Category Archives: Drought

Drought Dichotomy

We often say water is the lifeblood of agriculture.  In a drought year like this, that truly is the case!  A case study showing the impacts of irrigated agriculture to Nebraska this year can be found here.

Interesting is the dichotomy we’re experiencing in south central Nebraska where irrigated fields that were truly fully irrigated may have some of the best yields producers have experienced while in so many areas of the State-even neighbors a few miles away-are experiencing the worst year they have ever faced.

Dryland yields have been all over the board mostly depending on tillage type.  Irrigated yields that were truly fully irrigated have been outstanding.  Hybrid Maize predictions for our area had been good all year for fully irrigated corn and it looks like they are even better than the long-term average predictions!

Yet, as I drive around the countryside I can’t help but wonder at how many corn stalks are already being disked under.  At a time when we’ve had several fires in our own State of Nebraska…when we have farmers and ranchers suffering trying to find forage for their livestock.  We are so blessed to have irrigation here and that buffers our producers from weather extremes.  But let’s not forget about the others who are hurting right now!  I would ask our producers with irrigated fields to please consider leasing your stalks for grazing or baling them this year to help those in need of forage.

Research from UNL shows that cattle and cornstalks go well together.

Some producers worry about compaction but in a dry year like this, compaction is essentially a non-issue-at least this fall.  UNL research from 1996-2011 showed the effects of fall and spring-grazing on subsequent corn and soybean yields.  On average,  yield of the following soybean crop was increased by about 2 bu/ac with fall-winter grazing, and 1.3 bu/ac with spring grazing, compared with no grazing of corn stalks.  Yield of corn as the second crop after grazing was not significantly affected resulting in an average of 1-3 bu/ac yield increase depending on fall or spring grazing. Check out this study and all our resources to help with drought decisions.

An upcoming Webinar called Cornstalk Grazing-Understanding the Values to Cattle Producers and Corn Farmers scheduled for  Oct. 2 from 12:30 to 1:10 p.m. will provide additional information.  If you are unable to view it, it will be recorded with all our Beef Webinars.

So while irrigation has provided life and good yields to many producers’ crops in the area, let’s not forget about our neighbors who are less fortunate.  Please consider leasing your corn stalks or baling them to help others in need of forage for their livestock!  You can connect with other producers by checking out the Hay and Forage Hotline at 800-422-6692.  This hotline lists hay and forage including cornstalks that is available via sale or donation.

Additional Resource:  How much to charge for cornstalk grazing?

More on Last #Irrigation

It’s been a long irrigation season thus far, but we are so thankful for irrigation in this part of the Country during this drought of 2012!  Questions continue to roll in regarding last irrigation for corn and soybeans.  Corn at 1/2 starch only needs 2.25″ to finish up so it’s important to know what your soil moisture status is.  For most irrigated producers, at 1/2 starch, you should be finished irrigating.  

For soybeans at R5 or beginning seed fill, you still need about 6.5″ to finish out the crop.  At R6 when the seeds are filling, that drops to 3.5″.  At R7 when you begin to see leaves yellowing, that is beginning maturity and you are finished irrigating.  They key is we don’t want to fill the profile going into the fall as we’d like to replenish the profile with fall and spring rains and winter snow.  However, with soybeans, it’s also critical not to stop irrigating too soon during seed fill.

Gary Zoubek, Extension Educator in York County sheds more light in the following video produced by UNL’s Market Journal.

Latest 2012 #Corn Yield Predictions

The 2012 corn growing season has been unusually hot and dry. To evaluate the impact on potential production at 12 sites across the Corn Belt, we used the Hybrid-Maize model to estimate end-of-season yield potential based on actual weather up to August 13 and historical long-term weather data thereafter. (Data  from each of the past 30 years was used.) This approach gives a “real-time,” in-season estimate of expected yield potential (the median value shown inTable 1), and the most probable range (25th to 75th percentiles) depending on weather conditions from August 13 until the corn crop reaches maturity.

