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Effect Of pH, Phosphate and/or Malate on Sulfate Sorption on Andisols R.C. Suelo Nutr. Veg.
Pigna,Massimo; Jara,Alejandra A; Mora,María de la Luz; Violante,Antonio.
The sulfate sorption was studied on Andisols with variable mineralogical composition and low organic matter content in presence and absence of phosphate or malate ligands at different pH. Crystalline clay mineralogy was similar for all the studied samples, except for the 2C horizon of the pedon 2, which did not show crystalline minerals. The soil samples showed content of allophane ranging from 16% to 42%. The sulfate adsorption decreased when descending the first 3 horizons (A1, 2A2 and 3Bw1) of the pedon 1. This behavior was attributed to the decreasing organic carbon content. At different pH sulfate sorption was drastically decreased by increasing the pH from 4.0 to 7.0, precisely by 80% for sample 5 to 100% for sample 1. Experiments on the competitive...
Tipo: Journal article Palavras-chave: Sulfate; Adsorption; Andisol; Mineralogical composition; Phosphate; Malate.
Ano: 2007 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912007000100005
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UREASE ACTIVITY AND NITROGEN MINERALIZATION KINETICS AS AFFECTED BY TEMPERATURE AND UREA INPUT RATE IN SOUTHERN CHILEAN ANDISOLS R.C. Suelo Nutr. Veg.
Cartes,Paula; Jara,Alejandra A; Demanet,Rolando; Mora,María de la Luz.
Incubation studies were carried out to evaluate the effect of temperature and urea supply level on both the urease activity and the kinetics of N mineralization in two Andisols of Southern Chile. Our results showed that urease activity was higher in Piedras Negras soil (PNS) than Freiré soil (FS) at 24 and 48 h, and the enzyme was activated when the temperature increased from 5 to 21 °C. Urease activity followed a simple Michaelis-Menten kinetics. In PNS, the Michaelis Menten constant (Km) decreased, whereas the maximum enzyme reaction velocity (Vmax) and the catalytic efficiency increased when the temperature was raised up to 21 °C at 24 and 48 h of soil incubation. In FS, urease activity was the highest at 24 h, and it decreased at 48 h as a consequence...
Tipo: Journal article Palavras-chave: Urease activity; N mineralization; Urea; Andisols.
Ano: 2009 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912009000100006
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