Abstract:
Soils of the Republic of Moldova are characterized mostly by a low content of mobile phosphorus. In the context of
sustainable agriculture restoration and maintenance of soil fertility has become a key problem. The main role in the
process of phosphorus mineralization in the soil, from organic compounds, belongs to orthophosphoric monoester
phosphohydrolases (phosphatases). The aim of this research was the assessment of phosphatasic activity in soil,
depending on the system of fertilization and crop type. The long-term field experiment (since 1972) is located in Balti
steppe, RM, on the typical chernozem soil. The results of comparative analysis of phosphatasic activity (acid – pH 5.0,
natural – un-buffered conditions and alkaline – pH 10.2) are presented. The extracellular activity was determined by soil
incubation with toluene, and with disodium p-nitrophenyl phosphate hexahydrate salt as the substrate. The soil samples
were collected under the following crops: vetch + oats, winter wheat and sugar beet, which are a part of a field crop
rotation. Three fertilization systems were analyzed: mineral, mineral + organic, organic and control – un-fertilized soil.
The investigation results revealed that in all examined treatments, the phosphatasic activity determined under conditions
of natural soil pH had higher values than those of acid and alkaline ones. Phosphorus mineralization process went more
intense in variants with organic fertilization. The soil enzymatic activity under the sugar beet was lower than in the soil
collected under the vetch + oats and winter wheat.
