Context: Getting the crop off to a great start is essential for a successful season. On dry years, it is sometimes necessary to start irrigating in May and June. However, it is critical to monitor soil moisture to balance crop needs with the risk of losing nitrogen and other valuable crop inputs. Monitoring will also help prevent unnecessary irrigation expenses, and if you have a water allocation, avoid using up water that is critical for later growth stages.

Question: what is essential for a successful growing season?

Answer: Getting the crop off to a great start

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Soil Sensor Install Tips: While other tasks may seem more pressing, early installation of sensors is critical to ensure their proper operation during the later critical growth phases. Early installation helps to minimize root damage, allows time for sensors to acclimate to read actual soil water conditions instead of water within the sensor or slurry, and gives a better chance for proper soil contact.

Question: what does the early installation of soil sensors allow for?

Answer: sensors to acclimate to read actual soil water conditions instead of water within the sensor or slurry

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: To identify possible issues developing with pressure regulators and/or sprinklers record and observe your system's flow rate and pressure over time, looking for changes. For further information on irrigation management, visit the Agricultural Irrigation section of Water.unl.edu.

Question: what should you do to identify potential possible issues developing with your irrigation systems regulators and/or sprinklers?

Answer: record and observe your system's flow rate and pressure over time, looking for changes

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: The Extremely Dry Winter/Spring 2022-23 Leaving the soil as dry as possible without lowering yields saves money on pumping costs and leaves room to store offseason precipitation. Most years, adequate precipitation will be received from October through May to refill the soil profile on fields that were fully irrigated the previous year in the entire state. A lot of years, even in the Panhandle, the two to four inches of recharge that fully irrigated fields can hold will be received from rainfall or snowfall. In addition to financial savings, leaving the soil drier will help reduce harvest delays due to mud if rain is received in the fall.

Question: in most years where will the two to four inches of recharge that fully irrigated fields can hold be received from?

Answer: rainfall or snowfall

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Grain Sorghum stage 6 crop stage, the stage of growth is known as half bloom, the approximate days to maturity is 34, and the water use to maturity is 9.0 inches. For Grain Sorghum stage 7 crop stage, the stage of growth is known as soft dough, the approximate days to maturity is 23, and the water use to maturity is 5.0 inches. For Grain Sorghum stage 8 crop stage, the stage of growth is known as hard dough, the approximate days to maturity is 12, and the water use to maturity is 2.0 inches. For Grain Sorghum stage 9 crop stage, the stage of growth is known as physiological maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate water use to maturity for grain sorghum in the stage 8 crop stage, the stage of growth that is known as hard dough?

Answer: 2.0 inches

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: To illustrate this, let's look at some data from the Upper Big Blue NRD. The NRD requires growers in six areas that have an increased median nitrate-nitrogen level in the groundwater, to use soil water monitoring equipment in one irrigated field and report the data collected annually. Most of the producers impacted by this rule use Watermark sensors that measure soil matric potential; thus, this study has largely focused on Watermark data for easy comparison. The soils in the NRD are mostly a silt loam or similar soil texture, making the field-to-field data comparable as well. The assumption was made that the farmers using Watermark sensors would represent all irrigators in the area. To protect privacy, the NRD removes names from the information prior to group analysis; therefore, the location for each field is an unspecified area in the Upper Big Blue NRD.

Question: what was one assumption made when examining the Upper Big Blue NRD data?

Answer: that the farmers using Watermark sensors would represent all irrigators in the area

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Internal combustion engines need quite a bit more attention.  Change engine oil and all filters.  Check engine hours and refer to the manufactures service interval on valve adjustments and other service that may be needed.  It would also be a good idea to run the Nebraska Extension App IrrigatePump to see where your well stacks up against the Nebraska Pumping Plant Criteria.  This will give you an idea on the efficiency of the power unit and pump.  In the current economic climate we want to be as efficient as possible.

Question: what can be used to where your pump stacks up against the Nebraska Pumping Plant Criteria?

Answer: Nebraska Extension App IrrigatePump

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: The description of a speed control VRI system is that its application rate is varied by changing the speed of the pivot and that the irrigation management zones are pie slice shaped. Considerations for the speed control VRI system are that it is relatively inexpensive - many picot panels are capable without additional investment. It also needs no special hardware on the sprinklers. Example uses of it are if spatial variation lines up well with pie slices, varying application based on topography (e.g. reduced application on low spots) if it lines up pie slices, multiple crops or varieties under one pivot, and on-farm research.

Question: what are some considerations that should be accounted for speed control VRI system?

Answer: it is relatively inexpensive - many picot panels are capable without additional investment

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.02, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.96. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.94. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.92. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.91. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.06, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.89. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.87. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.08, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.86. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.09, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.84. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.83. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.11, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.81. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.8. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.13, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.78. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.14, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.77. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.15, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.76. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.74. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.17, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.73. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.72. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.19, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.71. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.2, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.69.

Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04?

Answer: 0.92

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: May and June are particularly vulnerable times for nitrate leaching in our irrigated fields because of several factors. First, the fields are left fairly wet from last season's irrigation, precipitation from October through May usually puts more water into the soil than it can hold, the crop is still small and not using much water, and most - if not all - the nitrogen for the corn crop has been applied.

Question: what months are particularly vulnerable for nitrate leaching in irrigated fields in Nebraska?

Answer: May and June

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Soil water monitoring data is easier to analyze once the crop has taken up water at the 16- to 24-inch depth during the vegetative growth stage. This drier zone can then be monitored with sensors to see if the area gets wetter or drier. If it keeps getting drier, the irrigation system needs to keep running. However, if it starts to get wetter, then stop irrigating for a few days. Ideally, the drier zone should slowly expand deeper with the crop using most of the subsoil water by the time the crop matures. For more information on this scheduling strategy, watch the Advanced Irrigation Scheduling Techniques video.

Question: if the drier zone, 16- to 24-inches in depth gets wetter what should an irrigator do with the irrigation system?

Answer: stop irrigating for a few days

Yonts, C. D., Lyon, D. J., Harveson, R. M., Hergert, G. W., Hein, G. L., & Santra, D. (2009). Producing Irrigated Winter Wheat. https://extensionpubs.unl.edu/publication/ec731/pdf/view/ec731-2009.pdf


Context: The Chadron aquifer is the sole source of water to more than 160 wells in the Nebraska panhandle and supplies some of the water to at least 50 additional wells, most of which are near the Perkins-Chase county line.

Question: how many wells is the Chadron aquifer the sole provider for in the Nebraska panhandle?

