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OSU Extension

College of Food, Agricultural, and Environmental Sciences

October 17, 2019 - 4:25pm --

I recently heard a presentation by Bill Weiss, OSU dairy nutrition specialist, advising dairy farms on strategic planning of forage resources, and especially silage.  We know 2019 was a difficult crop and forage year.  On some farms, corn silage and high-quality forages are in short supply.   Bill recommends dairy farms inventory forages and make feeding adjustments now so that big ration changes are not needed next summer.   I’ll summarize some of the steps and key points from Bill’s presentation.

The first step is to estimate the farm’s forage inventory.  The goal is to provide an estimate of the tons of forage by forage type and quality.  To get tonnage figures use farm harvest records if available or estimate tonnage by using tables and charts.  Spreadsheet and tables to determine silo capacities and silage bag capacities are available on-line by typing in “silo capacity calculators” into any browser.  I can also provide hard copy information for those without internet access.  Ideally, a forage test analysis will accompany each type and quality of forage in the inventory.  Reduce the silage inventory number by 10% to account for shrink.

The next step is to determine the maximum forage use per day.  Nutritional requirements and ration formulation are based on dry matter (DM).  Convert forage inventory tons to DM tons and divide by the days this inventory must last.  In the case of corn silage, the next harvest is 365 days away. For something like a hay crop silage such as alfalfa, alfalfa/grass or a small grain, the next harvest is next April or May so you might use 210 to 240 days of feeding the current inventory.

 For example, if you harvested 100 acres of corn silage with an average yield of 22 tons/acre that equals 2200 tons harvested.  If the average moisture content was 65%, this is 35% DM.  Your DM tons of corn silage is 2200 x .35 = 770 tons.  Now reduce that by 10% to account for shrink (770 x 0.9) equals 693 tons available for feeding.  Dividing that amount by 365 equals 1.89 tons or about 3795 pounds/day as the maximum amount DM that can be fed to lactating cows, dry cows, and heifers each day. 

The final step for dairy farms is to estimate the maximum forage use per day of lactating cow quality forage.  The process is the same as described in the preceding paragraph, except now the focus is on the best quality forage, including silage, baleage and dry hay.  Convert forage inventory tons into DM tons.  Divide that number by the days until the next harvest.  This will provide the maximum amount of this lactating cow quality forage that can be fed per day.  With this number plus the corn silage number, work with your nutritionist to plan and formulate your feed rations. 

Dairy cows do not like surprises in their rations.  Some planning now to manage forage inventories to avoid big ration changes next summer is worth the effort. 

Fall Sampling for SCN

Soybean harvest has made good progress and once the soybeans are off the fields this is an opportunity to sample soil for soybean cyst nematode (SCN) populations.  The SCN Coalition theme for the next few years is What’s your number?  Do you know which fields have SCN and what is the current population level? We know that Ohio is now “polluted” with SCN, fortunately most of those fields are at very low levels – which is where they should be kept.

From samples received to date of a statewide Ohio survey of 50 counties as part of the SCN Coalition sampling, here are the numbers from 378 fields.

SCN Population Level

Total Fields

None detected


Trace (40-200)


Low (200-2000)


Moderate (2000-5000)


High (5000+)




Yield losses have been measured as high as 25% with no above ground symptoms in populations of 2,000 and higher.

  • 60% of the Fields sampled in 2018 and 2019 in Ohio have detectable levels of SCN
  • 15% of these have populations at economically damaging levels – do you know your number?

In addition to soybeans, SCN will also feed on a few weed hosts and cover crops.  If you have SCN in your fields, it is important to control winter annuals such as henbit and purple deadnettle and stay away from certain cover crops such as winter peas, field/forage peas, cowpea and hairy vetch. 

Fall sampling for SCN is recommended because in most cases this is what the population will be in the spring.  Hopefully there is ample time before soil freeze up to collect and process the samples in plenty of time for spring planting.

SCN samples from Wayne County soybean fields, especially those that are low yielding, are needed to get a better picture of how prevalent SCN is in Wayne County. Free sampling is available through this fall.  Contact the Wayne County Extension office at 330-264-8722 for more information about sampling your soybean field for SCN this fall.

For some additional information on Management of SCN check Ohio’s SCN fact sheet and other SCN resources as well:


Rory Lewandowski is an OSU Extension Agriculture & Natural Resources Educator and may be reached at 330-264-8722.

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