By comparing this range of possible simulated end-of-season yield potential against the long-term average (long-term Yp, fourth column from right in Table 1), it is possible to estimate the likelihood for below-average (25th percentile), average (median), or above-average (75th percentile) yields. Comparing estimated 2012 yield potential versus the long-term average gives the size of the expected yield difference. While the 25th percentile projection is most likely if weather conditions are harsher than normal from August 13 until crop maturity, the 75th percentile scenario is more likely if weather is more favorable than is typical at a given site. There is roughly a 50% probability that final yield potential will fall between the 25th and 75th percentile levels, a 75% chance that yield will be at or below the 75th percentile, and a 25% probability that it will be at or below the 25th percentile value.

Simulations were run for dryland corn in Iowa, Illinois, and South Dakota, and for both irrigated and dryland corn in Nebraska. Simulations were based on the typical planting date, hybrid relative maturity, plant population, and soil properties at each location. Underpinning data used in these simulations are provided in Table 1. Details about the Hybrid-Maize model and our simulation forecast methods can be found in a previous CropWatch article.

As the season progresses, the range of yield outcomes shrinks and the 25th and 75th percentile values converge toward the median value. Indeed, August 13 projections give a much narrower range than our projections two weeks earlier based on July 30 simulations. The good news is that projected yield potential since July 30 has stabilized or even increased slightly at 7 of 12 sites as weather has improved, especially during the most recent week. The bad news is that projections of final yield potential are below the long-term average at all but two sites.

Dryland Corn

Even in hot, dry years like 2012, parts of the Corn Belt escape untouched and catch adequate rainfall. This appears to be the case in the northern tier of the Corn Belt (e.g. Brookings, South Dakota) and near the Great Lakes (e.g. Dekalb, Illinois) where projected dryland yield potential is within 2% of the long-term average. In contrast, there is moderate yield loss of 26-33% for dryland corn in south central Nebraska (Clay Center), central and northeast Iowa (Gilbert and Nashua), and west central Illinois (Monmouth). Severe yield loss of 40-65% is projected for dryland corn in eastern and northeastern Nebraska (Mead, Concord), northwest Iowa (Sutherland), and south central Illinois (Bondville).

Irrigated Corn

In contrast to large loss of yield potential in these dryland systems, drought years like 2012 highlight the value of irrigated agriculture and the stability it provides to our food system. Although hotter than average temperatures have shortened the grain filling period at all irrigated sites, which reduces yield potential somewhat, projected decreases are modest at about 5% in south central Nebraska (Clay Center, Holdrege), and 10% in east and northeast Nebraska (O’Neill, Concord, Mead). High grain prices are likely to offset the impact such losses will have on profits from irrigated corn.

Model Reliability

Given the severity of reductions in yield potential at some locations, and the apparent lack of negative impact at others, the question arises as to how reliable these projections are? In areas with relatively little heat or water stress, past experience indicates that predictions of yield potential using Hybrid-Maize are robust. In contrast, we would expect predictions of yield loss to be underestimated by Hybrid-Maize in areas where there was high temperature stress during the critical two to three day period of pollination, or where there were large water deficits that severely reduced development of the leaf canopy before tasseling. Both phenomena are not well accounted for in the current version of the model although we plan to release an improved version of Hybrid-Maize later this year that addresses these deficiencies.


The bottom line is that 2012 will be a difficult year in terms of U.S. corn production. Although irrigated yields will be somewhat lower than long-term averages, dryland corn yield potential in much of the Corn Belt will be moderately (25-33% below normal) to severely reduced (40-65% below normal). Where both prolonged drought and high temperature stress at pollination occurred, yields could be reduced by 65% or more. The final outcome will be determined by weather conditions until maturity. Fortunately, predicted weather patterns indicate a trend toward more normal temperatures and rainfall in many places.

While 2012 will certainly be a significant drought year, episodic droughts of this magnitude have occurred at regular intervals in the U.S. Corn Belt over the past 100 years of recorded weather data. Nebraska is fortunate that about 70% of total corn production comes from irrigated systems, and that improved agronomic management practices such as conservation tillage and more stress-tolerant hybrids can significantly reduce dryland corn yield losses under moderate drought. But there is little that can be done to mitigate the impact of severe, prolonged drought especially when coupled with high temperature stress at critical growth periods.

