The geographic framework shown here delineates spatial units with shared soil and climatic properties, where one might expect agronomic tools and/or products to perform similarly, if all other farm management variables are constant. AGROTAIN® PLUS trials conducted using UAN are super-imposed on the framework, which we refer to as Technology Extrapolation Domains or TEDs. Please see the text below for more explanation of how this framework is being used to show trial results.
Field trials play an important role in the testing and implementation of new agricultural products and management practices. Properly conducted trials give a good indication of a products’ performance in the soil and climatic conditions present at the trial site. However, extrapolating results from field experiments conducted at one or more locations to a larger, spatially explicit domain has been a major challenge confronting agronomic science due to the large variation in soil properties and climate governing crop response to management.
The heart of the challenge is to achieve a balance between having a spatial scheme that is so coarse that environmental variation within a technology extrapolation domain (TED) is large—leading to substantial variation in performance of a given technology, or so fine that the number of field study locations and data requirements are overwhelming. Recent advances in geographic information technologies and publicly accessible databases on soils and climate now make it possible to establish such a framework.
The framework NutrientStar uses draws heavily on the spatial scaling protocols developed to support the Global Yield Gap Atlas developed by Drs. Ken Cassman, Patricio Grassini, Justin Van Wart and the University of Nebraska.
The TED framework delineates spatial units with shared soil and climatic properties, where one might expect agronomic technologies to perform similarly, all other variables being constant. On the map above, TEDs are depicted as colored regions with trial locations indicated by icons, which are colored according to fertilizer form. These TEDs correspond to the areas of greatest rain-fed corn production in the US.
The tables below provide information about yield impacts of AGROTAIN® PLUS in plot studies grouped according to the TED where the study was conducted. The NutrientStar team had to estimate which TED a study was located within, because precise GPS coordinates were not provided for most plot studies. To make this estimate, a buffer of 5 km was drawn around each study location, and the TED represented by the largest number of pixels within the buffer was chosen as the TED for that study, after eliminating all pixels without corn/soybean production. The column in the table showing the estimated TED for each study is entitled “Plurality TED”.
The confidence level for each grouping of studies is the percentage of pixels within the 5 km buffer representing the plurality TED – again, after eliminating all pixels without corn/soybean production. Confidence levels are categorized and color-coded as: high confidence (greater than 75% of pixels in buffer = green), medium confidence (greater than 50% to 75% of pixels in buffer = yellow), and low confidence (less than 50% of pixels in buffer = red).
Each TED is also ranked in terms of its importance to corn production in the Eastern US, both by number and by percent. For example, in the first study conducted by Schwab and Murdock, there is a low confidence level that the plurality TED is accurate for the study, and that TED is ranked second in terms of area in corn production in the Eastern US, representing 6.0% of corn production. Studies that were conducted in TEDs that do not fall within the top 75% of corn-producing areas, or that were conducted in Canada, are shown in the table in grey shading. The weighted mean values for delta yield in bushels per acre and delta yield in percentage for the entire data set are also shown at the bottom of the table.
AGROTAIN® PLUS, made by Koch Agronomic Services, is a fertilizer additive intended to reduce ammonia volatilization. Targeted specifically for liquid manure or UAN (urea ammonium nitrate) fertilizers, AGROTAIN® PLUS contains the nitrification inhibitor dicyandiamide (DCD) as well as the urease inhibitor NBPT. Like AGROTAIN®, AGROTAIN® PLUS slows urea hydrolysis to reduce ammonia losses, but the DCD can also increase nitrogen efficiency by depressing the activities of the Nitrosomonas bacteria over a period of time, therefore delaying the bacterial oxidation of the ammonium-ion (NH4+) into nitrite (NO2-), which is then transformed into nitrate (NO3-) by Nitrobacter and Nitrosolobus bacteria. Nitrification inhibitors, including DCD, have been used regularly in agriculture to slow down this typically rapid conversion of ammonium-N to the nitrate form.
AGROTAIN® PLUS is for applied with liquid manure or UAN to all crops to reduce ammonia volatilization.
Farmers who wish to increase NUE by reducing ammonia volatilization.
Varies based on volume.
AGROTAIN® PLUS is fertilizer additive for UAN and liquid manure.
NutrientStar reviewers found no published research results from field scale strip trials.
Chemistry trials can provide information concerning the effectiveness of a product in laboratory and greenhouse settings but do not provide information related to a products’ effectiveness in the field.
Early laboratory experiments demonstrated DCD’s ability to limit nitrification (Reddy 1964) and early field trials showed that DCD could be as effective as nitrapyrin (another nitrification inhibitor) in limiting nitrification, while also being more soluble in urea (Ashworth and Rodgers 1981; Malzer et al. 1989).
An intensive an extensive review of the literature was completed to assess the effectiveness of AGROTAIN® PLUS to increase yield of corn. All the research was completed on small plots. Plot sizes varied, but no plots were larger than .15 acres in size.
The average yield increase measured for AGROTAIN® PLUS when AGROTAIN® PLUS –treated UAN was compared with non-treated UAN was 2 bushels/acre, with a 95% confidence interval range from -2 to 6.5 bu/acre.