Rhizosphere phosphorus depletion by three crops differing in their phosphorus critical levels

RUBIO G; FAGGIOLI V; SCHEINER JD; GUTIERREZ BOEM FH,

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE-ZEITSCHRIFT FUR PFLANZENERNAHRUNG UND BODENKUNDE

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2012 vol. 175 p. 810 - 817

1436-8730

It has been reported for many soils that maize (Zea mays L.) has a higher soil-P critical levelthan soybean (Glycine max L.) and sunflower (Helianthus annuus L). The objective of this workwas to compare the rhizosphere P depletion in these three species in order to investigate if theydiffer in their capacity to acquire soil P. Sequential P fractionation and pH were determined in rhizosphere and nonrhizosphere soil samples from field and greenhouse experiments. Neither sunflower (the species with highest rhizosphere acidification) nor soybean or maize showed a significant relationship between P depletion and rhizosphere pH. The labile P fraction and the NaOHPi fraction had lower values in the rhizosphere than in the bulk soil in 38% and 77% of the studied cases, respectively. Sunflower and especially maize presented a more intense Pi depletionthan soybean. The comparison between sunflower and maize revealed that neither of them tooka clear advantage over the other in terms of P depletion. Rhizosphere Pi depletion was associatedwith the amount of P acquired by the plants. We conclude that the accessibility to differentP pools does not explain the differences in soil-P critical levels among the three species.