Cordovil, Cláudia Marques dos SantosSilva, Ana Beatriz de Albuquerque Morais2012-03-062012-03-062011Silva, Ana Beatriz de Albuquerque Morais - Phosphorus cycling in dry and rewet incubated soils subjected to different fertilization histories. Lisboa: ISA, 2011http://hdl.handle.net/10400.5/3919Mestrado em Engenharia do Ambiente - Instituto Superior de AgronomiaPhosphorus continuous application in fertilizers, in quantities superior to those required by plants causes a P buildup in soils, potentially increasing nutrient losses and compromising water quality by eutrophication process. This work was aimed at assessing the effect of DRW cycles, in two soils with different fertilization histories subjected to organic and mineral fertilization, over P availability. Soils were collected from a long-term fertilizer management platform (NW Italy) divided in two plots experiencing since 1996 different fertilization management (one plot fertilized with low N and K levels and no P and another with fertilization high on N and P levels), and each was divided in 3 subplots treated with mineral, compost and without fertilization, since 2010. The soils were subjected, under laboratory conditions, to four DRW cycles and compared with another set at constant moisture. Weekly the soils were sampled and analyzed for some of their P forms. Soluble P increased in compost fertilized soil, especially after the third dry and rewet cycle, following microbial decay. Yet, this was more pronounced in the overfertilized soils. From these findings it is possible to conclude that the availability of P may be further enhanced by water content variations as by compost addition.engphosphorusfertilizationdrying and rewettingsoilseutrophicationmaster thesis