EFECTO DE LA INCORPORACIÓN DE RESIDUOS ORGÁNICOS Y DOS TIPOS DE LABRANZA SOBRE LA ACTIVIDAD DE LA UREASA EN UN ALFISOL

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Abstract

A study was performed in order to evaluate the enzimatic acti-vity (urease) on an Oxic Haplustalf of the agricultural area of the Yaracuy valley (Yaritagua, Estado Yaracuy, Venezuela). The soil tillage was done with minimum and conventional til-lage operations and maize was planted. Three kinds of organic residues (

Crotalaria juncea, Pennisetum purpureum y Pha-seolus lunatus) were incorporated. Sampling was made (every 15 day) two depths (0-10 cm and 10-20 cm) and urease activity was determined. Urease activity varied from 91 to 156 ìg urea.g soil^-1.h^-1 in the first 10 cm, and 66 to 109 ìg urea g soil¹. h^-1 at 0-20 cm depth in the different treatments. The variation in the enzimatic activity was possibly due to changes in the soil moisture level.

Key words: Organic residues, urease, Yaracuy, tillage