Determination and use of the soil equivalent in fertilizer experiments

Alexander N. Sadovski

Abstract: The article presents the bases of a quantitative theory of the response of agricultural crops to mineral fertilization. Several additive and multiplicative empirical mathematical models of yield are described. The main equation represents yield as an intrinsically non-linear function of macro element fertilization. A new quantity is considered - soil equivalent, with the help of which is possible to estimate the quantity of the nutrient in the soil which is readily available to plants in a form equivalent to the applied fertilizers. Methods for determining the value of the soil equivalent and its use in estimating the parameters of mathematical models, as well as the values of fertilizers at which the maximum yield is obtained, are presented. The application of the models and the use of soil equivalent is illustrated by two examples. The first is from a field experiment with wheat at the experimental station in Nikolaevo, Pleven district, Bulgaria. The second is from the “3414” application design of NPK fertilizer for 3-yr-old Panax notoginseng in Yunnan Province, China.

Keywords: crop response; fertilizer experiments; soil equivalent

Date published: 2021-02-25