Abstract
Tests of ammonification and nitrification on the nitrogen of soybean cake and herring cake in two strong acid citrus orchard soils were made in the laboratory, under the dryfarm condition. The results may be summarized as follows : In these strong acid soils, the most part of the mineralized nitrogen in the soybean cake and herring cake plots remained in the form of ammonium nitrogen during the experiment lasted 175 days, while the addition of calcium hydroxide accelerated the nitrification in these plots. The rate of mineralization of the nitrogen in the case of soybean cake was slightly inferior to that of herring cake in both soils.
