Bioavailable soil P as a main key for sustainable agriculture: its functional model determined using isotopic tracers

摘要

Sustainable agriculture is defined in many ways. In all of them, two main complementary concepts appear: this agriculture must first satisfy the human needs of foods for the present and second must not compromise the ability for the future generations to meet their needs. Therefore, concerning P, the sustainability in an ecosystem can be maintained only if: (i) bioavailable soil P is not a limiting factor of crop yields in the considered conditions; (ii) all the parameters describing the available soil P will be unmodified each time that P is simultaneously taken by crops and returned to soils; and (iii) P inputs and outputs must be without negative consequences on environment. Whatever the ecosystem, P nutrition can be described in terms of fluxes of P between soil and plant roots. The isotopic exchange method gives information not only on bioavailable soil P but also on potential fluxes of P between soil and soil-solution. As roots take phosphorus in the soil solution, it is concluded that this method can be used to predict not only potential P uptake by plants or crops in native soils but also the contribution to crop nutrition of a P application in soil. Isotopic tracers of P seem to be, at the present time, the simplest tool useful to describe, with a high accuracy, the main link of P cycle in sustainable agriculture: the bioavailable soil P. (authors). 9 refs., 1 fig., 1 tab. (authors). (Atomindex citation 26:036793)