Response of crops to fertilizer application in volcanic soils

Abstract

Potassium (K) has been considered as a non-deficient nutrient in most Ethiopian soils. However, some studies recommended K application to K sufficient soils if K/Mg ratio is 351 mg kg−1). The K/Mg values ranged from 0.60 to 0.80 in Mollic Nitisols (aric, humic), 0.70 to 0.88 in Pellic Vertisols (aric, gilgaic, mazic) and 0.71 to 1.04 in Vertic Luvisols (aric, nitic), and the values increased with an increasing K rates. However, wheat, tef and maize grain yields showed an increasing trend up to K/Mg ratio of 0.71 in Mollic Nitisols (aric, humic), 0.78 in Pellic Vertisols (aric, gilgaic, mazic) and 0.88 in Vertic Luvisols (aric, nitic), respectively, and declined above these values.

Keywords

• K critical level
• K/mg ratio
• Luvisols
• Nitisols
• Vertisols
• Physics