Factors that Influence Loss of Fall Applied Fertilizers and Their Probable Importance in Different Sections of the United States

The purpose of this paper is to attempt to reconcile observed differences in effectiveness of fall versus spring applied fertilizers between states, and to point out factors that influence loss of fall applied fertilizers and their probable importance in different parts of the United States. Particular emphasis is placed on nitrogen fertilizers. Possibilities for leaching losses from fall applied fertilizers are evaluated from the standpoint of percolation of water from the soil in various areas and temperatures as they relate to conversion of ammonia‐nitrogen in fertilizers to leachable nitrate forms. On this basis, it appears that leaching losses would be negligible in the plains states and parts of Minnesota and Iowa. Progressing eastward, leaching from most soils is likely to increase, and fall applied nitrogen becomes questionable. In the South, where high percolation and temperatures predominate, fall application appears inadvisable. Possibilities for losses from fall application are also discussed from the standpoint of erosion losses, volatilization of nitrogen, and immobilization and reversion of nutrients.