CMEG Crop Management Extension Group

Field Crop News

Website Address: http://fcn.agronomy.psu.edu/

August 8, 2006    Vol. 06:15

IN THIS ISSUE:

Keys to Silage Harvest Success — Paul Craig, Dauphin County

Moisture Level at Harvest

Probably the most critical condition for proper silage harvest is the whole plant moisture level. Silage feeding trials show the best performances when silages are harvested from 65% to 70% moisture. Unfortunately at higher moistures, seepage and poor fermentation can cause additional feeding challenges. Each storage type has specific moisture guidelines for producing best quality.

Storage Type Optimum moisture content
Bunkers/Piles 65 – 70%
Bags 60 – 70%
Concrete Uprights 62 – 67%
Sealed Uprights 50 – 60%

Determining Moisture Level

Visually looking at a corn plant is not an accurate method to determine harvest. A starting point to begin monitoring plant moisture levels is when the ear begins to dent. At this stage sugar in the kernel is being converted into starch and the kernel begins to shrink. When the milk line, which shows the change from milky starches to hard starch in the kernel, is ½ of the way down the kernel, whole plant moistures will be close to optimum moisture levels, on average 63%. Unfortunately crop moisture levels can vary greatly across hybrids and locations at ½ milk line, (ranges - 53 to 73%). Do not depend on this method for accurate moisture levels.

The best method is to cut representative stalks, shred them and run an accurate moisture determination test. After denting, whole plant moisture levels will decrease approximately 0.6% per day. Silage harvest can be predicted but additional monitoring of moisture will be needed. As plant moistures approach 62%, the dry-down rate rapidly increases. Don’t get caught with too dry silage.

Length of Cut

Recommendations for length of cut for silage vary depending on crop condition. Drier crops should be cut finer to produce smaller particles that minimize air pockets. Use of highly digestible hybrids requires a slightly longer cut to maintain effective fiber. General recommendation is a 3/8 inch theoretical length of cut (TLC) but more mature crops may require a shorter length. For non-processed silage the recommended chop length is 3/8 to ¾ inch TLC. Some farms rely on their nutritionists to fine tune the chop length based on farm specific conditions. Take the time now to tune up your chopper or consult with your custom chopper and nutritionist.

Height of Cut

In recent seasons some producers are cutting silage at a 10 to 20 inch height. This practice reduces silage fiber and lignin percentage and increases starch and energy content. However silage yields are reduced five to ten percent. Higher chopping can also be used to change whole plant moisture contents. By cutting higher, harvest may advance by 3 to 4 days. Higher chopping may be an option if excess forage dry matter is available. However, this will increase the final cost per ton. To balance this trade-off between quality and yield, the decision should be based on an economic assessment that considers feeding options.

Processing Silage

At lower whole plant moistures, crop maturity may affect silage quality. Fiber and starch digestion decreases as corn dries down. Processing at harvest may be needed to maximize digestion on more mature crops. The goal of processing is to ensure breakage of the kernel and cob to assist digestion. Processing also can affect fiber length so choppers equipped with a processor typically lengthen their cut to ¾ inch.

2006 will go down as a season of early plantings. We used to say “knee high corn by the 4th of July”. This year many fields of corn were 9 feet tall by the 4th and tasseling by July 7th. Areas in south central Pennsylvania are already opening corn silage fields and making small piles and bags. Silage harvest will be just around the corner, will you be ready??

Setting Up for a Fall Alfalfa Harvest — Marvin Hall, Forage Management Specialist

In my travels around the state I’ve had several farmers ask about alfalfa harvest management in August and how that will affect timing of harvest during the fall. Fall harvesting of alfalfa is a site specific and variety specific decision. Often we balance the need for additional high quality forage against winter injury. A chart to help evaluate the risk of winter injury due to a late fall cutting can be found on page four of Agronomy Fact Sheet #7 “Cutting Management of Alfalfa, Red Clover and Birdsfoot Trefoil.”. Working down through the chart can shed some light on your decisions.

Burcucumber Desiccation and Corn Harvest — Dwight Lingenfelter, Extension Agronomist

Burcucumber is becoming evident in corn fields as it grows overtop of the corn which will make harvest very difficult, if not impossible.  Therefore now is the time to take action to lessen the impact of burcucumber vines during harvest and reduce seed numbers for future seasons.  Some suggestions include the use of a harvest aid herbicides and harvesting silage early.

Harvest Aids: Paraquat, glyphosate, and 2,4-D are some options to consider for corn for grain.  Although we have not done extensive research with burcucumber and harvest aids, we do have anecdotal information from ag professionals and farmers regarding harvest aid efficacy. 2,4-D only provides suppression of burcucumber so we really don’t recommend this option. Glyphosate (0.75-2 lb ae) generally provides moderate control of burcucumber, while paraquat (up to 0.56 lb ai) usually provides better desiccation of burcucumber; so these are more frequently used at this application timing.  Check the label for specific restrictions when using these products as harvest aids.

Early silage harvest: Another consideration would be to harvest silage earlier, if possible.  Since burcucmber seeds mature relatively late in the season, harvesting the crop early can prevent viable burcucumber seed production. Penn State research shows that ensiling green/immature (milk to dough stage) burcucumber seed is an effective means to killing the seed.  Once the burcucumber seed matures and turns brown, ensiling does not kill it.

