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Forage Facts July 2007
Keys to Higher Corn Silage Yields
Many
factors are important to producing forage yields. Key management practices
that make corn forage production profitable include: 1.
Hybrid selection 2.
Proper timing of harvest 3.
Remembering that a trade-off exists between yield and quality for
management decisions 4.
Early planting date 5.
Slightly higher plant populations than what is normally used for
grain production 6.
Cutting height 7.
Adequate soil fertility – predicted by soil sampling 8.
Narrower row spacing increases yield 9.
Pest control 10.
Crop rotation One
of the early decisions that must be made in the production of corn forage
is whether yield or quality is to be optimized. The best management
practices are slightly different depending upon the objectives of the
producer and his operation. For example, bmr
corn hybrids differ dramatically for stover quality characteristics than
hybrids with the leafy
trait. The trade-off between these two hybrid types is between yield and
quality. Likewise more milk per ton (better quality) is produced in a
field where the population is lower or cutting height is higher than a
more normal population or normal cutting heights. The trade-off is reduced
yield. Hybrid Selection
Numerous
hybrids for producing corn forage are available from seed companies today.
Since grain is nearly 95 percent digestible most recent breeding
activities are concentrating on changing the stover portion of corn
forage. Hybrids with special quality traits such as the bmr
gene that increases stover digestibility or hybrids that contain the leafy
trait with greater leaf numbers above the ear. More examples of these
hybrids are being developed by plant breeders that maximize the amount of
energy available in the stover portion of corn forage. In
addition to hybrids with special quality traits, numerous hybrids are
available with special transgenic traits such as Bt, Liberty Link and
Roundup Ready hybrids. These hybrids allow improved corn production under
sometimes difficult field situations. Regardless
of the specialty traits available in corn forage hybrids, the basic
objective remains to select a hybrid to maximize the amount of energy
available as forage to the animal being fed. Either maximizing energy per
ton or maximizing energy from an area of land can achieve maximizing
forage energy. Both approaches may be valid depending upon the objectives
of the producer. For example, someone buying all their forage from a
neighbor would like to by forage with the highest amount of energy per ton
because it reduces the costs associated with handling, hauling, storage
and feeding the forage. Someone else may be most interested in maximizing
energy from their farm land base and should be thinking about energy per
acre as a hybrid selection criteria. A
final consideration in selecting corn hybrids for forage purposes is
flexibility. A good dual purpose hybrid, one that produces good grain and
forage yields, gives the producer flexibility at harvest when many forage
decisions are actually made. A bmr
or leafy hybrid planted in the spring should only be harvested for forage
use in the fall because of reduced grain yield potential with these
hybrids. Proper Timing of Harvest Environment influences harvest date. The goal of
harvesting is to time harvest so that the forage is at the proper moisture
to enable fermentation and preservation of the forage. Too wet the forage
will sour, too dry the forage will become moldy. The proper moisture
depends upon the storage structure where ensiling will take place. For
example, optimal ensiling in a concrete stave silo will take place at 65%
moisture. Currently the only way to predict corn forage harvest date is to use kernel
milkline as a guide to timing when a plant moisture sample should be
measured for a field (Table 1). Once the moisture of a corn forage field
is known use a drydown rate of 0.5% per day to predict when to either
check moisture again or begin harvest. Trade-off Between Yield and Quality for
Management Decisions In
general, management practices that optimize grain yield will optimize
forage yield. The optimum range for a management practice is typically
wider for corn forage than for grain production. However, there are some
management practices that maximize yield of either grain or forage, but
reduces forage quality. Often a trade-off exists between yield and
quality. Management decisions that fall into this include planting date,
plant density and cutting height.
Early Planting Date Early planting date is important for maximizing corn
grain and forage yields . But,
corn of the same maturity grown for forage uses can be planted up to a
week later without much change in risk and still be within 95% of the
maximum yield. The risk of planting corn in April and May is the same
regardless of planting date. In some years early planting will result in
low yield, while late planting results in high yield. The opposite can
also occur with equal frequency. Thus the recommendation for corn planting
is to plant as many acres as possible around the optimum date.
Contact your local extension agent for optimum planting dates for
your area. Ideal Plant Population The ideal plant population for corn
grain yield in Wisconsin is 30,000 harvested plants per acre on most soils
and 26,000 plants per acre on lighter soils. For forage yield the optimum
plant populations are slightly higher by about 1,000 to 2,000 plants per
acre. However, in a recent Wisconsin study (Cusicanqui and Lauer, 1999)
greatest milk per ton corn forage was at 18,000 plants/acre while greatest
forage yield was at 42,000 plants/acre. Maximum Milk per acre was achieved
at 32,000 plants/acre. This illustrates the yield and quality trade-off
that is often seen when comparing best management practices for grain
versus those for forage yield and quality. Soil Fertility Corn
grown for forage production requires more soil fertility than corn grown
for grain. Greater nutrient removals are taken in forage production with
stalk and leaf removal from the field. Fertility recommendations are
continuously being fine-tuned for various soils, but yield responses are
generally known and can be predicted. The decision to fertilize soil for
corn forage production depends upon obtaining a soil test for the field. Pest
Control Adequate pest control is important for
obtaining high yield and uniform quality within a field. In general,
economic threshold levels are lower for corn forage than for grain because
greater opportunity and grower return is seen when the forage is fed to
beef or dairy cattle.
