Harvest

Corn Silage Harvest Timing

Source: Mark Sulc, Peter Thomison, Bill Weiss, OSU

Silage harvest has begun in some parts of Ohio. Proper harvest timing is critical because it ensures the proper dry matter (DM) concentration required for high quality preservation, which in turn results in good animal performance and lower feed costs. The proper DM concentration is the same whether it is a beautiful, record breaking corn crop or a severely drought stressed field with short plants containing no ears.

The recommended ranges for silage DM are:

Bunker: 30 to 35%

Upright: 32 to 38%

Sealed upright 35 to 40%

Bag: 32 to 40%

Chopping corn silage at the wrong DM concentration will increase fermentation losses and reduce the nutrient value of the silage.  Harvesting corn too wet (low DM concentration) results in souring, seepage, and storage losses of the silage with reduced animal intake. Harvesting too dry (high DM concentration) promotes mold because the silage cannot be adequately packed to exclude oxygen. Harvesting too dry also results in lower energy concentrations and reduced protein digestibility.

Corn silage that is too dry is almost always worse than corn silage that is slightly too wet. So if you are uncertain about the DM content, it is usually better to err on chopping a little early rather than a little late. Follow the guidelines below to be more confident in your moisture assessment.

Kernel stage not a reliable guide for timing silage harvest

Dry matter content of whole plant corn varies with maturity.  Research has shown that the position of the kernel milk-line is NOT a reliable indicator alone for determining harvest timing. Geographic location, planting date, hybrid selection, and weather conditions affect the relationship between kernel milk-line position and whole plant DM content. In a Wisconsin study, 82% of the hybrids tested exhibited a poor relationship between kernel milk-line stage and whole-plant % DM. In Ohio we have seen considerable variation in plant DM content within a given kernel milk-line stage.

Appearance of the kernels should only be used as a guide of when to begin sampling for DM content, see section below When to Begin Field Sampling.

Determining silage moisture

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Estimating Corn Yield

According to the latest Ohio Crop Weather Report 94% of the Ohio corn crop is silking, 6 percentage points ahead of the 5-year average.  39% of the crop is in the dough stage and 1 percent of the Ohio corn crop is dented.

This time of year many of us begin to think about our potential corn yield.  The most popular yield estimator is the  THE YIELD COMPONENT METHOD.  This procedure was developed by the Agricultural Engineering Department at the University of Illinois. The principle advantage to this method is that it can be used as early as the milk stage of kernel development, a stage many Ohio corn fields have probably achieved. The yield component method involves use of a numerical constant for kernel weight which is figured into an equation in order to calculate grain yield. This numerical constant is sometimes referred to as a “fudge‑factor” since it is based on a predetermined average kernel weight. Since weight per kernel will vary depending on hybrid and environment, the yield component method should be used only to estimate relative grain yields, i.e. “ballpark” grain yields. When below normal rainfall occurs during grain fill (resulting in low kernel weights), the yield component method will OVERESTIMATE yields. In a year with good grain fill conditions (resulting in high kernel weights) the method will underestimate grain yields.

In the past, the YIELD COMPONENT METHOD equation used a “fudge factor” of 90 (as the average value for kernel weight, expressed as 90,000 kernels per 56 lb bushel), but kernel size has increased as hybrids have improved over the years. Dr. Bob Nielsen at Purdue University suggests that a “fudge factor” of 80 to 85 (85,000 kernels per 56 lb bushel) is a more realistic value to use in the yield estimation equation today. For more on this check http://www.agry.purdue.edu/ext/corn/news/timeless/YldEstMethod.html.

Step 1. Count the number of harvestable ears in a length of row equivalent to 1/1000th acre. For 30‑inch rows, this would be 17 ft. 5 in.

Step 2. On every fifth ear, count the number of kernel rows per ear and determine the average.

Step 3. On each of these ears count the number of kernels per row and determine the average. (Do not count kernels on either the butt or tip of the ear that are less than half the size of normal size kernels.)

Step 4. Yield (bushels per acre) equals (ear #) x (avg. row #) x (avg. kernel #) divided by 85.

Step 5. Repeat the procedure for at least four additional sites across the field. Keep in mind that uniformity of plant development affects the accuracy of  the estimation technique.

