The Importance of Potassium Buffer Power in the Growth and Yield of Cardamom

Abstract

Cardamom (Elettaria cardamomum M.), one of the world's most valuable spice crops, has very high potassium (K) requirement and the K fertilizer recommendations for it are routinely made on the basis ofNH4OAc extractable K which has not given satisfactory results in many instances. When prices of K fertilizers escalate, as has recently happened in India, and the K fertilizer recommendations are unreliable, farmer confidence will be at risk. This investigation was initiated to test whether, as an alternative, determination of the K buffer power of the soils and its integration into routine soil test K data would result in better predictability of soil K availability. Results showed that as opposed to a non-significant low r value between NH4OAc extractable K and leaf K in the absence of the K buffer power, its integration resulted in a very highly significant r value explaining nearly 44% of the variation in leaf K. Soil samples and leaf samples were obtained from 94 locations on nearly 20,000 ha in the two most important cardamom growing states of Southern India. Capsule yield was closely related to the K buffer power of the soils and not NH4OAc extractable K and it is suggested that a re-orientation of K fertilization schedule based on K buffer power of the soils, rather than merely on NH4oAc extractable K, might lead to better and more reliable K fertilizer recommendations.