On-Farm Crop Management Research — Somewhere Near You — Ron Hoover, Penn State On-farm Research Coordinator

Two new multi-location on-farm projects were begun this spring and two others will be concluded at the end of the 2006 growing season.  The new projects include an evaluation of soybean stands during the year to determine when plant loss occurs and a field evaluation of a product that may be useful in conserving nitrogen in surface applied manure.  Twelve county-based extension educators are participating in the soybean population study.  They worked with growers to calibrate drills and planters and have been making repeated plant counts of marked areas in the field.  The study will enable us to report on the variability in rates of emergence and when during the bean growing season plant loss is occurring.  There is interest in possibly expanding these evaluations to include seed treatments in 2007.

The manure N study is testing a product that has been proven to conserve commercial fertilizer N. Four farms are participating in this study, two hog and two dairy operations.  The product was added to manure as the slurry spreader was being loaded.  Treated and nontreated (control) manure was applied to multiple field-length strips at each farm prior to corn planting.  PSNT soil tests taken at the appropriate time revealed little difference in soil nitrate levels between treated and nontreated manure.  The plots at all locations will be taken to silage or grain yield.

A six-farm evaluation of newer pasture forages that was begun three years ago will formally terminate this fall.  The locations are in the north central or northern part of the state.  Twenty entries, mostly grasses, were no-till drilled behind either banded or broadcasted applications of glyphosate during August 2004.  Dry matter production and winterhardiness are the primary measures of interest.  Periodic pasture sampling has revealed that entries establishing more quickly also produced the most forage during early 2005.  The perennial ryegrasses and festuloliums, as a group, lead the other species.  The relatively mild winters that past two years have resulted in little winterkill.  Most host farmers have expressed an interest in allowing these plots to remain through the termination of the NE SARE research grant for the purpose of making longer-term winterhardiness observations.

A two-year Pennsylvania Department of Agriculture funded study investigating the effectiveness of fungicides in improving soybean grain yield in the absence of soy rust will also end this fall.  Eight large plot trials, most on private farms, and four small plot trials at the experiment station have recently been sprayed.  Differences in soy foliar disease will be noted in the coming weeks.  Grain yields will be recorded at harvest.  Results from the 2005 trials were mixed.  Half the southern PA trials demonstrated enough yield increase to pay for use of the product while no yield improvement was observed in trials conducted in central PA.

National Perspectives on Soybean Rust — Erick De Wolf, Plant Pathology

Soybean rust continues to spread slowly in the deep south.  During the past two weeks the disease has been reported in central Louisiana, but remains restricted to the southern third of Alabama, Georgia and Mississippi.  Hot and dry weather continues to hold the disease to low levels and rust appears limited mostly to kudzu and soybean sentinel plots.  The growth stage of commercial soybeans in these areas range from R1 to R7 depending on maturity group and planting date.  The Extension specialists in these states are suggesting that their growers consider fungicide applications in areas known to have rust and the soybeans are in mid-reproductives stages of growth (R3-R4).  Interestingly they also indicate that growers in the Northern parts of these states should NOT apply fungicides for soybean rust until signs of further disease spread.

The risk of soybean rust in Pennsylvania and most Northern states is very low.  The local soybean crop is rapidly moving through the reproductive stages of growth, and most parts of the state are reporting full season beans are now at the R4 stage of growth.  Once the crop has reached the R6 (green seed) stage of growth the potential for yield loss from soybean rust is greatly reduced.  We may still see soybean rust spread this year, but I think the full season crop is almost out of danger.  The double crop soybeans in PA are just flowering and it will be several weeks before we can give the ‘all clear’ for these fields.  We will continue to monitor the PA sentinel plots, and alert people of any changes to the risk level in the commonwealth. Until then, enjoy another rust free day.

Stretching Forage Supplies with Stockpiled Fescue — Marvin Hall, Forage Management Specialist

Some areas of the state haven’t had rain for several weeks and are beginning to worry about adequate forage supplies. One technique for stretching those stored forages is to utilize areas of fescue for late-fall grazing. Fescue isn’t the most palatable grass during the “dog days of summer” but fall growth is much more palatable. Consider utilizing this change in palatability to stretch forage supplies. Stockpiling involves allowing a forage to grow during the fall and then grazing it after frost. Tall fescue is the best adapted grass for stockpiling. Stockpiled fescue provides high quality pasture for late fall and winter grazing with twice the sugar (energy) content of spring and summer pasture, high digestibility and high protein.

Follow these simple steps to produce high quality stockpiled tall fescue:

  1. Graze or mow the fescue down to 2 to 3 inches during early to mid-August. Essential to allow high quality regrowth.
  2. Topdress with 50 to 80 lbs nitrogen per acre during early to mid-August. Apply phosphorus, potassium and lime as recommended.
  3. Keep livestock off this pasture until late fall for maximum stockpile production.
  4. Where possible, stockpiled tall fescue fields should be strip grazed to minimize trampling and wastage.

Contributors: State Specialists:  Sjoerd Duiker, Erick De Wolf, Marvin Hall, Dwight Lingenfelter, Ron Hoover  Extension Agents:  Kevin Fry (Armstrong), Jere Wingert (Franklin), Jeff Graybill (Lancaster), Mena Hautau (Berks), Don Fretts (Fayette), Paul Craig (Dauphin), Del Voight (Lebanon), Andrew Frankenfield (Montgomery) and Mark Madden (Sullivan)

Editor: Mark Madden

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