Microbial community diversity and enzyme activity varies in response to long-term fertilisation in a continuous potato (Solanum tuberosum L.) cropping system

ContextThe misuse of chemical fertilisers is still prevalent in potato cultivation. However, the large-scale application of manure is increasingly being accepted by growers to improve soil health.AimTo clarify what effect manure and chemical fertilisers have on the development of soil microbes in potato fields.MethodsThe status of soil microbial community abundance and structure were determined by analysing soil metagenomes, which were assessed by applying high through-put sequencing technology. The potato field received one of the following treatments for 9 years: manure (M); manure plus nitrogenous (N), phosphatic (P), and potassic (K) fertiliser (MNPK); NPK fertiliser; NP fertiliser; NK fertiliser; PK fertiliser; and no fertiliser.Key resultsThe application of manure significantly increased soil organic matter, and this increase was one of the main factors in reducing bacterial Shannon and Heip indices and increasing the Simpson index. The MNPK treatment significantly reduced the relative abundance of alpha-Proteobacteria and beta-Proteobacteria in the soil, which are essential microorganisms involved in nitrogen cycling. The M treatment significantly increased the abundance of Actinobacteria.ConclusionsIn summary, applying manure increases Actinobacteria's abundance, and using MNPK fertilisers decreases the abundance of Proteobacteria, whereas chemical fertilisers are detrimental to soil fungal diversity.ImplicationsApplying MNPK fertilisers has a complex effect on soil microorganisms. It is not simply a combination of the effects of manure and chemical fertilisers on microbes; the interaction mechanism of microbial succession needs to be further explored.