The Coordination Mechanism And Pattern Of Greenhouse Gas Reduction And Yield Increase In Potato Field

Agricultural production is the important sources of greenhouse gases. An important scientific problem of agricultural sustainable development is how to ensure both greenhouse gases reducing and yield increasing. This study selected dry potato fields as the research object in WuChuan County Inner Mongolia of Agro-pastoral Ecotone of Northern China. This study quantitatively analyzed the effects of fertilization, water and crop patterns on greenhouse gases emissions (N2O and CH4) and yield by the combining method of field experiment and the experimental of soil microorganisms. And put forward the reasonable coordination mechanism and model of greenhouse gases emissions reducing and yield increasing in potato field. The results and conclusions from this study were descried as following.(1) Rain-fed potato fields were the source of N2O, where the average annual N2O emissions was approximately0.76±0.06kg/ha/yr. N2O emissions are primarily a factor of the ammonia-oxidising bacteria (AOB) in the rain-fed potato field. N2O emissions increased with an increase in fertilization, temperatures below19.6℃and a soil volumetric water content<15%. Crop rotation appreciably decreases N2O emissions by34.4%to52.4%compared to continuous cropping in rain-fed potato fields. N2O cumulative emissions of film mulching was only56.4-72.1%of no film mulching.(2) The results indicate that the rain-fed potato fields were CH4sink with an average annual methane absorption (negative emission) of-0.57±0.04kgC/ha/yr. The cumulative methane absorption first exhibited a decreasing and subsequently increasing trend with the increase of fertilization within a certain range. Cumulative methane absorption significantly increased with the increase of temperature when temperatures were below19.6℃. Cumulative methane absorption also showed an increasing and subsequently decreasing trend with the increase of soil moisture. Crop rotation was observed to increase the methane absorption in rain-fed potato fields and reduce nearly one time that under continuous cropping. Cumulative methane absorption of film mulching was74.1-84.3%%of no film mulching. Based on these analyses, a mechanism concept model and a statistical analysis model of the methane exchange in rain-fed potato fields are advanced in this paper.(3)The potato yield showed an increasing and subsequently decreasing trend with the increase of fertilization and water consumption. The relationship between fertilization and water use efficiency (WUE) was a quadratic function. The highest yield was19780.2kg/ha when the fertilization was82.7kgN/ha and water supply was262.8mm by calculation the regression equation of the impact on yield of fertilization and water supply.(4) The yield of crop rotation was20.5～23.9%higher than continuous cropping. The yield of film mulching was13.5-18.0%lower than on film mulching. The water consumption of crop rotation was higher than continuous cropping (P＜0.01), but there was no significant difference between film mulching or not. The WUE of crop rotation was significant10.5%-16.5%higher than continuous cropping. And the WUE of film mulching was lower than no film mulching (P<0.05).(5) N2O emission factor (EF) was increased with increasing fertilisation. EF in the crop rotation was only20%of that in the continuous cropping. And EF of film mulching was lower than no film mulching. High nitrogen fertilization would significantly decrease the index for climate smart agriculture (ICSA). The ICSA of crop rotation was1time higher than continuous cropping, but there was no significant difference between film mulching or not. The highest ICSA was0.047kg·gCO2-e-1when the fertilization was40.0kgN/ha and water supply was253.8mm by calculation the regression equation of the impact on ICSA of fertilization and water supply.