The Nitrogen Cycle. Ammonium (NH4+) and nitrate (NO3â) are the predominate inorganic forms of nitrogen in soils. Ammonium exists in exchangeable and nonexchangeable forms. Nitrite (NO2) and nitrous oxide (N2O) are present in soil in lesser quantities. Plants normally use nitrogen in only the ammonium and nitrate forms. Nitrite is actually toxic to plants. The nitrogen cycle (Figure 5.2) shows reactions that various inorganic nitrogen compounds undergo in soil.
Ridgefield, Washington. Ridgefield is a city in the pastoral, rolling-hills countryside of northern Clark County, Washington, in the United States. The population was 4,763 at the 2010 census.
Ridgefield, New Jersey. Ridgefield is a borough in Bergen County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 11,032, reflecting an increase of 202 (+1.9%) from the 10,830 counted in the 2000 Census, which had in turn increased by 834 (+8.3%) from the 9,996 counted in the 1990 Census.