PHOSPHORUS ADSORPTION AND DESORPTION PROPERTIES OF MINNESOTA BASALT LUNAR SIMULANT AND LUNAR GLASS SIMULANT

Phosphorus (P) adsorption and desorption characteristics of Minnesota Basalt Lunar Simulant (MBLS) and Lunar Glass Simulant (LGS) were evalu ated. Results of P interactions with lunar simulants indicated that mi neral and glass components adsorbed between 50 and 70% of the applied P and that between 85 and 100% of the applied P was desorbed. The Exte nded Freundlich equation best described the adsorption data (r(2) = 0. 92), whereas the Raven/Hossner equation best described the desorption data (r(2) = 0.97). Kinetic desorption results indicated that MBLS and LGS released most of their P within 15 h. The expanded Elovich equati on fit the data best at shorter times while t/Q(DT) equation had a bet ter fit at longer times. These results indicate that P does not strong ly adsorb to the two simulants and that any P that was adsorbed was re adily desorbed in the presence of anion exchange resin. This work sugg ests that multiple small applications of P (10-20 mg P kg(-1)) should be added to the simulants to ensure adequate solution P for plant upta ke and efficient use of P fertilizer.