Owing to the fact that sweet clover thrives on the barren Selma chalk (rotten-limestone) hills of Alabama and Mississippi and grows abundantly on worn-out, abandoned land in north-central Kentucky, it is often assumed that it will grow on soils too depleted in plant food to produce other crops. These regions represent soils which have become exhausted primarily in nitrogen and humus as the result of continuous cropping with nonleguminous plants. Some of these soils contain sufficient phosphorus and potassium for fair crop production, although this supply may be in such a condition that it will not become available fast enough to supply the needs of most crops. Sweet clover, like all legumes, has the power to extract nitrogen from the atmosphere, and on account of its extensive root system it is able to obtain phosphorus and potassium from a larger area than most plants. The large roots not only add a quantity of humus and nitrogen to the soil but they also open it up to a considerable depth, thus providing better aeration and improving its physical condition. Improved physical condition causes the bacterial flora to increase and thereby indirectly causes a larger quantity of unavailable phosphorus and potassium to be made available for plant use. On soils which are known to be low in phosphorus or potassium an application of fertilizer containing the necessary element should be made when sweet clover is sown without a nurse crop. However, when it is sown with a nurse crop or in the late summer or early fall on grain stubble, the residues left in the soil from fertilizers applied to the nurse crop will, under ordinary conditions, be sufficient for the plants. That sweet clover will respond readily to applications of phosphorus on soils low in this element has been well demonstrated by the farmers of Livingston County, Ill. In this county finely ground rock phosphate was applied to a portion of a number of fields at the rate of 1,500 to 2,000 pounds per acre. The phosphate was thoroughly incorporated with the soil just before seeding oats and sweet clover. In the growth of sweet clover there was a marked difference the following year between the treated and untreated portions of the fields. Those portions of the fields which received an application of phosphate not only contained many more plants on a given area, but the vigor and growth of the plants were most marked. On June 1 the plants on the treated areas were 12 to 15 inches taller than those on the untreated parts of the fields. This difference in the thickness of stand and the height of plants was so striking that the last round of the phosphate spreader was plainly distinguishable.