Simulation of nitrogen mineralization in the below-ground food webs of two winter wheat fields.


Food webs in conventional (high-input) and integrated (reduced-input) farming systems were simulated to estimate the contribution of soil microbes and soil fauna to N mineralization during the growing season. Microorganisms accounted for ∼95% of the biomass and ∼70% of total N mineralization under both management practices. Among the soil fauna, amoebae and bacterivorous nematodes were the most important contributors to N mineralization. The contribution of nematodes showed more temporal and spatial variability than that from amoebae. The model calculated N mineralization rates close to those observed in both fields and different depth layers. In the integrated plot the mineralization rates were relatively greater between 0-10 cm than between 10-25 cm. In the conventional plot no differences were observed between the depth layers. The impact of the functional groups on N mineralization was evaluated by calculating the effect of group deletion on total N mineralization: this impact was considered sufficient to exceed the simulated direct contribution to N mineralization.

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