Ag Connection

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Special Issue
August 1997
Drought Information from Ag Connection
This information was compiled by University Outreach and Extension staff in Central Missouri on August 13, 1997. Some of the articles are on this page, other titles link to articles in previous editions.

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Please send your comments and suggestions to Maryann Redelfs, Agronomy/Information Technology Specialist, University Extension, Courthouse, 200 Main, Boonville, MO 65233, call 816-882-5661, or send messages by e-mail to:

To send a message to an author, click on the author's name at the end of an article.

Ag Connection - Other Issues

University Extension

Stress from the Drought
Possible Tax Issues Related to Drought
Other WWW Sites for More Drought Related Information
     Estimating Corn Yields Prior to Harvest
     Conditions Ripe for Spider Mite in Soybean
     When Should You Stop Irrigating?
     Corn for Hay or Silage
     Utilizing Temporary Bunker Silos
     Valuing Drought Damaged Corn for Silage
     Good Harvest and Storage Techniques Reduce Silage Problems
     Use Your Microwave Oven to Test Forage Moisture
     Maturity, Moisture Content and Cutting Length for Silage Harvest
     Keep Silage Fresh During Feeding
     Safety at Silage Time
     Other Resources on Silage: G04590: Corn Silage
Feeding Livestock
     Feeding Drought Corn to Calves
     Preventing Nitrate Toxicity Problems with Livestock
     Using Feeds with High Nitrate Levels
     Aflatoxin Alert
     Purchasing Strategies to protect Against High Feed Costs
     Strategies for Using Alternative Feeds In Ruminate Diets
     Swine Feed - Alternatives to Corn
     Using Cool Season Cereals to Extend the Grazing Season
     Fall Oats for Emergency Forage
     Anhydrous Ammonia Treatment of Low Quality Forages
     Six Steps for Successfully Using Ammoniated Forages
     Other Resources on Feeding: G04970: Plants Poisonous to Livestock

[Other Drought Topics] [Ag Connection - Other Issues Online]

Stresses from the Drought

The effects of the drought can create much stress for farm families. Individuals have a tendency to withdraw from others when faced with the problems associated with the drought. We all need to be aware of the symptoms of stress and be ready to see that those affected most by it receive the help they may need. University Outreach and Extension has some resources that can help. Some resources are also available from North Carolina on the Internet at

Author: Don Day, Ag Engineering/ Information Technology Specialist

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Estimating Corn Yields Prior to Harvest

There are several techniques for estimating corn grain yield prior to harvest. A numerical constant for kernel weight is figured into the following equation in order to calculate grain yield. Since weight per kernel will vary depending on hybrid and environment, yield will be overestimated under poor grain fill conditions, while it will be underestimated if grain is larger than average, which may occur with poor pollination, but good grain fill conditions.

  1. Count the number of harvestable ears per 1/1000th acre.
  2. Count the number of kernel rows per ear on every fifth ear. Calculate the average.
  3. Count the number of kernels per row on each of the same ears, but do not count kernels on either the butt or tip that are less than half size. Calculate the average.
  4. Yield (bushels per acre) equals: (number of ears) X (average row count) X (kernel count)

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Corn for Hay or Silage

Don’t get in a hurry to salvage corn as forage. When hope of harvesting a grain crop is lost or extremely low, consider the following points:

  1. Determine if it contains toxic nitrates. Contact your local extension center for a qualitative test.
  2. If nitrates are found —
    a. Nitrates are most concentrated in the lower stem. Cut the silage higher to reduce the amount of nitrates in the silage.
    b. Delay harvest — rains may allow growth, moving excess nitrates into the grain.
    c. The ensiling process reduces nitrates. Haying does not reduce the presence of nitrates.
    d. If green chop is utilized, feed immediately, do not hold overnight.
  3. If stressed corn is harvested for silage, wait for moisture to lower to an acceptable level (60 to 70%). The loss of a few leaves won’t substantially reduce yield.
  4. Don’t attempt to make hay without a crimper to crush stalks in order to facilitate dry down.

