Corn test weight is a term the is frequently misunderstood. Some confusion exists the high test weight corn contributes to yield potential and also provides an financial benefit.

Corn test weight is a term that is frequently misunderstood. Some confusion exists the high test load corn contributes to yield potential and also provides an economic benefit. Both of these perceptions room incorrect. Choosing the corn moisture contents for harvest is frequently a economic decision.

Test load is a measure up of bulk density or weight of a unit volume of serial (bu/lb). Iowa State college reports the corn test weight worths can variety from 45 lbs/bu to end 60 lbs/bu.1 The United states Department of agriculture established the typical test load of a bushel of corn together 56 lbs/bu based on 15.5% moisture content. Table 1 lists different test weights the corn essential to same one bushel that No. 2 shelled corn at 15.5% moisture as soon as corn is harvested at various moisture levels.2 For part specialty food corn, test load is supplied as one indicator the grain attributes which space favorable for processing.

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Today in the unified States, grain yield is quiet referenced in bushels every acre, however it is actually traded and sold ~ above a weight basis. Test load is quiet measured as soon as grain is sold. Grain price can be influenced by test weight in particular areas such as those that have actually premiums because that high test weight or once selling in the whole food great market. However, in many cases, just test weights that are below the minimum because that No. 2 yellow corn (3

Is yield influenced by check weight? any type of stress that prematurely stop or reduces grain fill and/or interferes with photosynthesis might lower yield potential as well as test weight. Grain productivity is determined by the variety of kernels every acre along with the load per kernel, i m sorry is shown in the equation below:

 


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In comparison, test weight procedures the weight of corn in pounds that will certainly fit right into a bushel. Productivity is a straight measure of kernel weight and also kernel number. However, test load is not a direct factor of grain yield. Test load is just partially regarded kernel weight since there is also the volume component connected with the measurement. Factors that impact test weight, but not corn yield, room those that influence how kernels fit or load together. These may encompass slipperiness the the particle coat and also kernel shape or size. As result of the volume component, test load will influence how numerous bushels can fit right into a bin, wagon or truck, however not yield every acre.

 


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Is there a correlation between yield and also test weight? There has been some that think yield will constantly be reduced if test load is lower and vice versa. If this to be true, corn assets with high test load grain would frequently out productivity corn commodities with mean test load grain. Yield can be high and also test weight can be low. For example, if the time for grain fill is reduce the seed size might be smaller but the thickness of the individual seeds continues to be unchanged.

Conversely, yield deserve to be low and test weight can be high. Popcorn is a great example that this together it is more dense than ar corn and has a fairly high traditional test weight of 65 lbs/bu contrasted to ar corn in ~ 56 lbs/bu. Yet, median popcorn yields are fifty percent as much as ar corn.4,5,6

In some instances, corn check weights might be lower than intended due to changes in kernel weight from stresses during kernel fill. Reduced kernel weight have the right to also an outcome in reduced yield and also therefore, the test weight deserve to be low together well. That is crucial to psychic that changes in yield and test weight room not constantly proportional or correlated.

Corn productivity is about the accumulation of dry issue in the kernel and also the number of kernels developed per acre. Controlled by the limitations of the environment and corn product yield potential, the maximum lot of dry matter feasible will be built up within that acre. If corn is grown in an environment that will support the manufacturing of 12,320 lbs the dry matter (220 bu) every acre and also two different corn commodities yield similarly but one has greater test weight 보다 the other, the greater test weight corn product has developed the same amount of dried matter but with less volume every unit the grain. However, the end result of tantamount yield has been reached.

Corn product selection impacting check weight: In enhancement to ecological stresses impacting test weight, corn product an option may likewise influence test load results. This is a result of corn commodities with higher vitreous (hard or flinty) endosperm having greater test weights than ones through floury (soft or dent) endosperm. Tough kernels have the right to have higher densities. However, this potential distinction in endosperm contents does not necessarily correlate to differences in genetic yield potential.

 


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Corn Drydown Rates

Choosing the corn moisture content for harvest is often an economic decision that weighs excess harvest losses against the energy expenses for dry corn. Other factors, such together stalk stamin or the visibility of ear rots, should additionally be considered when determining the target harvest date. Harvesting early may be a good practice since field losses can increase when harvest is delayed, as well as when the crop dries under after maturity.

