Nitrate-Nitrogen is the most common pollutant found in groundwater across Nebraska and is also the most unregulated contaminant applied on land surfaces today. Nitrates in groundwater are readily usable by crops, specifically corn, and should be credited towards a fertilizer program to utilize the available resource, save money, and reduce future nitrate contamination going forward.
An additional benefit of using nitrates from groundwater applied as irrigation generally occurs only in-season, if over irrigation isn’t a factor, the effective root zone (~24”) will readily capture and utilize the nitrates as it transpires moisture through the plant. Timing of irrigation applications generally coincides with rapid uptake and growth by the crop. Irrigation and precipitation can both leach nitrates to the groundwater, so careful application of both fertilizer and irrigation are a must.
This calculator can be used to estimate the nitrogen available to your crop through your irrigation water by utilizing the UNL irrigation credit formula of, (ppm)x(.227)x(inches of water)= pounds of nitrogen per acre. By entering your Nitrate PPM, your expected irrigation in acre/inches, and your cost per pound of nitrogen, you can calculate the pounds per acre you could credit from your water and how much money that could save you in your yearly nitrogen application. Try it out!