Lebanon Crop Management Video

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18 July 2011

Managing Crops in a Severe Drought

Del Voight - Penn State  Extension Agent
I have assembled some useful information for growers to utlize as we continue with the extended dry weather. I have heard from key producers that grass has dried to the point that cattle are on supplemental feed. Further in lighter soil conditions corn has been wrapping during the day for the last several days.  This is of concern here are some ideas to think about. In some areas forage supply may need to be taken seriously and options for supplemental forage is included with some idea of tonnage differences.


         

Corn

                Many areas of Pennsylvania are experiencing a severe drought due to the lack of rain since late June. Corn growth has stopped in many areas and in the worst areas corn fields are beginning to dry up.   Other grain and forage crops are drought stressed as well.  Although we can do little to change the weather, we can make some management decisions now to help minimize losses and salvage as much from a bad situation as possible.  Some key questions that silage and grain producers should consider are listed below.

What should be done now?  There are several things that should be initiated immediately.  The condition and yield potential of the crop should be assessed.  Dairy and livestock producers may want to collect a forage sample to assess moisture, forage quality and nitrate levels.  Grain farmers may want to begin identify ways to market their crop as silage.  All producers should be check with their crop insurance or FSA representative before harvesting the crop.

What is the yield potential of the field?  This will be variable depending on the severity of the drought.  For corn fields that are losing leaves and not unrolling at night, the yield potential will be likely low- from 0-50 bushel/acre or so.  For fields  that have a good stand and are exhibiting leaf rolling only during the day, there may still be good yield potential if the drought is broken soon.  Even many of these fields have lost a significant amount of their top end yield potential, perhaps 50 bushels per acre or more, if conditions would be perfect until the end of the season.

When should you decide to salvage the crop and harvest for silage? When leaves cease to unroll at night and the tops start to brown out, the plants are probably not going to recover.  As browning of the crop continues, the forage quality will decline as the plants are using stored carbohydrates in the leaves and stalk to sustain itself.  Producers should probably consider harvesting it for silage.  Delaying harvest will reduce yield and quality and reduce the potential for planting a second crop.  The moisture content may be higher than desired, so a dry feedstuff like chopped ear corn or hay may need to be to adjust the silage moisture and energy  for good fermentation.  If the forage is extremely wet (greater than 75-80%), then harvest should likely be delayed.  No definitive guidelines are available, but I would suggest that if half the leaves are dead or dying it would be a good candidate for evaluating for silage harvest.

What is the yield potential of this type of crop?  A rough estimate of wet (70% moisture) silage yield is about 1 ton per foot of height of corn without ears or poorly pollinated ears.  This estimate may be high on very short  (1-3 foot tall) crops.
What kind of silage will this crop produce?  This crop will likely be higher in protein than normal silage and lower in energy.  A ballpark estimate of silage quality might be  an NEL of 0.60- 0.64 and a crude protein of 9-12 percent.  Some preharvest forage testing may be appropriate to assess the quality, the level of nitrates, and the potential use of the forage.  If it were to rain, fields that have some recovery potential could produce some good quality silage. in these drought stressed crops that recover the ear to stover ratio will be good and the fiber digestibility is usually high.

Are nitrates a concern in this kind of crop?  Yes.  The potential is greatest for high nitrate levels in young plants, especially in the stalks and especially in heavily manured fields.  The potential is generally greatest for 3-4 days following a drought ending rain, but can be a problem anytime.  High nitrates can contribute to animal feed problems and deadly silo gas.  Producers should be especially cautious when filling silos with these suspect crops. Nitrates can be reduced by leaving a 12 inch stubble in the field- this would reduce yields, however, and may not be advisable unless a forage test confirms the presence of nitrates.  Because the nitrate potential can be reduced through ensiling, grazing and green chopping drought stressed corn are less desirable harvesting alternatives.

Is it worth harvesting these crops?  On some fields it may be a tossup. The variable costs such as fuel, labor and repairs, associated with chopping a light corn crop are in the $15 to $25/acre range, so if producers can harvest at least one ton of silage per acre valued at perhaps $20/ton they will break even.  To achieve this yield may require corn about two feet tall. 

