Platte Valley Nitrogen and Irrigation Management Demonstration Project

Within these boundaries there are areas with groundwater nitrate-N concentrations in excess of 40 ppm which are among the highest in Nebraska. Due to a combination of coarse-textured soil, shallow groundwater, intense irrigation and over application of nitrogen on acres in corn production, nitrate contamination exists in a large portion of the CPNRD. With areas of the CPNRD exceeding the 10 ppm set by the Environmental Protection Agency, the NRD was required to develop a Ground Water Management Plan (GWMP) addressing ground water quality BMPs to help clean up the groundwater. In 1988 Nebraska requirements forced the NRD to develop regulations involving nitrogen application; this plan has addressed the contamination problem using a phase system based on the average nitrate-N found within areas of the NRD. As levels of nitrate-N increase, producers are required to provide more information to the district. Each of the Phase requirements are listed below.

Phase I

• Fall N application prohibited until November 1
• Fall N application prohibited on coarse-textured soils. Spring application after March 1

Phase II (in addition to Phase I requirements)

• Annual soil residual nitrate analysis from every field
• Annual nitrate analysis of irrigation water for each well
• Annual report to NRD for each field, consisting of soil and water analysis, expected yield, crop grown, rates of fertilizer and irrigation applied, actual yield
• Manual and legume N credits must be utilized
• Farm operators must be certified in nitrogen management by NRD

Phase III (in addition to Phase II requirements)

• Fertilizer application prohibited on all soils until after March 1
• Preplant N application in excess of 80 pounds requires the use of an approved nitrification inhibitor.

Phase IV (may be established in the future, in addition to Phase III requirements)

• Expected yield set by the NRD, (prior 5 years + 5%)
• Nitrogen application must not exceed NRD recommendations