Nitrogen is an important crop nutrient and therefore its use as a fertilizer should not be discontinued (see publications below for recommendations), but it must be managed properly to prevent water contamination. Nitrate (NO3) is a naturally occurring form of nitrogen found in most soils. Nitrate is a colorless, odorless, and tasteless compound and it is also one of the most common groundwater contaminants in Nebraska. Though nitrate occurs naturally in some groundwater, in most cases levels above 3 ppm are the result from human activities. Nitrates form when microorganisms break down commercial fertilizers, decaying plants, manures or other organic residues involved in crop production systems. Other sources of nitrate in water include septic systems, wastewater treatment effluent, animal wastes, industrial wastes, and food processing wastes. Usually plants take up these nitrates, but sometimes precipitation or irrigation water can transport nitrates out of the crop rootzone and into the groundwater. Several health concerns may be related to the consumption of high nitrate water, which is defined by the EPA acording to the Safe Drinking Water Act as 10 ppm NO3-N.
Nonpoint source contamination of groundwater by nitrate-nitrogen is a problem across Nebraska. One reason that the 23 Natural Resource Districts (NRDs) in Nebraska were created was to manage groundwater quality and quantity using locally developed management practices. Each NRD has developed and is implementing a groundwater quality and quantity management plan that outlines actions to be taken to address nitrate contamination and conserve groundwater. You can find more information about your local NRD with this NRD locator. Producer education is a key component of all NRD Groundwater Management Plans. The University of Nebraska Extension developed the original version of a training program that was delivered via face-to-face interactions between producers and UNL Educators.
Nutrient Management: Nitrogen Publications
Nebraska Extension has many tools and resources for interpreting soil tests. Most of the materials do not focus on one nutrient, but discuss all the nutrients related to a specific crop.
One regional publication focuses on nitrogen specifically:
Agricultural Nitrogen Management for Water Quality Protection in the Midwest: a Heartland Regional Water Coordination Initiative Publication RP189; PDF* ( 1.85 MB; 32 pages)
Our complete nutrient management guide explains each nutrient and gives recommendations for each crop:
Nutrient Management for Agronomic Crops in Nebraska Extension Circular 155
A guide to nutrient use from all sources for the production of Nebraska's major agronomic crops. Content in this 176-page book is divided into two main areas: the basic principles of soil fertility for the primary, secondary and micronutrients and fertilizer recommendations for individual crops.
NebGuides for each of the major crops:
Fertilizing Winter Wheat EC 143* (890KB; 10 pages)
Soil testing, recommended rates, and timing for fertilizing winter wheat with nitrogen, potassium, and micronutrients.
Fertilizer Management for Alfalfa* G1598
NebGuide discusses adequate soil fertility in alfalfa production on dryland and irrigated soils.
PDF only (225 KB; 4 pages)
Fertilizer Suggestions For Corn EC117* (632KB; 6 pages)
Fertilizer nutrient requirements for corn are based on expected yield and nutrient levels in the soil.
Fertilizer Suggestions for Grain Sorghum G1669
Fertilizer nutrient needs for grain sorghum are based on expected yield, nutrient levels in the soil and fertilizer-nitrogen costs.
PDF version (592 KB; 4 pages)
Fertilizing Sugarbeet,* Chptr. 8 from the Sugar Beet Production Guide, EC 156 (536 KB; 6pages)
Soil testing and calculating recommended rates for nitrogen, phosphorus, potassium and micronutrient fertilizers for sugarbeet.
*Document in pdf format. Download the free Acrobat Reader.