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.
Ridgeville, Ohio. Not to be confused with North Ridgeville, Ohio or Ridgeville Corners, Ohio. Ridgeville is an unincorporated community in central Clearcreek Township, Warren County, Ohio, United States. It is located on State Route 48 in the north central part of the county, in sections 30 and 36, T4R4, Between the Miami Rivers Survey.