For more information on silage, see “Good Harvest and Storage Techniques Reduce Silage Problems” and other related articles.

Authors: Dale Watson, Livestock Specialist and Ron Alexander, Agronomy Specialist

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Grasshopper numbers are moderate to high in most areas of the state. Adults and later nymph stages are present. During the past three weeks, numerous soybean fields have required insecticide applications to reduce grasshopper numbers and prevent further feeding on soybean foliage and pods. Other crops at risk from grasshoppers include grain in sorghum heads and newly seeded plantings of alfalfa and wheat.

If drought conditions and high grasshopper numbers persist, damage to field crops could be heavy. Typical damage consists of large irregular shaped holes extending from the margin to the center of the leaf. Grasshoppers are capable of doing considerable damage in a very short time.

The economic thresholds for soybeans are 8 or more grasshoppers per square yard and 3 or more grasshoppers per plant in corn. At this time in the season, use the higher recommended rate when attempting to control large nymphs and adult grasshoppers. If ground application equipment is used, apply a minimum of 15 gallons of water/insecticide spray per acre for optimal coverage in thick crop canopies. Be sure to read and follow all pesticide label directions and precautions. Contact your local extension center for specific pesticide recommendations and rates of application.

Author: Wayne Bailey, Entomologist, UMC

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Conditions Ripe for Spider Mite in Soybean

There have been reports of spider mite damage in soybean from our neighbors in Illinois, Nebraska and Kansas during the last few weeks. In Missouri’s Bootheel, isolated spider mite outbreaks have been reported in soybean and cotton. Keep an eye open for early symptoms caused by the most common mite found in Missouri soybean fields — the twospotted spider mite.

Twospotted spider mites can complete an entire life cycle in about 5 days when temperatures are high, and each female will lay 50 to 100 eggs. Therefore, populations can quickly explode to economically damaging levels. Outbreaks may be especially severe during extended drought in July and August (particularly following mild winters).

Damaged leaves initially appear mottled yellow and sandblasted and symptoms first occur on lower leaves. If the outbreak is severe, leaves prematurely turn bronze, wilt and drop, so that circular patches of beans appear “scorched” and stunted. Although the highest soybean yield losses are associated with early, untreated spider mite infestations, an outbreak at seed set results in smaller, wrinkled seeds and seed abortion. Infested soybean fields may show increased discoloration in drought stressed areas that producers may not recognize as spider mite damage.

Damage symptoms are typically first noted along the southern or western field margins and then spread in the direction of the prevailing winds, because spider mite movement is mostly the result of “ballooning” on silken threads. Infestations are often first discovered next to overwintering sites, which include undisturbed areas such as grassy fencerows, waterways, pastures, and alfalfa or red clover fields.

Adult twospotted spider mites are about 1/60-inch long, have 8 legs and are yellowish in color with dark spots on each side of the body. Mites feed by sucking plant juices from individual cells and this feeding damage appears as chlorotic stippling (yellowing) of the leaf. Use a 10X hand lens to examine the undersides of yellowed soybean leaves along field edges for fine webbing covering the mite colonies. To verify the presence of mites, shake discolored leaves over white paper and watch for moving “specks”. If you find neither mites nor webbing, eliminate other possible causes of leaf yellowing such as soybean cyst nematode or herbicide injury. Suspect fields should be scouted once a week or more often.

There is no specific economic threshold for spider mites in soybeans. Consider treatment when soybean plants along field margins show leaf discoloration and mites are still present, especially if drought conditions continue. Cool and humid weather promotes the suppression of twospotted spider mites by a naturally occurring fungal disease. Heavy rainfall often causes the collapse of spider mite populations.

Insecticides recommended for the control of twospotted spider mites are Lorsban 4E (0.5 to 1 pint product per acre) or Cygon 400 (1 pint product per acre). For ground applications use high pressure and gallonage for good coverage of the underside of the canopy. Consider a spot treatment if you catch a border infestation before dispersal, but monitor closely for reinfestation. Treat an area 2 to 3 times the size of the apparent infested areas. Try to avoid driving through uninfested areas during spot treatments. Once the soybeans have reached physiological maturity, pesticide treatments will not increase yields.