Answer: 160

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Many irrigators apply more water than necessary toward the end of the irrigation season because the crop is using less water per day. The crop is getting more mature and the days are getting shorter and cooler. The average crop water use rate drops from around 2.1 inches per week at silking to only about 1.2 inches per week by the full dent stage. This 40% reduction requires irrigators to adjust their thinking about how much water needs to be applied each week.

Question: what does the 40% reduction in average water use between the silking and full dent stages require irrigators to think about?

Answer: how much water needs to be applied each week

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In the weighted average normal to wet years, 2017, 2018, 2019, 65% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 66% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 37% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 15-25 inch zone became wetter from August to Sept. 15 in the wet years of 2017, 2018, and 2019?

Answer: 65%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The Upper Cretaceous aquifer supplies water to only about 13 wells, mostly in western Scotts Bluff County, although it is heavily used in the Denver area. The Upper Cretaceous aquifer has high sodium, and sometimes high chloride concentrations in Nebraska.

Question: what element sometimes has high concentrations in the Upper Cretaceous aquifer in Nebraska?

Answer: chloride

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: How does CornSoyWater work in the background? CornSoyWater uses crop simulation models (Hybrid-Maize for corn and SoySim for soybean) to predict crop growth, development, crop water use, and soil water balance. Based on the location of the field, the program automatically determines the weather station that is closest to the field in the weather station network, and the soil texture for the field.

Question: what crop simulation model does CornSoyWater use for corn?

Answer: Hybrid-Maize

Yang, H. (2017). CornSoyWater: An Online App to Aid in Irrigation Management | UNL Water. https://water.unl.edu/article/agricultural-irrigation/cornsoywater-online-app-aid-irrigation-managemen


Context: The top foot will go above field capacity (30cb) after every irrigation or heavy rain. However, if the second foot gets above 30 cb, it would indicate that over-irrigation is occurring. The data in the chart indicated that the field was this dry on a given day and not how many days the soil was drier than 70 cb. The 70 cb level is equal to about 70% of plant available water (PAW) and stress should not start until below 50% of PAW during the summer and 40% in late August and September. Soil types such as those with high sand or clay content would require different levels other than 30 and 70 cb.

Question: what soil types will require different field capacities other than 30 and 70 cb

Answer: high sand or clay content

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2022, 36% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 20% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 18% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 25-36 inch zone became wetter from August to Sept. 15 in 2022?

Answer: 20%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For silt clay or clay, the available water in 1 foot of soil at 100% of available water is 1.6 in/ft, the available water in top 4 feet at 100% of available water is 6.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.6 in/ft. For fine sandy loam, silty clay loam, or clay loam, the available water in 1 foot of soil at 100% of available water is 1.8 in/ft, the available water in top 4 feet at 100% of available water is 7.2 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.9 in/ft. For sandy clay loam, the available water in 1 foot of soil at 100% of available water is 2.0 in/ft, the available water in top 4 feet at 100% of available water is 8.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 3.2 in/ft.

Question: what is the minimum balance for water in the top 4ft of sandy clay loam soils at 40% of available water?

Answer: 3.2 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Value of Using Sensors to Manage Irrigation and Tips for Proper Installation: With planting wrapping up across the state, now is an excellent time to turn attention to soil water sensor and ETgage installations if they haven't already been completed.  Timely installation is important to gain the true benefits of sensors, leading to reduced irrigation costs, reduced chances of overwatering leading to anaerobic soil conditions, and less nutrient leaching.

Question: what is important to get the true benefits of the soil sensors?

Answer: Timely installation

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: For corn in the V4 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.21 inches and the estimated water use during the week of June 19-25, 2023 is 1.30 inches. For corn in the V6 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.41 inches. For corn in the V8 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.60 inches.

Question: what is the estimated water usage for corn in the V6 crop growth stage during June 12-18, 2023?

Answer: 0.41 inches

Stone, G., & Qiao, X. (2023). Estimated Crop Water Use for June 19-25, 2023 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/estimated-crop-water-use-june-19-25-2023


Context: University of Nebraska Extension irrigation scheduling recommendations encourage irrigators to allow the crop to continue using more and more of the stored soil water starting in August and continuing into September when the crop matures. The recommendation is to lower the soil water level from the usual summer water condition of a minimum of 50% plant available water in the top three feet of soil to 40% in the top four feet after the dough stage (R4) is reached. Thus, the stored soil water content should be significantly lower when the crop matures in September than earlier in August.

Question: what is the University of Nebraska Extension's recommendation to lower the soil water condition?

Answer: 40% in the top four feet after the dough stage (R4) is reached

Melvin, S., & Ingram, T. (2021). Scheduling the Last Few Irrigations of the Season Deserves More of Your Management Time Than Earlier Irrigations | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2021/scheduling-last-few-irrigations-season-deserves-more-your-management-time-earlier-irrigations


Context: As described in the video, walking and visually observing an irrigation system when it is running often can help locate where there are mechanical causes for poor uniformity. In some cases, obvious or easily noticeable issues can be identified, such as the broken gooseneck shown in the video. However, other instances such as stuck sprinklers or clogged nozzles may be less noticeable, especially if the sprinklers are on drops in a tall crop canopy.

Question: what are two examples of issues with an irrigation system that may be less noticeable especially if the sprinklers are on drops in a tall crop canopy?

Answer: stuck sprinklers or clogged nozzles

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: The description of a zone or nozzle control VRI system is that the sprinklers are pulsed on and off and pivot speed may vary and that irrigation management zones may be any shape or size. Considerations for this VRI system are that has greatest flexibility in application, it is more expensive, and may require additional maintenance and management effort. Example uses include avoiding application on irregularly- shaped uncropped areas for water surfaces. It can also vary irrigation on irregularly- shaped management zones as needed to maximize yield and profits.

Question: what can zone or nozzle control VRI systems vary to maximize yield and profits?

Answer: irrigation on irregularly- shaped management zones as needed

Barker, J. B. (2017). Considerations in Adopting Variable Rate Irrigation for Center Pivots and Lateral Systems. http://extensionpublications.unl.edu/assets/pdf/ec2000.pdf


Context: Both methods require the basic information for the pivot. All the needed details can be found on the sprinkler chart for the center pivot. The sprinkler chart is the documentation that came with the sprinkler package for the pivot and describes the basic layout of the pivot, water flow rate, pressure, size of each sprinkler, etc. If the current sprinklers on the pivot came with the machine when it was new, the pivot dealer should be able to provide a copy. Otherwise, ask the company that sold the current sprinkler package for it. If you do not have the sprinkler chart, then you will need to determine the needed data by measuring the pivot.

Question: where can the sprinkler chart be found for the pivot?

Answer: The sprinkler chart is the documentation that came with the sprinkler package for the pivot

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: In recent years irrigators have begun to install variable frequency drives (VFDs) to monitor and control the speed of their irrigation pumps powered by electricity. This has led to several recent questions: Should VFD be installed on all electric motor power irrigation pumps? Will VFDs pay for the expense of installation?

