study of potassium fixation capacity in some under-cultivation sugarcane soils in khuzestan

abstract this study was conducted to investigate, under incubation conditions (fc moisture and temperature of 30o c), the effect of the potassium concentration and the cultivation background on the k- fixation in khuzestan’s sugarcane under-cultivation soils. for this reason, 70 complex soil samples in 35 pairs each coupled out of two different depths (0-30 and 30-60 cm), chosen from the under-cultivation soils of 3 different farmland: haft tappeh agro- industry (with a maximum cultivation background of 41 years), karun (with a maximum cultivation background of 30 years), and sugarcane development plan (with a maximum cultivation background of 8 years) were supplied. in order to study of the effect of the potassium concentration and the sugarcane cultivation background on the k- fixation, a factorial experiment with 4 levels of the k concentration (0, 150, 300, 600, mg kg -1), and 4 levels of the cultivation background (less than 10 years, 10-20, 20-30, and more than 30) in based on completely randomized design was conducted. the results showed that the amount of potassium fixation ranged from 17.74 mg kg -1 to 129.15 mg kg-1. with an increase in the potassium concentration, the amount and percentage of the k- fixation were both increased (p <0.01).the results showed that even after 6 month of incubation, about 70 percent of the k added still remained in the form of available for the plant. until before 30 years of cultivation background, there was not observed any significant difference between various backgrounds and amount of k- fixation as well as increase in potassium availability, but at longer times, k- fixation was increased with increase of cultivation background. (p<0.01).the results showed that the amount of available potassium, in 82.8 percent of the surface soils (0-30 cm), and 85.8 percent of subsurface soils (30-60 cm), is less than 120 mg/kg of soil. a negative and significant correlation between the amount of potassium fixation and clay, ph, cec, om, exchangeable and available potassium was obtained.