A field and laboratory study of nitrite accumulation under arable soil conditions was carried out using a considerable number of nitrogen fertilizers applied at various seasons of the year. The results show that nitrite will accumulate under neutral or alkaline soil conditions provided the rate of fertilization is heavy enough to produce a considerable concentration of the ammonium ion. Under field conditions, especially where the soils are not warm enough for rapid biological activity, the nitrite produced may persist for several months. For example, nitrite accumulating from urea applied in January (43 ppm N as NO2) persisted into May (31 ppm N). Amounts of nitrite up to 90 ppm N were produced under favorable conditions. More nitrite was produced from urea than any other nitrogen fertilizer. This is considered due to the high ammonia and pH conditions resulting from application of this material. In none of the field studies was there any evidence of nitrite accumulation from denitrification though occasionally heavy fertilization with nitrate fertilizer supplemented with straw was immediately followed by heavy rains or irrigation. From these studies, it appears that wherever two conditions occur, namely, fairly high ammonium concentrations and neutral or alkaline soil conditions, more or less nitrite accumulation may be expected.

Introduction. Experimental procedure Preliminary experiments. Sand-culture experiment Automatically operated sand cultures Composition of nutrient solutions. Control of nutrient concentration Methods of analysis. Nitrogen. Phosphorus. Sulfur Chlorine Calcium, magnesium, and potassium Results. The effects of high chloride and high sulfate Calcium-potassium relations Nitrogen-phosphorus relations The effect of increased nitrate on chloride and sulfate absorption Leaf color and nitrogen content as an index of nitrogen deficiency or excess. Symptoms of potassium and chloride excess. Discussion and conclusions. Li terature cited .

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There is an enormous amount of literature concerning various phases of the nitrogen problem. Most of the work reported, however, has been carried out under cropping, management, fertilization, soil, and climatic conditions foreign to those common to this region, and hence has little or no local value. Only such work, therefore, as shows the general trend of findings elsewhere is reviewed here.Relative to unaccounted-for losses of nitrogen, there is evidence that under some conditions considerable nitrogen escapes to the atmosphere. Russel (1921)6 reports that on one of the Broadbalk wheat plots receiving 14 tons of farmyard manure per acre annually, nearly 70 per cent of the nitrogen was unaccounted for and presumably disappeared into the air by gaseous volatilization. In the first five years of a study with a group of California soils in galvanized-iron tanks, Burd and Martin (1931) reported unaccounted-for losses of nitrogen averaging about 100 pounds per acre per year from both cropped and uncropped soils.Lipman and Blair (1921), working in New Jersey, obtained evidence of unexplained losses of nitrogen from a loam soil, amounting to 1,000 pounds in a ten-year period. In lysimeter experiments on New York soils, Bizzell (1944) reports unaccounted-for losses of nitrogen under cropping systems of continuous timothy, as well as in rotations of corn, oats, and timothy, ranging from 289 to 436 pounds of nitrogen per acre for a twelve-year period. In another fifteen-year lysimeter experiment reported by Lyon and Bizzell (1927), the nitrogen loss unaccounted for by crop removal and drainage amounted to 25 pounds per acre per year. In lysimeter experiments at the New York State Agricultural Experiment Station, Collison, Beattie, and Harlan (1933) reported losses ranging from 11 to more than 80 pounds per acre per year.In a study of nitrogen and organic-matter losses of Utah soils, Bracken and Greaves (1941) noted that amounts of nitrogen considerably in excess of those removed by crops were lost from the soil. They think that leaching or erosion accounts for but a small amount of this loss, and suggest that chemical or biological changes promote the volatilization of nitrogen.