The contribution of natural and anthropogenic causes to soil acidification rates under different fertilization practices and site conditions in southern China

Xingjuan Zhu; Gerard H Ros; Minggang Xu; Donghao Xu; Zejiang Cai; Nan Sun; Yinghua Duan; Wim de Vries

doi:10.1016/j.scitotenv.2024.172986

The contribution of natural and anthropogenic causes to soil acidification rates under different fertilization practices and site conditions in southern China

Sci Total Environ. 2024 May 9:934:172986. doi: 10.1016/j.scitotenv.2024.172986. Online ahead of print.

Authors

Xingjuan Zhu¹, Gerard H Ros², Minggang Xu³, Donghao Xu⁴, Zejiang Cai⁵, Nan Sun⁵, Yinghua Duan⁵, Wim de Vries⁶

Affiliations

¹ State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Arable Land Quality Monitoring and Evaluation, Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Wageningen University and Research, Environmental Research, Environmental Systems Analysis Group, PO Box 47, 6700AA Wageningen, the Netherlands. Electronic address: xingjuan.zhu@wur.nl.
² Wageningen University and Research, Environmental Research, Environmental Systems Analysis Group, PO Box 47, 6700AA Wageningen, the Netherlands.
³ State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Arable Land Quality Monitoring and Evaluation, Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Electronic address: xuminggang@caas.cn.
⁴ Wageningen University and Research, Environmental Research, Environmental Systems Analysis Group, PO Box 47, 6700AA Wageningen, the Netherlands; College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, China Agricultural University, 100193 Beijing, China.
⁵ State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Arable Land Quality Monitoring and Evaluation, Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
⁶ Wageningen University and Research, Environmental Research, Environmental Systems Analysis Group, PO Box 47, 6700AA Wageningen, the Netherlands. Electronic address: wim.devries@wur.nl.

PMID: 38729375
DOI: 10.1016/j.scitotenv.2024.172986

Abstract

Excessive application of mineral fertilizers has accelerated soil acidification in China, affecting crop production when the pH drops below a critical value. However, the contributions of natural soil acidification, induced by leaching of bicarbonate, and anthropogenic causes of soil acidification, induced by nitrogen (N) transformations and removal of base cations over acid anions, are not well quantified. In this study, we quantified soil acidification rates, in equivalents (eq) of acidity, by assessing the inputs and outputs of all major cations and anions, including calcium, magnesium, potassium, sodium, ammonium, nitrate, bicarbonate, sulphate, phosphate and chloride, for 13 long-term experimental sites in southern China. The acidification rates strongly varied among fertilizer treatments and with the addition of animal manure. Bicarbonate leaching was the dominant acid production process in calcareous soils (23 keq ha^-1 yr^-1) and in non-calcareous paddy soils (9.6 keq ha^-1 yr^-1), accounting for 80 % and 68 % of the total acid production rate, respectively. The calcareous soils were strongly buffered, and acidification led no or a limited decline in pH. In contrast, N transformations were the most important driver for soil acidification at one site with upland crops on a non-calcareous soil, accounting for 72 % of total acid production rate of 8.4 keq ha^-1 yr^-1. In this soil, the soil pH considerably decreased being accompanied by a substantial decline in exchangeable base cation. Reducing the N surplus decreased the acidification rate with 10 to 54 eq per kg N surplus with the lowest value occurring in paddy soils and the highest in the upland soil. The use of manure, containing base cations, partly mitigated the acidifying impact of N fertilizer inputs and crop removal, but enhanced phosphorus (P) accumulation. Combining mineral fertilizer, manure and lime in integrative management strategies can mitigate soil acidification and minimize N and P losses.

Keywords: Acid consumption; Acid production; Acidification; Manure; Mineral fertilizer.