Adsorption of phosphorus by soils from dilute solu tions showed a closer agreement with the Langmuir iso therm than with the Freundlich isotherm. Constants calculated from the Langmuir isotherm and interpre tations based upon the meaning of these constants permit a sound theoretical approach to some of the problems of phosphorus retention in soils.The adsorption maximum calculated from the Lang muir isotherm was closely correlated with the surface area of soils as measured by ethylene glycol retention. The correlation coefficients and regression equations were r = 0.98 and y = 0.276x f 3.47 for 10 alkaline soils, and r -0.96 and y = 0.641x f 5.73 for 12 acid soils, where y -mg. P per 100 g. soil and x = rag. ethylene glycol retained per g. of soil. For a given surface area, i.e., 30 mg. glycol per g. soil, the acid soils held 2.17 times as much phosphorus' as the alkaline soils.The average values of a second constant, k, derived from the slope and intercept values, were 0.92 and 4.39 for the alkaline and acid soils, respectively. As the value of this constant increases, .the bonding energy of the soil for phosphorus increases. Thus, the acid soils re tained more phosphorus per unit of surface area and also held the phosphorus with a greater bonding energy than the alkaline soils ''HE reaction of fertilizer phosphorus with soils depends upon the nature and amount of adsorbing surface as

No abstract

No abstract

No abstract

No abstract