Farming Magazine - August, 2014

COLUMNS

Forages: Think Globally, but Farm Locally

By Everett D. Thomas


Photo by Maksymowicz/thinkstock.com.

One of the advantages of writing for a regional farm publication is the somewhat greater similarities in farm enterprises, crop choices, size and scale, weather and climate. For instance, only about 7 percent of last year's U.S. corn crop was harvested for whole-plant silage. But in New York and New England, less than half of the 1.4 million acres of corn planted in 2013 was harvested for grain, with almost all of the grain acreage in New York. Furthermore, since the main farm economy in this region is dairy farming, nutrients from manure are available for much of the cropland, including a large portion of those 1.4 million acres of corn, greatly impacting fertilizer programs. Therefore, farming in the Northeast is, well, different. Following are a couple of the ways our farming practices are affected.

To till or not to till, that is the question

A friend from western New York has occasionally chided me for what he refers to as "recreational tillage," because much of the cropland at Miner Institute is conventionally tilled, while he's a fan of no-till. Conventional tillage includes both moldboard and chisel plowing. With the exception of the 10 percent of Miner Institute cropland that's under continuous no-till because of extreme stoniness, all the cropland on the farm is moldboard plowed at least twice during a normal eight to 10-year cropping cycle.

The crop rotation consists of four or five years of corn followed by a similar number of years in alfalfa-grass. Normal practice is to moldboard plow the sod the fall before planting to corn, and to moldboard plow once again the fall before seeding the field back to alfalfa-grass. This does two things: It results in a better distribution of nutrients throughout the plow layer, since manure is commonly topdressed onto established alfalfa-grass fields, and it also plows down herbicide residues and weed seeds that may be left after several years of corn production. Many weed seeds buried several inches deep by the plow won't germinate and will die before a subsequent plowing can bring them closer to the surface. In addition, any herbicide residues will have long since lost their potency by the time the field is moldboard plowed again. The result: More uniform soil fertility and fewer challenges from weeds and herbicide residues.

However, every tillage pass is at the expense of soil structure. Continuous tillage, year after year, could certainly cause problems, but while the most common rotation in the Corn Belt consists of corn and soybeans, most farmers in the Northeast break this row crop cycle with several years of perennial forages. The root systems of annual crops such as corn and soybeans are only living for a few months each year, so there's nothing to contribute to maintaining soil structure for the rest of the year. That's one reason why no-till has become so popular in corn-soybean cropping systems, because it limits the breakdown of soil structure. But during the years farms grow perennial forage crops, there's a living root system year-round, and as a result these soils can better tolerate the occasional "clean tillage" operation.

Feed the soil or feed the plant?

Some Corn Belt agronomists are recommending that farmers use deep banding of fertilizers to supply nutrients to corn, especially with the high yields that are often achieved there. They note that "feeding the soil" through broadcast fertilizer applications can be wasteful, since plant uptake is much less efficient with these methods. However, many farmers in the Northeast have a ready supply of dairy manure that in almost all cases is broadcast across the whole field; the only exception is injected manure, and even then the nutrients are seldom placed next to the corn row.

The idea behind feeding the plant is to position the fertilizer so that it will become readily available to plant roots. The initial corn root (radicle) and the roots developing soon after that (seminal roots) both head down at about a 45-degree angle. That's why starter fertilizers are placed in a 2-by-2 band: 2 inches below the seed and 2 inches to the side of it. Roots don't seek out the fertilizer band; they blunder into it. I think that's why when you look at young corn plants some appear a bit more vigorous than others. The best-looking plants are probably those whose roots ran into the fertilizer band.

Unlike corn, the early roots of alfalfa and other forage legumes head straight down like a carrot, which is why it's recommended to "band seed," placing the band of fertilizer directly below the row of seeds. In this case, all the alfalfa seedling roots should grow into the fertilizer band.

The nutrients in some fertilizers are tied up by the soil, which decreases their availability to plants. This includes phosphorus (P), one of the most important nutrients during germination and early growth. Soil fertility experts say that it takes 5 pounds of broadcast P to produce the same results as 1 pound of P in a properly positioned fertilizer band. However, on dairy farms P isn't a limiting nutrient: Dairy manure contains plenty of P, enough that some fields with a long history of manure application have higher soil test P levels than are desirable from an environmental standpoint. Precise P fertilizer placement on highly fertile fields isn't as critical as on low-P soils for which fertilizer is the only source of this nutrient. Therefore, on dairy farms we use a smaller amount of starter fertilizer - sometimes none at all - to feed the plant because repeated manure applications have done such a good job of feeding the soil.

So, continue reading national farm magazines because they contain a lot of useful information, but remember that because of differences in soils, crop rotations and agricultural enterprises, it's important to take a regional approach to crop management.

Ev Thomas has worked as an agronomist in New York for 48 years, first with Cornell University Cooperative Extension, then with the William H. Miner Agricultural Research Institute in Chazy, New York, 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 written our Forages column for 16 years and has been an expert contributor on a number of other topics.