Effects of Organic Fertilizers on the Soil Microorganisms Responsible for N2O Emissions: A Review

Abstract

The use of organic fertilizers constitutes a sustainable strategy to recycle nutrients, increase soil carbon (C) stocks and mitigate climate change. Yet, this depends largely on balance between soil C sequestration and the emissions of the potent greenhouse gas nitrous oxide (N2O). Organic fertilizers strongly influence the microbial processes leading to the release of N2O. The magnitude and pattern of N2O emissions are different from the emissions observed from inorganic fertilizers and difficult to predict, which hinders developing best management practices specific to organic fertilizers. Currently, we lack a comprehensive evaluation of the effects of OFs on the function and structure of the N cycling microbial communities. Focusing on animal manures, here we provide an overview of the effects of these organic fertilizers on the community structure and function of nitrifying and denitrifying microorganisms in upland soils. Unprocessed manure with high moisture, high available nitrogen (N) and C content can shift the structure of the microbial community, increasing the abundance and activity of nitrifying and denitrifying microorganisms. Processed manure, such as digestate, compost, vermicompost and biochar, can also stimulate nitrifying and denitrifying microorganisms, although the effects on the soil microbial community structure are different, and N2O emissions are comparatively lower than raw manure. We propose a framework of best management practices to minimize the negative environmental impacts of organic fertilizers and maximize their benefits in improving soil health and sustaining food production systems. Long-term application of composted manure and the buildup of soil C stocks may contribute to N retention as microbial or stabilized organic N in the soil while increasing the abundance of denitrifying microorganisms and thus reduce the emissions of N2O by favoring the completion of denitrification to produce dinitrogen gas. Future research using multi-omics approaches can be used to establish key biochemical pathways and microbial taxa responsible for N2O production under organic fertilization.

Effects of Abiotic Stress on Soil Microbiome

“…Organic fertilizers include (i) manures (livestock feces), (ii) compostable organics, (iii) beneficial microbial inoculants, and (iv) humic compounds [253,254]. Since these are utilized in agro-ecological farming, organic fertilizers provide a variety of C compounds with varying chemical compositions, ranging from labile to recalcitrant, that soil microbes can employ to boost their growth rates and biomass throughout the mineralization process [255]. Microbial proliferation in the soil is also promoted when raw and composted organics like kitchen waste are added [256].…”

Temperature Sensitivity and Composition of Nitrate-Reducing Microbiomes from a Full-Scale Woodchip Bioreactor Treating Agricultural Drainage Water

“…Nitrate removal in WBRs is primarily based on heterotrophic bacterial denitrification [ 8 ], which is an anaerobic respiration with sequential reduction of NO 3 − and nitrite (NO 2 − ) to the gaseous N forms of nitric oxide (NO), nitrous oxide (N 2 O), and dinitrogen (N 2 ). Each step in denitrification is catalyzed by independent enzymes in a modular process and the energy metabolism, using NO x as the electron acceptor, is coupled to the oxidation of labile carbon (C) compounds [ 15 , 16 , 17 ]. In WBRs, the labile C compounds are derived from complex woodchip polymers that are degraded by lignocellulolytic microorganisms [ 18 ].…”

Combination of Compost and Mineral Fertilizers as an Option for Enhancing Maize (Zea mays L.) Yields and Mitigating Greenhouse Gas Emissions from a Nitisol in Ethiopia

“…Applying organic fertilizers was shown to have positive yield effects in a broad range of cropping systems [4][5][6][7][8] and also has environmental benefits, as evaluated in a life cycle assessment study [9]. With regard to soil fertility, among others, organic materials were shown to enhance aggregation and stability of the soil and reduce erosion ( [10,11], suppress soil borne diseases [12], store nutrients [13], and improve biological functions [14,15]. Despite the advantages of organic fertilization, various studies agree that the combination of organic and mineral fertilizers can provide even better results concerning CSA than sole organic or mineral fertilizer.…”

“…Although, improper application of organic fertilizers can result in considerable releases of greenhouse gases (GHG) [14,17], combining organic and mineral fertilizers was frequently described as a viable option to reduce nitrogen (N) losses and emissions of GHGs, especially carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) in different cropping systems [3,[18][19][20]. The potential to reduce GHG emissions depends largely on the type of the organic amendments and their effects on soil microbial community structure and functions [14]. Mainly processed amendments, as compost, were found to increase the carbon (C) stocks in soils and to reduce the emissions of N 2 O [14,21].…”