Effects of organic-matter application on phosphorus adsorption of three soil parent materials

In this study, poultry manure compost and organic fertilizer were added to soils derived from basalt, granite, and river alluvial deposits for use as soil parent materials. Following incubation periods of 30 or 60 days at 25 degrees C, the physical and chemical properties and adsorption characteristics of the soils were studied. The results indicated that the application of poultry manure compost or organic fertilizer increased the available phosphorus (P) and organic matter content in all soils; however, the quantity of P and organic matter decreased with an increase in incubation time. The organic materials added via the treatments reduced the strength of P adsorption by the soil derived from basalt. For soils derived from granite and river alluvial deposits, the strength of P adsorption declined after poultry manure compost was added, but increased after the application of organic fertilizer. All soil treatments derived from basalt fitted well with the three adsorption isotherm equations. For soils derived from granite and alluvial deposit as parent materials, the data conformed to the three adsorption models in the order: Langmuir > Freundlich > Temkin. The maximum phosphate buffering capacity (MPBC) and standard P retention (SPR) of soil derived from basalt decreased following the application of poultry manure or organic fertilizer, whereas changes in MPBC and SPR for soils derived from granite and alluvial deposits were dependent on the organic content and incubation time.