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Soil Carbon and Nitrogen (C/N) Cycling
Published in Yeqiao Wang, Landscape and Land Capacity, 2020
Sylvie M. Brouder, Ronald F. Turco
Soils and fresh additions of plant and animal materials present the resident microorganisms with a compositionally diverse array of organic substrates as potential energy and nutrient sources; genetic and associated functional diversity of the soil microbiology ensures ongoing soil C/N and other nutrient cycling in the ever-changing physical and chemical environments.[14] Simplistically, nutrient cycling reflects two sets of processes by which microorganisms meet their need for (i) energy and (ii) essential nutrients (e.g., C, N, phosphorus [P], sulfur) to maintain or increase their biomass (cell numbers). Because both bacteria and fungi must assimilate nutrients across a membrane, organic substrates must first be solubilized into physically smaller fractions. In organic residues of plant origin, the cell walls composed of lignin and cellulose form a recalcitrant physical barrier to degradation. Fungi are one of a few kinds of organisms that can secrete the enzymes necessary to break down cellulose to glucose and the only known organism that can completely degrade lignin via in-place oxidation. Thus, initial decomposition typically involves hyphal extension and enzyme excretion into newly introduced organic material to release labile substances (Figure 25.1, P 3). This release process is general and creates a pool of soluble materials including physically smaller C and N molecules such as simple sugars, amino acids, and proteins that can be accessed by other bacteria, fungi, and growing plants. Labile materials not immediately assimilated by fungi may be washed out of decomposing tissue by rainfall; once these substrates reach the soil, they are transported into the soil matrix in soil water and diffuse to the resident microorganisms inside and outside of the soil aggregates (Figure 25.1, P 5).
Production of xylanases by Bacillus sp. TC-DT13 in solid state fermentation using bran wheat
Published in Preparative Biochemistry & Biotechnology, 2020
Isabela da Silva Vasconcelos Rodrigues, Jessyca Teles Barreto, Brenda Leite Moutinho, Mayara Mendes Gonçalves Oliveira, Rafael Salomão da Silva, Marcelo Ferreira Fernandes, Roberta Pereira Miranda Fernandes
The organism used was Bacillus sp. TC-DT13 isolated from soil earlier in the Soil Microbiology Laboratory Collection (Embrapa Coastal Tablelands). These bacteria were stored in 50% glycerol at −80 °C and reactivated in liquid basal medium (MLB) composed of beef extract 0.3%, NaCl 0.5%, KNO3 0.2%, K2HPO4 0.1%, MgSO4.7H2O 0.05%, and xylan 1% as the carbon source.[25]
Growth and lead uptake by Parkinsonia aculeata L. inoculated with Rhizophagus intraradices
Published in International Journal of Phytoremediation, 2021
Manuel A. González-Villalobos, Tomás Martínez-Trinidad, Alejandro Alarcón, Francisca O. Plascencia-Escalante
The inoculum of R. intraradices (Soil Microbiology, Colegio de Postgraduados, Mexico) was valued according to the number of spores extracted by sieving and decanting (Gerdemann and Nicolson 1963) followed by centrifugation with 20% and 60% sucrose gradients (Sieverding 1983). The spores were observed under a stereoscopic microscope, and only intact spores were counted.
Phytoremediation efficacy of native vegetation for nutrients and heavy metals on soils amended with poultry litter and fertilizer
Published in International Journal of Phytoremediation, 2023
Ngowari Jaja, Eton E. Codling, Dennis Timlin, Laban K. Rutto, Vangimalla R. Reddy
The analyses of water samples from the lysimeter depths of 30 cm, 60 cm, and 90 cm are shown in Figures 3–5. The concentration of nitrate and ammonium in water samples for NVM and NVN plots are shown in Figures 3 and 4. The 2-year experiment indicated a higher level of nitrates and ammonium in the fertilized plots particularly with the samples collected within the last four months of sampling in the first year. The first two months of sampling did not show any difference for the first year. Subsequently, the concentration for the lysimeter leachate from the fertilized plots was higher all through the months of sampling. This could be due to leaching losses of NO3- from the poultry manure applied as an N source of fertilizer. The U.S. Environmental Protection Agency (US-EPA 2022) standard for nitrate in drinking water is 10 mg/L of nitrate. The results indicate almost double the allowable limit in the water collected within the first 60 cm depth of the lysimeters and does not affect the ground water levels beyond the 90 cm depth. The high nitrate level could be due to leaching since heavy rainfall and irrigation might have contributed to N leaching. As a breakdown product of poultry manure, urea exhibits dynamics which correspond to the temperature and moisture conditions of the soil. In a normal scenario, with an adequate soil moisture in the presence of enzymes and microbes, NH3 which is the initial urea product from the breakdown will quickly convert to NH4+ and finally to NO3− for plant uptake. However, there are situations when NH4+ could be removed from the soil mainly via nitrification, volatilization, and leaching, which is harmful to the environment and has led to a series of agroecological issues (Ding et al.2016). It has been indicated that the volatilization of NH3 is directly proportional to the concentration of ammonium (NH4+) in soil solution (Shaviv and Mikkelsen 1993), which is also associated with the formation of N2O and high nitrate (NO3−) concentrations in soil (Jenkinson 1990; Wang et al.2021). Therefore, minimizing the accumulation of soil inorganic N (NH4+, NO3−, etc.) or manure which contributes to their accumulation in soils could reduce N2O emissions. This is with the understanding that concentrations of NO3− and NH4+ in soils are regulated by numerous factors, such as soil temperature, pH, soil microbiology, fertilizer form, and moisture (Schmidt 1982; Nieder et al.2011) among others.