填闲作物既降低氮淋溶也减少土壤CO_2排放（英文）

Catch Crop Known to Decrease N-leaching also Counteracts Soil CO_2 Emissions

我们研究了沙质施肥农业土壤有或没有填闲作物情况下的CO2大气排放。种植填闲作物的最初目的是降低氮淋溶,但我们也想通过本研究发现填闲作物在气候变化背景下是否有起着某种作用。填闲作物样地显示土壤CO2排放有所降低。因为早先的结果表明填闲作物有效减少了氮淋溶,我们建议把种植填闲作物作为应对气候及富营养化问题的有效措施。CO2排放的季节差异表明,施肥农业土壤在6月、相邻一块无管理措施的草地在8月,排放值分别达到最高。样地中填闲作物的CO2排放于7月和8月有所降低但之后的秋天里又有所上升。施肥农业土壤呈现出收获后土壤内CO2汇的特征,即土壤内CO2的收贮。NH4+加强着CO2汇而等量的NO3-增加了CO2排放,NH4+或NO3-的有效性似乎影响着土壤内CO2汇。

CO2 emissions to the atmosphere were studied in a fertilized sandy agricultural soil with and without a catch crop sown into the main crop. The catch crop was grown primarily with the purpose to decrease N-leaching but this study also wanted to find out if the catch crop could have an effect in a climate change perspective. Plots with catch crop showed decreased CO2 emissions from the soil. Since previous results have shown that catch crops effectively decrease N-leaching we recommend growing catch crops as an effective measure for helping both the climate and the eutrophication issue. Seasonal variations in CO2 emissions were pronounced with maximum emissions from the fertilized agricultural soil in June and from an adjacent unmanaged grassland in August. From the plot with catch crop emissions decreased in July and August but somewhat increased later in the autumn. Fertilized agricultural soil showed a within-soil CO2 sink after harvest, i.e. within-soil CO2 uptake. Availability of NH4＋ or NO3- in the soil seems to influence the within-soil CO2 sink, with NH4＋ enforcing the sink while the same amount of NO3 instead increased CO2 emissions.