The more variable crop development is across a field, the greater the number of samples that should be taken to estimate yield for the field.

Example: You are evaluating a field with 30‑inch rows. You counted 29 ears (per 17′ 5″ = row section). Sampling every fifth ear resulted in an average row number of 16 and an average number of kernels per row of 33. The estimated yield for that site in the field would be (29 x 16 x 33) divided by 85, which equals 180 bu/acre.

2020 Ohio Wheat Performance Test

Source:  Laura Lindsey, Matthew Hankinson, OSU

Yield results for the 2020 Ohio Wheat Performance Test are online at: https://www.oardc.ohio-state.edu/wheattrials/default.asp?year=2020

The purpose of the Ohio Wheat Performance Test is to evaluate wheat varieties, blends, brands, and breeding lines for yield, grain quality, and other important performance characteristics. This information gives wheat producers comparative information for selecting the varieties best suited for their production system and market. Varieties differ in yield potential, winter hardiness, maturity, standability, disease and insect resistance, and other agronomic characteristics. Selection should be based on performance from multiple test sites and years.

In fall 2019, wheat was planted at four out of the five locations within 10 days of the fly-free date. Due to poor soil conditions, wheat was planted in Wood County 21 days after the fly-free date; however, wheat grain yield averaged 99.5 bu/acre at that location. Wheat entered dormancy in good to excellent condition. Early season wheat growth and development were slower than previous years due to cool temperatures and above average precipitation. Harvest conditions were favorable and harvest dates average. Results from Union County were not included in this report due to extreme field variability caused by high rainfall. Overall, grain test weight averaged 58.8 lb/bu (compared to an average test weight of 55.0 lb/bu in 2019). Across the Wood, Wayne, Darke, and Pickaway locations, grain yield averaged 93.8 bu/acre.

Field Drying and Harvest Losses in Corn

Source: Peter Thomison, OSU (edited)

Late corn plantings and sporadic rain in some areas are not helping with field drying. Some growers are delaying harvest until grain moisture drops further. However, these delays increase the likelihood that stalk rots present in many fields will lead to stalk lodging problems (Fig. 1). Leaving corn to dry in the field exposes a crop to unfavorable weather conditions, as well as wildlife damage. A crop with weak plant integrity is more vulnerable to yield losses from stalk lodging and ear drop when weathering conditions occur. Additional losses may occur when ear rots reduce grain quality and can lead to significant dockage when the grain is marketed. Some ear rots produce mycotoxins, which may cause major health problems if fed to livestock.

Several years ago we conducted a study that evaluated effects of four plant populations (24,000, 30,000, 36,000, and 42,000 plants/A) and three harvest dates (early-mid Oct., Nov. and Dec.) on the agronomic performance of four hybrids differing in maturity and stalk quality. The study was conducted at three locations in NW, NE, and SW Ohio over a three-year period for a total of eight experiments. Results of this study provide some insight on yield losses and changes in grain moisture and stalk quality associated with delaying harvest. The following lists some of the major findings from this research.

Key Findings:

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Safety at the Bin

Source: Lisa Pfeifer – OSU Ag Safety and Health Education Coordinator

Approaching harvest makes for a busy time on the farm. Stop and take the time now to inspect on-farm grain handling facilities before the combine heads to the field. Assess the 10 items on our list and make repairs or improvements to deficiencies. OSU Ag Safety & Health wishes you a safe fall harvest.

Stalk Quality Concerns

Source: Peter Thomison, Pierce Paul, OSU Extension

2019 may be an especially challenging year for corn stalk quality in Ohio. Stress conditions increase the potential for stalk rot that often leads to stalk lodging (Fig. 1).  This year persistent rains through June caused unprecedented planting delays. Saturated soils resulted in shallow root systems. Corn plantings in wet soils often resulted in surface and in-furrow compaction further restricting root growth. Since July, limited rainfall in much of the state has stressed corn and marginal root systems have predisposed corn to greater water stress.

