Comparison of soil nitrate extracted by potassium chloride and adsorbed on an anion exchange membrane in situ
1995
Pare, T. | Gregorich, E.G. | Ellert, B.H.
The 2M potassium chloride (KCl) extraction method used to measure soil nitrate (NO3(-)-N) concentrations in soils may introduce some artifacts caused by soil sampling, processing, and handling. Furthermore, this method provides soil NO3(-)-N concentrations for soil sampled at a particular time, whereas the dynamics of this anion in situ need to be better understood in order to develop a reliable in situ method as an alternative, an anion exchange membrane (AEM) was tested for its ability to adsorb NO3(-)-N from a soil cropped to corn (Zea mays L.) and amended with manure or inorganic nitrogen (N). In a field study, we compared the amount of NO3(-)-N adsorbed on an AEM and extracted with the 2M KCl method. The AEM was calibrated in the laboratory and placed at 15-cm soil depth for 2-wk periods during the corn growing season. Nitrate adsorption on the AEM and KCl-extractable NO3(-)-N were larger in the inorganic N treatment than in the manure or the control treatments throughout the growing season. The NO3(-)-N concentrations measured by the AEM method were correlated with NO3(-)-N extracted with 2M KCl (r2 = 0 78***), suggesting that the AEM method could be used to measure NO3(-)-N concentrations in agricultural soils.
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