Miner Institute: Reduced-lignin alfalfa should have you asking questions

Farm magazines are buzzing with news about reduced lignin alfalfa varieties. Alforex Seeds is marketing two Hi-Gest® varieties for 2015 (one with a fall dormancy rating of 3 which is suitable for Northern regions) and Monsanto planning the sale of HarvXtra™, a glyphosate-resistant alfalfa, for 2016. Where does this new technology fit on your farm? That will depend on how you intend on using reduced lignin alfalfa, and also whether you seed a forage grass with alfalfa.

When alfalfa breeders develop an alfalfa variety they give little or no thought to the possibility that farmers would be planting a grass with it. While Alforex Seeds" reduced lignin varieties were developed using conventional plant breeding, Monsanto's reduced lignin alfalfa will be Roundup Ready and therefore a GMO. In most U.S. dairy regions (except for the Northeast) grass is considered a weed when it's growing in an alfalfa field. This attitude is changing, but only slowly.

One of the advantages claimed for reduced lignin alfalfa is that farmers may be able to delay harvest by up to a week, resulting in higher yields and perhaps a reduction in the number of harvests per year. It would certainly be a plus to get the same yield and quality from three cuts as you normally would from four. However, if you seed alfalfa-grass you'd need to use a grass variety that wouldn't head out until at least a week later than your normal first cutting date, and there are precious few cool-season grass varieties that will do this. And delaying cutting second and subsequent harvests by a week will result in reduced grass quality regardless of the grass variety used. Forage quality of grass regrowth declines fairly rapidly even if it doesn't head out. The overall yield impact may be small if there's not much grass in the second and later cuts (as is often the case with timothy), but the current trend is to plant a grass variety (such as tall fescue) that yields more summer forage when seeded with alfalfa. So, the result of a week's delay in second and third cuts of reduced lignin alfalfa-grass would be normal alfalfa quality but lower grass quality. Cornell University forage agronomist Jerry Cherney's opinion is that any gain in alfalfa quality would be more than wiped out by a decline in grass quality. How is that a plus?

Here are three questions regarding reduced lignin alfalfa that need to be answered:

  1. What will be the impact on milk production if the first cut is made at the bud stage? So far we have forage analyses but no "cow data".
  2. If the first cut is made at the bud stage will a one-week delay in 2nd and following harvests result in enough yield increase (and/or a reduction in the number of cuts) to justify the higher seed cost of reduced lignin alfalfa varieties? Suggested retail price of Hi-Gest® is $290/50 lb. bag, about $100 more than that of many other modern varieties.
  3. In alfalfa-grass seedings how much will forage grass yield and quality decline with a week's delay in first cut? The economics of reduced-lignin alfalfa-grass would improve if we could find a grass variety that will reliably be in the boot stage when the alfalfa is 10% bloom. A late-maturing orchardgrass variety, Dividend VL, developed in Ontario and sold in the U.S. and Canada, plus some varieties of perennial ryegrass might meet this criterion. We have Central N.Y. heading date data on these varieties when grown in pure stands, but nothing on their performance when seeded with alfalfa. And we'd still have lower grass quality with a one-week delay in second and subsequent harvests.

Anything offering the potential for higher forage quality is worth serious consideration, and I expect that where alfalfa is grown without a forage grass reduced lignin alfalfa will be a hit. Data from the companies developing these varieties suggest that when grown in pure stands yields will be competitive with those of normal varieties. And even if there is a modest yield drag it may be outweighed by the impact of increased forage quality. That's been the case with BMR corn hybrids. But before going "all in" on this new technology farmers growing alfalfa-grass will need answers to the above questions.



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