Effect of sampling date on chemical indices of the mineralizable nitrogen in soil

Abstract

In the 1960s and 1970s there was great emphasis on selecting simple laboratory methods to estimate the potentially available soil N that could be routinely used as a method for the N recommendations systems (Keeney and Breniner, 1966; Stanford and Smith, 1976). Many chemical extractants were investigated (acids alkali, salts, water…) as possible tools for assessing how much N may be mineralized, varying the concentration of the extractant, temperature and time of extractions.