Pedosphere 26(5): 636--642, 2016
ISSN 1002-0160/CN 32-1315/P
©2016 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Changes in Olsen P in relation to P balance in contrasting agricultural soils |
I. DÍAZ1 and J. TORRENT2 |
1Departamento de Ingeniería Aeroespacial y Mecánica de Fluidos, Escuela Técnica Superior de Ingeniería Agronómica (ETSIA), Universidad de Sevilla, Ctra de Utrera km 1, 41013 Sevilla (Spain)
2Departamento de Agronomía, Universidad de Córdoba, Edificio C4, Campus de Rabanales, 14071 Córdoba (Spain) |
| ABSTRACT |
| Maintaining soil phosphorus (P) at adequate levels for plant growth requires assessing how the long-term P balance (viz., the difference between P inputs and outputs) results in changes in soil test P. The hypothesis that routinely measured soil properties can help predict the conversion factor of P balance into Olsen P was tested at 39 sites in agricultural areas of the Mediterranean region in Spain. A set of soil samples from each site was analyzed for Olsen P, inorganic P (P extracted using 0.5 mol L-1 H2SO4), pseudototal P (P extracted using 0.5 mol L-1 H2SO4 following ignition at 550 oC), and organic P (the difference between pseudototal P and inorganic P). Organic and Olsen P were uncorrelated in most of the 39 soil sets, which suggests that organic P content changed little with P inputs and outputs. The slopes of the regression lines of Olsen P against pseudototal and inorganic P, which were used as two different measures of the conversion factor, ranged widely (from 0.03 to 0.25 approximately), with their average values (about 0.10) being similar to those found in long-term experiments conducted in temperate areas. Neither conversion factor was significantly correlated with any routinely measured soil property; however, the conversion factor for inorganic P was significantly lower for calcareous soils than for noncalcareous soils. Our negative results suggest the need to isolate the influence of soil properties from that of management systems and environmental factors relating to P dynamics in future studies. |
| Key Words: calcareous soils, conversion factor, inorganic P, noncalcareous soils, organic P, pseudototal P, soil property, soil test P |
| Citation: DÍaz, I. and Torrent, J. 2016. Changes in Olsen P in relation to P balance in contrasting agricultural soils. Pedosphere. 26(5): 636-642. |
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