ABSTRACT
T HE ASPECT OF FERTILIZER EVALUATION to be considered here is the ex-perimental comparison of two or more fertilizers supplying a common U nutrient to find the relative biological value of the nutrient in the different
sources. Chemical analyses can be made to determine the concentrations of the nutrient. But because the nutrient may occur in different chemical compounds, in different mixtures of compounds, and in different physical conditions, such as particle sizes, equal biological values often are not associated with equal quantities of the nutrient from different sources. Fertilizer evaluation is an important aspect of soil fertility research.
