Calculation of K Uptake by Two Crops Grown under Field Conditions Using a Mechanistic Model

Abstract

The objective of this study was to compare simulated and
actual potassium uptake by two crops, using soil and plant parameters
obtained from a field experiment conducted in 2003, in Bavaria, southern
Germany. Sugar beet (Beta vulgaris L. cv. Kawetina) and wheat (Triticum
aestivum L.cv. Star) were grown on a sandy clay loam in the field. The K
transport in soil and uptake by the plants were simulated by a mechanistic
model which encompasses uptake by root hairs as well. A sensitivity
analysis was carried out in an attempt to understand the significance of
single soil and plant parameters for nutrient uptake. The simulation model
calculated only 34 % of the measured sugar beet uptake throughout the
growing period. The lowest calculated K influx (only 9 % of measured
value) corresponded to the period June 24th
–July 8th of highest actual
uptake. Sensitivity analysis showed that, under low K concentrations, K
concentration in the soil solution was the most important factor
controlling K uptake, especially for sugar beet. This indicates that roots
may have increased the K concentration in soil solution by chemical
mobilization. Research is needed to understand the mechanism by which
this is achieved.