21 In controlled exmerincents, “enzel has ghown that the available strontium-% We fenzel, 2, G., Soil Seicnce 77, 419 (195k). to available calcium ratio in plants is about half the corresponding soil ravic, Under uncen' rolled field conditions, the relation of plant and soil level will be influenced by many comlicating factors including rnossible leaf reicntion of strontium-90 falleut, variable root depth and soil moisture depth, the shurn gradient of strontium-90 concentrati-n in the soil surface layer, and the anrilcation of fertilizers comaining calcium. These factors undoubtedlr account “or considerable scatter in the results, In the last column of Table 5S, thé strontium~90 to calcium level in al- folfas are arbitrarily connsred to the some ratio in the 0-2" layer of the scils on which they vere grown, The resvits arvear quite reasoneole with the excor- tion of those for ‘ickee, Yan ‘Jinkle and Carver ferms. The high concentration for the McKee farm plant material may be expleincd by the fact that the samnle taken vas a mixture of bromegrass and ladino clover vith snallower root denth than that of alfalfas and thus may relate to a higher soil level, Furthermore, the growth was short and sparse and was gleaned from several scattered patches apart from the point of soil sampling. Thus, dirfer- enees in soil calcium or strontium~90 or a higher leaf retention effect mav be involved, That this samnle is nct cheracteristic of the average “icKee farm vecetation is indicatcd by the result of 0,51 +-0,03 SU. for the bone of a ~ NYOO “eKee farm stecr killed in September 1955 (see CL 813-P and compare with CL 1011 and 1012). The three 1955 Chicago }iilkshed animal bone samples show the lovest strontium-90 level for the farm vith the highest soil calcium level and the highest bone level for that of the lovest calcium, as would normally be expected. SZ