WITH the development of highly sensitive γ-ray detectors, it has become possible to carry out nondestructive measurements of the low levels of γ-ray activity emitted by various biological materials. Since γ-ray measurements may be made rapidly without any special preparation or modification of the material measured, the application of this technique to agricultural research problems has much to recommend it. The advantages of the nondestructive γ-ray measurement technique appear to justify exploratory research to determine if such measurements may be used to estimate other factors to which they may be related1.