Question: what does VFD stand for?

Answer: variable frequency drives

Kranz, B. (2018). Economics of Variable Frequency Drives for Irrigation Pumps. UNL CropWatch. https://cropwatch.unl.edu/2018/economics-variable-frequency-drives-irrigation-pumps


Context: Poor water distribution can result in over- and under-irrigated areas. Insufficient irrigation can reduce total biomass, grain yield, and grain quality; whereas, excessive irrigation can cause runoff, soil erosion, deep percolation of water and nutrients, and anaerobic soil conditions (plant oxygen stress). Consequently, poor water distribution can have a negative effect on a farm's net return as well as lead to potential environmental concerns (Rudnick and Irmak, 2015). Routine maintenance to improve and maintain high system uniformity and application efficiency is desired

Question: what can result in over or under irrigated areas?

Answer: Poor water distribution

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Corn R2 crop stage, the stage of growth is known as blister, the approximate days to maturity is 45, and the water use to maturity is 10.5 inches. For Corn R4 crop stage, the stage of growth is known as dough, the approximate days to maturity is 34, and the water use to maturity is 7.5 inches. For Corn R4.7 crop stage, the stage of growth is known as beginning dent, the approximate days to maturity is 24, and the water use to maturity is 5.0 inches. For Corn R5 crop stage, the stage of growth is known as 1/4 milk line, the approximate days to maturity is 19, and the water use to maturity is 3.75 inches. For Corn R5 crop stage, the stage of growth is known as 1/2 milk line - full dent, the approximate days to maturity is 13, and the water use to maturity is 2.25 inches. For Corn R5 crop stage, the stage of growth is known as 13/4 milk line, the approximate days to maturity is 7, and the water use to maturity is 1.0 inches. For Corn R6 crop stage, the stage of growth is known as physiological maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate days to maturity for corn in the R6 crop stage, the stage of growth that is known as physiological maturity?

Answer: 0

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Beans develop based on day length. So with the same hot dry windy conditions, they will use more water per day and will still mature at about the same date resulting in more water use than predicted in the charts. Thus, it is very important to monitor soil water in beans until they reach maturity. For additional details and charts, see NebGuide Predicting the Last Irrigation of the Season.

Question: where can growers find more information about irrigation timing?

Answer: NebGuide Predicting the Last Irrigation of the Season

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: However, the data shows that in the dry years, 2020, '21 and '22, 15-20% of the irrigators let their fields get dry late in the season, maybe even dry enough to have resulted in small yield losses. So, in dry years, data driven decisions could lead some irrigators to apply more water.

Question: in dry years what could data driven decisions lead some irrigators to doing?

Answer: apply more water

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: In about 50% of the field sites studied the best pressure sensor location was near Tower 8.  For 20% of the systems the best place was near Tower 7 and for 15%, it was near Tower 6.  Results point strongly to evaluating each center pivot installation separately to determine where the sensor should be placed on the center pivot.

Question: how should center pivot installations be evaluated to determine where the sensor should be placed on the center pivot?

Answer: separately

Kranz, B. (2018). Economics of Variable Frequency Drives for Irrigation Pumps. UNL CropWatch. https://cropwatch.unl.edu/2018/economics-variable-frequency-drives-irrigation-pumps


Context: The broken gooseneck on this pivot, as shown in the video, is one cause of non-uniform water application. Walking the irrigation span to visually inspect it can help identify issues before crop yield is affected.

Question: what can be a cause of non-uniform water application?

Answer: broken gooseneck

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: Keep in mind that the plants next to the probes are an integral part of the sensor and must be protected so they can represent all the other plants in the field. Do not install sensors when the soil is too wet and make as few footprints as possible to prevent soil compaction.

Question: what should be limited as much as possible when installing the soil sensors to prevent soil compaction?

Answer: footprints

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.02, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.96. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.94. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.92. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.91. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.06, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.89. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.87. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.08, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.86. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.09, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.84. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.83. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.11, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.81. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.8. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.13, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.78. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.14, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.77. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.15, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.76. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.74. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.17, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.73. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.72. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.19, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.71. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.2, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.69.

Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05?

Answer: 0.91

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: The second reason is to help prevent extended harvest delays because of rain. If the field is kept at field capacity, any rain can cause delays and lead to soil compaction from harvest equipment.

Question: if the field is kept at field capacity what can cause delays and lead to soil compaction from harvest equipment?

Answer: any rain

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: Total dissolved solids and sodium concentrations are uniformly high, but other aspects of water chemistry vary from place to place. Arsenic and uranium concentrations have both been documented to exceed their recommended maximum contaminant levels in places, and Chadron well owners should consider testing their wells for these compounds.

Question: what elements and concentrations vary from place to place in the aquifer?

Answer: Arsenic and uranium concentrations

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Question: what is the approximate days to maturity for corn in the R4 crop stage, the stage of growth that is known as dough?

Answer: 34

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Nebraska Extension has educators and specialist across the state that would be happy to help you develop a plan as well. Feel free to send an email to xxxxx xxxxxx if you would like to set up a time to talk.

Question: who can a grower send an email to get help with developing an irrigation plan?

Answer: xxxxx xxxxxx

Melvin, S. (2020). Is It Too Easy to Turn Irrigation Water On? | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2020/it-too-easy-turn-irrigation-water


Context: The tendency should not be a surprise, because humans are creatures of habit. We get out of bed every day on the same side, we sit at the same place at the table for breakfast, etc. Farmers are no different - they tend to plant about the same number of seeds per acre each year, they apply about the same amounts of fertilizer each year, they plant the rows the same direction, etc. Well, you get the point, and without any compelling reasons, why make changes, right? However, irrigation scheduling should be an exception to this approach because the rainfall amounts and their timings are different each year.

Question: why should the amount of irrigation a farmer applies each year change?

Answer: because the rainfall amounts and their timings are different each year.

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: This article (Barker and others, 2017) investigated the use of soil water sensors for VRI management. If VRI will be used to meet the crop water needs in each part of the field, a combination of soil water sensors and remote sensing will likely be needed.

Question: what will likely be required if VRI is used to meet the crop water needs in each part of a field?

Answer: a combination of soil water sensors and remote sensing will likely be needed

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: In a dry year, aerial imagery can be a useful tool to help identify systematic patterns (i.e., rings) within a field as a result of water stress from poor uniformity. However, in high rainfall areas (i.e., low irrigation requirements) aerial imagery may not be able to visually identify differences in the crop canopy. In these instances, it's recommended that catch cans be used to evaluate application uniformity. Evenly distribute cans of equal size across the system, measure the depth of water applied, and compare to identify areas of nonuniform water application.