What should grain producers be assessing?  Grain producers in the worst areas may need to be identifying silage markets for their crop.  This will help to alleviate potential feed shortages and provide a market for drought damaged corn crops that will produce little grain. They could also be considering plans for establishing other fall forage crops- there may be a significant market for these crops this fall.

What crops are a potential for replanting following corn?  This will depend on the herbicide program used for corn.  Generally, sorghum-sudan grass may be the most viable option if planting can be achieved by early August.  Small grains or soybeans are also alternatives in some situations, but the dry weather may  make atrazine carryover high which will damage the more sensitive crops like oats and soybeans.  Check herbicide labels for replanting restrictions.  If corn fields are unsatisfactory for planting fall forage crops, producers may want to consider no-tilling into small grain stubble fields- although these soils may be hard until it rains again.  Call the Extension Office for copies of raising alternative crops which will detail seeding rates and how to properly establish the different crops. 

Greg Roth
Associate Professor
Department of Agronomy
Penn State University



Nutritive Value of Drought Soybeans as a Forage Crop

       R. S. Adams, Emeritus, Professor of Dairy Science
       Penn State University


       Drought stricken soybean plants can be used as a forage crop. Allow plants to
       mature as much as possible before harvesting. Some pod or bean development
       enhances feeding value of plants harvested either as hay or silage. Soybean
       forages are high in calcium (about 1.3% on a DM basis).  For this reason it
       should be avoided as the major forage for dry cows.

       If ensiling, it is important to ensile before plant moisture drops below
       60-65%.  If possible, mix soybeans with other forages, preferably during
       ensiling, to enhance their palatability.  If plants are high in moisture and
       lack pod or bean development, add 100-200 lb of ground grain per ton when
       direct-cutting rather than wilting to 60-65% moisture.

       Stems are not very palatable, and if animals have the opportunity, they will
       sort them out.  Chopping hay and feeding it in a total mixed ration (TMR) will
       help prevent sorting, and stretch forage supplies.

       If soybean forage contains substantial amounts of developed beans, reduce the
       amounts of other fats and oils in the ration, or the ration may be too
       laxative.  Also, it may be difficult to dry down pods for hay if beans are too
       well developed.  Soybeans can be pastured.  If cows are removed before all
       stems are eaten, there may be regrowth.

       The table below gives some estimates of the nutrient content of soybean forage
       on a dry matter basis:

       Expected Nutrient Content of Soybean Forage
       Stage of Maturity                     CP %      ADF %Nel    Ca %       P %      Mg %
           avg silage, hay                       17.7         35        .54    1.25        .49      .34
           avg hay                                  16.5         35        .55    1.20         .47      .32
           mid bloom                            17.8           35        .57    1.25         .49      .34
           seed developing                   17.5           35        .59    1.20         .47      .32
           seed dough stage                  16.8          35        .61    1.15        .45      .30

       The dry matter content for average silage is 28%, while that for hay is 88%. 
       Test soybean forage or mixed forages containing soybeans to enable proper
       ration balancing.

      





Precautionary note:
       You need to consider some of the herbicide restrictions. If you look on page
       118 in the 1995-1996 Agronomy Guide, you will fine Table 6-17. Feeding
       restrictions on soybean forage and grain. Unfortunately with few exceptions,
       most soybean herbicides do not allow feeding the soybean plant as forage. The
       exceptions are Basagran, Lexone, or Sencor, and Lasso/MicroTech. I suspect
       that the reason that most of the newer herbicides don’t allow this use is
       because the ingredients simply never received a forage tolerance. Soybeans are
       not typically harvested as forage and it costs the manufacturer a great deal
       of money to conduct tolerance/residue studies.  Think about how few product we
       have labeled on alfalfa. Although this explanation may not help, its what on
       the product use label.

