Abstract
Phosphorus deficient supply enhances Lupinus root secretions in the form of organic acids that lower down the soil pH. The rhizosphere pH change was determined in a green house experiment by the use of a micro -potentiometer)? system based on a W° pH electrode and CuiCu(11)1120 reference electrode. A linear Nikolsky type response was obtained, y = -43.39X — 44.86, R2 = 0.9962. Total microscale acid base &rations showed the response of E= f (pH). The rhizosphere pH change was calculated during 6 weeks starting from 21 day old plants. The pH decrease by the wheat was negligible compared to that of Lupinus. The decease measured in control (P0) was prominent by Lupinus either growing alone (22.3%) or in association with wheat (25%). However, the water-soluble fertilizer (TSP) depressed the acidification process and the pH reduction was only up to 14.9%, while the sparingly soluble P compound had no effect.
Muhammad Akhtar, V. E. Hernandez, A. Baeza, A. M. Qazi, R. N. Escobar. (2003) The use of W° micro biosensor to measure the site-specific pH chances in the rhizosphere of lupinussilvestrisferthized with different sources of P, The Journal Soil & Environment , Volume 22, Issue 2.
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