Sources of Nitrogen from the Landscape

Nitrogen in Agricultural Areas

There are four major inputs of nitrogen in rural areas:

1. Nitrogen Fertilizer

Approximately 1.5 million acres of land is cropped in the Neuse Basin. Some of this cropped acreage is double-cropped every year. This means that two or more crops are produced on the same land in the same year. All of these crops require nitrogen fertilization. Some of these acres receive commercial fertilizers, while other acres receive animal waste.

Below is a table estimating nitrogen use from agriculture in the Neuse. The estimates are based on average nitrogen fertilizer use rates and the different acreage of crops planted (1996). These numbers will change based on the year-to-year cropping practices. The estimated nitrogen fertilizer (both commercial and animal) applied during this year was ~60,000,000 pounds of nitrogen per year.

Crop	Corn/Corn Silage	Soybeans	Potatoes	Small Grain	Hay*	Cotton	Tobacco
Acres (Ac)	161,704	230,500	12,934	133,025	26,153	123,309	68,309
N rate: lb/Ac	120/150	0	90	100	200	90	80
Total N: M lb/Ac	22.6	0	1.2	13.3	5.2	11.1	5.5

*Most of the hay has animal waste applied on it.

Crop use of applied nitrogen is variable. Nitrogen use depends on the rate of nitrogen applied, the type of crop, weather during the growing season, and general crop cultural practices. Apparent fertilizer nitrogen use efficiency for crops (nitrogen uptake in the grain or harvestable portion and stover) is presented below for the major crops produced in the Neuse Basin.

Crop		NUE (%)*	Reference
Bermudagrass		75	Woodhouse, 1969
Corn:	Tidewater/Arenic	40	Chancy, 1982;
	Coastal Plain/Irrigated	55	Kamprath, 1986;
	Piedmont Conventional Tillage	40	Wagger, 1992
	Piedmont Conservation Tillage	55
Sweet Potato		40	Ortega, 1996
Wheat		45	Scharf, 1993; Frederick & Camberato (pers. Comm.)
*NUE = Apparent nitrogen use efficiency

2. Animal Waste

The majority of animals produced in the Neuse River Basin are pork and poultry. Pork producers use lagoon systems to discard the animal waste. The nitrogen in the lagoons is applied at agronomic rates and used by growing crops.

3. Atmospheric Deposition

Cars produce nitrogen compounds that are released into the air. These nitrogen compounds can be returned to the ground attached to dust particles or through rain events, which adds nitrogen into urban areas.

4. Wildlife

Wildlife, such as squirrels, raccoons, birds, and even deer, add nitrogen to the urban environment. Wildlife is considered to be a minor source of nitrogen.

Dr. Deanna L. Osmond, Extension Specialist, NCSU, email: deanna_osmond@ncsu.edu