Influence of potassium fertilization, water and salt stress, and their interference on rheological soil parameters in planted containers

Rheological parameters of an artificial mixture of soil and quartz sand were analyzed with regard to potassium (K) fertilization, water and salt stress (via sodium). The examinations were part of a plant container experiment where originally plants were subjected to the factors mentioned beforehand. While for the plants, K fertilization had a positive impact on water use efficiency and could compensate partly for the negative impact of salinity and water stress, the soil itself showed no clear impact of K fertilization on maximum shear stress during an amplitude sweep test in oscillatory modus. Instead, the impact was overridden by the coarse substrate and the other influencing factors water and salt stress as well as the state of drainage in which the samples were measured. The results show a destabilizing effect of sodium, while the water stress caused no significant additional aggregation in the soil because of the coarse and thus rapidly drained substrate. However, homogenization revealed structure development during the plant experiment. It can be assumed, that in less coarse soil material the impact of the considered factors K fertilization, water and salt stress is more pronounced.