Decomposition characteristics of woody peat and its mixtures with liable organic materials in a newly reclaimed saline-alkali soil: A one-year incubation experiment

Abstract

The combined application of woody peat with labile organic materials has been shown to be an effective strategy for rapidly improving soil organic matter (SOM) and soil fertility in newly reclaimed lands. However, their decomposition dynamics, which can be greatly influenced by the residue-mixing effect, are not well understood. Therefore, this study investigated the decomposition characteristics and residue-mixing effect of woody peat, corn straw, organic manure and their binary mixtures in a newly reclaimed saline-sodic soil through a 360-day incubation experiment. The results revealed that both straw and organic manure contained large amount of O-alkyl C, leading to rapid degradation in mass and organic C (OC). In contrast, woody peat is rich in alkyl C and aromatic C, exhibiting the highest alkyl C/O-alkyl C (A/O-A) ratio and aromaticity. As a result, woody peat only lost less than 6.4% OC and showed minimal changes in mass and nitrogen content within a year, indicating strong degradation resistance in the saline-sodic soil. The combination of woody peat with straw or organic manure induced significant non-additive synergistic effects on mass and OC loss, aromatic C, carbonyl C, A/O-A ratio and aromaticity. This suggests that the addition of woody peat significantly slowed down the degradation of the mixtures and prolonged the retention of OC in soil. On the contrary, the mixing of straw and organic manure led to significant non-additive antagonistic effects on mass and OC loss, indicating that their combination accelerated the decomposition of the mixture. Consequently, this study suggests that, in contrast to the applicated of various labile organic materials, the combined application of recalcitrant woody peat with labile organic materials can extend the presence of organic matter in the soil, thereby promoting a sustained increase in active and passive SOM content and soil fertility.