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Managing Corn Harvest this Fall with Variable Corn Conditions

Source:  Jason Hartschuh, Elizabeth Hawkins, James Morris, Will Hamman, OSU Extension

Thanks to the weather we had this year, corn is variable across fields and in some areas we will be harvesting corn at higher moistures than normal. Stalk quality may also be variable by field and amount of stress the plant was under, see the article Stalk Quality Concerns in this weeks CORN Newsletter. This variability and high moisture may require us to look harder at combine settings to keep the valuable grain going into the bin. Each ¾ pound ear per 1/100 of an acre equals 1 bushel of loss per acre. This is one ear per 6, 30 inch rows in 29 feet of length. A pre harvest loss assessment will help with determining if your combine is set properly. Initial settings for different combines can be found in the operator’s manual but here are a few adjustments that can be used to help set all machines. Thanks to the weather we had this year, corn is variable across fields and in some areas we will be harvesting corn at higher moistures than normal. Stalk quality may also be variable by field and amount of stress the plant was under, see the article Stalk Quality Concerns in this weeks CORN Newsletter. This variability and high moisture may require us to look harder at combine settings to keep the valuable grain going into the bin. Each ¾ pound ear per 1/100 of an acre equals 1 bushel of loss per acre. This is one ear per 6, 30 inch rows in 29 feet of length. A pre harvest loss assessment will help with determining if your combine is set properly. Initial settings for different combines can be found in the operator’s manual but here are a few adjustments that can be used to help set all machines.

Corn Head

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Is a late soybean harvest in your future?

Source: James Morris, Will Hamman, Jason Hartschuh, Elizabeth Hawkins

The variability of the 2019 cropping year is continuing into harvest. With a broad range of planting dates this spring, many soybean producers will be faced with variable harvest conditions. Additionally, the hot and dry conditions this late summer into early fall has sped up the senescence and dry down of many soybean fields. While seed quality is currently very good, a few weeks of wet weather can degrade quality quickly. Be sure you are ready when the soybeans are.

When harvesting soybeans, harvest loss can be a real concern. The ideal time to harvest soybeans is when the soybean seed reaches 12-15% moisture. This will allow for optimal threshing and reduced harvest loss. Harvest loss can be very simply calculated by getting out of the combine and counting the soybean seeds on the ground. By randomly selecting a 1-foot by 1-foot area in a harvested part of the field, a producer can estimate harvest loss. Counting 4 soybean seeds per square foot is equal to 1 bushel/acre of loss. Due to the mechanical nature of a combine it is nearly impossible to gather every soybean seed in the field. An acceptable level of loss is 3% of yield or less, which is equivalent to 1-2 bushels/acre. If harvest conditions and combine adjustments are not optimal, harvest loss can reach 10% of yield and that can become very costly to the producer. Continue reading Is a late soybean harvest in your future? →

Corn Grain Test Weight

Source: R.L. Nielsen, Purdue Univ. (edited)

Among the top 10 most discussed (and cussed) topics at the Chat ‘n Chew Cafe during corn harvest season is the grain test weight being reported from corn fields in the neighborhood. Test weight is measured in the U.S. in terms of pounds of grain per volumetric “Winchester” bushel. In practice, test weight measurements are based on the weight of grain that fills a quart container (37.24 qts to a bushel) that meets the specifications of the USDA-FGIS (GIPSA) for official inspection (Fig. 1). Certain electronic moisture meters, like the Dickey-John GAC, estimate test weight based on a smaller-volume cup. These test weight estimates are reasonably accurate but are not accepted for official grain trading purposes.

The official minimum allowable test weight in the U.S. for No. 1 yellow corn is 56 lbs/bu and for No. 2 yellow corn is 54 lbs/bu (USDA-GIPSA, 1996). Corn grain in the U.S. is marketed on the basis of a 56-lb “bushel” regardless of test weight. Even though grain moisture is not part of the U.S. standards for corn, grain buyers pay on the basis of “dry” bushels (15 to 15.5% grain moisture content) or discount the market price to account for the drying expenses they expect to incur handling wetter corn grain.

Growers worry about low test weight because local grain buyers often discount their market bids for low test weight grain. In addition, growers are naturally disappointed when they deliver a 1000 bushel (volumetric bushels, that is) semi-load of grain that averages 52-lb test weight because they only get paid for 929 56-lb “market” bushels (52,000 lbs ÷ 56 lbs/bu) PLUS they receive a discounted price for the low test weight grain. On the other hand, high test weight grain makes growers feel good when they deliver a 1000 bushel semi-load of grain that averages 60 lb test weight because they will get paid for 1071 56-lb “market” bushels (60,000 lbs ÷ 56 lbs/bu).

