02068nam a2200193 a 450000100080000000500110000800800410001910000210006024500740008126000730015530000100022850000200023852015450025865000160180365000170181965000130183665300150184965300100186413311332002-11-22       1977    bl uuuu  m   00u1 u    #d1 aNOVAES, R. F. de  aPhosphorus supplying capacity of previously heavily fertilized soils.  aRaleigh: Faculty of North Carolina State University at Raleighc1977  a153p.  aTese Doutorado.  aIn this study, Ap horizon material from four Ultisols from the Coastal Plain province, Goldsboro, Wagram, Portsmouth, and Norfolk, and one Piedomont Ultisol, Georgeville, all of which had high residual phosphorus with cropping on different soil phosphorus parameters was studied. The following parameters were measured initially and after each crop grown on the soils: a) the available soil phosphorus with N.C., Bray 1, and Olsen extractants; b) the quantity factor as amounts of the various forms of inorganic soil phosphorus; c) the intensity factor as phosphate potential; d) the capacity factor as phosphate buffering capacaty; and e) the Langmuir and Freundlich phosphorus adsorption isotherms. The kinetics of phosphorus adsorption by the five soils before cropping was also studied. After the soils were cropped for nine consecutive times, phosphorus was added at five levels to determine how much phosphorus had to be added to bring the available phosphorus back to the original levels. From the results the following conclusions can be drawn. The depletion curves of the available soil phosphorus with N.C., Bray 1, and Olsen extractants as related to phosphorus uptake by plants followed linear relationships for all the soils. The slopes for the Goldsboro, Norfolk, and Wagram soils were similar. These slopes for the N.C. and Bray 1 extractants were significantly correlated with the soil capacity factors which permitted the derivation of equations to predict the slope values from the capacity factor values. The ............  aFertilidade  aFertilizante  aFósforo  aCapacidade  aSolos