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Phosphorus (P) is an essential element for plant and animal growth and its input has long been recognized as necessary to maintain profitable crop and sustainable agriculture. However, intensification of crop and animal farming in many areas has created regional imbalances in P inputs in feed and fertilizer and P output in farm produce.
In many of these areas, soil P has built up to levels in excess of crop needs and now has the potential to enrich surface runoff with P. This is the case in Galicia, northwestern Spain, where many cultivated soils analyzed were ranked in categories with high or excessive of phosphate evels.
A number of extraction methods have been proposed to assess soil phosphorus availability. The extractable capacity of these methods and their suitability depends on the type of soil and the degree of accuracy that we want to obtain.
Soil type: Umbrisol
Soi texture: loam
Rotation: maize and winter cereal
Sampling: at 0-5, 5-10, 10-20 and 20- 40 cm depth
DETERMINATION OF AVAILABLE PHOSPHORUS
AER and O extractions
Sharpley, A.N., R.W. McDowell, and P.J.A. Kleinman. 2004. Amounts, forms, and solubility of phosphorus in soils receiving manure. Soil Sci. Soc. Am. J. 68:2048–2057
TOTAL AND EXTRACTABLE PHOSPHORUS CONCENTRATIONS AT DIFFERENT DEPTHS
IN A SOIL FERTILIZED WITH MANURE
R. DA SILVA DÍAS 1, C. A. de ABREU 2, R. M. MESTAS VALERO 1, J. M. MIRÁS AVALOS 1 & E. VIDAL VÁZQUEZ 1
1 University of Coruña (UDC). Faculty of Sciences. A Zapateira 15008, La Coruña-Spain. E-mail: firstname.lastname@example.org
2Agronomic Institute of Campinas (IAC).Barão de Itapura, 1481, Campinas, SP, Brazil. E-mail: email@example.com
The aim of this work was to evaluate the effect of soil surface roughness on soil losses and runoff for different tillage systems.
MATERIAL AND METHODS
Mean P contents at sussesive depths. Total P= after microwave digestion, M3=Mehlich-3 (ICP and COlL: Colorimetric), AER= Resin and Ol= Olsen. Different letters in the column indicate significant differences (P < 0.05)
Summary of methods used for extraction and determination of available phosphorus