ASSESSING NITROGEN MINERALIZATION FROM SOIL ORGANIC MATTER USING ANION EXCHANGE MEMBRANES

摘要

A simple method to assess differences in potential contribution of organic nitrogen mineralization to plant available N among soils may be useful in fertility research as well as routine soil testing. We deployed a method to assess mineralizable soil organic N using anion exchange membrane (AEM) burial. The method is based on a simple closed incubation system in which strips of AEM are buried directly in soil to adsorb NO3- released from organic matter. An index of mineralization was obtained using the amount of NO3- adsorbed on an AEM strip removed at the end of each incubation. The same incubation system but using 0.001 M CaCl2 solution to extract NO3-N was used as the reference method. The mineralization indices obtained from both methods were compared with each other and with plant uptake. A total of 74 soils from across Saskatchewan were used in the study to provide a range of soil properties. Correlations between test values and N uptake by plants in two separate experiments showed the 2 week AEM incubation to be more closely correlated with plant N uptake (r(2) = 0.86**** and 0.57 respectively) than the reference method (r(2) = 0.60**** and 0.48****, respectively).