25 than in 195). Another possible explanation would be the reduced effect of plowing on lowering the average Sr90 level at root depth in successive years, The data in Figure 5 indicate that the sampling was surprisingly good, since the only considerable scatter occurs during the sharp spring rise, The monitoring of milk from large dairies appears to provide a good record of plant and dairy product activity levels over the growing season for a given area and also provides a basis for comparison of the activity of plants and dairy products t from widely scattered areas.