Ecosystem Fertility: A new paradigm for nutrient availability to plants in the humid tropics

AbstractSoil fertility has been an important factor in sustainable plant production in native and agricultural fields in temperate climates such as that in Japan. Soil fertility is assessed based on the availability of nutrients, in particular inorganic nitrogen (N) and phosphorus (P), from soil-accumulated organic matter (SOM) via microbial immobilization and mineralization. However, the pool sizes of SOM in humid tropics such as those in Thailand are small and they are turned over rapidly; under such circumstances, the tropical soil fertility would soon be depleted. To meet the urgent requirement of plant nutrients for high plant productivity, we define a direct supply of plant nutrients (i.e., residue fertility) from raw plant and microbial residues. The residue fertility may be driven by the activities of soil fauna (e.g., earthworms, collembolans, termites) and micro-organisms (e.g., saprophytic fungi, protozoa, bacteria), and the released nutrients may be collected and absorbed directly by plant roo...