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Advances in Crop Science and Technology

.: Home > Advances in Crop Science and Technology > 2015 > Volume 3 Number 2 > Zinabu Wolde1 *, Wassie Haile2 and Dhyna Singh2

Phosphorus Sorption Characteristics and External Phosphorus Requirement of Bulle and Wonago Woreda, Southern Ethiopia

Zinabu Wolde1 *, Wassie Haile2 and Dhyna Singh2
1Graduate student of Soil Science, Hawassa University, P. O. Box 05, Hawassa, Ethiopia 2Gedeo Zone Agricultural Office, Gedeo Zone, P. O. Box 128, Dilla, Ethiopia
Abstract :

Determination of the P-sorption characteristics of soils is important for economic fertilizer application and to recommend appropriate management strategies for high P-fixing soils. Thus, the objectives of this study were to evaluate P-sorption characteristics of soils occurring in some areas of southern Ethiopia and identify factors contributing to P sorption. Composite surface (0-20 cm) soil samples from 6 sites of two locations were collected. The results revealed that the P-sorption data were fitted well with both Langmuir and Freundlich models with r2 values of 0.99. But later model was found to better in describing P-sorption data than the former model. The adsorption maxima (Xm) and distribution coefficient (Kf) values of soils ranged from 909-2000 mg PKg-1 and 245-487 mg PKg-1 based on Langmuir and Freundlich models respectively. The corresponding SPR values ranged between 57-196 mg P kg-1 and 71.8-211 mg P kg-1 based on Langmuir and Freundlich models respectively. Bonding energy constant (K) of Langmuir model and Freundlich constant (b) ranged from 0.15-1.4 and 0.54-0.66 Lmg-1 respectively. The bonding energy constant (K) of Langmuir model was found to be more valuable than Xm in discriminating the study soils as high and low P sorbing soils. Based on both models soils of Bulle had SPR values >150 mg PKg-1 and then were classified as high P-fixing soils while soils of Wonago had SPR values <150 mgPKg-1 were classified as low P-fixing. The result of path analysis revealed that exchangeable Al and Clay had direct effect on P-sorption parameters of both models. It is concluded that P-sorption models can effectively be used to discriminate soils based on P-fixation ability. However, validation of both models through real time experiments in greenhouse and field is recommended before the models used for large scale.

Keywords :
P-Sorption/Fixation; Standard P requirement (EPR); Exchangeable Al; Fe; Langmuir model; Freunlich model

Date Deposited : 04 Apr 2016 12:41

Last Modified : 04 Apr 2016 12:41

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Volume 3, Number 2, May 2015 , ISSN ISSN: 2329-8863

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