Corn Maturity and also Drydown: when corn reaches physiological maturity or black layer, that is around 30% moisture. Over there are numerous factors that can impact how quickly corn dries under in the field after getting to maturity. Warm, dry weather have the right to speed up the drying rate, vice versa, wet and cool weather have the right to slow the down. Additionally, late-planted and full-season corn products tend to dry more slowly.

After getting to maturity, usual drying rates may range from 0.4% to 0.8% ns of moisture content per day. Rates of drydown vary depending on temperature and moisture levels and can be as low together 0.3% or higher than 1%. Typically, the rate of moisture content loss proceeds to decrease as temperatures cool and also days acquire shorter. Corn maturing at the beginning of September is supposed to dry down quicker than corn maturing in ~ the start of October.

After physiological maturity (black layer), moisture content of the kernel is influenced by the atmosphere surrounding the kernel and also physical qualities of the ear and husks that affect the atmosphere surrounding the kernel. The moisture difference in between the kernel itself and the surrounding air leads to moisture activity out of the kernel till an equilibrium is reached. A year with wet weather and also delays in planting may result in slower ar drying of corn. Other factors may likewise come into play if harvest is delayed. For example, corn might have arisen a shallow root system since of the early-season moisture. In addition, problems may have actually been conducive for the advance of stalk rots and also stalk cannibalization in corn. These factors can lead to higher than normal harvest losses due to the fact that of an boosted risk because that stalk lodging in corn this fall.

Germplasm Characteristics: Ear and also husk qualities of various corn germplasm can impact the rate of drydown. These qualities have the largest result when weather problems are unfavorable for rapid grain drying:

Number and Thickness of Husk leaves - fewer husk leaves and also thinner leaves can lead to quicker moisture loss. Dieback that Husk pipeline - previously dieback of rice peel leaves deserve to lead to more rapid grain drying. Husk Coverage of the Ear - Husks that are open up at the pointer of the ear may provide for much faster grain humidity loss. Tightness that Husk pipeline - Looser installation husks ~ above the ear deserve to lead to quicker grain drying.Ear angle - ears that droop indigenous an upright position after maturity tend to lose moisture an ext quickly. Upright ears can capture added moisture indigenous rainfall. Properties the Kernel Pericarp - diluent pericarps (outer layer spanning a corn kernel) have been associated with faster drying prices in the field.

Harvest Loss: The optimum harvest moisture contents for corn is roughly 23% come 25%. In ~ this humidity level, kernels shell easily and stalks usually stand better, which can make harvesting more efficient. A normal harvest lose level of a timely and efficient harvest is about 1 to 2%.

Delaying harvest until corn dries under to 17% to 19% moisture content deserve to save on fabricated drying cost. However, together corn dries down in the ar there is better potential because that excess harvest losses from stalk lodging and also ear drop. Many harvest losses space mechanical, brought about by kernel wrecking or corn never obtaining into the combine. Enabling corn to drydown in the field could an outcome in excess harvest losses, as lot as 2 come 8% above normal level v a timely and also efficient harvest.

If stalk lodging or ear drop difficulties are observed, harvest timing will certainly be more an important to maximize yield potential. Time have to be taken to watch crop condition in the ar in an effort to balance field drydown through harvest loss.

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Sources:

1 Hurburgh, C. And Elmore, R. 2008. Corn quality problems in 2008 – moisture and test weight. Iowa State college Extension. Integrated Crop News. Http://www.extension.iastate.edu/ . 

2 Lauer, J. 2002. Approaches for calculating corn yield. University of Wisconsin. Field plants 28.47-33. Http://corn.agronomy.wisc.edu/. 

3 Bern, C. And Brumm, T. 2009. Grain test weight deception. Iowa State college Extension. PMR 1005. Http://lib.dr.iastate.edu/ 

4 Carter, P.R., Hicks, J.D., Doll, E.E., Shuler, R., and also Holmes, B. Popcorn. University of Wisconsin and University that Minnesota. Alternate Field plants Manual. Http://www.hort.purdue.edu/.

 5 Duffy, M. And also Calvert, J. 2010. Enterprise budget: popcorn. Iowa State university Extension and also The Leopold Center. BFC 16. Https://www.leopold.iastate.edu/.