Limitations of the Olsen method to assess plant-available phosphorus in reclaimed marsh soils |
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Authors: | Antonio Delgado María del Carmen
Del Campillo José Torrent |
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Institution: | 1. Departamento de Ciencias Agroforestales, EUITA, Universidad de Sevilla, Ctra. Utrera km 1, 41013 Sevilla, Spain;2. Departamento de Ciencias y Recursos Agrícolas y Forestales, Universidad de Córdoba, Edificio C4, Campus de Rabanales, 14071 Córdoba, Spain |
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Abstract: | The aim was to assess the ability of bicarbonate-extractable P (Olsen P) to estimate total plant-available P (TPAP) in reclaimed marsh soils (Aeric Endoaquepts) which differed widely in P buffering capacity (PBC). Total plant-available P was estimated as the cumulative P uptake for a final concentration of 0.02 mg P/L in the soil solution which is the typical P requirement for field crops. The Olsen P estimated for that concentration was adopted as the critical level for crop production. We found that TPAP was better predicted by anion exchange resin-extractable P (AER-P) (65% of variance accounted for) than by Olsen P, probably because the effectiveness of the AER depends on the soil P buffering capacity, a factor that greatly influences the availability of P to plants. The critical Olsen P level was found to depend on those soil properties affecting the relationship between sorbed P and P in soil solution, viz. the P buffering capacity of soil, the Na/Ca mole ratio in the 1:1 soil:water extract, which explained 63 and 84% of the variance in the critical level, respectively, and the affinity of the sorbing surfaces for P. These properties must be taken into account when using Olsen P as the P index for fertilizer management. |
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Keywords: | Buffer capacity critical levels for fertilizer response plant available P Olsen P resin extractable P |
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