Question: how can an irrigator use catch cans?

Answer: Evenly distribute cans of equal size across the system, measure the depth of water applied, and compare to identify areas of nonuniform water application

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: The analysis focused on dividing the fields into one of six categories based on the soil water levels in the heart of the season (July and August) and on Sept. 15. The six categories were developed based on the readings from the Watermark sensors. The sensors generate data reported in centibars and have a range from 0 (wet) to 240 (dryer) centibars (cb). Centibar is a unit of measure that refers to the force required by the plant to pull the water out of the soil and into the plant. Typically, installations use a set of three sensors, with one sensor installed at six to 12 inches, one at 18-24 inches, and one at 30-36 inches.

Question: what type of sensors were used to perform an analysis on Nebraska fields?

Answer: Watermark sensors

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Getting the crop off to a great start is essential for a successful season. On dry years, it is sometimes necessary to start irrigating in May and June. However, it is critical to monitor soil moisture to balance crop needs with the risk of losing nitrogen and other valuable crop inputs. Monitoring will also help prevent unnecessary irrigation expenses, and if you have a water allocation, avoid using up water that is critical for later growth stages.

Question: when is sometimes necessary to start irrigating in May and June in Nebraska?

Answer: dry years

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Question: what will improve and maintain high system uniformity and application efficiency?

Answer: Routine maintenance

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Dry Beans R5 crop stage, the stage of growth is known as early seed fill, the approximate days to maturity is 35, and the water use to maturity is 7.0 inches. For Dry Beans R6 crop stage, the stage of growth is known as mid-seed fill, the approximate days to maturity is 25, and the water use to maturity is 4.2 inches. For Dry Beans R7 crop stage, the stage of growth is known as beginning maturity, the approximate days to maturity is 15, and the water use to maturity is 2.0 inches. For Dry Beans R8 crop stage, the stage of growth is known as harvest maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate days to maturity for dry Beans R7 crop stage or the stage of growth that is known as beginning maturity?

Answer: 15

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Variable rate irrigation or VRI is 'the ability to spatially vary water application depths across a field to address specific soil, crop, and/or other conditions' (Evans and others, 2013). This technology has many potential uses that might enhance farm profitability, irrigation water productivity (i.e., yield produced per unit of irrigation water applied), and water quality.

Question: what does VRI denote?

Answer: Variable rate irrigation

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Context: The primary source of low uniformity is faulty sprinkler nozzles as well as pressure differences along the system. Faulty sprinklers can be comprised of missing, clogged, and worn nozzles, stuck sprinklers, and out of sequence nozzle packages.

Question: what can faulty sprinklers comprised of?

Answer: missing, clogged, and worn nozzles, stuck sprinklers, and out of sequence nozzle packages

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: The categories are as follows: Good - At least one sensor out of the three depths drier than 70 cb early and one sensor drier than 70 cb on 9/15. Fair - At least one sensor drier than 70 cb early and one sensor drier than 30 cb on 9/15. Wet Late - At least one sensor drier than 70 cb early but no sensor drier than 30 cb on 9/15. Wet Early - No sensor drier than 70 cb early, but one sensor drier than 30 cb on 9/15. Wet All Season - Both sensors measuring the second and third foot not drier than 70 cb all year, but one sensor between 30 to 70 cb on Sept. 15. Very Wet All Season - Both sensors measuring second and third foot not drier than 70 cb all year and no sensor drier than 30 cb on Sept. 15.

Question: what is the criteria for a field to be considered "wet early"?

Answer: No sensor drier than 70 cb early, but one sensor drier than 30 cb on 9/15

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2017, 72% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 75% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 66% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 25-36 inch zone became wetter from August to Sept. 15 in 2017?

Answer: 75%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: ETgage Install Tips: As with soil sensors, early installation of atmometers or ETgages is important, so remember to take the time to get them out now (Figure 4).  By installing early, we will make sure that everything is working properly during less critical growth stages and reinforces the importance of reading the ET gage every week. Remember to use distilled water when you are setting up your ETgage.

Question: what does installing the ETgage early in the season ensure and reinforce?

Answer: make sure that everything is working properly during less critical growth stages and reinforces the importance of reading the ET gage every week

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: OK, That is Great, But I Want to Use My End Gun. The best answer may be to just not use the end gun because of its lower uniformity and the fact that it will lower the nitrogen application rate when it comes on. However, two methods of solving this problem come to mind. The first is to purchase a variable rate injection pump and the second is, if the pivot is equipped with a computer panel, keep using the lower cost fixed rate injection pump and simply slow the pivot down when the end gun turns on.

Question: what are two reasons an irrigator should not use their end gun for irrigation?

Answer: its lower uniformity and the fact that it will lower the nitrogen application rate when it comes on

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Corn R2 crop stage, the stage of growth is known as blister, the approximate days to maturity is 45, and the water use to maturity is 10.5 inches. For Corn R4 crop stage, the stage of growth is known as dough, the approximate days to maturity is 34, and the water use to maturity is 7.5 inches. For Corn R4.7 crop stage, the stage of growth is known as beginning dent, the approximate days to maturity is 24, and the water use to maturity is 5.0 inches. For Corn R5 crop stage, the stage of growth is known as 1/4 milk line, the approximate days to maturity is 19, and the water use to maturity is 3.75 inches. For Corn R5 crop stage, the stage of growth is known as 1/2 milk line - full dent, the approximate days to maturity is 13, and the water use to maturity is 2.25 inches. For Corn R5 crop stage, the stage of growth is known as 13/4 milk line, the approximate days to maturity is 7, and the water use to maturity is 1.0 inches. For Corn R6 crop stage, the stage of growth is known as physiological maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: what is the approximate water use to maturity for corn in the R5 crop stage, the stage of growth that is known as 1/2 milk line - full dent?

Answer: 2.25 inches

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Question: if three sensors are typically installed how deep is the second sensor?

Answer: 18-24 inches

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: CornSoyWater provides irrigation recommendations in real time mode, based on a quantitative prediction of amount of available water in the soil root zone along with stage-related threshold for irrigation, and possible crop water stress.

Question: what are CornSoyWater's irrigation recommendations in real time mode based on?

Answer: a quantitative prediction of amount of available water in the soil root zone along with stage-related threshold for irrigation, and possible crop water stress

Yang, H. (2017). CornSoyWater: An Online App to Aid in Irrigation Management | UNL Water. https://water.unl.edu/article/agricultural-irrigation/cornsoywater-online-app-aid-irrigation-managemen


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2021, out of 53 reports, 57% were ranked good, 6% were fair, 6% were wet late, 25% were wet early, 4% were wet all season, and 4% were very wet all season.