Insects of Importance during a drought

Adult Corn Rootworm Emergence - Adults of the corn rootworm are beginning to emerge in central Pennsylvania. Emergence begin about 10 days ago in the southwest, southeast, and south central areas of the state. Expect emergence to begin in the more northern and highland areas around the first of August. Adult
numbers appear to be very high this year. Because of the drought conditions, there is a chance that some fields may benefit from sprays to control adults and prevent silk clipping which leads to poor pollination.   Counts from corn rootworm scouting can be used to determine whether adult control in the current year is advisable or whether larval control during the next cropping year is warranted. If beetle numbers exceed the
economic threshold, a corn grower may decide to rotate to a crop other than corn next year, apply an insecticide at-planting time or control adult populations to prevent egg laying in the field. Depending on whether adult control is aimed at preventing silk clipping or to eliminate adults before eggs are laid in the field, different economic
thresholds are used. Five beetles per plant is enough to warrant control to avoid economic levels of silk clipping, which can interfere with pollination of the ear. If an adult control program is desired to prevent economic populations for next, the economic thresholds are the same as for a at-planting time application: 1.0 beetle per
plant in first year corn fields and 1.5 beetles per plant in field that have been in corn for two or more years. Adult control should be implemented when the economic threshold is exceeded. For prevention of silk clipping, an insecticide should be applied just prior to silk emergence or when an economic infestation is noted. Note: Once at least 50% of the plants have brown silks, an indication that pollination is complete, treatment is no longer justified. Sevin, Lorsban, dimethoate, Asana, Warrior, malathion, Lannate,
Penncap-M, Ambush, and Pounce are registered for adult corn rootworm control. With the exception of Sevin and malathion, the insecticides should provide at least 7 to 10 days of silk protection. If beetle numbers begin to increase to economic levels before 50% brown silk, a second application may be necessary. It is important not to
get over anxious and apply insecticides to whorl stage corn when number get high. Too early an application will kill beetles in the field at that time, but may not provide protection once corn begins to shed pollen. At that time new beetles will be attracted in the field that may cause economic silk clipping.



Potato leafhopper - Numbers of this pest continue to be extremely high across the state. The third and fourth cutting will very vulnerable to severe stunting and injury by the pest. New seedings are particularly vulnerable to feeding by this pest. In some areas of the state, reports of dimethoate (Cygon) and chloropyrifos (Lorsban) not
holding up are coming in. Maryland is reporting similar problems. It is not clear why these failures are occurring.

Two-spotted Spider Mites - The dry, hot conditions in recent weeks are perfect for population explosions of mites in soybeans. Soybean fields should be watched closely over the next few weeks for the development of the pest. Several fields in the Landisville, Pa area are already showing evidence of injury. The recent rains will help
reduce numbers, but if the hot temperature return mite numbers will rapidly increase. Applications of dimethoate will reduce mite populations if injury is noted to the soybeans.

Grasshoppers - So far there has not been many report of grasshopper injury to field crops. However, the dry, hot conditions are ideal for the development of localized outbreaks. If the dry, hot conditions continue, keep your eyes open for the development of high populations and crop injury. Sevin 4-Oil, Furadan 4F, dimethoate, Asana, malathion, and Penncap-M are registered for grasshopper control. See the Agronomy Guide for rate information.

Japanese Beetle - This pest is now attacking corn and soybean fields in the state. As corn fields begin to silk, keep an eye out for significant silk clipping. If an average of two to three beetle per ear are seen feeding on silks before pollination, then an insecticide application may be warranted. Several formulations of carbaryl (Sevin),
methoxychlor, and Penncap-M are registered to control this pest. Carbaryl and Penncap-M are also registered for corn rootworm beetle control. See the Agronomy Guide for rate information.
MANAGING ALFALFA DURING AND FOLLOWING A DROUGHT

       Alfalfa in some areas of Pennsylvania is experiencing water stress and the question of alfalfa management during this time is being raised. But before we discuss the management of water-stressed alfalfa, lets look at how alfalfa responds to drought conditions.  Alfalfa is commonly referred to as a drought tolerant plant. During the onset of drought conditions, alfalfa will stop using carbohydrates for stem and leaf production and store those carbohydrates in the roots. This provides high levels of root carbohydrates for long term survival if drought conditions persist and the leaves become photosynthetically inactive. However, alfalfa's ability to survive a drought does not mean that alfalfa will not show drought related symptoms. Water-stressed alfalfa will experience decreased stem elongation and in some cases mature more rapidly. Leaf production is less effected by water stress than stem elongation. This results in higher forage quality of water-stressed plants than their unstressed counterparts.