Patricio Grassini, Research Associate Professor, Department of Agronomy and Horticulture
Jenny Rees, UNL Extension Educator
Haishun Yang, Associate Professor, Department of Agronomy and Horticulture
Kenneth G Cassman, Professor, Department of Agronomy and Horticulture

Table 1.  2012 In-season yield potential forecasts as of August 13  using UNL Hybrid-Maize Model

Location, State

Water Regime


RM¶ (days)

Planting Date

Yp (bu/ac)

 2012 Forecasted Yp (bu/ac)



Holdrege, NE




 April 27




Clay Center, NE




April 23
April 23




Mead, NE




 April 30




Concord, NE




May 3




O’Neill, NE




 May 3




Brookings, SD




 May 4




Sutherland, IA




 May 1




Gilbert, IA




 April 26




Nashua, IA




 May 1




Monmouth, IL




 April 27




DeKalb, IL




 May 1




Bondville, IL




 April 20




  Simulations based on dominant soil series, average planting date, and plant population (PP) and relative maturity (RM) of most widespread hybrid at each location (Grassini et al., 2009).
 Average (20+ years) simulated yield potential (Yp).
* 75th percentile yields, which represent favorable and unfavorable weather scenarios for the rest of the season.

Cover Crops & Fall/Spring Forage Options

With corn being harvested for silage, corn maturing early, and livestock producers looking for forage options, I’ve received questions about seeding cover crops or forage options.  Mike Burgert from the Clay County Natural Resources Conservation Service also wanted me to share the concern of the loss of reside and the increased likelihood of soil erosion.  He said if harvesting crops for forage takes place on a USDA program participant’s “highly erodible” acres, this would likely not be an approved conservation system and could cause ineligibility for USDA programs on all of their land in programs. He also said they have cost share for drought related practices (cover crops for forage on cropland, stock water well/pipe/cross fencing/water facility, etc.).  

Dr. Bruce Anderson shared the following information:  Before planting anything, review your herbicide history. Prior use of contact herbicides like glyphosate won’t cause any problems, but some herbicides have a long soil residual effect that could prevent successful establishment of some crops.  Double crop choice is likely to be different for rainfed and irrigated conditions. One ton (dry weight) of forage production is likely to use 4-5 inches of water. For rainfed conditions, a crop that will winter kill is preferred in order to accumulate soil water from snow melt and spring rainfall for the next crop. For irrigated conditions, forage production will be more with a crop that survives winter and is spring harvested—although irrigation for the forage and following crop will likely need to be increased compared with no double cropping.

Fall Forage options:  Determine when the forage crop is to be harvested and how it will be used. For fall-harvested hay or silage, oats or other spring cereals will outyield all other options. Plant about 100 lb. of seed per acre. Various legumes like hairy vetch, field peas, or winter peas can be added to increase protein concentration a percentage point or two, but they are unlikely to increase dry matter yield; the forage from the cereal alone will meet most cattle protein needs. Also be wary of spending more for the seed than the extra protein might be worth. For grazing this fall and winter, turnips and oats (separately or in a mixture) usually will provide the most feed.
     Early planting and emergence (irrigation or soil moisture must be available immediately) is essential for successful fall forage. Plantings after Labor Day rarely produce sufficient growth for mechanical harvest in the fall and the amount of fall grazing becomes negligible for plantings made after mid-September. Even earlier planting dates may be needed for sites north of the Platte River. Later plantings should consist of winter cereals. Also, the chances for successful establishment are low unless soil is sufficiently moist to at least an eight-inch depth at time of planting.

Spring Forage Options:  For spring forage, the winter cereals rye, triticale, and wheat tend to be the best choices. Rye is your best choice for early spring pasture and produces much growth before being terminated for timely planting of a row crop. Some rye varieties also provide enough fall growth for some light grazing if planted early enough. Rye also may be the most reliable crop when planted under stressful conditions. Rye has some drawbacks. It turns stemmy and matures much earlier than triticale or wheat, with a loss in feed value and palatability, although this should not be an issue if harvest ends in time for spring planting of a row crop. Also, it should not be used in fields that will be used to grow grain wheat due to potential contamination that could lead to discounts/dockage when wheat grain is sold.
     Triticale holds on to its feed value best into late spring. This makes it well suited for hay and silage, or for stretching grazing well into June if grazing begins two or three weeks later than it could begin with rye. Triticale often is more susceptible to winter injury than rye and wheat.
     Winter wheat will provide very little grazing for fall. During spring, forage quality and acceptance is very high but forage yield is less than rye and triticale. It can be grazed and then allowed to produce grain if grazing ends when plants begin to joint and elongate.
     Mixtures often can be desirable and can be designed for individual needs. For example, an early planting of 30 lb. of oats plus 75 lb. of winter rye per acre may provide both fall grazing from the oats and spring grazing from the rye. 

