Testing of Zeolite-Glauconite Phosphorite Mixtures for Decrease of Lead Uptake by Plants


1 N. Poushkarov Institute for Soil Science and Agrochemistry, BG-1080 Sofia, Bulgaria
2 NIPRORUDA S. A., Mineral Agroengineering Laboratory, BG-1370 Sofia, Bulgaria


PETKOVA, D., S. POPANDOVA, T. POPOVA and K. CHAKALOV, 2000. Testing of zeolite-glauconite phosphorite mixtures for decrease of lead uptake by plants. Bulg. J. Agric. Sci., 6: 321-326

A vegetation experiment was carried out with light gray forest soil contaminated with 200 mg/kg lead in order to establish the efficiency of CaCO3 and three ameliorants: No 1 80% zeolite + 20% phosphorite fraction; ameliorant No 2 80% zeolite + 20% glauconite fraction and No 3 phosphorite fraction for the decrease of lead adsorption by radish (Raphanus sp.) as a test plant.
It has been established that in the variant with CaCO3 input soil acidity was neutralized to pH = 6. The same effect was achieved by the input of phosphorite fraction in soil. Lead content of radishes with these ameliorants has decreased approximately three times compared to radish grown on lead contaminated soil.
The input of zeolite-glauconite and zeolite-phosphorite compositions did not result in soil acidity neutralization but lead content of radishes decreased approximately twice compared to radishes grown on contaminated soil, which is due to their high ion exchange capacity and hemosorption. Lead input in soil has a much stronger effect on its content in plants than on yield.
The clearly expressed lead accumulation in radishes, calculated by the coefficient of biological accumulation (CBA), indicates the possibility to use them as a test-plant for defining lead contamination rate of soil.

Key words: pH, lead, zeolite, glauconite-phosphorite, phosphorizing, liming, coefficient of biological accumulation