Molybdenum Enrichment of Plants Grown on Fly Ash‐Treated Soils

Abstract

AbstractAlfalfa, bermudagrass, white clover, barley, and Swiss chard (Medicago sativa L., Cynodon dactylon L., Trifolium repens L., Hordeum vulgare L., and Beta vulgaris L., respectively) were grown on calcareous and acid soils treated with fly ash at rates ranging up to 80 g kg−1. The objectives were to investigate the availability of Mo to crops in relation to rate of fly ash application, type of recipient soil, and time of harvest. Application of fly ash to soil resulted in marked enrichment in plant Mo, especially at rates ≥ 40 g kg−1. Except for white clover, Mo concentrations in plants grown on the calcareous soil were greater than those in plants grown on the acid soil. Comparison between Mo concentration in early‐ and late‐season clippings of alfalfa and white clover and in plants grown sequentially indicated the presence of a relatively long‐term supply of Mo in fly ash. It is concluded that in situations where soils are deficient in Mo, plants may benefit from small applications of fly ash to soils, but Mo concentrations in plants grown on fly ash‐treated soils should always be carefully monitored.