Cutting Height Adjusting cutting height influences
yield and quality in corn forage production. This decision is influenced
by forage needs of the producer. If forage supply is low, then lowering
the cutter bar will result in greatest yields. If supply is adequate to
excessive, then raising the cutter bar on the forage chopper will decrease
yield, but increase milk per ton and reduce overall milk per acre only
slightly. Raising the cutter bar will also leave more residue in the field
helping to reduce soil erosion potential. Rotation Crop rotation has been shown to
increase grain yield about 10% over that of continuously grown crops. The
yield increase due to the rotation response lasts about two years, and by
year three yield levels are similar to continuously grown crops. Similar
responses of would be expected for corn grown for forage although this has
been little studied. Certainly pest control better in rotated crops
compared to continuously grown crops. Row
Spacing In numerous row spacing trials conducted in Wisconsin,
narrower rows (15 or 20 inch row spacing) increases dry matter yield 6 to
9% with no corresponding changes to Milk per ton. In conclusion, the upper yield potential so far measured
for typically managed corn in Wisconsin is approximately 13.5 tons of dry
matter per acre. Numerous
factors influence the maximum yield for a farm and each factor contributes
not only to yield but also influences quality. Integrating these all these
factors into a farm management system is the challenge to the producer. Improve the Quality of Your High Moisture Corn
There
are many factors that can effect the quality of your high moisture corn at
harvest and feed-out time. You will need to consider ear corn versus shell
corn, the moisture level at which it is harvested, processing, and your
method of storage. Following is information that can help you to make the
most of your high moisture corn and help you control mold in your stored
feed. HMSC vs. HMEC High
moisture shelled corn (HMSC) and high moisture ear corn (HMEC) have
similar energy values, despite the higher fiber levels in HMEC. HMEC will
yield 12-20% more dry matter per acre at harvest than HMSC. HMEC has a
tendency to trap more air, has a higher chance of mold and mycotoxin
contamination, and separates more when fed. HMEC has much higher energy
than dry ear corn because the cob harvested at higher moisture is more
digestible. Moisture Level The
recommended kernel moisture for both HMSC and HMEC is 26-32%. The cob in
HMEC increases total ear moisture by about 4-6 points. The cob which
represents about 12-20% of the dry matter of the corn ear, contains
approximately 1½ times the moisture content of the kernel. Harvest
recommendations are based on the following factors: 1. Minimizing
field, harvesting, and storage losses 2.
Providing favorable conditions for fermentation during storage 3. Optimizing
feeding value Harvest
can typically begin once corn has reached physiological maturity which is
indicated by the formation of a black layer at the tip of the kernel.
Kernels at black layer will vary from 28-35% moisture depending on hybrid
and environmental conditions. Harvesting grain at higher than the
recommended moisture contents will reduce dry matter yields and can lead
to extensive fermentation, resulting in increased energy loss during
storage. Harvesting
below the recommended moisture range also reduces dry matter yields due to
increased ear drop and weather damage and makes it more difficult to pack
and exclude air. Entrapped air increases the risk of mold growth and/or
excessive heating which will lead to nutrient loss. It is important to add
Crop Cure to your corn at the appropriate rate to help reduce mold growth
and improve the quality of your grain. Producers
should consider adding water during ensiling if moisture content drops
below 25% for HMSC or below 32% for HMEC. Specific moisture guidelines for
various structures are located below:
HMC MOISTURE GUIDELINES
Silo Type Crop
Upright Bag
Bunker Oxygen-limited HMSC (whole) --
--
--
22-28 HMSC
26-32 26-32
26-32
-- HMEC
32-38 32-38
32-38
32-38
Processing HMSC
not stored in an oxygen limiting structure should be processed.
Incorporate the use of a hammer mill, roller mill, or blower with recutter
attachment so that at least 90% of the kernels are cracked. Avoid grinding corn
too fine. HMEC can be picked and processed with a tub grinder or hammer
mill before ensiling. Cobs should be broken into pieces 1/2 inch or less
to prevent separation in the silo. Feedout
Losses
Once
ensiled HMC is re-exposed to oxygen during feedout, aerobic (oxygen
loving) microorganisms will begin to grow and metabolize nutrients in the
grain. Generally, the first sign of aerobic spoilage is heating. In order
to minimize this aerobic loss, it is essential that that producers remove
a minimum of 2-4" of material in conventional structures each day
during cool weather and as much as 4-6" in the heat of summer. Losses
from aerobic deterioration can be significant (5-10%) if proper management
is not followed. Losses are usually 2-4% higher for HMEC compared to HMSC.
Applying Crop Cure at the correct rate at time of harvest and storage will
help reduce the heating that can occur.
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We reserve the right to change product specifications at any time. The information contained here is reasonably accurate at the time of posting, however we rely on the warranty and product specifications on the products themselves, not the information on the site. Crop Cure® is a trademark of Domain, Inc. registered in the United States Patent and Trademark Office. Copyright © 2001, 2002 Crop Cure®. All rights reserved. | ||||||||||||||||||
