Recently, a study conducted at the Qiyang Red Soil Experimental Station of the Chinese Academy of Agricultural Sciences revealed the mechanism of pH regulation on organic carbon in acidic red soil under long-term lime and straw amendment. The research findings have been published in the Journal of Environmental Management.

Soil acidification and low soil organic matter (SOC) pose significant constraints to the sustainable utilization of red soil resources in southern China. Liming and straw incorporation are widely adopted strategies for ameliorating acidification and improving fertility in acidic soils However, the impact of pH manipulation on SOC and its fractions following long-term lime and straw application remains unclear..

Based on a 31-year field experiment at the Qiyang Station, the study investigated the effects of lime and straw application on SOC and elucidate the relationship between SOC and pH. Results indicated that liming increased SOC and mineral-associated organic carbon (MAOC) under nitrogen and potassium (NK) fertilizer application, whereas its impact on SOC in nitrogen, phosphorus and potassium fertilizer (NPK) application was negligible. Straw application alone or in combination with lime increased particulate organic carbon (POC) and total SOC, but straw combined with lime reduced MAOC. POC increased with increasing pH, while total SOC and MAOC demonstrated an initial increase at lower pH followed by stabilization as pH continuously increasing. The partial least squares path model  revealed that pH influences SOC through two pathways: (i) enhancing SOC by positively impacting the content of Fe and Al oxides and aggregate stability, and (ii) negatively affecting SOC by increasing ratios of fungi/bacteria and Gram-positive bacteria/Gram-negative bacteria.

The study contributes to understanding the pH regulation on SOC with lime and straw amendments, offering valuable insights for mitigating acidification and managing SOC in acidic red soil..

Ph.D. candidate Shen Zhe from the Institute of Agricultural Resources and Regional Planning of the Chinese Academy of Agricultural Sciences and Dr. Han Tianfu from the College of Agriculture at Zhengzhou University are the co-first authors, with Researcher Zhang Huimin as the corresponding author. The research was supported by the National Natural Science Foundation of China and the Innovation Project from the Chinese Academy of Agricultural Sciences.

Original article link: https://doi.org/10.1016/j.jenvman.2024.122063