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 "very wet all season"?

Answer: Both sensors measuring second and third foot not drier than 70 cb all year and no sensor drier than 30 cb on Sept. 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: Overall, our results indicate that an electric motor running at a constant 1770 rpm will use excess energy for much of the center pivot revolution. VFD operation includes the installation of a pressure sensor somewhere on the system. The controller part of the VFD adjusts the motor speed to maintain a set pipeline pressure wherever the sensor is positioned. Some sensors are placed at the pump outlet, but if the irrigated area has a lot of topography, that position is often the worst location for the sensor.

Question: what is one thing that is included in the operation of a VFD system?

Answer: the installation of a pressure sensor somewhere on the system

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: However, the winter and spring of 2022-23 has been an exception for most of Nebraska, with off-season precipitation well below normal. This has highlighted the only downside to leaving the soil dry at the end of the irrigation season: In years when we have a very dry off-season, we will need to pump some water in June to refill the profile before the high water demand days of July arrive. The data showed that some fields were at field capacity at the end of the irrigation season in 2022, but many of the silt loam soil fields would require four to five inches of water to refill the profile. The problem is, without soil water monitoring equipment, one will not know if their field is already refilled to field capacity or not. Other lighter soil texture fields will take less water to refill them.

Question: what will an irrigator have to do in in Nebraska when there is a very dry off-season?

Answer: pump some water in June to refill the profile before the high water demand days of July arrive

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 is current being evaluated using data from irrigators' field and research plots. Irrigators and crop consultants are encouraged to try it out and send their comments and feedbacks to the developers. Potentially, this software could be implanted into irrigation control modules for automated irrigation control, variable rate irrigation, and other irrigation decision supports packages.

Question: what software could potentially be implanted into  irrigation control modules for automated irrigation control, variable rate irrigation, and other irrigation decision supports packages?

Answer: CornSoyWater

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 description of a static VRI irrigation prescription is that this prescription stays the same or changes only a few times during the season. Considerations include that it is relatively simple to apply. Does not account for change in spatial variability over a season. Example uses include avoiding irrigation on uncrossed areas, mining differences in soil available water capacity, and variable rate chemigation.

Question: what do static VRI irrigation prescriptions not account for?

Answer: change in spatial variability over a season

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: Table II. Total available water in top 4 feet if soil is at field capacity and minimum balances at physiological maturity. For fine sands, the available water in 1 foot of soil at 100% of available water is 1.0 in/ft, the available water in top 4 feet at 100% of available water is 4.0 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 1.6 in/ft. For loamy sands, the available water in 1 foot of soil at 100% of available water is 1.1 in/ft, the available water in top 4 feet at 100% of available water is 4.4 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 1.8 in/ft. For sandy loams, the available water in 1 foot of soil at 100% of available water is 1.4 in/ft, the available water in top 4 feet at 100% of available water is 5.6 in/4 ft, and minimum balance in top 4 feet at 40% of available water is 2.2 in/ft.

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

Answer: 1.1 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 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 15-25 inch zone became wetter from August to Sept. 15 in 2017?

Answer: 72%

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: 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 2022, out of 60 reports, 70% were ranked good, 8% were fair, 3% were wet late, 15% were wet early, 2% were wet all season, and 2% were very wet all season.

Question: In 2022 out of 60 reports, what percentage of Nebraska fields were considered wet late?

Answer: 3%

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: Determine the average rainfall per week for the remaining weeks of crop growth and add it into the prediction of how much water may be needed from irrigation. This number should be recalculated each week until the crop is mature. Use Figures 2 and 3 to determine the average rainfall per week in August and in September for central Buffalo County. The chart shows that, on average, central Buffalo County gets 0.60 inch of rain per week in August and 0.55 inch per week in September. The crop is expected to continue growing for three weeks in August and two weeks in September. Remaining available water at maturity is 5.25 inches. The you subtract the average august rain for three weeks which is 1.80 inches. Then you subtract the average September rain for 2 weeks which is 1.10 inches. This gives us that the water we need after accounting for average rain is 2.35 inches. The chart predicts that if average rainfall is received over the next five weeks, only 2.35 inches of irrigation would be needed to mature the crop.

