Both carbon sequestration and yield are related to particulate organic carbon stability affected by organic amendment origins in mollisol

Purpose Exploring how organic amendments influence carbon sequestration by affecting particulate organic carbon (POC) and determining the optimum amendment for protecting and restoring mollisol and increasing yields. Methods Differences of POC properties and maize yields in 3-year soils amended with organic material of different origins were studied. POC was separated by a wet sieving method, and the structure was analyzed by C-13 NMR spectroscopy. Results We found that SOC accumulation in soils amended with plant origin organic materials resulted from increasing organic fractions other than POC, while that in soils amended with animal origin materials resulted from increasing POC. The proportion of POC net variation in SOC net variation was significantly negatively correlated with SOC (p < 0.01). POC, mainly composed of alkyl C and alkoxyl C (more than 68%), had its stability more accurately evaluated through combined analysis of the carbonyl C content and alkyl C/alkoxyl C ratio. The addition of organic materials improved POC stability by increasing the alkyl C/alkoxyl C ratio and decreasing the carbonyl C content. Maize yields were positively correlated with SOC content and POC stability (p < 0.01), which increased by at least 2012 kg ha(-1) with the addition of organic materials. Conclusion Increasing more stable POC will promote the carbon sink. The order of the stability of POC in mollisol amended with organic materials of different origins was woody plant material > herb material > livestock dung > poultry dung. The woody plant material was the optimum organic amendment for mollisol, enhanced POC stability, and promoted SOC sequestration while increasing the yield.

Automated summary

The study found that adding organic amendments can improve the stability of POC and the sequestration of SOC, with a positive impact on increasing yields. Different sources of organic materials have varying effects on the stability of POC in mollisol, with woody plant material being the optimal choice for enhancing POC stability.