Question: In 2021 out of 53 reports, what percentage of Nebraska fields were considered wet early?

Answer: 25%

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Question: In 2021 out of 53 reports, what percentage of Nebraska fields were considered very wet all season?

Answer: 4%

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In the weighted average normal to wet years, 2017, 2018, 2019, 65% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 66% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 37% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 25-36 inch zone became wetter from August to Sept. 15 in the wet years of 2017, 2018, and 2019?

Answer: 66%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Keep in mind that the plants next to the probes are an integral part of the sensor and must be protected so they can represent all the other plants in the field. Do not install sensors when the soil is too wet and make as few footprints as possible to prevent soil compaction.

Question: the plants next to the probe that measures soil moisture are an integral part of the senor why must they be protected?

Answer: so they can represent all the other plants in the field

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Each time the user logs in and selects a field, the program will make a prediction regarding the need for irrigation (Figure 3), using up-to-date weather data for that field and other crop and soil information the user provided at field registration. When the user irrigates a field, the irrigation date and amount must be entered into the program so the next prediction will reflect the irrigation.

Question: when a user of CornSoyWater irrigates a field what information should they update in the program so the next prediction will reflect the irrigation?

Answer: the irrigation date and amount

Yang, H. (2017). CornSoyWater: An Online App to Aid in Irrigation Management | UNL Water. https://water.unl.edu/article/agricultural-irrigation/cornsoywater-online-app-aid-irrigation-managemen


Context: 3) Center Pivot - The pivot will take a little more time to go through.  Start by checking each tower:  Check tire pressure and condition, check driveline knuckles for wear, drain water from gearboxes and top off with appropriate gear oil, visually inspect the tower box and the alignment system and then check operation.

Question: what are all components that should be checked on each tower of a center pivot irrigation system?

Answer: Check tire pressure and condition, check driveline knuckles for wear, drain water from gearboxes and top off with appropriate gear oil, visually inspect the tower box and the alignment system and then check operation

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: Nebraska is a groundwater-rich state, thanks in part to the High Plains Aquifer. Many people are familiar with the High Plains Aquifer (also sometimes called the Ogallala aquifer), but fewer people know that there are other aquifers in the state. In fact, Nebraska has seven secondary aquifers, which are much smaller in areal extent than the High Plains Aquifer and generally have poorer water quality, but are nonetheless important in places where the High Plains Aquifer and shallow sand gravel deposits are absent.

Question: what is Nebraska considered, thanks in part to the high plains aquifer?

Answer: a groundwater-rich state

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: For sugarbeets in the 10-30% Cover crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.17 inches and the estimated water use during the week of June 19-25, 2023 is 1.20 inches. For sugarbeets in the 30-50% Cover crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.25 inches. For sugarbeets in the 50-70% Cover crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.40 inches.

Question: what is the estimated water usage for sugarbeets in the 50%-70% cover crop growth stage during June 12-18, 2023?

Answer: 0.40 inches

Stone, G., & Qiao, X. (2023). Estimated Crop Water Use for June 19-25, 2023 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/estimated-crop-water-use-june-19-25-2023


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For silt clay or clay, the available water in 1 foot of soil at 100% of available water is 1.6 in/ft, the available water in top 4 feet at 100% of available water is 6.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.6 in/ft. For fine sandy loam, silty clay loam, or clay loam, the available water in 1 foot of soil at 100% of available water is 1.8 in/ft, the available water in top 4 feet at 100% of available water is 7.2 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.9 in/ft. For sandy clay loam, the available water in 1 foot of soil at 100% of available water is 2.0 in/ft, the available water in top 4 feet at 100% of available water is 8.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 3.2 in/ft.

Question: what is the minimum balance for water in the top 4ft of silt clay or clay soil at 40% of available water?

Answer: 2.6 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2019, 54% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 54% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 38% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 15-25 inch zone became wetter from August to Sept. 15 in 2019?

Answer: 54%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The 2017 growing season started with warm dry planting conditions, followed by significant rain delays in May in many parts of the state, and a summer of intermittent weeks of hot and cool temperatures. The net result is that crops may mature over a longer period than usual this fall. Fortunately, the following procedure for making end-of-season irrigation decisions is based on crop maturity stage rather than the calendar.

Question: what should end of season irrigation decisions be based on instead using the calendar?

Answer: crop maturity stage

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: The sand and sandstone units in the Brule Formation were deposited in ancient stream valleys and generally have higher porosity than the Brule siltstone that is common elsewhere in western Nebraska. More than 140 wells currently source all of their water from Brule sand-sandstone units and generally have good water quality.

Question: how many wells currently source all of their water from Brule sand-sandstone units and generally have good water quality?

Answer: More than 140

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.02, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.96. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.94. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.92. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.91. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.06, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.89. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.87. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.08, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.86. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.09, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.84. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.83. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.11, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.81. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.8. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.13, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.78. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.14, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.77. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.15, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.76. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.74. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.17, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.73. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.72. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.19, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.71. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.2, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.69.

Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1?

Answer: 0.83

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Leave Room for Storing Rainfall Monitoring soil moisture and leaving it moderately dry during the vegetative growth states also leaves room for the soil to store any rainfall that may come. Too wet and you'll lose that rainfall as runoff or deep percolation. Each inch of rainfall you store saves irrigation, input costs and prevents nitrate leaching.

Question: what saves irrigation, input costs and prevents nitrate leaching?

Answer: rainfall you store

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Center pivot irrigation systems are designed and managed to apply water as uniformly as possible to enhance crop production. Uniformity has a direct effect on the system's overall application efficiency, which is a measure of how well an irrigation system delivers water to a crop's root zone.

Question: what does uniformity have a direct effect on with regard to efficiency?

Answer: the system's overall application efficiency

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Irrigators wanting to purchase equipment should keep in mind that many NRDs across the state offer incentives to purchase irrigation scheduling equipment.

Question: what systems across the state of Nebraska offer incentives to purchase crop irrigation scheduling equipment?

Answer: NRDs

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: If you need a refresher on how to prime the ETgage, please view the assembly video at http://water.unl.edu/cropswater/awmdnvideos. It is a good idea to replace the green covers and white wafers on a regular basis to ensure accurate readings, so if you don't have any on hand it may be a good idea to check with your local supplier.

Question: if you don't have any green covers or white wafers on hand where should you check for some?

Answer: check with your local supplier

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2020, out of 39 reports, 64% were ranked good, 21% were fair, 0% were wet late, 3% were wet early, 5% were wet all season, and 8% were very wet all season.

Question: In 2020 out of 39 reports, what percentage of Nebraska fields were considered wet late?

