Forage Nitrate Risk Assessment - Utilizing new Technology

Published: 2022
By Mike Schuldt

The ability to accurately evaluate the risk of potentially toxic nitrates in various forages in the field has long been a service producers rely on MSU Extension to provide. Changes in production practices coupled with three years of drought have caused a drastic increase in the use of annual forage crops as feed for livestock. Along with this comes an increased demand for evaluating nitrate risk as these annual crops accumulate nitrate at toxic levels much more readily than traditional perennial grass or legume forage crops. Testing methods traditionally utilized by MSU Extension agents for field testing were developed in the 1960s. Current research shows that the methods are not as reliable as they could be and may result in incorrect risk analysis of the forage being tested. Nitrate toxicity can result in production losses due to nutritional stress, late-term abortions, and even animal death. The Custer County MSU Extension agent has identified the need for better testing methods. An improved testing method developed by a research scientist at the University of Georgia in the 1980s was implemented at Custer County MSU Extension in 2016. This method utilizes a water extraction and test strip measuring process that is more reliable than the acid test of the 60s, however, accuracy and result interpretation are issues that impede good analysis of risk for producers. Utilizing information published by the Ag Research Service on a study of field-testing methods for nitrate, the Custer County MSU Extension agent has identified three potential "new technology" methods that promise to provide more accurate results. Two of these methods have now been employed to evaluate forage samples submitted for nitrate analysis to run parallel comparisons and evaluate applicability for use in the county office setting. Results are still preliminary, however, for a modest investment of $600-$700, an electronic nitrate meter can be purchased. When used according to the developed protocol, this meter will provide improved information and accuracy of nitrate risk analysis. This improved information will allow Extension agents to provide recommendations to producers that will increase the quality of harvested forages and safer utilization of grazed forages. In Custer County, the impact of this effort is wide-ranging. During the last two drought-impacted seasons, over 700 samples were evaluated for nitrate risk by the staff at Custer County. With an average of 15 acres represented by each sample, 10,500 acres of forage have been tested, representing a harvested forage value of just over $3 million (1.5 ton per acre at $200/ton).