THE NITROGEN CONTENT OF THE SOIL AS RELATED TO THE PRECIPITATION-EVAPORATION RATIO

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Abstract
A study was made to ascertain the relation between N.S. quotients (substitute for the true precipitation-evaporation ratio) and total N of soils in regions of equal temp. The 2 isotherms selected belong to the temperate region (annual temp. 51-53[degree]F.) including territory in Colorado, Kansas, Missouri, Illinois, Indiana, Ohio, and New Jersey, and to the subtropical region (annual temp. 64-68[degree]) in Texas, Louisiana, and Mississippl. In both regions the average N of grassland soils increases logarithmically with humidity factors (N.S. quotients) while that of subtropical timber soils is not influenced by humidity factors. The N-humidity factor relationship is discontinuous, consisting of 2 separate curves, one for grassland soils and one for timber soils. In the temperate region the C:N ratio does not vary with the humidity factors. Its average value is about 113.