Nutrient Content and Enzyme Activity of Cold-waterlogged Soil in Fields with Open Drainage Ditches

With a 30-year-old drainage ditch system in a field of cold-waterlogged soil, the ecological stoichiometry characteristics of C, N, P and enzyme activity of the soil was studied.The results showed that the total C, N (except for the 5msite) and P in the soils from the 5, 15 and 25msites (which were 5, 15 and 25m, respectively, away from the ditch) were significantly lower than those of the control (i.e., a typical cold-waterlogged soil site, which was 75 maway from the ditch) .The C/N ratio of the soil at 5, 15 and 25msites, reduced significantly by2.56, 1.03 and 0.91 units, respectively.Similarly, the enzyme activities of catalase and invertase declined by 0.3%-10.0% and 36.6%-62.5%, respectively.On the other hand, the activities of urease, phosphatase and nitrate increased 117.6%, 393.2% and 796.3%, respectively, at the 5msite.There was a significant correlation among C, N and P, as well as between the C/N ratio and the urease, phosphatase and nitrate activities.It appeared that the C/N ratio could be used as an index in evaluating the transforming effect of cold-waterlogged soils.