Nitrogen and Phosphorus Fertilizer, and Synthetic Soil Conditioner Treatments, as They Affect Small Grains on Eastern South Dakota Soils

The use of fertilizer is rapidly becoming an essential part of the soil management program of eastern South Dakota. Commercial fertilizer should be used to help correct the plant food deficiencies that normally occur under our best soil management systems. At the present time, most South Dakota soils have the capacity to supply all the essential elements required for general crop production except nitrogen and phosphorus. These two elements are required in large amounts by crops and as a consequence of our extensive type of farming are now deficient in many of the soils. Potassium is also required in large quantities by crops, but South Dakota soils are generally capable of furnishing sufficient amounts of this element. The soils have lost much of their productivity through cropping, erosion, and cultivation; therefore, fertilizer must be used to insure maximum crop yields. The increasing interest in irrigation in the James River Basin makes a study of factors limiting crop production very desirable. It is obvious that lack of moisture can be removed as a limiting factor by irrigation, but the possibility of other factors such as soil fertility and physical condition of the soil make investigations of fertility and other soil problems necessary in this area. The Redfield Development Farm has been under irrigation for six years and nitrogen deficiency was extensive on the entire farm until fertilizer or legumes had been used. This deficiency was especially severe where leveling had been done and was associated with compaction of the surface and removal of part of the topsoil. The purpose of this report is to record observations made in studies of the limiting factors of fertility and physical conditions of the soil, and the possible effects on these factors of synthetic soil conditioner applications. These studies were conducted in field and greenhouse experiments in which commercial fertilizers and synthetic soil conditioners were used