Effect of particle-size distribution, soil organic carbon content and organo-mineral aluminium complexes on acid phosphatases of seasonally flooded forest soils

We studied the acid phosphatase activity (APA) and its relationships with some soil physico-chemical properties along a seasonally flooded forest gradient. The soil samples were collected during the non-flooded period in three zones subjected to different flooding periods: a zone inundated 8 months per year (MAX), a zone inundated 5 months per year (MED), and a zone inundated 2 months per year (MIN). In the MAX zone APA was low and negatively correlated with the fine earth fraction of soil. In this zone, clay minerals appeared to reduce the enzymatic activity. In the MIN zone acid phosphatase had a relatively higher activity, which was positively correlated with the soil organic C content and with Al associated with the organic matter. The highest value of APA was obtained in the MED zone, and no correlation was found between edaphic factors and the enzymatic activity in this zone. However our results are restricted to a single sampling date and, therefore, they do not take into account the seasonal dynamics of acid phosphatase in relation to other soil factors over time.