Evaluating soil phosphorus tests and nutrient limitations in Mediterranean pastures

Lolium multiflorum Pasture fertilization Resin-P Soil phosphorus Trifolium subterraneum

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August 29, 2025
October 29, 2025
December 9, 2025

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Reliable phosphorus (P) fertilization guidelines for Mediterranean pastures remain uncertain due to inconsistent soil testing methods, the complexity of mixed-species systems, and the neglect of other limiting nutrients. This study primarily aimed to identify reliable soil P tests and secondarily to explore potential nutrient limitations by assessing seven acidic Portuguese soils under Mediterranean conditions using subterranean clover (Trifolium subterraneum) and ryegrass (Lolium multiflorum) as model species. Five P extraction methods (Egner-Riehm, Olsen, Bray II, Mehlich I, and anion exchange resin) were compared alongside a pot experiment with clover, ryegrass, and their mixture. Biomass production, plant nutritional status, and soil–plant relationships were used to assess nutrient availability and plant response. The Egner-Riehm method proved the most reliable, showing linear correlation with the resin method (R² = 0.89), widely regarded as the best indicator of soil P bioavailability. P availability was therefore not a limiting factor for biomass production. The lowest soil P content (54 mg kgâ»Â¹ Pâ‚‚Oâ‚…, Egner-Riehm) was close to the medium threshold (50–100 mg kgâ»Â¹), yet plant growth indicated adequacy. In contrast, nitrogen (N) emerged as the main growth constraint, and boron (B) deficiency further restricted clover performance, confirming additional nutritional imbalances. A linear relationship between soil and tissue B supported its association with DMY, and tissue B levels were below sufficiency thresholds. Overall, in acidic Portuguese soils under Mediterranean conditions, soil P was adequate, whereas N and B acted as key constraints to productivity. These findings support more accurate and efficient fertilization strategies for Mediterranean pastures.

How to Cite

Arrobas, M., Raimundo, S., Sawimbo, A., Rodrigues, N., Jongen, M., Teixeira, R. F. M., Domingos, T., & Rodrigues, M. Ã. (2025). Evaluating soil phosphorus tests and nutrient limitations in Mediterranean pastures. SAINS TANAH - Journal of Soil Science and Agroclimatology, 22(2), 444-456. https://doi.org/10.20961/stjssa.v22i2.108545