Potentialities and soil impact analysis of rock phosphorus fertilization of perennial and annual legume crops

ABSTRACT

The objective of this study is to evaluate the impacts of the direct use of natural rock phosphates on two forage legumes, Vicia sativa, and Medicago sativa. Crops were grown in pots containing two P deficient soils and fertilized with Tunisian rock phosphate (TRP) or chemical triple superphosphate (TSP). TRP amendment significantly increased shoot dry yield (+53% to +162%), P-content, protein content, and chlorophyll content mainly at the rate of 150 kg P ha⁻¹. No significant effects were observed on mycorrhization and antioxidant enzyme activities. However, TSP negatively affected the frequency of root mycorrhization and stimulated antioxidant enzyme activities. TRP amendment induced an increase in fluorescein diacetate activity, alkaline phosphatase activity, and species richness. The stimulation involved mainly Actinobacteria, Proteobacteria, and Firmicutes with higher stimulation of Actinobacteria in the case of vetch. The present work indicated a better P-use efficiency of vetch. It suggested also that at least a part of the enhancement observed in plant-growth parameters following TRP fertilization is driven by changes in the structure of rhizosphere microbial communities. Nevertheless, the correlation between changes in microbial composition and phosphorus uses efficiency needs to be investigated further.

KEYWORDS:

• Rock phosphate
• legumes
• microbial communities
• diversity
• rhizosphere

Acknowledgements

The authors are grateful to Mrs Dorsaf Hellal (Institut National des Grandes Cultures, INGC) and Mr Mohamed Ali Bouslimi (Centre de Formation Professionnelle Agricole dans le domaine de la mécanique à El Kantra, Siliena) for their help in getting access to the phosphorus-deficient soils used in this work. The authors are also grateful to Pr. Bekki (University of Oran) for the help in root mycorrhization counting. This work was supported by the Tunisian Ministry of Higher Education and Scientific Research.

Disclosure statement

No potential conflict of interest was reported by the authors.