This study evaluated the forms of phosphorus accumulated in plant tissue cover crops and their release from the mineralization of their residues. The field work was conducted in the agricultural year 2008/2009, in the town of Mantiqueira, in the municipality of Touch-Me-Not, RS, Brazil. The treatments were: black oats ( Avena nuda), rye ( Secale cereale), pea ( Pisum sativum subsp. arvense) and radish ( Raphanus sativus var. oleferus). Observations showed that the chemical fractionation of P in plant tissue used in this study is a reliable method that aids in understanding the dynamics of the release of P. The cover crops accumulate different forms of P in plant tissue, which interferes with the dynamics of release of this element. It was also observed that rye is a plant that releases the P tissue with greater speed to the ground, while the pea tissue P releases more slowly.