Question: to find the amount of water needed for irrigation in inches using the remaining available water at maturity and the average rainfall for September and august what should be done?

Answer: you subtract the average august rain for three weeks which is 1.80 inches. Then you subtract the average September rain for 2 weeks which is 1.10 inches.

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: 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 very wet all season in the normal to wet years of 2017, 2018, and 2019?

Answer: 12%

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: 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: where can an irrigator enter weekly ETgage data after logging into the NAWMN website?

Answer: 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

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 amount of irrigation applied last year or the year before may have very little to do with the amount needed this year. The long-term average of irrigation application depth and timing is relatively meaningless for the decisions producers need to make on any given day in the current growing season. However, without any additional data, all an irrigator can do is put on about the same amount of water as in the past and make slight adjustments if the weather is dry or wet.

Question: is the long term average irrigation application depth and timing useful to producers for irrigation application decisions?

Answer: relatively meaningless for the decisions producers need to make on any given day in the current growing season

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: 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 have a negative effect on a farm's net return as well as lead to potential environmental concerns?

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: Strategies for Early Season Irrigation Last year's irrigation will have left the soil fairly wet compared to dryland fields. On a typical year, a silt loam soil that was reasonably well irrigated the previously year (full yield) may only hold two to four inches of water from precipitation in the non-growing season. Sandy soils will hold even less. This means most years, irrigated fields will be at or above field capacity in May, particularly in the eastern two-thirds of Nebraska.

Question: particularly in the eastern two thirds of Nebraska when will irrigated fields be at or above field capacity?

Answer: May,

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: 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 R8 crop stage or the stage of growth that is known as harvest 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: 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: in a dry year what can be a useful tool in identifying systematic patterns within a field as a result of water  stress from poor uniformity?

Answer: aerial imagery

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: 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: why do irrigators install variable frequency drives?

Answer: to monitor and control the speed of their irrigation pumps powered by electricity

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: Chadron wells average about 350 feet deep, and the majority (64%) are used for domestic supply, but livestock and irrigation wells account for 15% and 12% of the wells, respectively. The biggest challenge to using the Chadron aquifer is poor water quality.

Question: what is the biggest challenge when using the Chadron aquifer?

Answer: poor water quality

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


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 2018, out of 50 reports, 40% were ranked good, 18% were fair, 16% were wet late, 12% were wet early, 10% were wet all season, and 4% were very wet all season.

Question: In 2018 out of 50 reports, what percentage of Nebraska fields were considered wet early?

Answer: 12%

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 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 is higher than normal in the Upper Cretaceous aquifer in Nebraska?

Answer: sodium

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


Context: Table I. Normal water requirements for corn, grain sorghum, soybeans, and dry beans between various stages of growth and maturity in Nebraska. For Soybeans R4 crop stage, the stage of growth is known as end of pod elongation, the approximate days to maturity is 37, and the water use to maturity is 9.0 inches. For Soybeans R5 crop stage, the stage of growth is known as beginning of seed enlargement, the approximate days to maturity is 29, and the water use to maturity is 6.5 inches.  For Soybeans R6 crop stage, the stage of growth is known as end of seed elongation, the approximate days to maturity is 18, and the water use to maturity is 3.5 inches.  For Soybeans R6.5 crop stage, the stage of growth is known as leaves begin to yellow, the approximate days to maturity is 10, and the water use to maturity is 1.9 inches.  For Soybeans R7 crop stage, the stage of growth is known as beginning 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 soybeans in the R6 crop stage, the stage of growth that is known as end of seed elongation?

Answer: 18

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: It also summarizes up-to-date water inputs (rain and irrigation), crop water uses and losses, and overall water balance. Users get those up-to-date predictions without going to the fields.

Question: what does CornSoyWater software summarize?

Answer: up-to-date water inputs (rain and irrigation), crop water uses and losses, and overall water balance.

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 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 ranked fair?

Answer: 21%

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: 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 well owners should consider testing their wells for arsenic and uranium in the aquifer?

Answer: Chadron well owners

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 is the average crop water use per week at the full dent stage?

Answer: 1.2 inches per week

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


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 R4 crop stage, the stage of growth that is known as dough?