Answer: 0%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The last few irrigations of the season require some of the most important water management decisions of the year. An extra irrigation may mean wasting 1 to 3 inches of water and 2 to 5 gallons of diesel fuel per acre. Furrow irrigators may want to decide sooner due to the typical higher application amounts with flood, while pivot irrigators can delay the decision and take advantage of any rainfall that may occur.

Question: what type of irrigators can delay their decison on their last irrigation date and can take advantage of any rain that falls late in the season?

Answer: pivot irrigators

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: These six categories were determined because the soil water level where deep percolation losses of water and nutrients slows to a low rate in a silt loam soil is about 70 cb; thus, it is recommended to keep at least one of the sensors in the second or third foot in this range or dryer. Yield losses would not be expected until all the sensors were approaching 140 cb, making the 70 cb level very achievable without any chance of causing yield loss. Field capacity in a silt loam is about 30 cb, so the goal is not to refill the soil above this level with irrigation in the second or third foot.

Question: what is very achievable without experiencing any yield loss?

Answer: 70 cb level

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Table II shows the typical amount of water that will be in the different soils types and can be used to help estimate the volume of water. Remember to use the top 4 ft of soil for the active root zone and plan to use the soil water down to 40% of plant available water (60% depletion) after the dough stage for corn/sorghum and the R5 stage for soybeans/dry beans.

Question: what part of the soil is considered the active root zone?

Answer: top 4 ft of soil

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: Risk of Early Season Leaching Excess irrigation has its own risks. Generally, when the soil is above field capacity, excess water leaves the root zone, called deep percolation. This is an essential function of the soil for groundwater recharge. When deep percolation takes agrichemicals past the root zone, it is called leaching. May and June are the most critical time for leaching losses all year.

Question: what is leaching?

Answer: When deep percolation takes agrichemicals past the root zone

Barker, J. B. (2017). Considerations in Adopting Variable Rate Irrigation for Center Pivots and Lateral Systems. http://extensionpublications.unl.edu/assets/pdf/ec2000.pdf.


Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03?

Answer: 0.94

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: The key to knowing the correct setting for the chemigation pump is to determine how many acres per hour the pivot will cover at the desired irrigation application depth or rate. Chemigation injection pumps are calibrated in gallons per hour (gph). So, if you know how much product you want to apply per acre -e.g., 10 gallons/acre - and how many acres the pivot will irrigate per hour - e.g., five acres/hour - then you will know how many gallons per hour the pump will need to deliver.

Question: what is key to know when determining the correct setting for the chemigation injection pump?

Answer: determine how many acres per hour the pivot will cover at the desired irrigation application depth or rate

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: For corn in the V4 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.21 inches and the estimated water use during the week of June 19-25, 2023 is 1.30 inches. For corn in the V6 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.41 inches. For corn in the V8 crop growth stage the estimated water use during the previous week of June 12-18, 2023 is 0.60 inches.

Question: what is the estimated water usage for corn in the V8 crop growth stage during June 12-18, 2023?

Answer: 0.60 inches

Stone, G., & Qiao, X. (2023). Estimated Crop Water Use for June 19-25, 2023 | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/estimated-crop-water-use-june-19-25-2023


Context: Once you have your ETgage out, we hope that you will once again post your weekly readings to the NAWMN website at https://nawmn.unl.edu. As a reminder, once you are on the main screen, you can login to your site by entering your site name and password and clicking on 'Login'. Once you have logged in, you will be taken to your weekly data from past weeks, including last year. To enter your weekly data, click on the 'Add new ETgage reading' link which will take you to the data entry page where you can enter your growth stage, rainfall, and ETgage change. If you've forgotten your site name or password, please contact xxxxx xxxxxx at xxxxxxxxxxxxxxxx orxxxxxxxxxxxxx.

Question: who should be contacted if you lose your login or password information for the NAWMN website?

Answer: xxxxx xxxxxx at xxxxxxxxxxxxxxxx orxxxxxxxxxxxxx

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: Differences in Late-Season Irrigation Timing for Corn/Sorghum and Beans: Corn/sorghum and beans are somewhat different in respect to crop water use as they approach maturity. For example, if hot dry windy conditions are experienced in September, daily crop water use will increase. However, since corn/sorghum develop based on heat units, they will use more water per day, but will mature in fewer days using about the average amount of water shown in the chart.

Question: if hot dry windy conditions are experienced in September what is expected to increase?

Answer: daily crop water use

Melvin, S. (2017). Predicting Late-Season Irrigation Needs. UNL Water. https://water.unl.edu/article/agricultural-irrigation/predicting-late-season-irrigation-needs


Context: Soil Moisture Monitoring In this drought year, many irrigated fields have very little subsoil moisture, while other portions of Nebraska have experienced significant rains over the last month. With irrigation, any grower can can over-irrigate early and create a wet spring. The most reliable method to know when and how much to irrigate is to monitor soil moisture at multiple depths. Keep in mind that when irrigation is applied with a center pivot an inch at a time on the soil surface, the top foot will stay very wet all summer.

Question: when irrigation is applied with a center pivot an inch at a time on the soil surface how much of the soil surface will stay very wet all summer?

Answer: the top foot

Melvin, S., Power, C., Daigh, A., & Taghvaeian, S. (2023). Early Season Irrigation During Drought. UNL CropWatch. https://cropwatch.unl.edu/2023/early-season-irrigation-during-drought


Context: Now is the time to get the probes in the ground. While other tasks may seem more pressing, early installation of sensors is important to ensure proper operation during the later critical growth phases. Early installation helps to minimize root and leaf damage and makes it easy to get around the field with the pickup or ATV to install the equipment.

Question: what does early installation of soil moisture sensors help minimize?

Answer: root and leaf damage

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2018, 58% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 58% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 47% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 15-25 inch zone became wetter from August to Sept. 15 in 2018?

Answer: 58%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For silt clay or clay, the available water in 1 foot of soil at 100% of available water is 1.6 in/ft, the available water in top 4 feet at 100% of available water is 6.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.6 in/ft. For fine sandy loam, silty clay loam, or clay loam, the available water in 1 foot of soil at 100% of available water is 1.8 in/ft, the available water in top 4 feet at 100% of available water is 7.2 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.9 in/ft. For sandy clay loam, the available water in 1 foot of soil at 100% of available water is 2.0 in/ft, the available water in top 4 feet at 100% of available water is 8.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 3.2 in/ft.

Question: what is the amount of available water in units of (in/ft) for fine sandy loam, silty clay loam, or clay loam soils at 100% of available water in the top 4ft of soil?

