Abstract:In order to investigate the importance of reaction in fertisphere (the soil zone immediately surrounds fertilizer and characterized with intense reactions) on phytoavailability of phosphorus (P) fertilizer, the transformation and the distribution of fertilizer-P with monocalcium phosphate monohydrate (MCP) application in a calcareous fluvo-aquic soil, which obtained from Henan China, were studied using slice sectioning by 31-day incubation with soil columns. There was about 30% of fertilizer-P remained as residue due to amphoteric hydrolyzation of MCP; otherwise, about 70% fertilizer-P was moving into soil columns. Fractionation studies showed that fertilizer-P moved into the soil columns major presented as Ca2-P and Ca8-P, then Al-P, water-extracted P (WE-P), and Fe-P, there was only slight increment of O-P, whereas, there was no significant change of Ca10-P. The proportions of new-increased P form were 9.6%, 35.8%, 34.9%, 13.8%, 5.4% and 0.5% for water-extracted P (WE-P), Ca2-P, Ca8-P, Al-P, Fe-P and O-P, respectively. However, in the fertisphere (0-2 mm), the proportion of new-formed Ca8-P significantly increased to 53.1%, and O-P also slightly increased to 0.6%, with the deceasing of other P forms, they were 25.0%, 11.4% and 4.4%, for Ca2-P, Al-P and Fe-P, respectively. Furthermore, the distributions of WE-P and Ca2-P showed two different stages: first they linearly declined down sharply, and then slowly they linearly reduced down to original levels of bulk soil; and the distribution of other P forms also characterized with two stages, which caught about 90% of fertilizer-P only moved to the halves of which it could be reached. WE-P and Ca2-P significantly increased in 45 mm, but major presented in 20 mm. Ca8-P, Al-P and Fe-P significantly increased in 30 mm, but major existed in 20 mm. however, O-P only formed and major presented in 10 mm. Whereas, the peaks of the distribution of all P forms were presented in 0-2 mm。 MCP significantly reduced the soil pH, and drastically destroyed soil CaCO3 in fertisphere. The Ca2+ released by CaCO3 dissolution could fix half of fertilizer-P that moved into soil, furthermore, the Fe3+ and Al3+ released form the decomposition of soil compounds also play an important role in P fixation. The results clearly demonstrated the amphoteric hydrolyzation and the dissolution of CaCO3 played a pivotal role in inhibiting the mobility, but enhancing the fixation of fertilizer-P with MCP application in calcareous soil.