Influence of salts on the microbial activity in arid and simi-humid soils.

The influence of salt mixtures consisting of Ca (H2PO4)2, trace elements, CaSO4, CaCO3, Na2CO3, NaCl, and K2SO4 in different combinations on the nitrifying power, evolution of carbon dioxide, and the total number of bacteria was studied in arid soils (sandy and alluvial) and semi-humid ones (chernozem and rendzina). Salt mixtures comprising either monocalcium phosphate or sodium chloride showed highly inhibiting action on the studied microbial activities in sandy, alluvial, and chernozem soils, while monocalcium phosphate stimulated the heterotrophs of rendzina. Trace elements favoured the autotrophs of the caly soils. The other different salt mixtures acted according to the salt combination and nature of the microbial activity.