Potassium Efficiency of Different Crops Grown on a Sandy Soil under Controlled Conditions

Abstract

The objective of this work was to study K efficiency of
different crops and determine the plant parameters affecting it. The study
was carried out using 14 different crops and cultivars grown on a sandy
soil rich in humus, with two potassium fertilisation levels under
controlled conditions. The studied crops showed different K efficiency
reflected in different dry matter yield production in unfertilised relative to
fertilised treatments. All crops had, at low K supply, less than optimum K
concentration in dry matter, indicating that the soil K concentration did
not meet the K requirement of the plants. Thus, the ability to produce high
dry matter yield indicated superior adaptability to K deficiency. The
efficiency mechanisms employed by the different crops were low shoot
growth rate and/or high root length - shoot weight ratio and a high uptake
rate per unit root, i.e. the influx, or low internal K requirement. Crops
with high influx had higher calculated concentration gradients, since they
caused further decrease of the concentration at the root surface. As such,
they were able to create steeper concentration gradients between bulk soil
solution and root surface. This resulted in higher diffusive flux to the
roots.