添加磷对水稻-油菜轮作土壤N2O排放影响

我国南方红壤区域普遍属于缺磷土壤,种植作物需要施用较多的磷肥,但添加磷对水稻-油菜轮作土壤中N_2O的排放影响并不明确.以潜江、咸宁两处水稻-油菜轮作模式下的土壤为研究对象,添加不同浓度的磷(0、15和30 mg·kg-1)和不同浓度的氮(0和100 mg·kg-1)进行室内培养实验,探究添加磷对水稻-油菜轮作土壤N_2O排放的影响.结果表明,添加磷对土壤中N_2O的排放有较为显著的影响,但影响的方式有所不同:在土壤本身氮比较少的情况下,添加磷会促进土壤中微生物对氮的固定,降低N_2O的排放;在土壤中有充足的氮情况下,添加较少的磷会促进土壤中硝化微生物的活动,促进N2O的排放,但添加较多的磷同样会促进土壤中微生物对氮的固定,相比于添加较少的磷处理会抑制N_2O的排放;在土壤本身磷的含量较为充足的情况下,无论土壤中的氮源是否充足,添加磷仅对土壤中N_2O的排放起抑制作用.

Effect of Phosphorus Addition on N2O Emissions from Rice-Rapeseed Rotation Soils

The red soils in southern China are generally classified as phosphorus-deficient, and therefore planting crops in these regions usually requires high applications of phosphate fertilizer. However, the effect of phosphorus addition on N₂O emissions in rice-rapeseed rotation soils is not clear. We carried out an incubation experiment with the rice-rapeseed rotation soil from Qianjiang and Xianning to explore the effect of different concentrations of phosphorus (0, 15, and 30 mg·kg^-1) and different concentrations of nitrogen (0 and 100 mg·kg^-1) on N₂O emission. Studies have shown that the addition of phosphorus has a significant effect on soil N₂O emissions, but the pathways of impact are varied:in the case of low nitrogen soil, the addition of phosphorus promotes the fixation of nitrogen in the soil by microorganisms and thus reduces N₂O emissions; in case of sufficient nitrogen content in soil, adding less phosphorus promotes the activity of nitrifies and thereby promotes the emission of N₂O, while adding more phosphorus also promotes fixation by microorganisms in the soil; when there is a high content of available phosphorus in the soil, whether the nitrogen is sufficient or not, the addition of phosphorus will inhibit the emission of N₂O.