Spring Cropping Decisions
Spring will soon be here, at least "calendar spring," which is March 20. Some farmers have a hard time thinking spring thoughts in March while a blanket of snow still covers their fields, but even in northerly areas spring will soon arrive. The arrival of spring also means that a few cropping decisions may need your attention.
Spring topdressing of grasses and winter small grains
Two crops that may need your earliest attention are winter small grains and cool-season grasses such as tall fescue, orchardgrass and timothy. Some farmers apparently think that all is well if fall-seeded small grains simply make it through the winter. However, for top yields, whether the crop will be harvested for forage or for grain, you should apply nitrogen to these crops. Most university recommendations simply say to apply nitrogen "early in the spring," but when is that? March 20? At green-up? This depends to some extent on whether you're growing grasses or small grains. Some small grains never turn brown over winter, especially during a snowy winter that insulates plants, so they're green as soon as the snow melts. Wait until you see spring growth before applying nitrogen; many agronomists suggest delaying nitrogen application on grains until the plants begin to tiller. For grasses, wait until spring growth begins. That's because nitrogen is leachable and also subject to runoff losses. The last thing you want is for that expensive nitrogen fertilizer to run off the field or to leach past the root zone before the grass has a chance to use it.
What form of nitrogen (N) should you use? Ammonium nitrate was once the fertilizer of choice for topdressing since it's easy to handle and doesn't volatilize much at all. However, ammonium nitrate has become increasingly hard to find and it's relatively expensive. Urea is the cheapest topdress N source, but is subject to volatilization losses. It's a good choice as long as rain occurs within a couple days of application; if not, adding Agrotain or a similar product to the urea will stabilize the nitrogen and greatly reduce environmental losses. UAN, also called liquid N, is a blend of urea and ammonium nitrate, and is another good N source. Dribble-on applications seem to work better than broadcast as long as the nozzles aren't spaced too far apart, but as with straight urea a nitrogen stabilizer will reduce losses. Ammonium sulfate doesn't volatilize much at all, and while more expensive per pound of nutrient than other N sources it may be the best alternative where soil sulfur levels are low.
At Miner Institute we used to topdress grasses with a 50-50 blend of urea and ammonium sulfate, a combination that worked quite well. How much N to use depends on where you farm and what crop you grow, but recommendations for both small grains and grasses often range between 50 and 100 pounds of actual N per acre. Consult your crop consultant, cooperative extension educator or university agronomist for recommendations localized for your state.
March and April: Critical times for grasses
If you routinely topdress grasses with manure during the summer you'll still need to fertilize them this spring. Few farmers have the type of land - and the time - to topdress manure in early spring. By the time grass fields are dry enough to get on them with manure-spreading equipment new growth is well under way and many other things need to be done. Even with high-priced nitrogen, the question isn't whether you can afford to apply nitrogen, but whether you can afford not to. Cornell University agronomist Jerry Cherney says that based on their research, if farmers don't use manure or fertilizer on grass fields the yield is often so low that the harvest cost exceeds the value of the crop. Even if you used plenty of manure during the previous growing season it's still profitable to apply N this spring. If you didn't use manure last year, spring application of N is critical.
Spring planting: How early is too early?
I've seen spring wheat planted in late March that did just fine, and we've made successful alfalfa-grass seedings at Miner Institute before mid-April. In general, field conditions are more important than the calendar date since most cereals and small-seeded forages are quite frost-tolerant. The possible exception is reed canarygrass, which at the seedling stage is sensitive to frost.
When farmers used to ask me how early they could plant corn I told them that if the soil is dry enough to work without making clods it's probably warm enough to plant. However, in recent years I've had to change this recommendation. In part because of the increased amount of pattern subsurface drainage at 30 and 40-foot spacing, farmers are able to get on their fields earlier than ever before. Several years ago one large grower in northeastern New York started planting corn about April 15 and had hundreds of acres in the ground within a few days. That scared the wits out of me, but the corn did just fine. That experience aside, in much of the northeastern U.S. I don't think we should push corn planting very far back into April. It's not when you start planting corn that's most important, it's how late you finish. If you can get all your corn planted in a couple of weeks, it makes no sense to plant so early that you risk cold weather damage. Cornell University date-of-planting research at Miner Institute (in far northeastern New York), while done many years ago, found that the earliest corn planting date did not result in the highest yield.
In some areas it's already getting too late to frost seed. That's because most successful frost seedings are made when there's still frost in the ground (thus the name), and several freeze-thaw cycles are expected after seeding. A late-season snow after frost seeding will help by keeping the soil surface moist. The advantage of frost is that you can drive over the fields with seeding equipment without making ruts. Once the soil is warm and dry it's too late to frost seed. Even with ideal conditions don't expect a frost seeding to produce a thick stand of new plants because only about 10 percent of the seed will germinate and survive to produce a harvestable plant. Successful germination is only half the battle; the seedling will then have to compete with established plants, and since the established plants already have an extensive root system it isn't a fair fight. In fact, the better the existing stand (particularly grasses), the less likely a frost seeding will be a success. Therefore, start early and use inexpensive seed, but don't expect miracles.
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.