NUTRIENT UPTAKE: A microcomputer program to predict nutrient absorption from soil by roots

Abstract

Soil nutrient uptake by plant roots can be described mathematically. Computer programs (Claassen-Barber, Barber-Cushman) have been developed to solve the mathematical model and predict nutrient uptake. The Barber-Cushman model uses the initial nutrient concentration in solution, the buffer power, the effective diffusion coefficient, and the mean water influx to describe the kinetics of nutrient supply through the soil to the root. The initial root length, the mean root radius, the rate of root elongation, and the half distance between roots are used to describe the root system. Michaelis-Menten kinetics with the maximal influx at high concentration (Imax), the nutrient concentration below which influx ceases (Cmin), and the nutrient concentration in solution minus Cmin where net influx is one-half Imax (Km), describe influx into the root. For each problem, the program gives the parameter values, a table of relative nutrient concentration with distance from the root and a plot of these data at the final time, a table of nutrient influx with time and a plot of these data, and the calculated nutrient uptake by the plant. Previously only mainframe computer programs were available. The objective of this article is to describe a user-friendly personal computer version of the Barber-Cushman model describing plant nutrient uptake.