#UNL #Drought12 Educational Summary

A survey of UNL faculty and staff provided a snapshot of the educational response UNL Extension has taken for Drought 2012.  Below is a one-page summary of these efforts.  For all UNL Drought-related information please check out 

2012 Last Irrigation Scheduling

While farmers may be tired of irrigating right now, I think all who have irrigation are thankful for it in such a dry year.  Honestly, thankfully with our irrigation we have some of the best looking crops in the Corn Belt right now.  Even so, with corn that hasn’t been replanted nearing dent or stages of starch fill, you may be wondering how to schedule for your last irrigation.

For those of you in our Nebraska Ag Water Management Network using watermark sensors, the goal is to use them to determine when the soil profile reaches 60% depletion (for silty-clay soils in our area aim for an average of 160 kpa of all your sensors).  You may be thinking, “An average of 90kpa was hard enough!” but as Daryl Andersen from the Little Blue Natural Resources District points out, you’re only taking an additional 0.30 inches out of each foot.  So if you’re averaging 90kpa on your three sensors, you have depleted 2.34 inches in the top three feet so you still have 0.96 inches left (see the Soil Moisture Depletion Chart).  If you add the fourth foot (using a similar number from the third foot), it would bring the water available to the plant up to 1.28”. 

At beginning dent corn you need 24 days or 5 inches of water to finish the crop to maturity.  If you subtract 1.28 from 5 you will need 3.72” to finish out the crop.  Corn at ½ milk line needs 13 days or 2.25” to finish the crop to maturity-so subtracting it from 1.28 would be only 0.97”.  

Soybeans at the beginning of seed enlargement (R5) need 6.5”.  Soybeans in R6 or full seed which needs 3.5 inches yet for maturity.  Subtracting off the 1.28” in the four foot profile would lead to 2.22”.  The UNL NebGuide Predicting the Last Irrigation of the Season provides good information on how determine your last irrigation in addition to showing charts on how much water the crop still needs at various growth stages.  

Several people I’ve talked to who have been irrigating using watermark sensors aren’t replenishing the second foot, so you may have a few rounds yet to go  on corn and beans.  For a quick way to know where you’re at, think about irrigating this way as explained by Daryl Andersen at the Little Blue Natural Resources District:

One way to look at this is by the numbers of days left.  At 1/4 starch, there are about 19 days before maturity so you can let your sensors average 130kpa on the first week and 150kpa on the next week.  If these targets are met during the week, you would put on about 1 inch of water.  By going to these numbers, it might give you a higher probability for rain in the next couple of weeks.  I’m hoping for many answered prayers that we will see rain in August!

Drought-Maintaining Silage Quality

Unfortunately the drought continues to intensify.  All Nebraska counties have now been released for haying and grazing of Conservation Reserve Program (CRP) lands.  Information and resources continue to be added to UNL Extension’s Drought Resource page at  Please check it out for drought information for livestock, crops, water, and gardening.

Some   have started chopping corn for silage or are about to soon.  Dr. Bruce Anderson, UNL Extension Forage Specialist, shares the following information about maintaining silage quality in the future.  “After silage has been chopped and piled and packed correctly, it still can be damaged seriously by air and moisture slowly penetrating the outer 3 to 4 feet. Animals often eat less when fed moldy silage and can even experience health problems due to mycotoxins.

Good, well-eared silage can lose over 20% percent of its feed value from fermentation and spoilage under normal conditions. Silage made from corn with little or no grain might have even greater losses. This loss can be cut in half or even more if the silage is kept well covered by plastic.

