Keeping Ammonia in the Soil

Catch the drift of ammonia

With the renewed emphasis on getting the most benefit out of fertilizers, no one wants to lose ammonia from applied N fertilizer. Research has given us excellent management tools for keeping ammonia where it belongs — in the soil. This includes using the right form of nitrogen (N) fertilizer and placing it correctly, keeping urea-based fertilizers off the soil surface, and even using additives when appropriate. Farmers are very concerned with avoiding the loss of a valuable crop input.

Ammonia is also a concern for air quality in many locations. When emitted to the air, ammonia reacts with oxides of nitrate and sulfate in the atmosphere to form very fine particles of 2.5 microns or smaller, called particulate matter (PM). These fine airborne particles can come from a variety of sources and travel deep into the lungs, where they pose respiratory problems for some people, particularly those with asthma.

Ammonia from multiple sources and many locations volatize into the atmosphere. Common sources of ammonia include livestock, fertilizer, soils, forest fires, industry, vehicles, oceans, humans, pets, wild animals and waste disposal activities. Of these sources, livestock ranks by far the single largest source of atmospheric ammonia in the United States. There is still uncertainty about the absolute amount of ammonia released from these various sources, but new measurement techniques and assessments are improving these estimates.

Emission of ammonia from agriculture is a growing area of concern to regulators. The ag industry can adopt many management practices that reduce volatile losses from fertilizer. When fertilizer is properly managed, ammonia losses from susceptible fertilizers are very small. However, solutions for reducing ammonia emissions from animals are more complex. For example, animal ammonia emissions can arise from barns, pastures, waste storage facilities or from manure spread on crop land, each source requiring different management practices.

Currently, no regulations govern the release of ammonia from fertilizers or manures, but future policies and control measures appear likely as public awareness of this issue grows. Use every opportunity and best management practice to keep ammonia on-farm and in the soil where it can help nourish crops.

Source: Dr. Robert Mikkelsen, Western North America Director, International Plant Nutrition Institute

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