Calculation of K Uptake by Three Crops Grown Under Controlled Conditions Using a Mechanistic Model

Abstract

The aim of this study was to compare simulated and actual K
uptake by three crops, under different K concentrations in the soil
solution, in order to try to explain the underlying mechanisms of nutrient
uptake by these crops. In 2002, wheat (Triticum aestivum L. cv. Star),
barley (Hordeum vulgare L. cv. Madras) and sugar beet (Beta vulgaris L.
cv. C+ T) were grown on a sandy clay loam, with various K
concentrations in soil solution, in the growth chamber at the Institute of
Agricultural Chemistry, University of Goettingen, Germany. Data were
collected on K transport in soil and uptake by the three crops and used for
simulation by a mechanistic model which encompasses uptake by root
hairs as well. To quantify the significance of single soil and plant
parameters for nutrient uptake, a sensitivity analysis was carried out.
Under sufficient K in the soil solution, where transport was not limiting
uptake, the model predicted the actual K uptake correctly. At deficient K
concentrations, the model over-predicted the K uptake by both wheat and
barley but under-predicted that of sugar beet. The calculated
concentration profiles around the roots showed that for cereals wrong
values of the uptake kinetics caused the over-prediction of K uptake,
whereas for sugar beet some processes more than was considered by the
model took place.