Cover freshly chopped silage with black plastic immediately after you finish filling the trench, bunker, or pile. Then cover the plastic with something to help hold it down. Old tires are readily available and do a good job of keeping the plastic from blowing away, but they only keep keep pressure on the silage directly under the tire. In between the tires, air can circulate and cause spoilage.

An even better choice would be a solid cover over the plastic, something like freshly chopped forage or weeds or maybe even a 3- to 4-inch layer of manure. This would ensure that the entire surface of silage is fully protected to reduce the chance for air bubbles to form under the plastic which could reduce silage quality. You go to a lot of time and expense to make good silage. Isn’t it worth it to protect that investment?”

Drought: Resources & Options for Corn

Well, the heat isn’t letting up.  Sixty-nine Nebraska counties are allowed to hay and graze Conservation Reserve Program (CRP)  lands.  In our area these counties include:  Hamilton, Hall, Webster, Nuckolls, and Thayer.  From Teri Post at the Webster Co. FSA office, this means that:  “If it (CRP) is hayed, it cannot be sold and cost to the livestock person cannot exceed the 10% reduction on contract payment.  Paperwork MUST be completed prior to anything being done.  If you do not have livestock but do have a CRP contract, you can lease your acres to a livestock producer.  They have also released CP25 (wildflower mix) for grazing only.  If you prefer to sell the hay and you qualify for managed haying, you may do that but you will be assessed a 25% payment reduction rather than the 10% with emergency release.  Also keep in mind that use of emergency haying or grazing restarts the time clock for when you can hay or graze next.  If you use the emergency hay or graze release, even if you hayed or grazed in a prior year you are now eligible to hay or graze again.”

Nebraska Farmers who have drought damaged corn which could be swathed and baled, chopped, or grazed can list that on the Nebraska Hay and Forage Hotline.  The hotline is available free of charge for buyers and sellers to list feed resources.  Call the hotline at 1-800-422-6692 to list the forage you have or to list your need for forage.  I’ve been contacted by Extension Dry Panhandle rangelandEducators in the Sandhills asking if we have any producers willing to rent cornstalks for grazing this year to please let me know and we will put you in touch with producers in the Sandhills who need forage.

UNL Extension has developed a Drought Resource Web resource that pertains to crop and livestock producers. Some of you have been asking about options for dryland crops right now.  Research has shown benefits to the following crop if stubble height is left at least 10 inches tall when haying or cutting silage from drought damaged corn fields.  Leaving a higher stubble height will also reduce the nitrate levels in the forage that has been cut. 

When it comes to your options on what to do with weather-damaged corn, Dr. Bruce Anderson, UNL Extension Forage Specialist and Tom Dorn, UNL Extension Educator, recommend to consider the following points before harvesting your crop as forage:

  • If grain prices remain high, grain yield may not need to be very high to justify selecting grain harvest over forage harvest.
  • Sometimes leaving the corn residue can result in increased yield next year and that increase may provide more value than that resulting from forage use. See NebGuide G1846, Harvesting Crop Residues for information on evaluating your situation.
  • Check labels of all chemicals applied to be sure they are cleared for forage use and that the minimum harvest interval has been met.
  • Check with the USDA Farm Service Agency and your crop insurer to maintain compliance with farm programs and crop insurance requirements.
  • Nitrate concentrations can reach toxic levels in weather-damaged corn. The harvest method can affect the nitrate, a particular concern when its being fed to livestock. Leaving a tall stubble (8 or more inches) will reduce nitrate risk but note eliminate it. Choose the harvest method accordingly.

Silage may be the safest method of harvest as fermentation usually (but not always) reduces nitrate levels and risk. Yield is about one ton per acre of silage for each harvested foot of earless corn plant (not counting the tassel). Feeding value is about 70% to 80% of well-eared corn silage. Corn with some grain (less than 50 bushels) tends to produce about one ton of silage for every five bushels of grain with a feed value about 80 to 90% of regular corn silage.

