V. S. Krutilina

Natural zeolite can be used as a heavy metals adsorbent from phosphogypsum, applied as a soil amendment. We used barley and corn seedling to investigate the effect of different methods of zeolite and phosphogypsum application on (a) growth, photochemical activity of chloroplasts and chlorophyll content; (b) uptake of strontium (Sr), calcium (Ca), and cadmium (Cd) in relation to photosynthetic activity, and content of these elements in the soil. Phosphogypsum was found to negatively influence the growth and development of the seedlings, affecting their morphology traits, biomass production and photosynthetic activity. Therefore, the application of phosphogypsum together with natural zeolite, according to the recommended technique, “in mixture”; completely erased consequences of phosphogypsum treatment. Uptake of Sr by barley plants was noticed to be highly dependent on photosynthetic activity and leaf area, however, there was no close correlation found between the content of water soluble Sr in the soil and its accumulation in plants.

Natural zeolite (clinoptilolite containing tuff) can be used as an adsorbent of strontium (Sr) from phosphogypsum when applied as a solonetzic soil amendment. This study investigated the influence of the zeolite on biological yield, content of water‐soluble Sr in soil, its availability, and plant uptake. A field experiment was conducted from 1993 to 1995 in the Volgogradskaya region of Russia. Two methods of phosphogypsum and zeolite application were used: “separate” and “as a mixture” (10 tons ha^‐1 of phosphogypsum and 0.5 ton ha^‐1 of zeolite in both cases). After the application of the amendments, barley (Hordeum vulgare) and grass sorghum (Sorghum sudanensis) were grown on the ameliorated sites in 1994 and 1995, respectively. Our results suggest that zeolite, being applied with phosphogypsum as a mixture, decreased by 15 to 75% the content of water‐soluble Sr in the soil, minimizing the risk of soil pollution. The uptake of Sr by plants depended on the biological character of the crop grown. Barley was found to be a “strong‐anticoncentrative” type of plant. However, grass sorghum was found to be more sensitive to the rise of Sr content in the soil. The highest biomass production of barley and grass sorghum was obtained with the application of zeolite and zeolite plus phosphogypsum. Plants grown on a single phosphogypsum‐treated sites had a declining tendency in biological yield. Our results suggest a positive influence of zeolite applied with phosphogypsum for the amelioration of solonetzic soils on the growth and uptake of Sr by plants.