Effect of Compound Fertilizer as a Sole Source of P and K On Potato Yield.

Potato crop requires relatively high amounts of N, P, and K for maximum yield.  Soils in the Kingdom of Saudi Arabia are usually deficient in N and P.  Furthermore, soil available K is not sufficient to produce high potato yield without K fertilizer supplement.  The objective of this experiment was to study the effect of compound fertilizer as a sole source of P and K and to determine the rate of 11-29-19 that would give farmers profitable yield.  Another objective was to evaluate the replacement of various P and K fertilizer sources with an NPK compound fertilizer for potatoes under commercial field conditions.

Field experiments were conducted in summer 2004 and 2006 in the Hail region of Saudi Arabia using a complete randomized block design with 6 levels (0, 600, 700, 800, 900, and 1000 kg of 11-29-19/ha) and 4 replications.  Addition of 800 kg/ha of 11-29-19 or more increased fresh tuber yield significantly (p < 0.05) in both years.  Leaf N and P concentrations at 45 days after emergence were increased with increasing levels of 11-29-19 in the first season, but no significant difference was detected in the second season.  Leaf K concentration was not significantly affected in both seasons.  Leaf nutrient concentrations were at or above optimum levels for high yield.  Results of this study indicated that soil application rates of 700-900 kg/ha at pre-planting besides natural soil and irrigation water K were sufficient to produce economical potato yield.