Overuse of N Fertilizers Leads to Nutrient Imbalance and Acidification of Soil in Zhangjiagang County, China

Darilek et al. (2009) conducted a study of the soil fertility parameters in conjunction with information from the county of Zhangjiagang, China, on the amounts of nitrogen, phosphorus, and potassium fertilizers used from 1980 to 2004. Within this county, which is part of the Yangtze River Delta area, there are two dominant types of soil, Cambosols and Anthrosols. Cambosols are found in the northern region near the river, while Anthrosols are prevalent in the southern plains region. Anthrosols experienced such a high increase in pH (or acidification of the soil), due to over-application of N fertilizers and an increase in industrial effluents that the area will be rendered useless for crop production in 25 to 30 years. —<!–[if supportFields]> CONTACT _Con-3EF86BDE1 \c \s \l <![endif]–>Maria Harwood<!–[if supportFields]><![endif]–>
Darilek, J., Huang, B., Wang, Z., Qi, Y., Zhao, Y., Sun, W., Gu, Z., Shi, X., 2009. Changes in soil fertility parameters and the environmental effects in a rapidly developing region of China. Agriculture, Ecosystems and Environment 129, 286-292.

 Jeremy Darilek and his colleagues collected soil samples from around the county of both Cambosols and Anthrosols in 1980, then again in 2004. These samples were analyzed for pH, organic matter, cation exchange capacity, total nitrogen, total phosphorus, available phosphorus, and available potassium. These data combined with information supplied by the county on the rates of N, P, and K fertilizer applied annually were used to determine the effects of the different fertilizers on the soil fertility parameters. The effects of the fertilizers on the environment were not evaluated directly, but were inferred from present knowledge on overuse of fertilizers and how this can lead to N leaching and eutrophication of surrounding water bodies.
The ratio of N:P:K fertilizer applied to the rice and wheat crops grown in this region has increasingly contained excessive amounts of N, above the needed requirements for the crops since 1990. P fertilizer rates have increased, but remain at levels beneficial to the growth of the crops due to a lack of P accumulation in the soil. Also over the years there has been a phasing out of the use of organic fertilizers, and an increased reliance on inorganic fertilizers. Among the two soil types, Anthrosols were found to have a great decrease in pH, demonstrating acidification of the soil, which if left unchecked will deplete the metal bioavailability, fertility, and microbiology of the soil to such an extent it will be inhospitable to crops in 25 to 30 years. The cause of this acidification is largely an increase in the application of N fertilizer, but also a result of the rapid industrialization of the county, which has led to greater numbers of factories, which spew industrial effluents that contribute to the rise of acidification. These nutrient imbalances in the soil resulting from incorrect application of fertilizer causes non-point pollution of N into the surrounding water bodies, endangering both human and ecosystem health. 

1 thought on “Overuse of N Fertilizers Leads to Nutrient Imbalance and Acidification of Soil in Zhangjiagang County, China

  1. Thanks for the favorable write-up! I think you did a good job summarizing the main points. Since this is a climate report blog, I think the C:N ratio trends are and aspect of this paper the readers might also be interested in.
    -J.L. Darilek


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