Abstract:
Potassium is the third macronutrient provided in a complete fertilizer. Exhaustive cropping of potassiumdemanding
crops like potato, sunflower and sugar beet leads to depletion of soil non-exchangeable potassium
and subsequent fixation of added potassium. In this study the effects of different soil moisture conditions on
potassium fixation were investigated in some potassium-depleted soils of Azerbaijan province. For this purpose
6 soil samples were selected from among 17 locations where the amounts of boiling nitric acid extractable-K
were considerably lower in cultivated soils compared to the adjacent non-cultivated soils. The amount of
potassium added to the soils (250 mg K kg-1) was equivalent to the amount of depleted K. Results showed that
the amounts of K fixation were significantly (P<0.001) increased (14.5%) after air-drying. There was a
significant (P<0.01) positive relationship between the amount of K fixation and clay content. Three soil samples
with different amounts of K fixation were chosen from among six soil samples for subsequent studies. Early airdrying
of the soils was significantly (P<0.01) caused more K fixation comparing to middle and late air-drying.
According to the results obtained the effect of soil matric potential (-30, -100, -500 kPa) on K fixation was
significant (P<0.001).The highest amount of K fixation was found for -100 kPa. Furthermore, K fixation during
two months of incubation was significantly (P<0.001) elevated with the increase in the number of wettingdrying
cycles (1, 5, 10 and 20 cycles). The amount of K fixation was increased by 23% with wetting-drying
incubation (under 20 cycles) compared to constant field capacity incubation.