Authors: Maureen O’Day, Anastasia Becker and Wayne Bailey, UMC and , Jim Jarman, Agronomy Specialist

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Utilizing Temporary Bunker Silos

A temporary storage facility for corn silage can be constructed relatively inexpensively. Packing the silage between two double rows of large round bales placed on top of the ground works quite well. The bales are placed perpendicular to the length of the silo. The spacing between the double rows should be determined by how fast the silage will be fed. The length is determined by how much silage is to be stored.

Bales should be lined with plastic in order to reduce the amount of spoilage. Using two layers of plastic allows for slipping and reduces the potential of tearing holes in the plastic when packing the silo. If plastic isn’t used, two to four feet of spoilage can be expected due to the transfer of moisture from the silage into the bales of hay. Set a post on the outside end of each bale to reduce the possibility of the bale slipping when silage is being packed with a tractor or loader. Keep in mind that equipment can easily overturn when make-shift storage facilities are being used.

Author: Dale Watson, Livestock Specialist

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Valuing Drought Damaged Corn for Silage

The value of corn for silage at the field is largely determined by the prices of corn and hay along with the distance to the feedbunk. The anticipated value of the crop for grain is fairly easily estimated. On the other hand, estimating the value of silage at the field is more elusive for many grain producers. The following worksheet, developed by Myron Bennett, retired University Outreach and Extension Agricultural Economist, is a tool producers can utilize to estimate the value of standing corn in the field. However, local supply and demand influence the settlement price. This year the supply of corn silage may exceed demand.

  1. Estimated grain yield per acre _______ bushels x $_______ price/bushel = $_______/acre
  2. Cost of grain harvest per acre $_______/acre
  3. Cost of hauling to market $_______/acre
  4. Net value of grain in field (line 1 minus lines 1 & 2) = $_______
  5. Estimated silage yield per acre (tons)_______
  6. Total tons dry matter (DM) = line 5 _______ x _______% DM =_______ tons 100% dry matter
  7. Pounds of 90% air dry feed = (line 6 _______ divided by 90%) x 2000 pounds = ________ pounds
  8. Weight of ear corn 90% air dry = bushels from line 1 _______ x 72 pounds =_______ pounds
  9. Net weight of stover (90% air dry) = line 7 _______ minus line 8 _______ = _______ pounds
  10. Value of stover = line 9 _______ x _______ price/pound for standing hay = $ _______/acre
  11. Maximum value per acre of corn in field = line 4 _______ + line 10 _______ = $_______/acre

The maximum value of standing corn for silage in the field will need to be reduced for the costs of harvesting, hauling, packing, storage, and the losses associated with harvest, storage, and feeding. Information from “Pricing and Use of Immature Corn as Silage for Beef Cattle”, a Michigan State University staff paper, suggests the storage losses might range from ten to twenty percent; harvest costs $2/ton; and hauling and packing at $1.50/ton, depending on distance. Location is as important in marketing silage as it is in real estate!

Prices and demand are volatile in drought driven markets and grain markets are more established than the silage market. If you plan to sell silage - “ESTABLISH A MARKET BEFORE CUTTING”!

Author: Parman R. Green, Farm Business Management Specialist

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Maturity, Moisture Content and Cutting Length for Silage Harvest

