emissions were monitored and calculated of different farming measures; the carbon emissions of fertilizer production, energy consumption during cultivation and seeding production of greenhouse gases were calculated, analyzed the carbon footprint and overall greenhouse of different farming systems by life cycle approach. According to test results:(1) Soil CO2 emission flux was mainly affected by soil temperature, and the two were in significantly positive relation, CO2 emission flux was decreased after the first increased from seeding to maturity stage, the specific performance was large bell stage>tasseling stage> small bell stage>milking to mature stage> seeding to jointing stage.(2)CO2 emission was effected by different farming measures, Compared with F, FP decreased by 23.3% and 27.5%, FC decreased by 18.3% and 25.2% in 2014 and 2015. FS had no significant effect on soil CO2 emission, Which showed that FP and FC treatment had certain extent on soil respiration. Among them the impact of FP treatment on soil CO2 emission reduction was more pronounced.(3)N2O emission in the soil was mainly affected by the fertilization time and fertilization amount, the value of which was high a while after the fertilization. The N2O emitted in the base fertilizing and topdressing phases accounted for 24.3%-27.3% and 32.0%-38.2% in 2014,23.3%-24.8% and 23.0%-27.1% in 2015 of the accumulated emission amount of N2O in the growth period;(4)The carbon footprint of FP and FC processing was low, which was decreased by 19.5% and 14.8% in 2014,16.3%and13.8% in 2015 respectively compared to F; The carbon strength of FP processing was also the lowest, and its carbon efficiency was the highest. Compared to other farming measures, it belonged to a low-carbon fertilization one with high production and low emission; The direct N2O emission with the application of nitrogen accounted for the largest share of carbon emission in the whole corn production life cycle (accounting for 74.9%-89.0% in 2014; 76.4%-89.9% in 2015), followed by the carbon emission in the fertilizer production process (accounting for 13.4%-17.8% in 2014; 13.8%-16.5% in 2015).(5)Maize yield in the order of different farming practices was FC＞FP>FS>F>CK both in 2014 and 2015. Therefore, under the premise of ensuring the crop yield, the reduction of nitrogen application and the improvement of nitrogen utilization was the key to reduce the carbon footprint in the corn production process. The carbon emission reduction management measure specific to the spring corn production in the brown earth area in this research was the pyridine coated urea.