Animal manure and anhydrous ammonia amendment alter microbial carbon use efficiency, microbial biomass, and activities of dehydrogenase and amidohydrolases in semiarid agroecosystems

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2006-10, Vol.33 (3), p.258-268
• Main Authors: Deng, S.P., Parham, J.A., Hattey, J.A., Babu, D.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Amidohydrolase; anhydrous ammonia; Animal manures; application rate; Biochemistry and biology; Biological and medical sciences; biotransformation; Carbon use efficiency; Chemical, physicochemical, biochemical and biological properties; Dehydrogenase; enzyme activity; fertilizer rates; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Microbial biomass; Microbial metabolic activity; Microbiology; nitrogen; nitrogen fertilizers; Nutrient cycling; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Physics, chemistry, biochemistry and biology of agricultural and forest soils; semiarid soils; soil amendments; soil chemical properties; Soil enzymes; soil microorganisms; Soil science; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2005.10.004

The potential negative impact of agricultural practices on soil and water quality is of environmental concern. The associated nutrient transformations and movements that lead to environmental concerns are inseparable from microbial and biochemical activities. Therefore, biochemical and microbiological parameters directing nitrogen (N) transformations in soils amended with different animal manures or inorganic N fertilizers were investigated. Soils under continuous corn cultivation were treated with N annually for 5 years at 56, 168, and 504 kg N ha −1 in the form of swine effluent, beef manure, or anhydrous ammonia. Animal manure treatments increased dehydrogenase activity, microbial biomass carbon (C mic) and N (N mic) contents, and activities of amidohydrolases, including l-asparaginase, urease, l-glutaminase, amidase, and β-glucosaminidase. Soils receiving anhydrous ammonia demonstrated increased nitrate contents, but reduced microbiological and biochemical activities. All treatments decreased C mic:organic C (C org) ratios compared with the control, indicating reduced microbial C use efficiency and disturbance of C equilibrium in these soil environments. Activities of all enzymes tested were significantly correlated with soil C org contents ( P < 0.001, n = 108), but little correlation ( r = 0.03, n = 36) was detected between C mic and C org. Activities of amidase and β-glucosaminidase were dominated by accumulated enzymes that were free of microbial cells, while activities of asparaginase and glutaminase were originated predominately from intracellular enzymes. Results indicated that soil microbial and biochemical activities are sensitive indicators of processes involved in N flow and C use efficiency in semiarid agroecosystems.