Crop Maturity Silo Type Length of cut (inches)
Bunker Stave Sealed
% moisture
Corn Silage milk line -2/3 down kernel 67-72 63-68 50-60 3/8-1/2
Alfalfa mid-bud to 1/10 bloom, wilt to... 65-70 60-65 50-60 1/4-3/8
Cereal Silage milk-soft dough, wilt to... 67-72 63-68 50-60 1/4-3/8
Grasses stems first head out, wilt to... 67-72 63-68 50-60 1/4-3/8
Clover 1/4-1/2 bloom, wilt to... 67-72 63-68 50-60 1/4-3/8
Forage Sorghum medium-hard grain or leaves begin to lose color 70-75 65-70 50-60 3/8-1/2
Sorghum-Sudan-grass 3-4 ft high 70-85 65-70 50-60 3/8-1/2
Whole plant Grain Sorghum medium-hard dough grain 67-72 63-68 50-60 3/8-1/2
Ground Ear Corn full dent 34-40 32-38 28-34 ......
Cracked Shelled Corn full dent 26-32 26-32 ...... ......
Whole Shelled Corn full dent ...... ...... 22-28 ......
Rolled Ground Sorghum Grain medium-hard dough 26-32 26-32 ...... ......
Whole Sorghum Grain medium-hard dough ...... ...... 22-36  

Other Forages for Silage

Crop Stage of Maturity to Harvest Percent Moisture at Harvest
Corn Residue Following Grain Harvest 50 to 60
Grain Sorghum Stover Grain Harvest to Killing Frost 60 to 70
Oats Late Boot or Early Head 82
Oats Milk 78
Oats Early dough 70
Wheat Late Boot to Early Dough 70 to 80
Barley Late Boot to Early Dough 70 to 82
Rye Late Boot to Early Head 75 to 80
Triticale Early Head 70

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Feeding Drought Corn to Calves

For corn producers unfortunate enough to be in one of the many drought pockets around the state, chopping and feeding corn may look like the best approach to salvaging a poor crop. The seasonal price pattern on calves works against feeding green chop. The annual low in calf prices usually comes in October.

Using corn silage to replace drought stricken pastures may seem like a good idea, but the odds are against making much money doing it. Because of fluctuating cattle prices, feeding a calf to produce a pound of gain does not always yield the same increase in value. Summer gains are typically much less valuable than winter gains.

For example, thus far in the 1990s, an average 550 pound steer calf in October has exceeded the value of a typical 450 pound steer in August by only $35.50. Thus, the average gross return to 100 pounds of gain from August to October has only been 35.5 cents per pound. In contrast, a 550 pound steer in February has exceeded the price of the average 450 pound steer in December by $80.98. So far this decade, the average gross return for putting 100 pounds of gain on a 450 pound calf from December to February has been nearly 81 cents per pound.

The same relationship holds true for heavier weight calves. Winter gains tend to be worth 50% to 100% more per pound than spring and summer gains.

So, for farmers who do chop their corn for silage, rather than buying calves now and feeding it immediately, waiting until later in the year to feed the silage should increase the probability of making a profit.

Author: Ron Plain, Extension Economist, University of Missouri

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Preventing Nitrate Toxicity Problems with Livestock

Acute nitrate/nitrite poisoning is caused by the presence of nitrite in the blood at a level sufficient to cause anoxia (internal suffocation). The chief symptom, anoxia or oxygen deprivation, causes a bluish color of the mucous membranes of stricken animals. The blood is chocolate-brown in color due to methemoglobin formation. These characteristics are very indicative of acute nitrate/nitrite poisoning. Abortion of fetuses may result.

In Kansas, Missouri and other cornbelt areas, cornstalk poisoning had been observed well before 1900, but the true nature of this nitrite intoxication was recognized as recently as 1954. This condition has been associated with corn growing under drought conditions on a wide range of soil types with adequate to high levels of available nitrogen for plant growth.

Young animals are highly sensitive to nitrite as compared to mature animals of the same species, because fetal hemoglobin is more sensitive to nitrite than adult hemoglobin. Pregnant animals often lose their fetuses because of anoxia (methoglobinemia) without any apparent long-range damage to themselves in nitrite/nitrate poisoning.

Hungry, depleted animals are less tolerant to nitrite/nitrate intake than are well-fed animals on adequate rations. Aged animals, especially those in poor nutritional state, are more sensitive than are younger mature animals to excessive nitrite, or the parent substance nitrate.

