寿光菜田土壤质量衰退的情况日趋严重，直接影响到了蔬菜产业的可持续发展。土壤碳、氮的演变调控着土壤中的物理、化学和生物学过程。为了明确寿光菜田土壤碳氮演变及其对土壤性质的影响，通过野外调查和室内土壤碳氮分析，得出以下结论：与附近粮田相比，寿光菜田的土壤C/N比下降了2.4个单位，有机质增加了4.1 g/kg，全氮增加了0.61 g/kg，土壤全氮的增长量是有机质增长量的2倍。设施菜田土壤NO₃^--N的显著升高不是菜田土壤C/N比下降的根本原因。菜田土壤碳素输入的量是粮田输入量的1.9倍，设施菜田氮素投入量分别是小麦和玉米的9.9和8.5倍。设施菜田投入的C/N比为4.2:1，粮田的为9.9:1，菜田碳氮投入比例低可能是菜田土壤C/N比下降的重要原因。土壤碳氮含量的增加和C/N比的下降，伴随着菜田土壤明显的酸化和盐渍化，同时也伴随着土壤氮磷钾养分的富集。

Soil quality deterioration in Shouguang vegetable fields has become more serious, which directly affects the sustainable development of vegetable production. Variations of soil carbon and nitrogen will influence soil physical, chemical and biological processes, and the objective of this research is to have a better understanding of these influences. The results of this research indicated that C/N ratio, organic matter and total nitrogen in Shouguang vegetable fields were 2.4 unit lower, 4.1 g/kg and 0.61 g/kg higher than that in the grain fields, respectively. The increased amount of soil total nitrogen was two times higher than that of organic matter. Dramatic increase in NO₃^--N content in protective fields was not the critical reason for the decrease in C/N ratio in vegetable fields. Carbon input in vegetable fields was 1.9 times higher than that in grain crop fields, and nitrogen input in protective fields was 9.9 and 8.5 times higher than that in wheat and grain crop fields, respectively. The ratio of input carbon and nitrogen was 4.2:1 in protective fields and 9.9:1 in grain fields, respectively. The lower ratio of carbon and nitrogen input in vegetable fields may be the important reason for the decrease in C/N ratio in those soils. The increase in soil carbon and nitrogen contents and the decrease in C/N ratio obviously induced soil acidification, stalinization and accumulation of soil nitrogen, phosphorus and potassium in vegetable fields.