Answer: 7.2 in/4 ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Value of Using Sensors to Manage Irrigation and Tips for Proper Installation: With planting wrapping up across the state, now is an excellent time to turn attention to soil water sensor and ETgage installations if they haven't already been completed.  Timely installation is important to gain the true benefits of sensors, leading to reduced irrigation costs, reduced chances of overwatering leading to anaerobic soil conditions, and less nutrient leaching.

Question: when  is an excellent time to turn attention to soil water sensor and ETgage installations if they haven't already been completed?

Answer: With planting wrapping up across the state

Nygren, A. (2017). Value of Using Sensors to Manage Irrigation and Tips for Proper Installation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/value-using-sensors-manage-irrigation-and-tips-proper-installation


Context: The Nebraska Extension NebGuide G888, Flow Control Devices for Center Pivot Irrigation Systems, describes the working principles of pressure regulators and provides guidelines for selecting a regulator. When regulators stop functioning properly, due to a worn out diaphragm and/or spring, they no longer provide the desired constant outlet pressure, and consequently flow rate.

Question: when regulators stop functioning properly due to a worn out diaphragm and/or spring, what do they stop providing?

Answer: the desired constant outlet pressure, and consequently flow rate

Rudnick, D. (2016). Sprinkler Irrigation System Maintenance for Improved Uniformity and Application Efficiency | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2016/sprinkler-irrigation-system-maintenance-improved-uniformity-and-application-efficiency


Context: 1) Pumping Plants - Electric motors account for the majority of the pumping plants in Nebraska, about 55% according to 2013 NASS Irrigation Survey.  They are relatively maintenance free but still need to be looked over.  It is a good idea to change the oil in the unit every year.  Next, open up the junction box and make sure the connectors are tight and have a good ground.  Also check for frayed wires and damage from rodents.

Question: when checking the box of an electric motor what should you check for?

Answer: frayed wires and damage from rodents

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2022, 36% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 20% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 18% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 15-25 inch zone became wetter from August to Sept. 15 in 2022?

Answer: 36%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The Dakota aquifer (formally called the Maha Aquifer) is by far the largest of these secondary aquifers, supplying all of the water to more than 3,400 wells in eastern Nebraska. Seventy-five percent of these wells are domestic, although in places the aquifer is capable of supplying a sufficient volume of water for irrigation and commercial use. The biggest limitation to using the Dakota aquifer is potentially high salt concentrations.  Geologists think the salty water probably moves into the Dakota aquifer from underlying rocks, a hydraulic condition that is increased by heavy pumping.

Question: how do geologists think salty water is moving into the Dakota aquifer?

Answer: underlying rocks, a hydraulic condition that is increased by heavy pumping

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: Other secondary aquifers in eastern Nebraska include the Niobrara aquifer (230 wells, mostly in Cedar County), the Codell aquifer (70 wells in Knox and Boyd counties), and the Western Interior Plains Aquifer System. Only one active well is currently installed in the Western Interior Plains Aquifer System in Nebraska, but the aquifer system was a historic source of water to the Omaha area, and still supplies huge volumes of water to Iowa and other states to our east.

Question: what aquifer supplies huge amounts of water to Nebraska's eastern neighbor Iowa?

Answer: the Western Interior Plains Aquifer System.

Divine, D. (2017). An Overview of Secondary Aquifers in Nebraska | UNL Water. https://water.unl.edu/article/agricultural-irrigation/overview-seondary-aquifers-nebraska


Context: The categories are as follows: Good - At least one sensor out of the three depths drier than 70 cb early and one sensor drier than 70 cb on 9/15. Fair - At least one sensor drier than 70 cb early and one sensor drier than 30 cb on 9/15. Wet Late - At least one sensor drier than 70 cb early but no sensor drier than 30 cb on 9/15. Wet Early - No sensor drier than 70 cb early, but one sensor drier than 30 cb on 9/15. Wet All Season - Both sensors measuring the second and third foot not drier than 70 cb all year, but one sensor between 30 to 70 cb on Sept. 15. Very Wet All Season - Both sensors measuring second and third foot not drier than 70 cb all year and no sensor drier than 30 cb on Sept. 15.

Question: what is the criteria for a field to be ranked "fair" in terms of wetness?

Answer: At least one sensor drier than 70 cb early and one sensor drier than 30 cb on 9/15

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Soil water monitoring data is easier to analyze once the crop has taken up water at the 16- to 24-inch depth during the vegetative growth stage. This drier zone can then be monitored with sensors to see if the area gets wetter or drier. If it keeps getting drier, the irrigation system needs to keep running. However, if it starts to get wetter, then stop irrigating for a few days. Ideally, the drier zone should slowly expand deeper with the crop using most of the subsoil water by the time the crop matures. For more information on this scheduling strategy, watch the Advanced Irrigation Scheduling Techniques video.

Question: what is a resource that has more information on the irrigation scheduling strategy?

Answer: Advanced Irrigation Scheduling Techniques video

Yonts, C. D., Lyon, D. J., Harveson, R. M., Hergert, G. W., Hein, G. L., & Santra, D. (2009). Producing Irrigated Winter Wheat. https://extensionpubs.unl.edu/publication/ec731/pdf/view/ec731-2009.pdf


Context: 2) Pump - The pump is a piece that is sometimes overlooked.  Before you start irrigating in the spring make sure you start the dripper to get the line shaft bearings lubed.  It needs 1 gallon of drip oil for every 100 feet of depth.  Set the dripper for 1 drip every 5 seconds.  The pump can only take oil so fast and you can't over oil them.  Also make sure the dripper line is attached and the fittings are tight.

Question: before irrigating in the spring what must be started on the pump?

Answer: start the dripper

Yonts, C. D., Lyon, D. J., Harveson, R. M., Hergert, G. W., Hein, G. L., & Santra, D. (2009). Producing Irrigated Winter Wheat. https://extensionpubs.unl.edu/publication/ec731/pdf/view/ec731-2009.pdf


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Dry Beans R5 crop stage, the stage of growth is known as early seed fill, the approximate days to maturity is 35, and the water use to maturity is 7.0 inches. For Dry Beans R6 crop stage, the stage of growth is known as mid-seed fill, the approximate days to maturity is 25, and the water use to maturity is 4.2 inches. For Dry Beans R7 crop stage, the stage of growth is known as beginning maturity, the approximate days to maturity is 15, and the water use to maturity is 2.0 inches. For Dry Beans R8 crop stage, the stage of growth is known as harvest maturity, the approximate days to maturity is 0, and the water use to maturity is 0.0 inches.

Question: hat is the approximate water use to maturity for dry Beans R8 crop stage or the stage of growth that is known as harvest maturity?

