Land Use Impacts on Phosphorus Sorption Isotherms: A Critical Assessment for Site-Specific Fertilizer Management in the Highlands of Southern Ethiopia
Abstract
Phosphorus (P) deficiency limits crop productivity in tropical acidic soils, yet information on P sorption dynamics across land uses is scarce in southern Ethiopia. This study evaluated P sorption and estimated external P requirements (EPR) for four land uses (coffee, enset, cultivated, eucalyptus) in Bule Hora district. Twenty-four composite soil samples (0–20 cm) were analyzed, and P sorption data fitted to Langmuir and Freundlich isotherms. EPR was defined as the theoretical P required to maintain 0.2 mg P L−1 in soil solution under laboratory conditions, as a comparative reference, not a field fertilizer recommendation. Soils were clayey, acidic (pH 4.99–5.68), with very low soil available P (<5 mg P kg−1). The Langmuir model best described sorption (R 2 = 0.89–0.98). Sorption maxima ranged 164.8–264.6 mg P kg −1 , and EPR 97.0–192.9 mg P kg −1 ; highest in cultivated and eucalyptus lands. The current DAP recommendation (100 kg ha −1 , 18-46-0) supplies ∼20.1 kg P ha −1 , equivalent to ∼8.4 mg P kg −1 . This is only 4.6–6.4% of the laboratory-derived EPR for cultivated land (131–183 mg P kg −1 ) required to maintain 0.2 mg P L −1 . Xm correlated positively with clay (r = 0.75) and negatively with organic matter (r = −0.75) and available P (r = −0.73). We conclude that Bule Hora soils have high P fixation. These EPR values require field validation before revising recommendations. Site-specific management combining validated EPR-based rates, organic matter amendments, and targeted liming may enhance P use efficiency and sustain productivity in these strongly sorbing soils.
Related
- Toward reliable water resource assessment: Correcting bias in satellite-based rainfall and model-derived discharge in Kenya’s Central Highlands
- Mapping and synthesis of evidence on soil fertility management, fertilizer use efficiency, and greenhouse gas outcomes
- Effects of exogenous microbial fertilizer and in situ green manure management on soil microbial community structure and predicted functional potential in Korla fragrant pear orchards
- Efficient removal of regorafenib from aqueous solutions using KOH-activated hazelnut husk-derived activated carbon: adsorption mechanism, kinetics, isotherms and thermodynamics
- How common is autonomous conservation? Insights from highlands and islands of Indonesia
BibTeX
@article{manore2026land,
title = {{Land Use Impacts on Phosphorus Sorption Isotherms: A Critical Assessment for Site-Specific Fertilizer Management in the Highlands of Southern Ethiopia}},
author = {Daniel Manore and Mengistu Liramo and Wassie Haile},
journal = {Air, Soil and Water Research},
year = {2026},
month = oct,
doi = {10.1177/11786221261502407},
url = {https://doi.org/10.1177/11786221261502407},
note = {CC BY},
}
RIS
TY - JOUR
TI - Land Use Impacts on Phosphorus Sorption Isotherms: A Critical Assessment for Site-Specific Fertilizer Management in the Highlands of Southern Ethiopia
AU - Daniel Manore
AU - Mengistu Liramo
AU - Wassie Haile
PY - 2026
DA - 2026/10/27
JO - Air, Soil and Water Research
DO - 10.1177/11786221261502407
UR - https://doi.org/10.1177/11786221261502407
AB - Phosphorus (P) deficiency limits crop productivity in tropical acidic soils, yet information on P sorption dynamics across land uses is scarce in southern Ethiopia. This study evaluated P sorption and estimated external P requirements (EPR) for four land uses (coffee, enset, cultivated, eucalyptus) in Bule Hora district. Twenty-four composite soil samples (0–20 cm) were analyzed, and P sorption data fitted to Langmuir and Freundlich isotherms. EPR was defined as the theoretical P required to maintain 0.2 mg P L−1 in soil solution under laboratory conditions, as a comparative reference, not a field fertilizer recommendation. Soils were clayey, acidic (pH 4.99–5.68), with very low soil available P (<5 mg P kg−1). The Langmuir model best described sorption (R 2 = 0.89–0.98). Sorption maxima ranged 164.8–264.6 mg P kg −1 , and EPR 97.0–192.9 mg P kg −1 ; highest in cultivated and eucalyptus lands. The current DAP recommendation (100 kg ha −1 , 18-46-0) supplies ∼20.1 kg P ha −1 , equivalent to ∼8.4 mg P kg −1 . This is only 4.6–6.4% of the laboratory-derived EPR for cultivated land (131–183 mg P kg −1 ) required to maintain 0.2 mg P L −1 . Xm correlated positively with clay (r = 0.75) and negatively with organic matter (r = −0.75) and available P (r = −0.73). We conclude that Bule Hora soils have high P fixation. These EPR values require field validation before revising recommendations. Site-specific management combining validated EPR-based rates, organic matter amendments, and targeted liming may enhance P use efficiency and sustain productivity in these strongly sorbing soils.
SN - 1178-6221
ER -