A study was made of several Indiana farm crops in greenhouse pot expts. where borax was added in varying amts. to limed and unlimed soils. The crops were analyzed for Ca and B. It was found that plants will take up varying quantities of Ca and B depending upon the availability of these elements in the soil. From plant analyses it appears that each plant has a specific need for Ca and B, but the range varies greatly for different kinds of crops. The plant will make a normal growth only when a certain balance in the intake of Ca and B exists. If this balance is upset by a small intake of Ca, such as occurs on acid soils, the plant will have a very low tolerance for B. On strongly acid soils that contain a small quantity of available Ca, small additions of borax applied to the soil may cause boron injury to the plant. On soils of the humid region that have a very high Ca content, such as alkaline or overlimed soils, the plants require more B than on the acid soils. On such alkaline soils the balance in the Ca and B relationship tends to be upset because of the excess Ca the plants have absorbed. On overlimed Indiana soils, the plant may require more B than is available. B can be added in larger quantities on alkaline or limed soil without causing any injury or toxic effect than when added to acid soils. In practice, this means that farmers should be advised to be on the lookout for B starvation, particularly on overlimed or alkaline soils, and should be careful not to add overdoses of borax to acid soils where it may cause injury if added in too high quantities. The ideal balance between Ca and B for tobacco appears to be about 1200 of Ca to 1 of B; this ratio is in terms of equivalent wts. of the 2 elements. For soybeans the ratio of Ca to B is about 500 and for sugar beets about 100. It appears that this information will be helpful in predicting where more B is needed as well as to indicate where the application of B to soils may cause injury.