Plants require many organic and inorganic nutrients to complete their life-cycle. It has been established that some elements are required by plants in relatively large amount and are called major elements or macronutrients, e.g., C, H, O, N, S, P, K, Ca and Mg. Micro-elements or minor elements or trace elements are required by plants in very small amount, less than 1ppm. For example, Fe, Cu, B, Zn, Mn, Mo, Cl. Thus, Cr is not a micro-element.