Resumen

RODA VACA, JOSE LUIS; RUIZ ALDERETE, DAVID  y  VIERA, MARY SELVA. Calibración de tres métodos de extracción de fosforo asimilable en suelos agrícolas del departamento de Santa Cruz. Univ. Cienc. Soc. [online]. 2011, n.4, pp. 55-61. ISSN 8888-8888.

This study was conducted at the Soil Laboratory of Tropical Agricultural Research Center (CIAT) in order to identify the most efficient and reliable extraction of available soil phosphorus. 14 representative samples of agricultural soils were taken from the towns of Okinawa I, Las Brechas, Saavedra, Portachuelo y Chané, in the department of Santa Cruz. Part of the samples were prepared for wheat planting in greenhouse conditionsand part were used in the laboratory for the determination of available phosphorus by Mehlich III, Bray I and modified Olsen methods. In addition to phosphorus, the pH, electrical conductivity, Ca2 +, Mg2 +, Na + and K +, Cation Exchange Capacity, base saturation, organic matter, total nitrogen and texture were also determined. In the wheat cultivation the weight of the leaf dry mass and the amount of phosphorus absorbed was determined. To identify the most efficient method of phosphorus extraction, a regression analysis and correlation was performed between each of the extraction methods and phosphorus absorbed by the wheat plants, as well as the dry mass produced. The study was supplemented by a regression analysis between the phosphorus extracted by different methods and soil characteristics: pH, exchangeable calcium, organic matter and clay content. A highly significant correlation (P <0.05) was verified between the phosphorus absorbed by the wheat plant and the Mehlich III method (r = 0.91), Bray I (r = 0.98) and modified Olsen (r = 0.91). However, the correlation between the phosphorus and dry weight of wheat was not significant. Likewise, there was no significant influence of soil characteristics on the amount of phosphorus available. Based on the results found in this research, it can be inferred that the modified Olsen method, due to its accuracy of results, reduced run time and lower costs is the most efficient method for the determination of phosphorus available to plants

Palabras llave : Extraction methods; Available phosphorus; Agricultural land.