Harvest timing is critical with silage to ensure the correct moisture for proper fermentation. Plants probably are about 80% moisture now and the desired moisture level for silage is about 65%. Plants with any green leaves usually are too wet to chop for silage. For proper moisture, most leaves may need to be dead before chopping. The stalk and ear hold amazingly high water concentrations. For corn with no grain, even if all leaves are dead, the whole plant (and silage) moisture can be 70% if the stalk is still green and alive. Once plants actually die they can rapidly dry down.  There are several ways to reduce moisture content:

  • If corn has pollinated, delay silage harvest until all chances of increased biomass tonnage have passed or plants naturally dry down to appropriate moisture levels.
  • Corn can be windrowed and allowed to partially dry before chopping.
  • Excessively wet material can be blended with drier feeds such as ground hay, cracked grain, or dried distillers grains. However, this can take a lot of material — about 500 lb of grain or hay to reduce each ton of chopped corn with 85% moisture down to 70% moisture.
  • Silage inoculants may improve fermentation and preservation of drought-damaged silage.

Green Chop:  Green chop minimizes waste but may be the most dangerous way to salvage corn. If present, nitrates will start to change into nitrites (about 10 times as deadly) as green chop begins to heat. Chop and immediately feed only an amount that animals will clean up in one feeding. Chop and feed two or three times per day instead of providing excess feed from a single chopping. If any green chop remains two hours after feeding, clean out bunks. Never feed green chop held overnight because nitrites can be exceptionally high. Be sure to allow plenty of bunk space (36 inches per cow is recommended) so boss cows don’t overeat and timid cows can get their share.

Hay:  Hay may be the most difficult method of mechanical harvest, especially if ears have started to form – the stalk and especially the ears will be slow and difficult to dry. If possible, use a crimper when windrowing. Unlike with silage, nitrate levels do not decrease in hay after it is baled. Some of the nitrate risk can be reduced by cutting to leave a tall stubble, about 8 inches. Tall stubble also will elevate the windrow off the ground, allowing air to circulate better through the forage and aid in drying.

Grazing:  Challenges with grazing include acidosis risk for cattle not accustomed to grain if ears have started to fill (smart cows will selectively graze ears), waste from excessive trampling, availability of drinking water, perimeter fencing, and nitrates. Reduce acidosis risk by feeding increasing amounts of grain similar to feedlot step-up rations before turning into standing corn that has much ear development.

Reduce waste by strip-grazing with at least two or three moves per week; daily is best. Back fences are not needed because regrowth is not expected. Water can be hauled in as with winter corn stalks or lanes might be constructed with electric fence to guide animals back to water sites that are nearby. If strip grazing, animals can walk back over previously grazed areas since back fences aren’t needed.

Perimeter fences can be built using the same fencing as for winter stalks. Cows are likely to respect such fencing but inexperienced calves may not remain where desired. To better control calves, use a double strand of electric wire and/or a more visible barrier such as electric polyrope or polytape. Animals not already experienced with electric fences may need some exposure and training before moving them to a corn field.

Nitrates usually are not a problem with grazing since the highest concentration is in the stem base, the plant part least likely to be consumed. Risk increases, though, if animals are forced to “clean-up” a strip before moving to fresh feed and when corn plants are short (probably less than 3 to 4 feet tall) with small, palatable stem bases. Tests for nitrate concentration (whole plant and just the bottom 8 inches of the stem base) can be made prior to grazing to assess risk. If nitrate levels are risky, the hazard can be reduced by offering enough desirable forage to discourage consumption of hazardous plant parts as a major component of diet. Also, delaying grazing until plants more fully mature often lowers nitrate risk.  NebGuide G1865, The Use and Pricing of Drought-Stressed Corn, offers additional information.

Windrow Grazing:  This method includes cutting as you would for hay and then grazing the windrows rather than baling them. It eliminates the cost of baling, transporting bales, feeding bales, and maybe hauling manure. It also eliminates any flexibility in feeding location and may reduce opportunities to sell the corn forage.

Windrowing tends to preserve forage quality better than allowing plants to stand. Usually it is easier to strip graze windrows than standing corn because building fences and estimating strip size are easier. Snow cover rarely causes problems if animals already know the windrows are there. They will use their hooves and face to push snow aside to access the windrow. Thick ice, however, can cause a significant barrier. Follow appropriate management recommendations listed earlier for hay and grazing for best utilization and safety.

Additional Resources: US Drought Monitor Map and High Plains Drought Monitor Map


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