The data given above show that on certain soil types in Iowa increases in the yield of wheat may be expected from top dressings with sodium nitrate. From these limited data it is difficult to determine which treatment may be the more profitable. The later applications were somewhat more efficient in increasing the protein content of the grain and approximately equal in increasing the yield when compared to early treatments. However, there is more difficultly connected with applying fertilizer to wheat at the later stages of growth. A top dressing of 100 or 200 pounds per acre of sodium nitrate to winter wheat in the early spring can be easily applied and might be very profitable. The increase in the weight per bushel due to the fertilizer treatment was not sufficient to be significant on either soil type. The increase in yield produced by the fertilizer was of more significance than the increase in protein content. The returns secured from the use of superhosphate were not appreciable on either soil type.