This is a presentation of the amts. of total Mn found in various crops and soluble and replaceable Mn found in a number of soils in Illinois. The data shows a relationship between the amounts of manganese taken up by plants and its availability in soils. There is a discussion of the factors affecting the amts. of Mn taken up by various crops such as: soil reaction, variety of plant, productive level of the soil, and use of various fertilizers. On the other hand, there are factors affecting the availability of Mn in soils, namely: soil reaction, total bases, seasonal variation and biol. activity, use of fertilizers, total N, and nitrate N or the productive level of the soil.