 To Harvest or Not to Harvest?
The primary criterion influencing the decision to harvest drought-stressed alfalfa should be based on the cost of harvesting and the value of the forage. The alfalfa plants may look weak and severely stressed during a drought; however, harvesting at the stage of plant development when you would normally harvest is recommended as long as adequate alfalfa is present to justify the cost of harvesting.  The plant, even though it may be very short, will already have stored more than enough root carbohydrates to insure survival if the drought persists or insure regrowth is sufficient rains remove the drought conditions.
EMERGENCY FORAGES IN DRY YEARS
Because of the drought conditions and the resulting less than anticipated forage
growth, I'm sure you have been asked what alternatives farmers have for forage production once the drought breaks. Here are some suggestions and sources for more detailed information.
       FARMERS WHO GRAZE:
These farmers may not have been able to produce sufficient hay/silage to get
through the winter. For them, an option is to plant some forage crops in August
 (hopefully it will be raining again by then) that can provide grazing this fall and           allow hay/silage to be made from their traditional pasture land. Following are some
options:

  Forage Brassica (e.g. Rape or turnip):
  Small Grains (e.g. wheat, barley, rye, or triticale) For additional information on growth characteristics, establishment, fertility, and grazing management of these crops refer to Agronomy Facts 33, "USE OF BRASSICA CROPS TO EXTEND THE GRAZING SEASON" and Agronomy Facts 41, "STRATEGIES FOR EXTENDING THE GRAZING SEASON".

       FARMERS WHO DON'T GRAZE:
Most of the crops that could be planted at this late time and produce some forage are better suited for harvesting as silage rather than hay. These crops are listed below along with sources for more detailed information.
  Summer-Annual Grasses (e.g. Sorghum, Sudangrass, Sorghum-sudan hybrids, and Millet). After July 15 these crops are really only an option for Pennsylvania's more southern and warmer counties. For most of the State these crops will not mature before cool fall weather and frost stop their growth. In a situation where the drought damaged corn has been harvested in July then these crops may be the     only option because of herbicides used on the corn and the greater potential for    carryover due to the dry conditions. For more information refer to Agronomy Facts 23, "SUMMER-ANNUAL GRASSES FOR SUPPLEMENTAL OR EMERGENCY FORAGE"









  Small Grains (Oats and Rye, use taller varieties). Small grains should be planted as soon as possible and harvested for silage in the milk to soft dough stage. Generally, the milk stage is less desirable than the early dough stage because it is less palatable and studies indicate that animal performance may be reduced. Moisture levels between 60 - 70% are best for ensiling small grain silage. Small grain silage below 60% moisture is difficult to pack and excessive heating and nutrient loss may occur. In addition, making sure that the theoretical length of cut is less than 3/8 inch is important with small grains because some stems are hollow and filled with air. Minimizing the length of the chopped material will help minimize silage heating and maintain forage quality.  In a Penn State study conducted at the Landisville (Lancaster Co.) Research Center small grains yielded more than sorghum-sudan grass when both were seeded on August 5.

       Yield and TDN of four crops seeded on August 5
       Corn (harvest on 10/5) - 1.5 ton/a and 61.2% TDN
       Sorghum-sudan hybrid (harvest on 10/5) - 1.6 ton/a and 61.2% TDN
       Oat (harvest at soft dough) - 2.1 ton/a and 75.8% TDN
       Rye (harvest at soft dough) - 2.1 ton/acre and 68.4% TDN

       Dr.  Marvin Hall
Penn State Forage Specialist

15 July 2011

Cobra Effect on Soybeans

Here is a shot of my plots. I applied Cobra on June 24th at V6 -R1. Today is July 15 interesting to see the impact.
I used the 6 ounce per acre rate and 1 quart COC.  Not that much damage to  the canopy.  One can see visually the shorter plants. I have another blog with the picture of the damage to the leaves.