Answer: 0.0 inches

Yonts, C. D., Melvin, S., & Eisenhauer, D. E. (2008). Predicting the Last Irrigation of the Season. UNL Extension Publications. https://extensionpubs.unl.edu/publication/g1871/html/view


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In the weighted average normal to wet years, 2017, 2018, 2019, 31% were ranked good, 13% were fair, 17% were wet late, 12% were wet early, 16% were wet all season, and 12% were very wet all season.

Question: what percentage of Nebraska fields were wet late in the normal to wet years of 2017, 2018, and 2019?

Answer: 17%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: The analysis found that all the fields in 2017, '18 and '19 were irrigated to a level preventing water stress all season, however 15% to 20% of the fields may have been underwatered late into the season just a little bit (it may or may not have affected the yield) late in the season in the dry years of 2020, '21 and '22.

Question: what years were all fields irrigated to a level preventing water stress all season?

Answer: 2017, '18 and '19

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Using the 40% recommendation, the data shows many irrigators are applying more water late in the season than is needed. Some years, a significant rain can cause the soil to be wetter in September, but it is usually due to applying more irrigation water than needed. The data shows that in 2017, 72% of fields were over-irrigated late in the season, and even in the drought year of 2022, 36% of fields were over-irrigated late in the year.

Question: what is the result of a significant rain or applying more irrigation water than is needed?

Answer: soil to be wetter in September,

Melvin, S. (2023b). Optimize Those Last Few Irrigations | CropWatch | University of Nebraska–Lincoln. https://cropwatch.unl.edu/2023/optimize-those-last-few-irrigations


Context: Average percent of fields by year fitting into the six categories. The dry years 2020, '21 and '22 are different than the other years. In 2019, out of 15 reports, 20% were ranked good, 7% were fair, 40% were wet late, 7% were wet early, 0% were wet all season, and 27% were very wet all season.

Question: In 2019 out of 15 reports, what percentage of Nebraska fields were considered wet late?

Answer: 40%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Additionally, we need to factor in the cost to pump the irrigation water and the danger of leaching nitrogen and sulfur below the root zone, so irrigation can get expensive very quickly. One inch of water that moves below the root zone, whether from rain or irrigation, will take at least five to 10 lbs. of nitrogen with it. This illustrates that putting nitrogen fertilizer on closer to when the plant will use it with a sidedress application or through chemigation should be considered a best management practice.

Question: what are some factors that can lead to irrigation becoming very expensive?

Answer: the cost to pump the irrigation water and the danger of leaching nitrogen and sulfur below the root zone

Melvin, S. (2023c). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Internal combustion engines need quite a bit more attention.  Change engine oil and all filters.  Check engine hours and refer to the manufactures service interval on valve adjustments and other service that may be needed.  It would also be a good idea to run the Nebraska Extension App IrrigatePump to see where your well stacks up against the Nebraska Pumping Plant Criteria.  This will give you an idea on the efficiency of the power unit and pump.  In the current economic climate we want to be as efficient as possible.

Question: what should be changed on internal combustion engines when checking to see if they're operational?

Answer: engine oil and all filters

Ingram, T. (2017). Is Your Irrigation System Ready For the Season? | UNL Water. https://water.unl.edu/article/agricultural-irrigation/your-irrigation-system-ready-season


Context: However, VRI is not likely to reduce the consumptive use of water (i.e., evapotranspiration). Producers who are considering whether to invest in VRI technology should carefully consider the potential costs and benefits to determine whether VRI is a good fit for their situation.  Types of VRI equipment systems, prescriptions (the map that tells the pivot how to apply the water), and potential uses are described below.

Question: what should producers who are considering investing in VRI carefully consider before to determine whether VRI is a good fit for their situation?

Answer: potential costs and benefits

Heeren, D., Barker, J. B., Lo, T. H., Melvin, S., Martin, D., & Luck, J. (2017). Considerations in Adopting Variable Rate Irrigation | UNL Water. https://water.unl.edu/article/agricultural-irrigation/considerations-adopting-variable-rate-irrigation


Question: In 2019 out of 15 reports, what percentage of Nebraska fields were considered wet early?

Answer: 7%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: Percent of fields that became wetter moving from August to Sept. 15. The dry years 2020, '21 and '22 fields are much drier than the other years in the fall.  In 2021, 44% of fields with soil in the 15-25 in zone became wetter from August to Sept. 15, 48% of fields with soil in the 25-36 in zone became wetter from August to Sept. 15, and 37% of fields with soil in both zones became wetter moving from August to Sept. 15.

Question: what percentage of fields with soil in the 25-36 inch zone became wetter from August to Sept. 15 in 2021?

Answer: 48%

Melvin, S. (2023). Study Reviews Farmer Irrigation Scheduling Tendencies in Dry Years. UNL CropWatch. https://cropwatch.unl.edu/2023/study-reviews-farmer-irrigation-scheduling-tendencies-dry-years


Context: When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.02, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.96. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.03, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.94. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.04, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.92. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.05, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.91. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.06, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.89. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.07, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.87. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.08, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.86. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.09, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.84. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.1, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.83. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.11, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.81. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.12, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.8. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.13, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.78. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.14, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.77. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.15, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.76. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.74. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.17, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.73. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.18, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.72. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.19, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.71. When the ratio of the end gun throw (Rg) to the pivot length (R) is 0.2, the the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) is 0.69.

Question: what is the pivot speed with the end gun on (Se) compared to the speed with the end gun off (S) when the ratio of the end gun throw (Rg) to the pivot length (R) is 0.16?

Answer: 0.74

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For silt clay or clay, the available water in 1 foot of soil at 100% of available water is 1.6 in/ft, the available water in top 4 feet at 100% of available water is 6.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.6 in/ft. For fine sandy loam, silty clay loam, or clay loam, the available water in 1 foot of soil at 100% of available water is 1.8 in/ft, the available water in top 4 feet at 100% of available water is 7.2 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.9 in/ft. For sandy clay loam, the available water in 1 foot of soil at 100% of available water is 2.0 in/ft, the available water in top 4 feet at 100% of available water is 8.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 3.2 in/ft.

Question: what is the amount of available water in units of (in/ft) for silt clay or clay at 100% of available water in 1 ft of soil?

Answer: 1.6 in/ft

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and


Context: The chemigation injection pump setting can be easily determined using the sprinkler chart. The method is very simple to use if one has the chart, or at least the speed chart part of it. The information can also be gained from looking at the readout on a computer-style pivot panel or the pivot control app.

Question: what can be used to determine the chemigation injection pump setting?

Answer: sprinkler chart

Melvin, S. (2023a). How to Determine the Chemigation Injection Pump Setting for a Center Pivot with the End Gun Off and On. UNL CropWatch. https://cropwatch.unl.edu/2023/how-determine-chemigation-injection-pump-setting-center-pivot-end-gun-and