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The impacts of rapid industrialization on spatio-temporal changes in soil pH have drawn major attention from the scientific community and decision-makers. A total of 1185 topsoil samples (0–20 cm) were collected from southern Jiangsu Province of China in 1980, 2000, and 2015, and the geostatistical sequential Gaussian simulation (SGS) was used to quantify the spatio-temporal patterns of changes in soil pH and identify the areas with significantly-declined pH. A significant topsoil acidification occurred in major croplands of the study area, with mean decrements of 0.56 and 0.52 units over the periods of 1980–2000 and 2000–2015, respectively. A significant decrease in pH occurred in the areas surrounding Taihu Lake during 1980–2000, and a further decrease was evident predominantly in the northeast during 2000–2015. Over the entire 35-year period, the soil pH for approximately 79% of the study area declined significantly. The decline over the first two decades (1980–2000) was largely attributed to increased chemical fertilizer inputs and the development of industries, while the further enhanced industrial emissions resulting from the significant expansion of factories were the primary reason for the accelerated soil acidification in the subsequent 15 years (2000–2015). Results from this study may serve as a basis for developing management strategies to achieve better soil quality in similar areas moving toward industrialization.

Agro-ecosystem models have been widely used to quantify soil organic carbon (SOC) dynamics based on digital soil maps. However, most of the studies use soil data of single or limited choices of map scales, thus the influence of map scales on SOC dynamics has rarely been quantified. In this study, six digital paddy soils databases of the Tai-Lake region in China at scales of 1:50,000 (P005), 1:200,000 (P02), 1:500,000 (P05), 1:1,000,000 (P1), 1:4,000,000 (P4), and 1:14,000,000 (P14) were used to drive the DNDC (DeNitrification & DeComposition) model to quantify SOC dynamics for the period of 2001⿿2019. Model simulations show that the total SOC changes from 2001 to 2019 in the top layer (0⿿30 cm) of paddy soils using P005, P02, P05, P1, P4, and P14 soil maps would be 3.44, 3.71, 1.41, 2.01, 3.57 and 0.10 Tg C, respectively. The simulated SOC dynamics are significantly influenced by map scales. Taking the total SOC changes based on the most detailed soil map, P005, as a reference, the relative deviation of P02, P05, P1, P4, and P14 were 7.9%, 58.9%, 41.6%, 3.9%, and 97.0%, respectively. Such differences are primarily attributed to missing soil types and spatial variations in soil types in coarse-scale maps. Although the relative deviation of P4 soil map for the entire Tai-Lake region is the lowest, substantial differences (i.e., 22⿿1010%) exist at soil subgroups level. Overall, soil map scale of P02 provides best accuracy for quantifying SOC dynamics of paddy soils in the study region. Considering the soil data availability of entire China, P1 soil map is also recommended. This study suggested how to select an appropriate scale of input soil data for modeling the carbon cycle of agro-ecosystems.

An extensive knowledge of the temporal variability of soil fertility parameters and how this variation affects the environment is imperative to a wide range of disciplines within agricultural science for optimal crop production and ecosystem preservation. This paper examines the temporal variability of soil pH, organic matter (OM), cation exchange capacity (CEC), total nitrogen (TN), total phosphorus (TP), available phosphorus (P Av ), and available potassium (K Av ) on Cambosols (Entisols) ( n = 179) and Anthrosols (Inceptisols) ( n = 95) in Zhangjiagang County, China from 1980 to 2004. Nutrient input was monitored from 1983 to 2004. Annual N fertilizer rates were significantly different during three periods (1983–1989, 1989–1999, 1999–2004), where annual rates increased significantly after 1989 and then decreased after 1999. Annual P fertilizer rates were significantly different during two periods (1983–1993, 1993–2004) where annual rates increased after 1993. No change was found in K fertilizer rates. Soil pH marginally increased by 0.14 units in Cambosols, but significantly decreased by 1.02 units in Anthrosols. OM, CEC, and TN increased in both soil orders an average of 2.15 g kg −1 , 1.6 cmol kg −1 , and 0.21 g kg −1 , respectively. TP decreased in Anthrosols by 70 mg kg −1 , P Av increased in Cambosols by 4.83 mg kg −1 , and K Av decreased in Cambosols by 15 mg kg −1 . Fertilizer input rates are causing nutrient imbalances, contributing to acidification in Anthrosols, and decreasing C/N ratios. Nutrient loading of N and deficiency of K is also a potential problem in the area. Efforts should be made to readjust soil nutrient inputs to reach an optimal, sustainable level.

There is growing concern about food safety and environmental contamination in the rapidly expanding peri-urban interface in Asia. Here, we present an integrated study of farming practices and the quality of water, sediments, soils and agricultural products in small-scale vegetable farming systems in two contrasting peri-urban areas with different levels of industrial development in the Yangtze River Delta Region of China. Application of large amounts of cow manure to vegetables in Nanjing, a vegetable-based peri-urban area, had caused an accumulation of N, P, Cu, Zn and available Cd in soil. This resulted in high Cd in some vegetables and high concentrations of N and P in surface water. Because of a shorter history of vegetable production in Wuxi, an industrialized peri-urban area, the accumulation of N and P in soils was less, but high available Cd due to low soil pH associated with application of large amounts of inorganic fertilizers had resulted in high Cd in some vegetables. Heavy metal pollution in the Wuxi area mainly came from atmospheric deposition and discharge of effluent from factories and was higher than in the less industrialized area in Nanjing. Development and dissemination of strategies for more efficient use of fertilizers in vegetable farming could benefit both farm profitability and the environment and should be coupled with treatment of municipal waste before discharge and control of factory emissions. Bringing about change in farming, municipal and industrial practice will require good relationships amongst a number of stakeholders. The uncertain status of immigrant vegetable farmers in Wuxi hampers their interaction with agricultural service providers and local governance structures and effective channels for communication need to be established.