Sampling should be done carefully. The analysis can be no better than the sample.

Dry forages — Whenever possible, send in a core sample from 15 to 20 bales. (Use Penn State Sampler or equivalent). For loose hay or without bale sampler, open 10 to 15 bales and take a grab sample of approximately one handful from each. Cut the forage into 2- to 4-inch pieces, being careful to preserve all leaf material. Pack tightly in a container.

Silage and fresh grass — Pack the sample (approximately 5 lbs.) in a plastic bag. This sample should be taken from a composite sample of at least four areas in the silo or pasture. Samples should be carried or sent immediately to the laboratory. If transit time will be more than three hours, freeze the samples to minimize bacterial action. If mailing, use a service that will deliver overnight. Otherwise, test results will be lower than in the feed offered to livestock. Chemical preservatives such as mineral acids, chloroform, toluene, etc., should not be added unless they have been cleared by the laboratory doing the analysis.

Water — Collect water in a clean, sterile bottle (2 oz. minimum). When collecting from a water system, allow enough flow to replace all the water in the lines and dilute out the pressure tank. Then take the sample. Ponds may be sampled from the drain pipe. In unimproved ponds, sample so as to avoid mud contamination.

Local extension offices are prepared to check samples for the presence of nitrate using the diphenylamine blue test. Additional information on nitrate toxicity is available in University Extension guides G09800 and G09811.

Author: Mark Stewart, Livestock Specialist

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Using Feeds with High Nitrate Levels

Feed Concentration as Nitrate Ion (Dry Matter Basis) Estimated Toxicological Significance for Cattle
0.00 - 0.44% Considered safe to feed under all conditions
0.45 - 0.66% Safe for nonpregnant animals under all conditions. Limit for pregnant animals to 50% of the total dry matter in the diet.
0.67 - 0.88% Limit to 50% of the total dry matter in the diet.
0.89 - 1.54% Limit to 35 - 40% of the total dry matter in the diet. Do not use for pregnant animals.
1.55 - 1.76% Limit to 25% of the total dry matter diet. Do not use for pregnant animals.
Over 1.76% Do not feed!!

The corn and grain sorghum plant as well as summer annual forages all have the potential for being high in nitrates. Of particular concern is the use of stunted corn plants for green chop. It is recommended that suspect forages be tested for nitrates. The diphenylamine blue test is a quick and easy way to determine if nitrates are present.

If nitrates are present, a quantitative test may be needed to determine the actual nitrate concentration. Once the amount of nitrate in the feed is known, a decision can then be made on how to use the feed safely. The table at right contains accepted recommendations for feeding high nitrate feeds.

The possibility of nitrates in other feed stuffs needs to be considered. If the livestock water source is contaminated with nitrates, an additive situation can occur. If it is necessary to test livestock water for nitrates, see information in “Preventing Nitrate Toxicity Problems with Livestock” .

Author: Mark Stewart, Livestock Specialist, Source Drs. George Rottinghouse and Stan Casteel

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Aflatoxin Alert

Several factors have combined to make aflatoxin in feed grains a concern this year. Corn ear worm damage has been a problem for early corn. Ear worm damage is an easy place for mold growth to start. Many acres of corn have been stressed by heat and lack of rain. This stress can also encourage mold growth. Following these stressors, cooler wet weather which can be expected beginning in early September provide ideal growing conditions for the mold if it becomes established in stressed crops.

Aflatoxicosis outbreaks are frequently observed as unthriftiness and weakness and possibly sudden death. A black light screen may indicate the presence of mold. However, it is not considered an effective screen for aflatoxin. If aflatoxin is suspected, a laboratory mycotoxin screen should be obtained. Your veterinarian or local extension center can help you send a sample for mycotoxin screening through the Veterinary Medical Diagnostic Lab, UMC.

Author: Mark Stewart, Livestock Specialist

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Purchasing Strategies to Protect Against High Feed Costs

Dry weather and short crops usually produce high feed costs. The adverse effects of high feed prices can be compounded if mass livestock liquidation occurs and lower livestock prices result.