Cobra damage 2 weeks after application

Here is a shot  plants are at R3. inside the canopy. One can see the affect leaves and the regrowth of the new trifoliates.  The plants are shorter than the check plots.  Applied on June 24th  V6 or R1 Cobra 6 ounce/ acre plus 1 quart/acre COC 20 gpa.


Checking K deficiency in Soybeans 2011 crop season

Soy Variety Trial 2011 R3 Observations

75 bu potential.
Plenty of insect feeding at the site.


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07 July 2011

How late can I apply N?

Del Voight Penn State Extension
Now that we are tasseling the next question is how late can we correct an N deficiency?  It is best to get the N on as early as possible. However, yield responses that return income greater than the costs for application and fertilizer materials have been observed for N applied up to and slightly beyond the tassel stage. The magnitude of yield increase is dependent upon the severity of N deficiency and the ability of the crop to recover and respond to applied N (the growth and yield potential left after water damage and early season N deficiency). Any surface application is dependent upon rainfall to move applied N into the root zone, otherwise it cannot benefit the corn crop. 
In the Lebanon area some contest fields in the past had recieved 100 lb of N at tassel only to gain a net yield increase of about 5 bu/acre so do not plan on increasing yields all that much.  There are alot of factors that play a role. If the field has obvious yellowing from bottom to mid plant then perhaps and N application will increase yields up to normal versus none at all. Penn State chlorophyll meter guidelines do not go over about 80 lbs of N  in season so I am not sure going extremely high on N applications farther above 50-80 will make much difference in the end.

05 July 2011

What about N losses in 2011?



Enlarge
Waterlogged soils/yellow N-deficient corn areas..

Estimating N loss

Research conducted in Illinois (reported in the 1993 Integrated Crop Management Conference proceedings, pp. 75-89, and in Torbert et al., 1993, "Short-term excess water impact on corn yield and nitrogen recovery," Journal of Production Agriculture 6:337-344) indicated approximately 4 to 5 percent loss of nitrate-N by denitrification per day that soils were saturated. An all-nitrate fertilizer was applied when corn was in the V1 to V3 growth stage. Soils were brought to field capacity moisture content and then an excess 4 inches of water (above ambient rainfall) was applied evenly over a 3-day period, which maintained saturated soils for 3 to 4 days on the heavier textured soils, or an excess of 6 inches of water was applied over an 8-day period (with saturated soils for an additional 3 to 4 days). The excess water application resulted in loss of 60 to 70 pounds N/acre on silt loam and clay loam soils, due to denitrification loss. On a sandy soil, virtually all nitrate was moved out of the root zone by leaching. On the heavier textured soils, addition of 50 pounds N/acre after the excess water was applied was sufficient to increase corn yields to approximately the same level where no excess moisture was applied. This was not the case on the sandy soil because more N was lost through leaching. When 8 inches of precipitation plus irrigation was received in May and June on the sandy soil, yield was reduced by 20 percent.
After the excess rain in the spring of 1995, four fields with a full rate of fall-applied N in Boone County, Iowa, had additional N sidedress injected with anhydrous ammonia. The data showed an average yield increase of 15 bushels/acre from addition of 50 to 75 pounds N/acre (A. M. Blackmer, 1996 Integrated Crop Management Conference proceedings, pp. 55-59). In similar studies, significant yield responses in some fields to additional N (UAN injected when corn was 1-foot in height or surface banded at the R1 growth stage) were measured in 1999 after the warm fall-winter and wet spring (Ellsworth et al., 1999, Integrated Crop Management Conference proceedings, pp. 301-304).

