What is Chemigation?
Chemigation is the injection any chemical such as nitrogen, phosphorus or a pesticide into irrigation water and applied to the land using the irrigation system. The proper use of chemigation is recognized as a Best Management Practice (BMP) for irrigated agriculture. However, to use chemigation to benefit your crop production, you must understand the equipment and management requirements and limitations.
Chemigation is not recommended for use with volume guns due to poor application uniformity and wind drift problems. Chemigation can be used with other forms of sprinkler irrigation systems such as wheel rolls; solid set, towline and hand move.
What equipment is required for Chemigation?
The equipment requirements for protection of the water source when chemigating have been incorporated. The law in some states specifically requires the following equipment:
- An anti-siphon device on the main water line
- A back flow device in the chemical line
- A pressure sensor on the pressurized water line
- An inspection port- to check the operation of the check valve
- An injection port downstream from the anti-siphon device
- A chemical resistant injection pump
- Interlock between the water pump and the injection pump.
Chemicals can be applied in timely manner at less cost and equal to or greater chemical efficacy using chemigation.
Different state laws require the installation and inspection of the safety equipment meant to protect the water supply from contamination.
Research conducted in Nebraska and other states provides information to protect workers from exposure and safe manure application rates.
Chemigation training programs are designed to delivers information producers need to use chemigation safely and effectively.
Chemigation with Center Pivot Irrigation has advantages, limitations, and risks that a producer must consider when deciding the best way to apply the desired pesticide.
- Chemigation can be an effective way of applying certain agricultural chemicals to some irrigated crops if the irrigation system can apply the pesticide/water mixture uniformly and at the proper amount.
- The greatest risk of chemigation is the potential for accidental back flow of chemical into the irrigation water source.
- To minimize this risk to the water source, you must use all of the required anti-pollution safety devices and the chemigation system must be properly set up, operated, and maintained.
Advantages and benefits
- Provides uniform distribution of chemicals when the center pivot sprinkler package is properly selected and maintained.
- Offers more flexibility in timing the chemical application, especially when the field is too wet for a tractor or an aircraft is unavailable.
- May increase pesticide activity and effectiveness for some compounds.
- May reduce the application cost in some situations.
- May reduce mechanical damage to plants caused by ground sprayer wheels.
- May reduce the risk of soil compaction caused by ground application methods.
Limitations and risks
- Uniform chemical application depends on uniform water distribution from the irrigation system.
- Application time is longer than most other chemical application methods.
- Most pesticide compounds are not approved for application with irrigation water.
- Potential risk exists for all or a part of the chemical to flow back into the irrigation water source (ground or surface) if two or more of the required safety devices malfunction while chemigating.
- Farm managers/operators must take time to learn about chemigation safety devices, calibration, and management practices.
- Extra investment must be made for chemigation system and for safety equipment.
- A chemigation permit from the MDA is required.
Irrigation Listings recommends that you contact your local NRD office, and check all State and Local regulations before you begin to chemigate through your center pivot or any other irrigation equipment. You should also contact you local irrigation dealer to see what options they can offer.