Right Source – This is the fertilizer selected to meet plant nutrient needs, considering soil chemical and physical properties, nutrient interactions, fertilizer blend compatibility, and nutrient forms available to the plant. When considering nitrogen sources there is not a significant difference between fertilizer source and increased N2O emissions, but varying site conditions may be a factor. Wet weather may enhance the denitrification process, leading to greater nitrogen losses. Utilizing slow release fertilizers or nitrogen stabilizers may reduce these losses. Manure applications were shown to have higher N2O and CO2 emissions compared to inorganic fertilizer sources. The largest emission contribution comes during the manufacturing processes, where ammonium nitrate production causes higher methane (CH4), N2O, and CO2 emissions compared to the production of ammonia and urea.

Right Rate – Discusses the amount of fertilizer applied, ideally determined by crop nutrient needs and soil test results. Determining appropriate nitrogen rates is a difficult task that comes down to a balance between the credit from the previous year’s crop, how much the crop can uptake, and economics. If nitrogen applications exceed optimum rates, then excessive nutrients may increase GHG emissions and groundwater leaching. Due to rate concerns the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa were developed. Further, each state has different protocols tying fertilizer costs, grain prices, and optimum rates for particular regions.
Right Time – Applying nutrients when needed. Plant growth characteristics, nutrient deficiencies, soil characteristics, weather forecasts, and planting dates should be considered. Limiting the time nutrients spend in the ground before uptake results in less loss. Whether doing a preplant application or side-dress, producers follow this practice to provide timely nitrogen as the crop needs it. Additional applications throughout the growing season may be necessary. Fall nitrogen applications should be avoided.

Right Place – Placing nutrients where crops can access the plant-available form. Placement is dependent on several factors: plant genetics, technology, tillage practices, plant spacing, crop rotations, and weather. Global Position System (GPS) technology has improved and helps prevent skips and over-application. Considering in-furrow, pop up, or 2x2 placement can improve crop use efficiency. Regarding application depth, shallower applications can reduce N2O emissions by 26 percent. It was reported that emissions were lower with 4-8” application depths compared to deeper 12” placement. However, surface applied urea also showed increased N2O emissions compared to shallow applications indicating some soil incorporation was beneficial.