ABSTRACT


Carlos Rojas W.1
 
Available phosphorus was measured by the North Carolina, Resin, Olsen, BrayKurtzN°1 and Bray-Kurtz N°2 methods, in 47 representative soil samples of theCentre South paddy area of Chile in Talca-Ñuble provinces.
The amount of P absorbed by rice plants (Oriza sativa, var. Oro) under flood conditions,in a greenhouse experiment, was obtained by plant analysis 30-60-90 daysafter seeding.Simple correlations were studied between: a) available P estimated by the fivemethods and P absortion by the rice plants; b) P absortion and available P with somechemical characteristics of the soils.
P absorbed by plants and that extracted by chemical methods gave positive and significantcorrelations with the organic matter content of the soils.P absortion by plants and that measured by chemical methods, gave the followingcorrelations coefficients: North Carolina, 0,879***; Resin, 0,800***; Olsen, 0,714***;Bray-Kurtz N°2, 0,683***, and Bray-Kurtz N°1, 0,635***.Because of the high correlation obtained by North Carolina and Resin methodswith P absortion by rice plants and the behaviour of such extractive solutions,both methods were better than the Olsen, Bray-Kurtz N°1, Bray-Kurtz N°2 methodsfor the evaluation of available P in this soils.
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1Ing. Agr. Programa Fertilidad de Suelos, Estación Experimental Quilamapu, Instituto de Investigaciones Agropecuarias (INIA), Casilla 426, Chile.