Soil salinization is a major problem in irrigated agriculture. A field study was conducted in the Sariosiyo district in the Surkhandarya region of southeast Uzbekistan to evaluate soil nitrogenase activity and nitrogen-fixing bacteria populations in saline serozem soils under wheat, maize, and alfalfa, as well as from adjacent fallow land. Composite soil samples were randomly collected from depths of 0-10, 10-20, and 20-30 cm in autumn, winter, spring, and summer, which were then 2-mm sieved and subjected to selected microbial population analysis and enzymatic studies. The results showed that alfalfa contributed both to high nitrogenase activity and to a large nitrogen-fixing bacteria population. The fallow soil had a lower nitrogenase activity and bacterial population. The nitrogenase activity was higher in the soil from a depth of 10-20 cm in spring. Results suggest that cropping, especially suitable crop rotation, is essential to support greater microbial biomass population and nitrogenase activity for improving the biological fertility of saline and nitrogen-poor calcareous arid soils.
Irrigated agriculture, salinity, season, soil depth, nitrogenase activity, microbial population
EGAMBERDIEVA, DILFUZA and KUCHAROVA, ZULFIYA (2008) "Cropping Effects on Microbial Population and Nitrogenase Activity in Saline Arid Soil," Turkish Journal of Biology: Vol. 32: No. 2, Article 3. Available at: https://journals.tubitak.gov.tr/biology/vol32/iss2/3