Assessing the Effect of Phosphorus Fertilizer Levels on Soil Phosphorus Fractionation in Rhizosphere and Non-Rhizosphere Soils of Wheat

ABSTRACT

This study evaluated the effects of phosphorus (P) fertilizer levels on inorganic P fractions. Wheat cultivars (Azadi and Marvdasht) were grown in the soils amended with the four rates of P fertilizer levels (no fertilizer, 10, 15, and 25 mg available P kg⁻¹ soil). Soils were sampled from rhizosphere and non-rhizosphere areas after 6 weeks. The mean of all P fractions was significantly different in various P fertilizer levels. The smallest and the largest amounts of all P fractions were observed in the soil with no P and in 25 mg kg⁻¹ soil P level, respectively. The Azadi cultivar, as P-efficient, showed the smallest increase in soil P fractions with increasing soil P levels. The means of all P fractions except Al-phosphates (Al-P) were significantly higher in non-rhizosphere soil. There were differences between these cultivars associated with the more inaccessible fractions at the 15 mg P kg⁻¹ soil level.

KEYWORDS:

• P efficiency
• P fractions
• rhizosphere
• root morphology

Acknowledgments

We would like to thank all the members of the Soil Science Department of Faculty of Agricultural and Environmental Sciences, University of Tehran, for providing the facilities to carry out this work and for their suggestions.