These emotions encourage the belief that high test weight grain (lbs of dry matter per volumetric bushel) is associated with high grain yields (lbs. of dry matter per acre) and vice versa. However, there is little evidence in the research literature that grain test weight is strongly related to grain yield.

Hybrid variability exists for grain test weight, but does not automatically correspond to differences in genetic yield potential. Grain test weight for a given hybrid often varies from field to field or year to year, but does not automatically correspond to the overall yield level of an environment.

Similarly, grain from high yielding fields does not necessarily have higher test weight than that from lower yielding fields. In fact, test weight of grain harvested from severely stressed fields is occasionally higher than that of grain from non-stressed fields, as evidenced in Fig. 2 for 27 corn hybrids grown at 3 locations with widely varying yield levels in Kansas in 2011. Another example from Ohio with 22 hybrids grown in common in the drought year of 2012 and the much better yielding year of 2013 also indicated no relationship between yield level and grain test weight (Fig. 3).

Conventional dogma suggests that low test weight corn grain decreases the processing efficiency and quality of processed end-use products like corn starch (U.S. Grains Council, 2018), although the research literature does not consistently support this belief. Similarly, low test corn grain is often thought to be inferior for animal feed quality, although again the research literature does not support this belief (Rusche, 2012, Simpson, 2000, Wiechenthal Pas et al., 1998). Whether or not low test weight grain is inferior to higher test weight grain may depend on the cause of the low test weight in the first place.

Common Causes of Low Grain Test Weight

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Converting Wet Corn Weight to Dry Corn Weight

Source: Bob Nielsen, Purdue University

Corn is often harvested at grain moisture contents higher than the 15% moisture typically desired by grain buyers. Wetter grain obviously weighs more than drier grain and so grain buyers will “shrink” the weight of “wet” grain (greater than 15% moisture) to the equivalent weight of “dry” grain (15% moisture) and then divide that weight by 56 to calculate the market bushels of grain they will purchase from the grower.

The two sources of weight loss due to mechanical drying are 1) the weight of the moisture (water) removed by the drying process and 2) the anticipated weight loss resulting from the loss of dry matter that occurs during the grain drying and handling processes (e.g., broken kernels, fines, foreign materials). An exact value for the handling loss, sometimes called “invisible shrink”, is difficult to predict and can vary significantly from one grain buyer to another. For a lengthier discussion on grain weight shrinkage due to mechanical drying, see Hicks & Cloud, 1991.

The simple weight loss due to the removal of grain moisture represents the greatest percentage of the total grain weight shrinkage due to drying and is easily calculated using a handheld calculator or a smartphone calculator app. In general terms, you first convert the “wet” weight (greater than 15% moisture) to absolute dry weight (0% moisture). Then you convert the absolute dry weight back to a market-standard “dry” weight at 15% grain moisture.

Concept:

  1. The initial percent dry matter content depends on the initial grain moisture content. For example, if the initial grain moisture content is 20%, then the initial percent dry matter content is 80% (e.g., 100% – 20%).
  2. If the desired ending grain moisture content is 15% (the typical market standard), then the desired ending percent dry matter content is 85% (100% – 15%).
  3. Multiply the weight of the “wet” grain by the initial percent dry matter content, then divide the result by the desired ending percent dry matter content.

Example:

  1. 100,000 lbs of grain at 20% moisture = 80,000 lbs of absolute dry matter (i.e., 100,000 x 0.80).
  2. 80,000 lbs of absolute dry matter = 94,118 lbs of grain at 15% moisture (i.e., 80,000 / 0.85).
  3. 94,118 lbs of grain at 15% moisture = 1681 bu of grain at 15% moisture (i.e., 94,118 / 56).

One take-home reminder from this little exercise is the fact that the grain trade allows you to sell water in the form of grain moisture… up to a maximum market-standard 15% grain moisture content (or 14% for long term storage). Take advantage of this fact and maximize your “sellable” grain weight by delivering corn grain to the elevator at moisture levels no lower than 15% moisture content. In other words, if you deliver corn to the elevator at grain moisture contents lower than 15%, you will be paid for fewer bushels than you otherwise could be paid for.