Abstract

Prediction of net N mineralization is required for optimization of the synchronization of N supply with plant N demand. Net N mineralization is the outcome of two concurrent and oppositely directed processes: gross N mineralization and gross N immobilization turnover (MIT). Consequently, an improved understanding of MIT can potentially improve our capability to predict net N mineralization patterns. The aim of the study was to measure MIT and respiration rates of widely differing plant materials and look for relations between them. Eight plant residues with a very wide range in C to N ratios were incorporated into soil and incubated at 16 degrees C. During 2-d intervals (5-6, 25-26, and 55-56 d after incorporation), MIT and respiration rates were determined. The respiration and gross N immobilization rates were correlated (R-2 = 0.74), whereas respiration and gross N mineralization rates were less well correlated (R-2 = 0.41). The correlation was improved (R-2 = 0.89) when only the data from the first incubation period and the C/N ratio of acid detergent solubles (ADS) were taken into account. Assuming that the soil microorganisms have a C use efficiency of 50%, this study showed that the gross N mineralization rate made up only 30% of the total gross litter N decomposition rate (i.e., the remaining 70% being directly assimilated by soil microorganisms in organic form). Net N mineralization rates, derived from the difference between predicted rates of gross N mineralization and gross N immobilization, could explain up to 64% of the variability in measured net N mineralization rates. In conclusion, this study revealed that MIT in the initial phase of decomposition can be derived from data on C mineralization and the C/N ratio of ADS, which can simplify the process of calibrating and validating mechanistic models and thereby improve our capability of predicting net N mineralization

Published in

Soil Science Society of America Journal
2006, Volume: 70, number: 4, pages: 1121-1128
Publisher: SOIL SCI SOC AMER

SLU Authors

• Stenberg, Bo

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Agricultural Science
Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.2136/sssaj2005.0133

Permanent link to this page (URI)

https://res.slu.se/id/publ/8552