By Chuck Burr
Rainfall the past several weeks in many areas of the state has been a big boost to the soil water profile. Most of Nebraska has received several inches of precipitation and most of it has soaked in. On rainfed fields this stored soil water is like money in the bank. However, on irrigated fields, if the soil water profile was fairly full at harvest last fall, this precipitation has more than likely passed through the soil profile taking residual nitrogen with it. Nitrogen leaching is a concern because it
- contaminates groundwater used for individual and municipal water supplies
- represents a loss of money to the producer, and
- may result in reduced yields or a need to apply more nitrogen fertilizer.
Knowing exactly how much nitrogen exited the root zone is difficult. Multi-year studies in Nebraska found an average of 5.7 to 10 lb of nitrogen leached per inch of drainage water leaving the soil profile (Irrigation Management Home Study Course, EC98-788-S, Chapter 5). This may require applying more nitrogen to the field. Chemigation would be an excellent application method for applying additional nitrogen later in the growing season when your crop’s nitrogen needs are highest. Matching application timing with greatest nitrogen plant use would limit the potential for nitrogen leaching below the rootzone.
Chemigation Requirements
While chemigation is an excellent application method, it does require time to meet the equipment approval and registration process. The Nebraska Chemigation Act was passed in 1986 and outlines the requirements for chemigation. Conducting chemigation requires a two-step process: First you have to become certified as a chemigation applicator. Second, you need to install pollution prevention equipment and have it inspected and approved by your local Natural Resources District.
To become a chemigation applicator you must attend approved training and pass a chemigation exam. Chemigators needing to recertify can take a home study course and complete the exam at one of 16 testing sites across the state. The training dates for initial chemigation applicators have all passed. Your options for this year would be to have a neighbor or ag business who is certified conduct the chemigation application this summer. Learn more about the Chemigation Act and UNL chemigation training and resources.
The second requirement is that pollution prevention equipment must be installed at each injection location (field). Such equipment includes:
- irrigation pipeline check valve;
- low pressure drain;
- vacuum relief valve;
- inspection port;
- injection line check valve; and a
- simultaneous interlock between injection pump and pumping plant.
Once the equipment is installed, you must apply for a Chemigation Permit for each injection location. The local NRD then has 45 days to inspect the equipment and issue, or deny, the permit, so plan your time accordingly. Chemigation permits expire on June 1 of the year following approval and must be renewed annually.
Chemigation can also be used for the injection of fungicides, herbicides or insecticides into irrigation water. Additional requirements may need to be met. Consult the product label for the insecticides, fungicides and herbicides you plan to inject. They may require that you also need to be a certified private pesticide applicator as well. For more information about pesticide certification see the Nebraska Extension NebGuide, Pesticide Laws and Regulations.