Reclaimed coastal areas were mostly used for agricultural purposes in the past, while land-use conversion was initiated in recent decades in eastern China. Elucidation of the effects of land-use conversion on soil properties and stoichiometry is essential for addressing climate change and ecological conservation. In this study, five land-use types in a reclaimed area were chosen to compare the differences of soil properties and stoichiometry, which comprised paddy, upland, upland-forest, forest, and vegetable garden, with a soil age of about 100 years. The results indicated that these land-use types significantly differed in soil water concentration, pH, bulk density, soil salt concentration, soil organic carbon content, total nitrogen content, and total phosphorus, as well as C:N, C:P, and N:P ratios. Positive correlations were found among soil organic carbon, total nitrogen, and total phosphorus; and among pH, bulk density, and soil salt concentration. Total phosphorus and soil organic carbon contents were the main factors shaping the topsoil among the land-use types. Contents of soil organic carbon, total nitrogen, and total phosphorus in paddy and vegetable garden soils were higher than that in upland and upland-forest soils, while bulk density, pH, and soil salt concentration showed the opposite trends. Forest soil demonstrated intermediate values for most properties. And the highest C:N occurred in the upland and vegetable garden, the highest C:P in paddy and vegetable garden, while the lowest C:N and C:P occurred in upland-forest. The highest and lowest N:P occurred in paddy and upland, respectively. The stoichiometric characteristics presented a narrow range of the ratio, and the C:N:P averaged 48:3:1 similar to the stoichiometry of average Chinese cropland soils. Rotations including legume, the use of organic fertilizers, and appropriate fertilization strategies were suggested for improving cropland management.

Urban parks are considered one of the most significant ecosystems when looking at urban green spaces, but ecological functions and the type of recreation space created can change depending on the park’s age and its vegetation type. Therefore, the effects of the vegetation types present and urban park ages on soil properties and bacterial communities were tested in Yancheng, as it is a typical rapidly urbanizing city in China, and one of the most densely populated metropolises among the central cities of the Yangtze River Delta region. We found that the soil properties and bacterial community composition vary depending on vegetation type and park age. In addition, the pH value of soil planted with Cynodon dactylon is higher, and the available phosphorus concentrations in the old parks are at the highest levels, which are 1.20–2.66 times higher than in the middle-aged and young parks’ soil. Gammaproteobacteria, Alphaproteobacteria, Acidobacteria_6, and Deltaproteobacteria are the predominant bacteria phyla in urban park soil. A higher level of bacterial operational taxonomic units (OTUs) are found in Metasequoia glyptostroboides soil (5479, 69.7%) and middle-aged park soil (5670, 72.2%). Saprospirae, Chloracidobacteria, and Alphaproteobacteria are negatively correlated with pH to a significant extent. Additionally, pH, available potassium, and soil organic carbon were positively correlated with saccharase activity. Available phosphorus and nitrogen are related to soil community composition. These results indicate that both park age and vegetation type contribute to the differences in soil pH, available phosphorus, soil organic carbon, available potassium, available nitrogen, alkaline phosphatase, and soil bacterial composition within urban parks in Yancheng.