INVESTIGADORES
DUVAL Matias Ezequiel
congresos y reuniones científicas
Título:
Use of a three-compartment model to evaluate the dynamics of cover crop residues
Autor/es:
DE SA PEREIRA, E.; GALANTINI, JA.; DUVAL, ME.
Lugar:
Valencia
Reunión:
Conferencia; Global Conference on Plant Science and Molecular Biology; 2017
Institución organizadora:
Magnus Group
Resumen:
Cover crop (CC) residues protect the soil from erosion and their permanence on the surface is largely influenced by their biochemical constituents. Simulation models have been proposed to evaluate the decomposition of residues in soil. Most of these models have taken in to account one or several compartments to describe the organicresidues, each decomposing according to first order kinetics. In this study, the dynamics of CC residue decomposition by applying mathematical models was described. The kinetics of decomposition of residues was obtained from a laboratory incubation experiment. Three CC shoot residues were applied on the soil surface and incubated for 362 days (withe ight sampling times). Total 72 samples (pots) were placed at random in a green house unde controlled conditions of temperature (25 ± 1°C). The basic treatment design consisted of pots in which CC residue (24 pots for each specie), oven-dried, was covered. The residues of oats, vetch and clover cut into 2?3-cm particles and were added to pots at 5.4, 5.4 and 2.7 g dry matter, respectively, which corresponded to biomass rates of 6, 6 and 3 Mg ha−1, respectively. This rate is equivalent to that observed in field experimental plots. There sults from the application of the three-compartment model (LIG, C + H and NSC, with their decomposition rate constants) for simulating decomposition of different CC residues showed a better fit with the real data than the estimation from the negative exponential equation. Oats and vetch residues decomposed the most than clover, where k values were 3.6 × 10−3,3.7 × 10−3 and 5.3 × 10−3 day−1, respectively. The three compartment model (non structural carbohydrates, cellulose?hemicellulose and lignin) to simúlate residue decomposition presented a close fit between simulated and measured data. The decomposition rate constant (k) of CC can be used to estímate how long residues will remain in the field and how they could affect soil organic carbon. Vetch residues initially showed a fast decomposition rate. They lost over 40% in the first 21 days after being placed in incubation pots, which allowed high N-availability in the soil. Oats residues decomposed more slowly and caused temporary N-immobilization in the soil, with a late partial release between 3 and 4 months after the residues were placed in the pots. Decomposition rates for oats, vetch and clover residues were different, where as the processesof mineralization and immobilization were enhanced by the C:N ratio of each CC. The decomposition dynamics of theCC can be described by a simple equation in the médium term, or else a three compartment model can be used for moreaccurate descriptions in the short term.