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Aims: Potato starch wastewater contains higher contents of essential nutrients, which can be fertilizer to help crop growth. However, the effects of fermented potato fertilizer on soil ecology and microbial community structure have not yet been elucidated. This study aimed to investigate the shifts of active ammonia oxidation microbial communities under different fertilization in a typical soil in North China. Methods: The different levels of fermented potato fertilizer without or with chemical fertilizer were designed by field experiment. Results: The results showed that applying fermented potato fertilizer could significantly increase crop yields by 165–399% compared to Control. The content of available soil nutrients and the activity of saccharase and cellulase were increased when fermented potato fertilizer was applied, and the combination fertilizers further increased the content of Olsen-P by 145.6–166.7%, NO3− by 15.2–81.1%, Total C by 13.8–14%, and Total N by 27.2–34.7% compared with fermented potato fertilizer (PW) treatments. In addition the fermented potato fertilizer significantly stimulated the diversity of soil microbial community and increased the differentiation and stability of soil microbial networks in deep soils. Finally, the change of niche of soil Comammox (COM), ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB) were found after PW treatments. It showed a significant positive correlation between AOA and COM (r = 0.79, P < 0.01), AOB and NOB (r = 0.7, P < 0.05) instead of theoretically the competitive relationship between AOA and COM. Conclusions: One of the reasons crop yield increase is that fermented potato fertilizer can modulate soil nitrification strategy bychanging the niche of soil functional microorganisms to increase fast-acting nutrients and increase crop yield. [ABSTRACT FROM AUTHOR]

In this study, soil samples from the typical rice-wheat cropping system in Jiangsu Province, China, subjected to different fertilizer application treatments-no carbon (CK), urea (UR), straw (SR), pig manure (PM), starch (ST), and glucose (GL)-were used to determine potential anaerobic ammonium oxidation (anammox) rate and its association with bacterial abundance, diversity, and activity by using DNA stable isotope probing combined with N isotope tracing and molecular techniques. The effects of different organic carbon sources on anammox were significant, in the following order: GL > ST, SR > UR > PM; anammox activity differed significantly across treatments; however, the C active anammox bacteria were only closely related to Ca. Brocadia. The anammox hydrazine synthase β subunit functional gene sequences were highly associated with the Candidatus genus Brocadia in PM and CK treatments. The different organic carbon sources had different inhibitory effects with anammox rate, which dropped from 3.19 to 1.04 nmol dinitrogen gas g dry soil h among treatments. About 4.2-22.3% of dinitrogen gas emissions were attributed to anammox and indicated that a specific population of anammox bacteria was present and varied with the addition of exogenous organic compounds in paddy soils, although a small part of dinitrogen gas was emitted from the soil via anammox. [ABSTRACT FROM AUTHOR]

Little is known about the effects of temperature and drying-rewetting on soil phosphorus (P) fractions and microbial community composition in regard to different fertilizer sources. Soil P dynamics and microbial community properties were evaluated in a soil not fertilized or fertilized with KHPO or swine manure at two temperatures (10 and 25 °C) and two soil water regimes (continuously moist and drying-rewetting cycles) in laboratory microcosm assays. The P source was the dominant factor determining the sizes of labile P fractions and microbial community properties. Manure fertilization increased the content of labile P, microbial biomass, alkaline phosphomonoesterase activity, and fatty acid contents, whereas KHPO fertilization increased the content of labile inorganic P and microbial P. Water regimes, second to fertilization in importance, affected more labile P pools, microbial biomass, alkaline phosphomonoesterase activity, and fatty acid contents than temperature. Drying-rewetting cycles increased labile P pools, decreased microbial biomass and alkaline phosphomonoesterase activity, and shaped the composition of microbial communities towards those with greater percentages of unsaturated fatty acids, particularly at 25 °C in manure-fertilized soils. Microbial C and P dynamics responded differentially to drying-rewetting cycles in manure-fertilized soils but not in KHPO-fertilized soils, suggesting their decoupling because of P sources and water regimes. Phosphorus sources, temperature, and water regimes interactively affected the labile organic P pool in the middle of incubation. Overall, P sources and water availability had greater effects on P dynamics and microbial community properties than temperature. [ABSTRACT FROM AUTHOR]