Kinetics of soil nitrogen mineralization from undisturbed and disturbed soil
2002
Ringuelet, A. | Bachmeier, A.O.
Knowledge of soil nitrogen (N) mineralization processes is essential for modeling soil processes in agriculture. Many authors have found discrepancies in N mineralization between disturbed and undisturbed samples. Nevertheless, most simulation models use a first-order kinetic model (exponential model) for all the layers under study, devised from studies using disturbed and superficial samples. The goal of the present study was to establish the best kinetic model to explain and predict N mineralization as affected by sample disturbance and soil depth in two soils of the semiarid region of Argentina. Disturbed (D: sieved <2 mm and quartz mixed) and undisturbed (UD) samples from two Haplustolls were subject to successive incubations and extractions to assess N mineralization rates. The amount of N mineralized in disturbed samples was up to 200% greater than undisturbed. Replicate D samples from the Torriorthentic had significantly higher variability (p<0.05) than samples from the Torrifluventic. In the latter, UD samples had a kinetic heterogeneity that was not apparent in the D samples. These results suggest that the incubation-technique for D samples is ineffective for these soils.
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