Date of Award:
Master of Science (MS)
Agricultural Systems Technology and Education
Howard B. Peterson
Wheat is one of the major crops of Utah and for more than 50 years farmers have been raising wheat on the dry lands of the state. The system they use is known as the alternate cropping or crop-follow system and consists of one year of crop alternating with one year of clean cultivation known as fallow.
Wheat removes a considerable amount of the natural plant food elements from the soil each year. This is especially true of nitrogen. According to Bracken and Greaves (9) the original low supply of nitrogen in most Utah soils together with the depleting effects of alternate wheat and fallow has the possibility of making nitrogen rather than moisture the limiting factor of crop production in certain dry-farm areas.
The amount of nitrogen removed from the soil by the wheat crop is only a portion of the total supply. Such factors as leaching to a lower depth beyond the feeding range of the plant, erosion, denitrification, and volatilization through biological and possibly chemical action are thought to be responsible for the loss of nitrogen unaccounted for by crop removal. The results of several investigators indicate that this loss is approximately twice as much as was removed by the crop.
Since nitrogen is one of the major factors responsible for high yields and high quality of wheat, it naturally follows that any reduction of the amount of nitrogen in the soil produces a corresponding reduction in yield and quality of wheat. Recent reports show that this condition exists in Utah as well as in other areas. As a result of this reduction in yield and quality of wheat, processors are concerned about the problems. The seriousness of the problem cannot be over-emphasized. Ways and means of checking these losses and subsequently increasing the yield and quality are being studied.
Three possible procedures for increasing soil nitrogen have been suggested: 1. the use of legumes, especially alfalfa, in a rotation program; 2. non-symbiotic nitrogen fixation: and 3. the use of commercial fertilizers.
Since legumes have not been grown to any great extent, the only other natural source of nitrogen has been non-symbiotic fixation. Evidence in this field of investigation, however, indicates that this source is inadequate and that other sources must be bad. Also, the data indicate that no effective methods have been found which increase non-symbiotic fixation. Limited information suggests that further study is needed on the use of legumes for increasing the nitrogen and organic matter content of dry farm soils. This investigation is confined to the use of commercial fertilizers as one solution to the general problem.
Sampson, I. G., "Fertilizer Trials on Dryland Winter Wheat" (1951). All Graduate Theses and Dissertations. 3660.
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