[Agronomic effectiveness of triple superphosphate and rock phosphate in wheat genotypes using the isotopic dilution method. II. Isotopic parameters] | Eficiencia agronomica de superfosfato triple y roca fosforica en variedades de trigo utilizando el metodo de dilucion isotopica. II. Parametros isotopicos

anglais. On one hand, the introduction of new genotypes adapted to the soils of the volcanic region of Chile has been considered as a good strategy to promote sustainable agriculture. On the other hand, important deposits of rock phosphate in Chile woul allow the use of an alternative source of P for these new genotypes. Thus, a greenhouse trial was carried out to evaluate the agronomic effectiveness of rock phosphate (RBI) from Bahia Inglesa and triple superphosphate (TSP) , through the sup32P isotopic dilution method. The parameters measured were P derived from the labeled fertilizer (%PdfF), P derived from de soil (%PdfS) and P derived from the RBI (%PdfR). Great differences among the cultivars tested were obtained for all the evaluated parameters. Isotopic techniques allow to measure the P from TSP and RBI and also P from the soil. The results showed that P from RBI is very low assuming that the RBI is not an effective alternative as phosphorus fertilizer for volcanic ash soils with pH higher than 5.5. The wheat genotypes tested exhibit great differences among them, with regard to availability of P in the soil and from the RBI. This means that both parameters are associated to genetic and physiologic characteristics of genotypes, considering the primary P availability was identical

espagnol; castillan. La introduccion de variedades adaptadas a suelos volcanicos en Chile, es una estrategia para el desarrollo de una agricultura sostenible; la existencia de yacimientos de roca fosforica permitiria la utilizacion de fosforo para estas variedades. Se realizo un ensayo en invernadero para evaluar la eficiencia agronomica de superfosfato triple (SFT) y roca fosforica de Bahia Inglesa (RBI) utilizando el metodo de dilucion isotopica. Se determino el % de P en la planta proveniente de SFT (%PddF), el % de P proveniente del suelo (%PddS) y el % de P proveniente de la RBI (%PddR); ademas, se determino el uso eficiente del SFT (UESFT), de la RBI (AsubR). Se encontraron diferencias estadisticamente significativas entre variedades de trigo . Tecnicas isotopicas se determinaron cuantitativamente las fuentes en estudio, SFT y RBI, incluyendo el P nativo del suelo. El P proveniente de la RBI, es bastante bajo, o sea que la RBI no es una alternativa efectiva como fertilizante fosfatado para los suelos derivados de cenizas volcanicas de pH superior a 5.5. Las variedades de trigo presentaron diferencias significativas en la disponibilidad de P en el suelo y de la RBI, indicando que estos parametros estan asociados a las caracteristicas geneticas y fisiologicas, debido a que inicialmente dispondrian de la misma cantidad de nutrimiento