Response of Irish Potato (Solanum tuberosum) to the Application of Potassium at Acidic Soils of Chencha, Southern Ethiopia
An experiment was conducted at at acidic soil of Chencha, Southern Ethiopia to investigate the effect of different levels of potassium (K) fertilizer on the tuber yield of potato for two years (2007-2008). The treatments were 0, 30, 60, 90, 120, 150, 180, 210, 240, 270 and 300 kg ha-1 K. Potato varity CIP392618-511 was planted in a plot size of 3.75 x 3.9 m with inter and intra row spacing of 70 cm and 30 cm, respectivelly. The experiment was laid out in RCB design with three replications. The resut revealed that application of K has significantly increased the tuber yield of potato compared with the control in both years. There was a steady increase in the tuber yield of potato for K levels from 30 kg ha-1 up to 150 kg ha-1 in both years. There was also an increase in yield for K levels beyond 150 kg ha-1, but the increase was with decreasing trend. Combined analysis of the two years data showed that still the highest yield was obtained at K level applied at of 150 kg ha-1. It increased the total tuber yield from 18 tha-1 in the control to 53 t ha-1 (190%). The relationship between K levels and yield is best expressed with quadratic equation of y = -0.000x2 + 0.0.301x + 16.0 with a significant R² = 0.904. The partial budget analysis data showed that the highets net benefit and marigenal rate of return (10755%) was obtained from K applied at 150 kg ha-1. It is concluded that there is a significant and positive response of potato to applied K and the highest biological and economic yield was obtained at K level of 150 kg ha-1 suggesting that soils of Chencha area are deficient in K. Thus it is recommended that K fertilizer should be imported and applied in acidic soils of Chencha area to mitigate K deficiency for enhanced potato yield.