Protecting feed prices with advance cash purchases or with forward contracts in anticipation of higher prices can reduce price risk. Cash purchases require an early outlay of operating funds, adequate storage for the grain or feed and the ability to properly manage the stored commodities in order to maintain quality. These disadvantages can be avoided by the use of forward contracts for later delivery. However, corn producers may be reluctant to sell corn or contract for later delivery at this time, as they anticipate higher prices too.

Hedging feed price by purchasing futures contracts offers price protection, yet provides for greater purchasing flexibility. The futures market is very liquid and sellers are always available. Hedgers seldom take delivery on the futures contract. Instead, they liquidate the futures position and buy in the cash market to get the actual feed supply. The futures price change, from the time of the hedge (futures purchase) until it is liquidated, offsets the cash price change and the net result is the earlier hedged (protected) price.

All of these strategies allow the livestock producer to "lock in" prices and avoid potentially higher prices. A disadvantage of these strategies is that, if prices drop unexpectedly for some reason, the producer is already committed and cannot take advantage of the lower price.

A call option offers the ability to protect against higher prices and still take advantage of lower prices. The purchase of a call option gives the producer the right, but no obligation, to buy a futures contract (enter a hedge) at a specified price (strike price). If prices go up, the option can be exercised and the feed purchase hedged at the strike price. If prices go down, the option is worthless (since there is no obligation) and the feed can be purchased at the lower cash price. The cost of using the call option strategy is in the form of a "premium" paid to the option seller (writer). The premium is a cash cost to the purchaser and paid to the seller for assuming the risk associated with the option.

Cross-hedging is a technique sometimes used to protect prices of a commodity not traded in the futures market. For example, a livestock producer wanting to hedge hay or byproduct feeds might purchase a corn futures contract (or call option). The theory is that the dry weather would have the same effect on the price of the other feeds as it did on corn. This is not a true hedge! It is speculation that the price moves will be similar. A cross-hedge should only be attempted by someone who is familiar with both markets and is able to react quickly to changing market conditions.

Author: Melvin Brees, Farm Management Specialist

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Strategies for Using Alternative Feeds In Ruminate Diets

Even without drought conditions the purchase and use of by-product feeds can be a profitable alternative to using traditional feedstuffs. The selection of by-product feed(s) is determined by several factors. These factors include:

Ultimately, the decision to use or not to use by-product feeds should be made after considering the options and factors discussed above. Specific inclusion rates in the diet or feeding recommendations should be based on an understanding of the unique characteristics of by-product feeds and how they can be used in the diets fed to ruminates.

Current By-Product Feed Prices

Author: Jim Spain, State Dairy Specialist

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When Should You Stop Irrigating?

Irrigation management near the end of the season should balance the following goals:

  1. Provide enough soil moisture to the root zone to carry the crop to maturity and to produce best yields.
  2. Deplete soil moisture reservoir as far as possible to allow room for storing off-season precipitation (minimizing fuel, labor, and water demands for the present next season) and allowing full entry into fields for harvesting this year.

Although these requirements appear to conflict, the problem can be solved if adequate field information is available or is can be predicted. The following information is necessary to predict whether one last irrigation may be called for:

Table 1. Countdown water and time requirements to finish off crops (after NE Guide G82-602-A)

Stage of Growth Approx. Number Of Days to Maturity Water Needed




     Full pod development (R4) 37 9.0 0.30
     Beginning seed fill (R5) 29 6.5 0.25
     Full seed fill (R6) 17 3.5 0.21
     Beginning maturity (R7) 0 0.0 ----
     Blister kernel 45 10.5 0.27
     Dough 34 7.5 0.25
     Beginning dent 24 5.0 0.23
     Full dent 13 2.5 0.19
     Physiological maturity 0 0.0 ----
Grain Sorghum
     Half bloom 34 9.0 0.36
     Soft dough 23 5.0 0.27
     Hard dough 12 2.0 0.17
     Physiological maturity 0 0.0 ----

  8/16 8/30 9/13 9/27
Columbia 52% 45% 43% 41%
Hannibal 42% 43% 48% 41%

This means that, in general, there is a near 50-50 chance of getting part of the rain that will allow crops to be finished off. Weather predictions are getting more and more accurate, and 3-day, 7-day, and 14-day estimates are available (e.g., ). Keep tuned in to reports on up-coming weather, and be ready to update your choice to irrigate or not to irrigate based on current conditions.