Using the late spring soil nitrate test

A procedure to measure additional N need is to use the late spring soil nitrate test. However, it is too late to sample with this test (1-foot soil samples should be collected when corn plants are 6 to 12 inches in height). If samples were collected at the appropriate time, then the following information can assist with interpretation of results. See ISU Extension publication PM 1714, Nitrogen Fertilizer Recommendations for Corn in Iowa, for full interpretation and use of this test.
For fields where less than full rates of N were preplant applied, a suggestion is to lower the critical concentration from 25 ppm to 20-22 ppm when rainfall from April 1 to time of sampling is more than 20 percent above normal. When full rates of N were applied preplant (fall or early spring) as anhydrous ammonia, or with manured soils, the suggested critical concentration is 15 ppm if May rainfall exceeds 5 inches (refer to Table 3 of PM 1714 to interpret test results). In these fields, if tests are between 16 and 20 ppm you may want to consider a small N application. These adjustments take into account nitrate that may have moved below the 1-foot soil sample, but remains within the effective rooting depth. In situations where manure or full rates of N were applied preplant, a suggestion would be to limit additional N application to 90 pounds N/acre, even if the test result is 10 ppm or less.
Taking chlorophyll meter readings. The corn plant expresses N deficiency through reduced leaf greenness that can be measured with a chlorophyll meter (SPAD meter). To effectively know whether deficiencies are occurring, readings need to be compared with adequately fertilized (non-N-limiting) reference areas or strips. A relative value less than 95 percent is often suggested as indicating N deficiency. This comparison reduces bias due to different growing conditions, soils, hybrids, or factors affecting leaf color other than N deficiency. Chlorophyll meter readings (values relative to the reference area) do not indicate an amount of N loss or additional need, but do give an indication of the severity of deficiency; that is, the lower the relative value the greater the N deficiency. Chlorophyll readings should be helpful in confirming suspected N-loss situations and need for supplemental N. The later into the growing season these readings are taken, the more they can indicate small N deficiencies and the more they relate to total crop N need.

Assessing the corn crop

Before a decision is made to apply supplemental N, you should consider the potential productivity remaining after soils have dried. Has the stand been damaged, will the plants recover, is the area planted late or replanted, and is the yield potential reduced because of conditions other than N loss? It is possible that the combination of N remaining in the soil, plus N mineralized during the rest of the growing season, can supply adequate N. If corn at approximately the V6 to V8 stage is showing N-deficiency symptoms (due to N losses and not just due to waterlogged soils restricting root activity and growth), but otherwise has a good stand and appears to be growing well, then application of additional N should be beneficial.
The magnitude of yield recovery depends upon the crop stage when N deficiency occurs and the severity of deficiency. When slight-to-severe deficiencies are corrected early (by approximately V8 growth stage), or slight deficiencies are corrected late in the season (by approximately VT to R1), then full yield potential is possible. Large N deficiencies corrected late in the season may show yield increase but not recover fully.
It is important to be as certain as possible that additional N is needed. If extra N is applied, but is not required, then excess N could remain in the soil at the end of the season. Applying strips of N at several locations across fields can provide reference strips to evaluate response to additional N. If these reference strips indicate corn is responding (for instance, indicated by SPAD chlorophyll meter readings in the nonstrip-treated areas that are 95 percent or less of the values in the N-treated strips), then additional N can be applied to the rest of the field.

How to apply needed N

When conventional application equipment can be moved through the field (the soils are dry enough and the corn is short enough), then injection of anhydrous ammonia or UAN solutions would top the list of best options. Next would come dribble UAN between corn rows, then broadcast urea. Broadcast UAN solution should be avoided because it can burn corn foliage, especially with large corn. If injection or conventional broadcast application is not possible (as is likely the situation due to the large corn in most of Iowa at this time), then UAN could be applied with high-clearance equipment with drop nozzles that direct the solution onto the ground, or urea could be aerially applied.

How late can I apply N?

It is best to get the N on as early as possible. However, yield responses that return income greater than the costs for application and fertilizer materials have been observed for N applied up to and slightly beyond the tassel stage. The magnitude of yield increase is dependent upon the severity of N deficiency and the ability of the crop to recover and respond to applied N (the growth and yield potential left after water damage and early season N deficiency). Any surface application is dependent upon rainfall to move applied N into the root zone, otherwise it cannot benefit the corn crop.