Annual applications of ammonium nitrate (449 and 898 kg/ha) were added to bromegrass growing on a Black Solonetz soil. Over a five-year period the average yield per year was 1,506 kg/ha on the check plots, 4,794 kg/ha on the plots receiving the 150-kg rate of nitrogen, and 6,779 kg/ha on the plots receiving the 300-kg rate.The nitrogen and potassium content of the bromegrass was increased from deficiency amounts on the check plots to sufficiency amounts on the fertilized plots- the sodium, aluminum, and iron content of the grass was somewhat reduced There was a significant reduction in soluble and exchangeable sodium in the A horizon of the fertilized soil as compared with the check. This, plus the greater growth of roots and the accumulation of nitrates in the subsoil of the fertilized soil, suggests a greater permeability in the fertilized plots. Supplementary experiments on Dark Brown Solonetz soils gave results similar to those obtained on the more humid Black Solonetz.
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Cairns et al. (1967) studied this question.