VRI: Increasing Irrigation Efficiency Can Increase Profit Margins
In 2017, the Rainwater Basin Joint Venture (RWBJV) piloted a whole field conservation delivery approach with a Hamilton County producer. The RWBJV partners worked with the producer to restore and fence a 55-acre wetland enrolled in the Wetland Reserve Easement Partnership (WREP) administered by Natural Resources Conservation Service (NRCS). The pivot irrigated system that crossed over the restored wetland was also retrofitted to support Variable Rate Irrigation (VRI). Upgrades included a new control panel (hardware and software), GPS telemetry, and a new sprinkler package. Electroconductivity (EC) mapping was completed on both the cropped area of the property, and the wetland area to assess the soil composition. Soil moisture probes were installed to report moisture content, soil temperature, and salinity at various depths in the soil profile. The pivot was now capable of limiting inputs over the wetlands acres and optimizing irrigation in the adjacent cropland based the soil profile and crop water needs. Data from the EC mapping and soil moisture probes, allowed for specialists at Precision Agronomy to develop daily recommendation and irrigation prescriptions throughout the growing season. The RWBJV provided 85% cost-share funding for a 3-year subscription to the prescription irrigation services. This project was a success and resulted in a Regional Conservation Partnership Program (RCPP) award from NRCS to Upper Big Blue Natural Resources District to replicate the whole field approach with 10 other producers.
Today, the RWBJV has provided cost-share funding to 11 landowners to implement the whole field approach on their properties. These sites are in four different Natural Resource Districts (Upper Big Blue, Little Blue, Central Platte, and Tri-Basin) in the Rainwater Basin. Recently, data was collected from each of these NRDs/landowners to determine the efficacy of the VRI following the 2022 growing season. In 2022, Nebraska experienced one of the worst droughts on record and was roughly 10-inches below normal precipitation making irrigation critical for row-crop production. For each site, data was provided on the number of acre-inches of water used for irrigation in 2022. Each NRD provided the average water usage (in acre-inches) for producers in their region. This allowed for a comparison between each RWBJV cooperator with VRI water usage versus the average water usage in that NRD.
The irrigation water savings for each of the NRDs was as follows:
• Upper Big Blue (5 sites): 7.88%
• Little Blue (3 sites): 24.33%
• Central Platte (2 sites): 10.35%
• Tri-Basin (1 site): 48.7%
The average irrigation water usage across all 4 NRDs in 2022 was 8.68ac-in. The average irrigation water usage of RWBJV cooperators with VRI in 2022 was 7.21ac-in. Thus, the RWBJV cooperators with VRI used 1.48ac-in less to irrigate than other producers in their area in 2022. These cooperating landowners used 16.5% less water than many of their neighbors. It can be assumed that other producers in the NRDs are using VRI as well, so the actual irrigation water savings are likely even higher. In 2022, RWBJV cooperating landowners with VRI are, on average, spending 16.5% less on irrigation than their neighbors.
The RWBJV plans to continue monitoring irrigation water use at each of these sites over the next several years to continue assessing how much water, and thereby how much money, producers are saving by implementing VRI technology on their sites and following irrigation prescriptions. Hopefully additional sites will be added to this project as well. It is also important to note that less irrigation water being used on these sites results in less groundwater pumping, while the restored wetlands can recharge upwards of 1.14 million gallons of water per acre over a 30-day hydroperiod. The 310 wetland acres restored through the RCPP can recharge 352 million gallons or enough water to irrigate 2,160 acres (18 pivots) with a six-inch irrigation allocation. So, while individual landowners are benefitting from using less water on their properties, all Nebraskans will benefit from the conservation of our shared groundwater resources.