Answer: 7.5 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 ranked good in the normal to wet years of 2017, 2018, and 2019?

Answer: 31%

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: Using this information for a center pivot that is set to apply one inch of water per irrigation, the suggested recommendation would be that the system should be off for the next few days to use some of the remaining water. The next inch of water should be applied within the next seven days. Then, the next irrigation should be recalculated using updated soil water readings. The best way to use the remaining water is to delay the start of the last few irrigations a few days each time and react to any rain that might occur during the period. Slowly using the water in the lower portion of the root zone starting in early to mid-August is much better than keeping the profile full until the very end and expecting the crop to use the water all at once.

Question: whats the best way to use up the remaining water stored in the soil in the late season?

Answer: delay the start of the last few irrigations a few days each time and react to any rain that might occur during the period

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


Context: Determine the average rainfall per week for the remaining weeks of crop growth and add it into the prediction of how much water may be needed from irrigation. This number should be recalculated each week until the crop is mature. Use Figures 2 and 3 to determine the average rainfall per week in August and in September for central Buffalo County. The chart shows that, on average, central Buffalo County gets 0.60 inch of rain per week in August and 0.55 inch per week in September. The crop is expected to continue growing for three weeks in August and two weeks in September. Remaining available water at maturity is 5.25 inches. The you subtract the average august rain for three weeks which is 1.80 inches. Then you subtract the average September rain for 2 weeks which is 1.10 inches. This gives us that the water we need after accounting for average rain is 2.35 inches. The chart predicts that if average rainfall is received over the next five weeks, only 2.35 inches of irrigation would be needed to mature the crop.

Question: how many inches of remaining available water is available at maturity?

Answer: 5.25 inches

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: These are just a few simple steps to take to check over your irrigation systems.  If you want additional information please check out the Ag Production tab on our website at water.unl.edu, or contact me directly.

Question: where can you find the steps that should be taken to check over your irrigation system?

Answer: Ag Production tab on our website at water.unl.edu

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: 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 2022, out of 60 reports, 70% were ranked good, 8% were fair, 3% were wet late, 15% were wet early, 2% were wet all season, and 2% were very wet all season.

Question: In 2022 out of 60 reports, what percentage of Nebraska fields were ranked good?

Answer: 70%

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


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

Answer: 16%

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 Brule sand-sandstone aquifer and the Upper Cretaceous aquifer are the other two secondary aquifers in western Nebraska. The Brule sand-sandstone aquifer is distinguished from wells installed in Brule siltstone.

Question: what are two secondary aquifers in western Nebraska?

Answer: Brule sand-sandstone aquifer and the Upper Cretaceous aquifer

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


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: if the soil is too wet what will you lose rainfall to?

Answer: runoff or deep percolation

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: 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 are the two primary sources of low uniformity in an irrigation system?

Answer: faulty sprinkler nozzles as well as pressure differences along the system

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


Question: on average how much rain (inch) per week does central buffalo county receive in September?

Answer: 0.55 inch

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

Answer: 5%

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


Question: where is the Upper Cretaceous aquifer heavily used?

Answer: the Denver area

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


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: for every inch of water that moves below the root zone, whether rain or irrigation, how much nitrogen will it take below the root zone?

Answer: at least five to 10 lbs. of nitrogen

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: The description of a dynamic VRI irrigation prescription is that it changes frequently during the season, possible for each irrigation event. Considerations include that it may be complicated and increase management efforts and that it may provide maximum gross benefit. Example uses include varying irrigation to each part of the field as needed and adjusting areas as needs change over the season as well as variable rate chemigation.

Question: what should be considered for VRI irrigation prescription?

Answer: it may be complicated and increase management efforts and that it may provide maximum gross benefit

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: In general, about one-third of the irrigators in the study on the normal to wet years are doing a good job of applying the correct amount of water to minimize deep percolation of water and nutrients and save pumping costs while producing top yields. The other two-thirds could have saved money and water without lowering yield. In fact, about one-third could have saved a lot! On the other hand, about 60% to 80% are doing a good job during the dry years as shown in Table 1.

Question: what percentage of irrigators are doing a good job of water application in dry years?

Answer: 60% to 80%

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