As an example, assume that your corn crop is beginning to dent, your lighter soil has just been well irrigated, and that you expect about 0.5 inches per week rainfall. The existing soil moisture means that 2.0 inches of the required 5.0 inches to finish off are already in the bank, as it were, and you or the good Lord need only to supply the difference, which is 3.0 inches. Since you have about 3 weeks to full maturity you can expect about 1.75 inch of rainfall, leaving an irrigation requirement of 1.25 inches. When do you need to apply this irrigation? Go back to Table 1 and notice that at the beginning dent stage the water use is about 0.19 inches per day. Since you can store about 2.0 inches in your profile, count on irrigating in 8 or 9 days if no rain occurs.

For those farmers using electricity from utility companies that have large associated demand charges another factor must be thrown into the balancing act — if a late season irrigation puts you into a new billing cycle, will starting up your pumps to put on one or two more small irrigations make you enough crop to justify their added cost.

It is important to have timely irrigation. However, the most important stages of growth during which the presence of ample water is important for most crops occurs during early- and mid-season. Although adequate moisture is important late in the season, it does not have the impact on final yield that water early on has. Many farmers try to compensate for water stress suffered early in the season, by pouring it on later on. Unfortunately this can be, as the saying goes, like pouring coals on New Castle.

Late season irrigations should be tapered down in size. This can be done by running the pivot at a faster speed.

You can stop irrigating when the crop is nearing maturity and you have enough moisture left in the soil to carry the crop to maturity. Following are guidelines on when to stop:

Soybeans — when early leaves are yellowing and dropping, 90 to 95 days after emergence.

Corn — when kernels are dented and starting to glaze, 95 to 100 days after emergence. Another good indicator is when the black layer appears. The ears will typically reach maturity 60 days after silking.

Grain Sorghum — at the hard dough stage, grain sorghum is about 12 days from maturity. It can use about 2 inches of water. Note, in claypan soils, we probably don’t want to apply more than about an inch of water at a time for optimal use of the water.

Other resources:

UMC Guide G04420:  Irrigating Soybeans
G76-301-A How to Tell Corn, Grain Sorghum Maturity -- Nebraska Guide
G82-602-A Predicting the Last Irrigation for Corn, Grain Sorghum and Soybeans -- Nebraska
     Caution, be sure to adapt this information for Missouri conditions.
Useful guides on Irrigation from Colorado State -- including one on how to estimate soil moisture.
     You must download Acrobat Reader to view these.
Irrigation Management Information from Minnesota

Author: Don Day, Agricultural Engineering/Information Technology Specialist, Joe Hengler, Extension Commercial Agriculture Irrigation Specialist

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Possible Tax Issues Related to Drought

Author: Parman R. Green, Farm Business Management Specialist

[Other Drought Topics] [Ag Connection - Other Issues Online]

WWW Sites for More Drought Related Information

Search University Outreach and Extension Information on the Web

Managing Drought-Stressed Corn for Silage — University of Florida

Drought Management Strategies Related to Production, Management, and Marketing of Corn and Sorghum in Texas

Nitrates in Livestock Feeding — Nebraska Extension Guide

Pricing and Use of Drought-Stressed and Immature Corn as Silage for Beef Cattle — Michigan State University (pdf files)

Drought Information Publications — North Carolina State University

[Other Drought Topics] [Ag Connection - Other Issues Online]

University ExtensionAg Connection - Special Drought Issue - August 1997 -- Revised: August 21, 1997