This research subject directly addresses the overall hypothesis that high productivity and high phosphate use efficiency can be achieved under phosphate-limited conditions by simultaneously adapting phosphate cycling and phosphate availability (sources) to the multipurpose phosphate demands (sinks) in maize-based food-feed-energy systems.

Further aims of this research subject are the planning and realization of central field experiments and sampling campaigns in existing long-term field experiments. Field experiments are based on the following hypotheses also addressing the other research subjects: (I) Under low phosphate conditions, (a) legumes in maize-based crop rotations increase the plant availability of phosphate for the maize crops; (b) placed fertilization of phosphate increases the phosphate fertilizer availability for the maize crops, in the placements areas; (c) the distribution of the different soil phosphate fractions differ from bulk soil, broadcast and no phosphate fertilization, favouring high plant availability; (d) with legumes soil organic phosphate increases in favour of the inorganic fractions. (II) Maize varieties derived from RS 1.1 are more efficient in phosphate acquisition at low phosphate soil status and at low phosphate fertilisation levels. (III) The plant phosphate availability of recycling fertilizers is comparable to common commercial fertilizers.

Results of all research subjects will be collected in a central database, which will be used to generate input data for generic modelling.