effects of wheat rhizosphere on phosphorus availability and some biological properties in soils treated with municipal sewage sludge

rhizosphere has different chemical and biological properties from the bulk soil. information about phosphorus (p) availability in the rhizosphere soils treated with municipal sewage sludge (mss) is limited. therefore, the objectives of this research were to evaluate the rhizospheric effects of wheat (triticum aestivum l.) on phosphorus availability and biological properties in 10 calcareous soils treated with mss under rhizobox conditions. dissolved organic carbon (doc), microbial biomass carbon (mbc), microbial biomass phosphorus (mbp), metabolic quotient (qco2) and available phosphorus (by 4 chemical extractants including olsen, mehlichі, brayіі and calcium chloride methods with different extraction mechanism), were determined in the rhizosphere and bulk soils. the results showed that doc, mbc and mbp strongly increased and qco2 strongly decreased in the rhizosphere soil compared with the bulk soil. also, the amount of p extracted with different tests in the rhizosphere was lower compared to the bulk soils. the correlation studies showed that dry yield of wheat had positive relationship with mehlichі and olsen-p in the rhizosphere and the bulk soil, respectively. the results of this research showed that mehlichі and olsenextractants could be used to estimate plant-available p in the rhizosphere and bulk soils, respectively.