Phosphorus Sorption Characteristics of Acidic Luvisols and Nitisols under Varying Lime Rates, and Response Validation Using Wheat

ABSTRACT

This study investigated phosphorous (P) sorption characteristics under lime rates, and validated them under field conditions. Soil samples from nitisols and luvisols were taken, mixed with lime(tha⁻¹) at[0,0], [5.25, 3.75], [10.5, 7.5] and [15.75, 11.25], respectively, and incubated for 30 days. It was equilibrated with KH₂PO₄ at 0, 10, 20, 30, 40, and 50 mgPL⁻¹. The data were tested with Freundlich and Langmuir models. External P requirement (EPR) and changes in chemical properties were evaluated. The field validation on wheat involved rates of P (0, 8.2, 16.4, 24.6, 32.9, and 41.1 kg ha⁻¹) and lime (0, 650, and 1300 kgha⁻¹) in a randomized complete block design with three replications. Freundlich was found the best-fitted model. Freundlich coefficient (Kf) ranged from 212 to 45 mgPkg⁻¹ (nitisols) whereas it was 112.7 to 16.29 mgPkg⁻¹ (luvisols). EPR (kgPha⁻¹) without and the highest lime rate were: nitisols (142.5 and 52.32 kgPha⁻¹) and luvisols (124.84 and 25.94 kgPha⁻¹). Liming reduced EPR by 63.3% (nitisols) and 79.3% (luvisols). Liming increased soil pH from [4.55 to 6.60 in the nitisols, and 5.33 to 6.51 in luvisols]; exchangeable acidity (cmol(+)kg⁻¹) 3.84 to 0.01 nitisols, and 0.72–0.05 luvisols, and available P (mg/kg) 3.2–6.32 nitisol, and 2.74–8.72 luvisols. Furthermore, applying 32.9 kgPha⁻¹ x 1300 kgha⁻¹ lime resulted in grain yield (4345.2 kgha⁻¹) that was 449% more than the untreated crop (791.3 kgha⁻¹). The validation result suggested higher P than blanket P recommendation. It also justifies that excess P or lime alone cannot be a complete solution for P management and increased yield.

KEYWORDS:

• Ethiopia
• external phosphorus requirement
• Freundlich model
• Langmuir model
• lime
• soil types

Acknowledgments

We are very grateful Wolaita Sodo University for funding this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

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Supplementary material

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Additional information

Funding

This work was funded by the Wolaita Sodo University.