ABSTRACT
Manganese is the eleventh most common element in the earth’s crust, with an average concentration of total Mn of 900 mg kg-1 [1]. Soils known to cause Mn deficiency to susceptible crops are usually impov erished siliceous and calcareous sandy soils of neutral or alkaline pH that favor chemical and microbial oxidation and immobilization of plant-available Mn2+. However, even these soils contain large reserves of total Mn relative to those removed in crop harvests. Therefore, result ing Mn deficiency of susceptible crops is due to insufficient availability of soil Mn to plants rather than an absolute shortage of soil Mn. Dis cussion on soil biogeochemistry of Mn is beyond the scope of this chap ter; the reader is referred to other sources [2-5]. While Mn availability can range from deficiency to sufficiency to toxicity, this chapter will concentrate on uptake and translocation of Mn in deficient and suffi cient conditions. Various other aspects of Mn nutrition can be found elsewhere [6-9].
