Farming Magazine - October, 2012
Forages: Buttoning Down 2012 Forage Crops
By now most of your forages, including both hay crops and corn silage, should be ensiled, packed and covered. There may be one last harvest of alfalfa - more on this in a bit - but it's likely that on most farms over 90 percent of next year's forages are either ensiled or, in the case of dry hay, mowed away. This doesn't mean you can forget about them, of course. Following are a few tips to help you maximize the value of the feed in your silos, plus some thoughts on fall harvest of alfalfa.
Are bunker and stack silos well covered?
In order to be effective, silo plastics must be tightly adhered to the silage surface. Any air getting under the plastic sheet, either through tears or wind getting under an unprotected seam, has almost the same effect as no cover at all. It's particularly important to protect seams between sheets of silo plastic, something I observed during windy conditions while on a consulting trip to Texas and New Mexico early last spring. Some dairies put a double row of whole tires along the seams on their stack silos (also called drive-over piles), which usually does a good job of preventing air from getting under the plastic. A single layer of tire sidewalls wasn't enough, and we saw several stack silos with large bubbles of air underneath the plastic.
I like tire sidewalls since they don't collect rainwater like whole tires do, something of real concern here in the Northeast, since tires can harbor disease-causing mosquitoes. However, one layer of auto tire sidewalls may not be enough in exposed areas, including on stack silos (also called drive-over piles). On one New Mexico dairy the wind got under an exposed edge of plastic and moved the tire sidewalls at least 20 feet from their original location, exposing the silage. Even if your silos are already covered it's not too late to inspect them, adding tires along plastic seams as needed. If you use tire sidewalls, either double up or add a row of whole tires along the seams.
Gravel bags are an excellent option for securing silo plastic, and I'm seeing more of them in use, not only in the Northeast but in the Southwest as well. Miner Institute has been using gravel bags for about 10 years now with good results. The bags cost a few dollars each and you have to fill them with pea gravel or some other type of smooth gravel - no sharp edges to cut the bag material. Do not use sand, since it can get wet and freeze to the silo plastic. With proper care the bags should last for many years, and they provide excellent plastic-to-silage contact. There's nothing magic about silo bags; they simply weigh a lot more than any other form of silo ballast. Some instructions suggest that the gravel bags be placed in rows 15 to 18 feet apart, plus a continuous row of bags along the bottom of the silage pile (for stack and drive-over piles) or along the walls (in bunker silos). The only modification I'd make to this would be to put some tires between the rows just in case there's a hole in the plastic. Most farms moving to gravel bags were using tires, so they should have plenty on hand. Even if you don't add the tires, the gravel bags provide such a tight seal that no air can get between the rows of bags, so a puncture in the plastic shouldn't result in as much spoilage.
As most dairymen know, cows hate rapid dietary changes. You're not feeding the cow, but a complex mix of what New Hampshire-based dairy nutritionist Charlie Sniffen calls "rumen bugs." Don't be in a hurry to feed new crop corn silage; let it ferment for at least two months, preferably three or four months. This will allow the kernels to soften, and corn silage starch digestibility improves with storage time. With corn grain as expensive as it is, you want to maximize the digestibility of the kernels in your corn silage. If you still have 2011 corn silage several months after the 2012 crop is ensiled, don't make the switch from one year's silage to the other overnight, transition from one silage to the other. Be sure to submit a sample of "new crop" silage for analysis as soon as you open the silo and are into normal-appearing silage.
Last but not least, fall alfalfa management
Fall-harvested alfalfa is often high in protein and low in fiber, what some farmers and dairy nutritionists call "cow candy" or "rocket fuel." However, this forage is so different from summer harvests of alfalfa or alfalfa-grass silages that unless it's fed carefully, like a rocket, it could blow up a ration. Beware of any forage where the crude protein content is higher than the acid detergent fiber (ADF) level, something I've seen on occasion with fall-harvested alfalfa. It's not that this forage can't be fed successfully, but it needs to be fed at an inclusion rate that ensures that the cows get enough physically effective fiber. Limit feeding fall-harvested alfalfa isn't usually a challenge on most farms, because yields are often quite modest, usually less than 1 ton of dry matter per acre. Use of a bacterial inoculant for fall-harvested alfalfa and alfalfa-grass is strongly recommended, since by now there may not be enough naturally occurring fermentation bacteria for good silage making. There's no practical way to determine this, but there are a number of high-quality commercial silage inoculants on the market at reasonable prices.
Should you take a fall harvest? My recommendation is to take a fall harvest only if there's a good crop, you need the forage, and you have a good place to store it. Only harvest healthy stands that have had six or seven weeks since the previous harvest. Be sure to leave a high stubble - at least 4 inches, preferably 6 inches - to catch and hold snow. If you do take a fall harvest, don't mow these fields earlier than normal next spring, this will allow the plants to accumulate additional carbohydrates.
Ev Thomas has worked as an agronomist in New York for 45 years, first with Cornell University Cooperative Extension, then with the William H. Miner Agricultural Research Institute in Chazy, N.Y., including managing its 680-acre crop operation. He continues to work part-time for Miner Institute and is now an agronomist at Oak Point Agronomics. He has a written our Forage column for over 13 years and has been an expert contributor on a number of other topics.