Potassium forms for main soil orders in the north of Iraq

الملخص EN

Fifteen soil samples were collected from five locations in the North of Iraq from three surface genetic horizons for the five locations (Semeel (Vertisols), Imerik (Aridisols), (ierderash (Inceptisols), Perdi (Aridisols) and Wermawa (Mollisols)] to study the forms of potassium and its distribution with the depth.

All studied soils are calcareous and non-saline soils contain low organic matter.

the studied forms of K in the surface horizons of the studied soils (soluble, exchangeable, available, non-exchangeable, mineral and total potassium) were ranged between (12 - 40, 82 - 229, 97 - 246, 656 - 3800, 462 - 2933 and 1200 - 5400) mg kg'1 respectively, while in the intermediate (A and Al) soil horizons were (5 -26, 67 - 214 , 72 - 216 , 676 - 3040 , 709 - 2048 and 1700 - 5200) mg kg'1 respectively and in the third horizon of studied soils were (4 - 14 , 68 - 191, 70 - 186 , 345 - 3232 , 419 - 4516 and 1700 - 5800) mg kg'1 respectively, this illustrates the amount of soluble, exchangeable, available (soluble + exchangeable), non-exchangeable decreases with the depth.

The constituted percent of the soluble, exchangeable; available; nonexchangeable and mineral potassium from total-K in all pedons equal to 0.469; 4.185 ; (4.538); 52.141 and 43.318 respectively.

Correlation study illustrates positively and significantly correlated between total potassium with exchangeable, available, non-exchangeable, mineral, while positively and significant relation demonstrate between exchangeable, available, non-exchangeable with silt content in the soils, but positively relation found between soluble potassium with pH and negatively to EC.

The high amount of soluble K found in Perdi pedon (Aridisols) but higher amount of the exchangeable, non- exchangeable, available and total-K demonstrate in Imerik pedon (Aridisols) while large amount of mineral-K shown in (ierderash pedon (Inceptisols)