Changes in Phosphorus Fraction on an Acidic Soil Induced By Phosphorus Fertilizer, Organic Matter and Lime

Abstract

One month of incubation experiment was implemented to evaluate the changes of phosphorus fraction in inorganic P (Pi) and organic P (Po) induced by phosphorus fertilizer (KH2P04), cow manure ( manure) and CaC03 (lime). A 0.5 kg oven-dried weight of arable layers of Latosol from Darmaga, Bogor was used in this study. The rates of manure were 0, 12.5 and 25 ffha, lime were 0, 1, 3 times the CaC03 equivalent required to neutralize exchangeable aluminum amounting to 0, 3.01, 9.03 t/ha respectively and the rates of phosphorus fertilizer in KH2P04 were 0, 40 and 80 kg Plha. All treatments increased resin-Pi (biologically available P). Application of phosphorus fertilizer also increased NaHC03-Pi which is also included as biologically available PI whi!e manure and lime only tended to increase this fraction. Phosphorus fertilizer and manure application were able to enhance NaOH-Pi (moderately resistant P related to AI-P and Fe-P ) but lime did not affect it. Phosphorus fertilizer, manure and lime increased HCI-Pi (moderately resistant P related to Ca-P). The changes of NaHC03-Pi to resin-Pi and P immobilization by microorganism, which was indicated by the increase of NaHCOrPo (readily mineralizable), can be attributed to the decrease of NaHC03- Pi. The increase of NaOH-Pi by phosphorus fertilizer and manure indicated that the complexation of P fixation sites by PO6 and organic acids likely had occurred.