LOSSES OF NITROGEN AND ORGANIC MATTER FROM DRY-FARM SOILS

Abstract

N and organic-matter changes were studied on 9 dry-farms in Cache Valley, Northern Utah, and 12 in Juab Valley, Central Utah. In Cache Valley, wheat land had lost 15.9% and 14.8% of N from the 1st and 2d to 3d feet, respectively, as compared to adjacent virgin land. The loss of organic matter amounted to 20.4% in the 1st foot. For Juab Valley the corresponding losses of N were 14.5 and 10.6%, and for organic matter 18.8%. On severely eroded areas in Cache Valley, loss of N and organic matter amounted to 58.5 and 57.8%, respectively, as compared to those from level uneroded land in wheat. In Cache Valley, it was estimated that crops of wheat removed 735 lbs. of N per acre out of a total loss of 2,560 lbs., leaving 1,825 lbs. or 71.3% unaccounted for. For Juab Valley the total loss amounted to 1,186 lbs. with 402 lbs. removed by the crops, leaving 784 lbs. or 66.1% unaccounted for. The N equilibrium for Juab Valley soils was considered to be near 0.09% and for Cache Valley soils approx. 0.17%. As a result of temp. studies in the field and laboratory, it was considered that the higher temp. in combination with soil moisture, particularly during the fallow period, may possibly be responsible for the unexplained losses of N.