The goal of the NutrientStar Program is to encourage evidence-based decisions regarding fertilizer choice, application, and management. The program will attain this goal by increasing the body of data available, as well as access to that data, about the performance of commercially available products and tools that are marketed to improve nutrient use efficiency.

These products and tools may contribute to the general goals of reducing the waste, cost, and environmental impacts of fertilizer application. But, they contribute to these goals in different ways and through various delivery mechanisms.

Below you will find descriptions of the three categories of products and tools NutrientStar assesses.

Chemical products consist of specially formulated fertilizers and additives designed for blending with traditional fertilizers. The chemical products represented in the NutrientStar review process fall into three broad groups: urease inhibitors, nitrification inhibitors, and sulfur additives.

In addition, some manufacturers produce blended products that utilize active ingredients in more than one of the above groups simultaneously. With the exception of sulfur additives, which are intended to improve nutrient use efficiency by reducing sulfur deficiency, these products are generally intended to increase the duration of time nitrogen and phosphorus are available to plants in forms that are not easily lost to the environment. These stabilizers can increase nutrient use efficiency by slowing nitrification, reducing ammonia volatilization, reducing fixation and decreasing losses from denitrification, leaching and runoff.

Decision support tools often come in the form of either software or subscription services and are frequently bundled with other agricultural products and equipment. NutrientStar assesses decision support tools that include nitrogen status as a component in order to focus on our primary goal of determining NUE benefits.

These tools are designed to provide an array of services to farmers and farm advisors — including reports about the nitrogen status of the soil, nitrogen rate recommendations, support for data gathering and analysis, or information to support late season/remedial nitrogen applications. Most decision support tools utilize multiple data sources, models or proprietary algorithms, and real-time equipment monitoring to produce their recommendations.

The scale of the information varies from whole field to individualized guidance for within-field variability. Ideally, decision support tools help farmers maximize yield and profit while minimizing excess fertilizer inputs and environmental impact.

The advent of powerful digital sensor technology, data recording systems and product control mechanisms has promoted the use of sensor technology in nutrient management settings. The sensor technology is generally employed to evaluate crop health in relation to plant nutrient content. The resulting data is used to adjust nutrient application rates. These measurements and resulting adjustments to application rates can be made in real time by mounting the required technological tools directly on applicator equipment, or by fitting sensors to other non-application terrestrial or airborne vehicles, resulting in a separation of data collection and application passes.

All data generated during this process can be recorded for many purposes, including record keeping and further post collection study. The data are frequently used by decision support tools to gain real-time site-specific measurements that can increase the quality of each recommendation. The hardware and software tools for collecting these data are advancing rapidly.