Potassium is a very important nutrient in sugarcane nutrition, as well as in its quantity and quality of yield. For an evaluation of soil potassium availability and fertilization management, Quantity-Intensity (Q/I) curves are useful. This study was conducted to obtain such Q/I parameters as readily exchangeable potassium ( , slowly exchangeable potassium (Kx), potassium activity ratio (ARK) and potassium potential buffering capacity (PBCK) as well as correlations between these parameters and physical & chemical charactristics in 0-30 cm samples of soil under sugarcane cultivation in Khuzestan Province of Iran. The results indicated that ranged from 0.0353 to 0.2257 with an average of 0.0835 meq100g-1 , Kx from 1.063 to 4.143 with an average of 2.325 me100g-1 , AR0 ranging from 0.0125 to 0.0941 with an average of 0.040 (mmol L-1) 0.5, and finally PBCK ranging from 1.2034 to 3.0651 with an average of 2.232 . The Q/I curves followed the common shapes observed in literature but varied in different soils. Correlations between PBCK and clay percentage (r=0.83**), CEC (r=0.81**), and exchangeable potassium (r=0.62*) were significant but between cultivation history, and soluble potassium, and pH were not significant . The results also indicated that long-term cultivation caused the available potassium to decrease but it had no effect on unavailable potassium.
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