IMPACT OF ACIDIFICATION ON ALUMINUM IN THE SOILS OF HIGHBUSH BLUEBERRY PLANTATIONS FERTILIZED WITH COMPOST OBTAINED FROM URBAN SLUDGE

Different fertilization systems cause changes in the content of mobile forms of Al (aluminum) in the soil, due to changes in pH. The toxicity Al is one of the major limitations that inhibits the growth and development of plants in acidic soils. In acidic soils (pH <5.0), phytotoxic aluminum (Al3+) rapidly inhibits root growth and subsequently affects the absorption of water and nutrients by plants. Stationary fertilization experiments with wastewater sludge compost treatments to blueberry plants were evaluated. In the spring of 2020, an experiment with increasing doses of compost of 0, 20, 40, 60, 80 t /ha in vegetation pots, under soil water controlled conditions, was organized. Three years after compost fertilization, a 4.2 pH level (strong acid) was experimentally induced in the soil of all vegetation vessels planted with blueberries. The content of phytotoxic forms of aluminum increased with increasing dose of compost, compared to unfertilized control. At the induction of the soil pH of 4.2, in the variant fertilized with the maximum dose of compost (80 t/ha) the mobile and phytotoxic content of Al increased 30 times compared to the same experimental variant from the pre-acidification conditions. In the same time, under the newly created conditions, the mobile phosphorus content in the soil decreased dramatically. In the compost maximum fertilization dose, the mobile phosphorus content from the soil was significantly lower than the unfertilized control.