Modeling Nitrogen Mineralization Kinetics in Arable Soils of Semiarid India

• Published in: Arid land research and management Vol. 17; no. 2; pp. 153 - 168
• Main Authors: Haer, Harmanjit Singh, Benbi, Dinesh Kumar
• Format: Journal Article
• Language: English
• Published: Taylor and Francis, c2001 01-01-2003; Taylor & Francis Group
• Subjects: arable soils; carbon; clay; linear models; mineralization; nitrogen; organic matter; semiarid soils; water potential
• ISSN: 1532-4982; 1532-4990
• DOI: 10.1080/15324980301586

Laboratory incubation experiments were conducted to study N mineralization kineticsin 15 benchmark soils of Punjab, India. Aerobic incubations were carried out for 112 days at 32°C and -33 kPa water potential. Cumulative N mineralization in different soils ranged from 8.2 to 75.6 mg kg -1 soil, which constituted 2.7 to 8.8% of soil organic N. For each gram of organic carbon (OC) kg -1 soil, about 9 mg N was mineralized in 112 days of incubation. Mineralization was faster during initial days of incubation followed by a relatively slower rate subsequently. Kinetic models of varying complexity were fitted to N mineralization vs. time data. The first-order single compartment (FOSC) model provided relatively poor fit to the data and systematically deviated from the measured values. Both the first-order double compartment (FODC) and the first-order zero-order (FOZO) models provided good fit to the data and yielded very low residual mean squares. In soils with OC content > 0.55%, the FODC model invariably provided the best fit. It was concluded that a minimum of two pools of organic matter may be considered to contribute towards organic N mineralization in these soils. Soil OC and clay strongly influenced the FOSC- and FODC-predicted N mineralization potential of soils. A linear regression involving OC and clay × OC interaction could be used to predict N mineralization potential of the soils.