Application of cattle manure increased the stability of organic carbon in the subsoil in Mollisols

Abstract

Abstract Aims: The cattle manure application to subsoil is an efficient and sustainable approach to increase soil fertility. However, the change of soil organic carbon (SOC) chemistry after manure amended in subsoil is remains elusive. Methods: Here, a pot experiment was used to investigated the SOC chemical structure (13C-NMR and FTIR), as well as microbial community composition (PLFA), with cattle manure amended in topsoil (T1M), and subsoil (T2M) and without manure in topsoil (T1) and subsoil (T2). Results: The utilization of cattle manure significantly improved SOC, total nitrogen (TN) content and PLFAs biomass, as well as the relative absorption of the band at 2920 cm-1 and 1640 cm-1 of SOC, while decreased the C/N ratio by 15.7-50.5%. T1M increased the proporations of O-alkyl C and Aromatic C by 3.8%-17.6% compared to T1, but decreased the proporations of Alkyl C and Carbonyl C by 9.9%-11.5% and the ratio of Alkyl C/O-Alkyl C (A/OA) by 60.0%. However, T2M showed the opposited trend compared to T2. The fungal to bacterial ratio (F/B) of T2 was lower than that of T1, while it was greater in T2M than that in T1M. Both RDA and MRT analyses demonstrated that the Cyanobacteria, Acidobacteria and Ascomycota were negatively association with O-alkyl C, and the Actinobacteria, Verrucomicrobia and Cyanobacteria were negatively association with Alkyl C. Conclusions: Our findings reveal application cattle manure in subsoil was more beneficial to decompose SOC owing the transfromation of bacterial to fungal and made the chemical structure of SOC more stabilization.