By Abia Katimbo and Todd Whitney et.al
Key Takeaways
Preparing early for better irrigation in the season can pay dividends.
Irrigation systems and pumping plants need to be assessed and maintained for efficient applications.
Ensure uniform water application in center pivots, proper drainage in furrow systems, and avoid major leakages with drip irrigation systems.
Utilize irrigation scheduling tools to increase irrigation efficiency.
Monitor soil moisture in at least the upper 1-foot of fields for proper timing of first and subsequent irrigation event(s) of the season.
Introduction
Soon after planting, the next phase of farm operations will be irrigating following crop emergence. Based on spring dry conditions and forecasted drought, it's critical for irrigators to follow best management practices to achieve high yields, improve water use efficiency, save energy and decrease water applications. However, this requires preparation focused on ensuring irrigation systems — including center pivots, furrow and drip irrigation systems — are functioning properly and paired with effective scheduling tools that monitor soil moisture for reliable, real-time water application decisions.
Irrigation Systems
Center pivots are the most commonly used irrigation systems in Nebraska, with their size varying depending on the number of acres in a field. Irrigation structures consist of spans where the sprinkler nozzle drops are connected, varying in size relative to the application rates and the pumping capacity the volume of water that can be pumped or discharged from the well, recorded as gallons per minute.
Furrow irrigation system consists of open furrows dug in the field that are uniformly flat or with gentle slopes less than 0.05% to allow easy flow of water down the furrows. Water at the upstream from the well or canal is typically discharged into these furrows downstream using either flexible polyvinyl pipes with holes or standard gated pipes, or even siphon tubes (but rarely used). The wetting fronts created by water flowing down furrows are determined by orifice size of each gate or port, since this determines the discharge or flow rates.
Drip irrigation systems are slowly gaining acres in Nebraska, mainly on small acreage installations. Typically, drip systems can have more than one manifold connected to the main pipeline, with sub-main pipelines connected to drip tapes buried belowground for each irrigated zone or field area. Each sub-main pipeline has a flow meter to measure the amount of water delivered to each area or zone across the field.
Checking Tips for Pumping Plant
Checking Tips for Center Pivot System
- Turn on the pump and walk the pivot along the spans. Use the manufacturer’s color-coded nozzle diagrams to verify correct nozzle sizes. Inspect for major leaks, missing or damaged sprinklers or nozzles, or poor applications rates from the sprinklers.
- Replace any faulty nozzles with the right color-coded size. If poor uniformity is discovered, then the sprinkler company must redesign the system based on the current discharge/flowrate to develop a new sprinkler chart for new sprinklers and nozzles to be installed.
- Conduct the catch-can uniformity test to assess water application distribution and actual application rates from each sprinkler/nozzle, then match with sprinkler chart.
- Use water charts to ensure the pivot is putting on the actual set application depth based on the percentage speeds. Otherwise, adjustments can be made, especially when the system is getting older. Contact your local irrigation equipment dealer, UNL irrigation specialist or extension office.
- Repair leaks, especially at connection points between spans (i.e., boots flexible union between span pipes) due to misalignment issues.
- Check pivot tracks for deep holes and cover them to avoid the pivot getting stuck or damaged from misalignment.
- Confirm that the flow meter is working properly and providing accurate flow rates; if not, repair or consider replacement.
- Confirm that the produced pressure is the same as designed, in addition to the flow rate.
Checking Tips for Sub-surface Drip Irrigation System
- Turn on the pump and walk through the whole field. Inspect for any major leaks caused by digging gophers or rodents chewing the drip tape, and for flowmeter failures at each manifold.
- Verify that the flows meters are measuring the right amount; if not, remove and clean them or replace.
- If a major leak is identified, dig around the leak to access the tape and fix it with the right tools. Before burying the tape, turn on the system to ensure there are no leaks.
- Make sure the inlets for main pipeline at all the manifolds are fully open to avoid pressure loss and low discharge into the drip tapes in the field.
- Confirm that all the filters are clean and in good working condition to avoid clogging of the emitters.
- Test the water quality, since chemicals can also lead to clogging of the emitters.
Checking Tips for Furrow Irrigation System
- Ensure the furrows are open and setup with a gentle slope. This will improve performance, increasing the wetting front for faster movement of water at the other end of the field.
- For open surface water, verify the drainage canal is clean with no materials or sediments.
- The furrows should be wide and deep enough to carry sufficient volume of water for better infiltration and uniform water delivery or application across the field, or for water to reach downstream at all ends of the furrows.
- Ensure there is a good drain at the end of the field to avoid waterlogging.
Right Irrigation Scheduling Tool
Although irrigation scheduling can be done by experience, hand probing and feeling the soil, observing the crop response to water stress (most times by curling of leaves) or checkbook method, utilizing new technology will likely improve efficiency. Using the right tools helps you to gauge how much soil-stored water remains before dryness causes water stress, which could reduce crop yields. Simply put, good scheduling technology is like a fuel gauge it shows how far you can go before running empty. This technology will help you plan an irrigation strategy that avoids costly consequences like water stress or yield loss.
Tips For Choosing the Irrigation Scheduling Tool
- As there are many different irrigation technologies, choose one that you feel comfortable using and will provide reliable data for better irrigation decisions.
- Scheduling technology with simple platforms are preferred, since real-time data is represented in a format that can be easily interpreted.
- Select a tool that can be easily integrated into normal farming operations, especially herbicide and nitrogen applications.
- Reliability of technology personnel support is important in case of any breakdown, or if you need more clarification on collected and presented data.
- Make sure you have a strong internet connection if opting for permanently installed technology, such as soil moisture sensors, otherwise there will be failures in data transfer.
- It’s important to note whether the technology can be maintained or installed by reliable service providers.
- Wait until the crop is big enough to identify locations with better representative crops that are healthy to collect accurate data.
- Understand the history of your fields when selecting locations to install your technology, choose field sites that will provide good data and manage irrigation for the whole field.
- Compare costs of varied soil and plant sensors technology.
- Get proper training on how to use data from new technology to make well-informed irrigation decisions.
- Reach out to WCREEC to participate in the Mobile Irrigation Testing program(s), which allows producers to test technology and learn how to use it. For more information about the program, contact Abia Katimbo, Ronaldo Marchezan (Mobile Lab manager), Todd Whitney, or other UNL Mobile Lab members.
Know Soil Moisture Conditions for Better Timing of First Irrigation Event
After you are confident with the performance of your irrigation system, the pumping plant, and have obtained irrigation scheduling technology, it is very important to ascertain soil moisture in the top 12-plus inches of your fields before you decide the first irrigation. Irrigation technology, such as soil moisture sensors, can be installed to monitor the available soil moisture. Wait to irrigate until sensors indicate drying in the top 12 inches of soil.
Notably, different soils hold water differently and should be managed differently avoid guessing the moisture content and measure with the right management tool. Typically, irrigation in west-central Nebraska can be started either in late May or early June, but this can change, particularly with dry springs during limited rainfall like 2025. There are consequences of irrigating too early, such as water losses, which increase energy costs. Another drawback is nitrate losses due to deep percolation, especially when most of the nitrogen for the corn crop is applied at pre-plant.
Final Remarks
To prepare for an intensive irrigation season with forecasted drought as is the situation for the 2025 growing season ensure your system can perform to the desired potential and invest in reliable irrigation scheduling tools. If you feel tempted to avoid crop water stress by irrigating early, use soil moisture sensors to first verify soil moisture in the top 12 inches of your fields and avoid unnecessary water and energy use.
Source : unl.edu