The effects of several environmental factors on the volatilization of ammonia from surface applications of urea on Dickson silt loam soil were studied under laboratory conditions. Increasing temperature and/or soil pH markedly increased ammonia volatilization. Ammonia volatilization from pH 6.5 soil was essentially the same when urea was topdressed, mixed with the top ¼ inch of soil or topdressed and watered into the soil with ¼ inch of water. Thus, it may be assumed that urea diffused through the soil to approximately the same extent with each of the three treatments. Some ammonia volatilization occurred without a concurrent drying process in the soil, but greater volatilization occurred when moisture was lost from the soil. The drying rate, however, varied over a wide range without affecting the rate of ammonia volatilization. Under conditions of very rapid drying, the soil became dry after 4 to 5 days of aeration, and ammonia volatilization was markedly decreased, presumably because hydrolysis of the urea was retarded due to lack of moisture. Ammonia volatilization was found to be directly related to initial soil moisture content presumably through the effect of this variable on the duration of the drying process.

Runoff samples from experimental plots at tour locations in Wisconsin were analyzed for total soil material, organic and ammonia nitrogen, available phosphorus, and exchangeable potassium. Correlation studies were carried out in an attempt to relate the selectiveness of the erosive process for a given fertility constituent to the quantity of eroded soil and concentration of suspended solids in the runoff. The relationship was found to be highly significant with multiple correlation coefficients of 0.63 for available phosphorus, 0.79 for nitrogen and for organic matter, and 0.87 for exchangeable potassium. The selectiveness of the erosive process for the four fertility constituents determined increases in the order: organic matter, organic and ammonia nitrogen, available phosphorus, exchangeable potassium. At the average values of erosiveness encountered in this study, the eroded soil material contained 2.1 times as much organic matter, 2.7 times as much nitrogen, 3.4 times 'as much available phosphorus and 19.3 times as much exchangeable potassium as the soil proper. The selectiveness of the erosive process for given runoff conditions appears to be greater on Fayette silt loam, 20% slope, than on Almena silt loam, 3% slope, or on Miami silt loam, 9% slope.

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In 31 inbred lines of maize, which varied widely in Zn concentration of the kernels, the germ (plus embryo), pericarp, and endosperm were found on the average to contain 138, 46, and 9.9 ppm Zn, respectively. The concentration of Zn in each of these kernel components varied widely among the 31 inbreds, however, and the concentration of Zn in the kernel could not be predicted from the relative size of the kernel components. In greenhouse experiments with 32 inbreds, Zn concentration in the kernel was not correlated with Zn uptake by plants or Zn concentration in plants grown on either Zn‐deficient or Zn‐fertilized soil. In field experiments, however, variation among inbred lines in their concentration of Zn in the kernel did appear to be related to the general level of Zn in the plant, but this factor was greatly modified by the extent to which the inbred was able to transfer Zn from the stalk and leaves to the ear. Inbreds Ky211 and Ky209 transferred approximately one‐third of their stalk and leaf Zn to the ear during grain formation. Approximately one‐fourth of the gain in ear Zn from tasseling to maturity by Ky209 × Ky21l could be accounted for by transfer from the stalk and a slight additional amount by transfer from the leaves.

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