Studies on nitrate accumulations in soils under the straw mulch and various kinds of tillage have shown that these treatments influence the nitrate content of the soil. The nitrates in an untilled soil, under sod, arranged by months are closely correlated with rainfall distribution of the year. Spring-plowed plats are regularly higher in nitrates than those unplowed, though this increase may not take place immediately following the plowing. These differences are pronounced during the summer season and almost disappear during the winter. Fall plowing has a distinct influence on nitrate accumulation as it is done in July or August. Significant nitrate increases follow after plowing for wheat, with greatest increases occurring in the middle of July. Weeds growing after wheat and plowed under in the middle of September seem to have no significant effect in raising the nitrate content to the equal of that in the soil without weeds and plowed early. Ordinary shallow surface cultivation increases the amount of nitrates in the surface soil, but excessive cultivation lessens it. The straw mulch has a decidedly depressing effect on the nitrate accumulation in the soil. This effect may be removed in about two months by removing the straw mulch.