“…The depth to the minimum phoaphorua value alao correaponda well with valuea for the Down# aeriea reported by theae reaeachera. The zone of phoaphorua depletion may form due to removal of thia element by planta, tranalocation downward with collodial conatituenta, or leaching in aolution (aneck, 1973;Runge, 1963;Tembhare, 1973;Ridley, 1984).…”