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| At last week's Agronomy Update Meeting in Wausau (one of several around the state), he advised producers to watch seed quality carefully. "We have paid little attention to Pure Live Seed - PLS - in the Midwest because we have generally had high quality seed - greater than 90 percent germ and 98 percent purity," Undersander reported. "But the short forage seed supply has caused some low quality seed to come on the market." To avoid being caught paying market price for low quality seed, he cautioned growers to take "special care to check the seed tag" and compare PLS among lots of seed to be purchased, he noted.
This forage specialist explained that a bag of seed consists of inert material such as dust, chaff and seed coating; weed and other crop seed; and Pure Live Seed of the desired species. Since every seed lot has a different analysis, and only PLS will produce plants, it's important to calculate the PLS in a bag. "This calculation will allow accurate price comparison and adjustment of seeding rate if necessary," he said
Check the sample seed tag for the analysis. Find "percent germination: - the percent of seeds that germinated in a standard test. Most crops have been greater than 90 percent germination, and producers have seldom made any adjustments. But with some short forage supplies at present, some lots of seed may have germinations as low as 60 percent, according to Undersander. "Check the label so you are not caught off guard," he warned.
Next, find the "percent purity" on the tag - the percent of the weight in the bag that's actually seed. High-quality seed lots will be over 95 percent "purity, but seed coating, for instance, may reduce the seed purity to 70 percent.
To find PLS, multiply percent germination times percent purity and divide by 100. For instance, (95 percent germination multiplied by 70 percent purity) divided by 100 equals 66.5 percent PLS. In other words, this lot of seed only has 66.5 pounds of actual live seed for every 100 pounds.
Use PLS to determine your best seed buy, said Undersander. Since PLS will produce plants in the field or pasture, seed cost per pound must be adjusted for PLS to accurately compare seed prices - particularly in today's market.
"To find out what you're really paying, first determine the PLS of seed you're considering (as described above)," Undersander directed. "Then divide the cost per pound by the PLS to get the cost per pound of PLS." For instance: ($4 per pound seed divided by 70 percent PLS) multiplied by $100 is really $5.71 a pound of PLS. Compare that to: ($4 per pound seed divided by 90 percent PLS) multiplied by 100 or $4.44 per pound of PLS.
Undersander has posted a table giving actual seed costs for 50-pound bags of seed with varying prices and PLS at http://www.uwex.edu/ces/forage/pubs/pure_live_seed.pdf.
To determine your needed seeding rate, check the seeding rate recommendations with the hay and pasture seeding rate calculator at http://www.uwex.edu/ces/forage/ or in UW-Extension publication A1525, "Forage Variety Update for Wisconsin, 2007 Trial Results" (available at county Extension offices). On page 22, there are planting rate recommendations for a long list of forages. The rates are for PLS of 90 percent or better.
If PLS is 70 percent and you intend to seed 10 pounds per acre, adjust as follows: (10 pounds divided by 70) multiplied by 100 PLS or 14.3 pounds.
"This is a significant difference and if you hadn't made this adjustment, you'd be about 40 percent under the target seeding rate," Undersander reported.
"Many times, purity and germination are high enough that a significant adjustment will not be necessary. However, even seed with 90 percent purity and 90 percent germination will have 20 percent less viable seed than you think if you don't consider PLS, so don't overlook PLS when you buy or plant forage seed," he said.
Coated seed reduces PLS, as noted. He cautions farmers to look at the percent coated seed. If it's up around 30 percent - to stretch seed supply - he doesn't think "that's helping us much."
Undersander added that grasses (in terms of supply) are in "tough shape," too. Beware of quality when making grass seed purchases as well this winter and spring.
Link to article http://www.agriview.com/articles/2008/01/17/crop_news/crops03.txt | |
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Non Coated Alfalfa Seed
