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Comparison of five soil organic matter decomposition models using data from a 14 C and 15 N labeling field experiment

2004; Wiley; Volume: 18; Issue: 4 Linguagem: Inglês

10.1029/2004gb002230

1944-9224

Marc Pansu, P. Bottner, Lina Sarmiento, Klaas Metselaar,

Bioenergy crop production and management

Five alternatives of the previously published MOMOS model (MOMOS‐2 to ‐6) are tested to predict the dynamics of carbon (C) and nitrogen (N) in soil during the decomposition of plant necromass. 14 C and 15 N labeled wheat straw was incubated over 2 years in fallow soils of the high Andean Paramo of Venezuela. The following data were collected: soil moisture, total 14 C and 15 N and microbial biomass (MB)‐ 14 C and ‐ 15 N, daily rainfall, air temperature and total radiation. Daily soil moisture was predicted using the SAHEL model. MOMOS‐2 to ‐4 (type 1 models) use kinetic constants and flow partitioning parameters. MOMOS‐2 can be simplified to MOMOS‐3 and further to MOMOS‐4, with no significant changes in the prediction accuracy and robustness for total‐ 14 C and ‐ 15 N as well as for MB‐ 14 C and ‐ 15 N. MOMOS‐5 (type 2 models) uses only kinetic constants: three MB‐inputs (from labile and stable plant material and from humified compounds) and two MB‐outputs (mortality and respiration constants). MOMOS‐5 did not significantly change the total‐ 14 C and ‐ 15 N predictions but markedly improved the predictive quality and robustness of MB‐ 14 C and ‐ 15 N predictions (with a dynamic different from the predictions by other models). Thus MOMOS‐5 is proposed as an accurate and ecologically consistent description of decomposition processes. MOMOS‐6 extends MOMOS‐5 by including a stable humus compartment for long‐term simulations of soil native C and N. The improvement of the predictions is not significant for this 2‐year experiment, but MOMOS‐6 enables prediction of a sequestration in the stable humus compartment of 2% of the initially added 14 C and 5.4% of the added 15 N.