Comunicação oral da qual só está disponível o resumo.Phosphorus (P) is a non renewable resource which highlights the
significance of developing and using alternative sources of P for a sustainable
agriculture. Animal manure is an option but its application to soils to meet crop
nitrogen needs requires careful management practices to minimize freshwater
eutrophication. The aim of this work was to evaluate the partitioning of applied P
between plant uptake, losses to water, and erosion losses when using different
animal manures and a mineral P fertilizer. A field trial was conducted at an erosion
experimental station. The treatments were: Control (0 kg P/ha); cattle manure; solid
fraction of pig and duck slurry and superphosphate, each applied at a rate of 50 kg
P/ha after Lolium sp was sown. Soil samples from each trial were collected over the
9-month study and the water extractable soil P determined. It was found that
desorption of P from all additions rapidly increased soon after P application (2
weeks). After that water extractable soil P remained fairly constant. While duck
slurry desorbed the largest concentration of P, all sources have the potential to
desorb P that could accelerate eutrophication. Plant uptake of P was greater with
cattle manure added and released the least amount of P to water compared with the
other sources of P. The partitioning of applied P between plant uptake and losses to
runoff and sediments ranged between 5-12 % with the higher values in Duck
treatment. Animal manures significantly increased soil Olsen-P, plant production and P
uptake relative to mineral fertilizer. Animal manures can be considered as a source of
available P nevertheless to avoid eutrophication risks increase plant P use efficiency is also
important
