Carbon and Nitrogen Mineralization in Tallgrass Prairie and Agricultural Soil Profiles

• Published in: Soil Science Society of America journal Vol. 62; no. 4; pp. 942 - 951
• Main Authors: Ajwa, H. A., Rice, C. W., Sotomayor, D.
• Format: Journal Article
• Language: English
• Published: Madison, WI Soil Science Society of America 01.07.1998; American Society of Agronomy
• Subjects: Agricultural land; Agronomy. Soil science and plant productions; Ammonia; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Carbon; Carbon dioxide; Chemical, physicochemical, biochemical and biological properties; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Geochemistry; Grasses; Leaching; Mathematical models; Mineralization; Minerals; Nitrates; Nitrogen; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plants (botany); Reaction kinetics; Soil and rock geochemistry; Soil profiles; Soil science; Soil types; Soils; Synecology; Terrestrial ecosystems; Great Plains of America; Kansas; United States; North America; America; Grassland; SOIL BIOLOGY; Organic matter; Ammonium; Agricultural soils; Cultivated soil; Carbon dioxide; Nitrates; SOIL CHEMISTRY; Inorganic element; Mineralization; Ecosystem; Pool; Chemical properties; Laboratory study; Property of soil; Natural soil; Mollisols; Nitrogen; Carbon; Long term; Physical properties; Agroecosystem; Carbon cycle; Edaphic factor; Biogeochemistry; Nitrogen cycle; PRAIRIES; Comparative study
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj1998.03615995006200040014x

In situ mineralization of N may contribute significantly to total inorganic‐N pools deep in the soil profile. We conducted long‐term laboratory incubation experiments to evaluate the net C and N mineralization in soils collected from various depths in tallgrass prairie and agricultural fields of the same geological materials and soil type. Samples were packed to a bulk density of 1.4 g cm‐3 in 5‐cm‐diameter by 10‐cm‐long cores. The cores were incubated at 35°C for 40 wk in sealed containers. Net C mineralization was measured by evolved CO2, and N mineralized was measured by periodic leaching with NH+4 and NO‐3 measured in the leachate. Carbon and N mineralization in the surface horizon were greater in the tallgrass prairie than in the agricultural soil. In both the tallgrass prairie and agricultural soil profiles, C mineralization was least at the water‐table depth. Carbon mineralization was described by a first‐order kinetic model, but N mineralization was described better by a consecutive (sigmoidal) reaction model. At most depths, the ratios of potentially mineralizable organic C (C0) to total organic C (C0/TOC) and potentially mineralizable organic N (N0) to total N (N0/TN) were greater in the agricultural soil profile than in the tallgrass prairie soil profile. The C0 and N0 in the surface soil (0–0.2 m) represented 11.6 and 12.2% of the total organic C and N pools for the tallgrass prairie soil profile, respectively, and 21.0 and 10.2% of the total organic C and N pools for the agricultural soil profile. Management practices affected the mineralization potentials and rates of both the surface and subsurface soils.