Potassium fixation as affected by moisture conditions in some soils of Azerbaijan

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.