Much of Maryland experienced corn yields that were approximately 50% less than normal production (138 bu./acre average during the previous four years), with some areas that were hit particularly hard with drought that yielded only about 25% of normal, says Bob Kratochvil, University of Maryland Extension grain and oil crops specialist.

Despite last year’s drought and disappointing corn yields, there is still strong interest among area farmers to grow corn following corn in 2008, he adds. “Yet, most research — including some conducted in Maryland with continuous corn — has found about a 10% loss in grain yield with continuous corn compared to rotational corn,” says Kratochvil. “As an Extension agronomist, I strongly urge farmers not to abandon crop rotation as the simplest, most sound agronomic tool they can practice. However, I do recognize the fact that dairy and cattle farmers are often not rotating their corn fields every year because they are trying to produce as much forage as possible and it simply is not economical to rotate hay ground annually. So, with limited acreage available, they generally go with two to three or more years of continuous corn before rotating into a hay crop.”

Don Robinson is one such farmer from northern Maryland. Robinson recently wrote to the Corn E-Digest to share his top-10 continuous-corn management tips. The following is what he writes:

“I raise beef and plant corn for silage and grain if there is any left to combine. Because our main acreage is dedicated to cows, most of our forage is grown on leased acreage and is split between corn and hay. Because we don’t replant hay on a yearly basis, corn normally follows corn. Because of the Chesapeake Bay (environmental concerns), we’ve been planting cover crops to take up any nitrogen (N) the corn doesn’t get. Our primary tillage is minimum-till to no-till. I haven’t had a moldboard on a tractor for about five years, and that was to get ridges out of a field we leased.

Yields have slowly increased, averaging 182 bu./acre on combined corn last year and about 25 tons/acre chopped. Although forage was shorter this year, at about 20 tons/acre, the average corn yield for grain was higher and averaged 190 bu./acre. This area also got a few timely showers in July that farms 50 miles north and south of us didn’t get, and our no-till did give us a few extra days of soil moisture conservation until we got those sprinkles.

I’ve been growing corn on corn now for about 20 years, and the few tips I have are probably those you have already seen. They are:

• Cut residue in the fall — it allows the stalk to break down and rot, destroys many weeds and clears the surface for next spring.
• If you plant a cover crop, burn it off early, unless you plan to harvest it for forage or grain. We have harvested wheat off cover acres, and have had mixed results on silage acreage following wheat covers, mostly depending on the amount of moisture available late in the season.
• If you have manure, use it. Mix it in with a disk or similar tool if you can. We store manure through the winter, spread early in the spring, disk, spray and plant.
• Keep an eye on fertility — especially with manure. First-year manure ground doesn’t always seem to respond, but there is a noticeable response the second year. This is where the fall disking can really pay off — it helps in incorporating the spring manure.
• While a disk is our main tillage tool, I’ve been toying with trying a Turbo Till from Great Plains Manufacturing for working our residue and manure in. I plant with a no-till planter and will sometimes skip tillage in the spring, but overall weed control seems better with at least once over with a disk.
• While deeper tillage may sometimes seem the way to go and have many champions, overall we may see a slight decrease in yields from no-till for about two years, but have seen increasing yields following the first period. I can’t say whether this is due to improved seed, but we have seen ground respond from fewer trips over it in the no-till method. There is less erosion, better moisture retention, and our no-till gives us a better ability in the spring to get the seed in quicker. Our surface tilth seems to be improving in organic matter and our water-carrying capacity.
• On chemicals, we are increasing acreage in Roundup Ready, but I have found that a spike of 2-4D or Banvel will greatly improve control of Canada thistle and horsenettle. There has also been improved control of marestail, which has seen some resistance to the Roundup.
• While no-till sometimes has detractors, the method does work well if a few simple mindsets are changed. No-till is really just tilling a slit to plant in. Burndown is necessary, whether pre- or post-plant. This is where a disk and a minimum-till tool can save a buck or two. I’ve found that a good dose of Roundup teamed up with Banvel and Bicep late post-plant seems to give us very good weed control all season. The disk has given weeds a knockdown early on, I’ve planted, waited until the corn has emerged and then gone over it with about 2 pints of glyphosate, 2 quarts of Bicep and about 1/2 pint of Banvel. This has given the weeds a chance to emerge where the Roundup can work, gets the Banvel on problem spots and gets the Bicep on for later season control.
• The fall disking in silage ground is not as necessary, but we try to put a cover of rye, barley or wheat on the ground. Because of a shortage of hay this past year, we may try winter grazing on some of our wheat cover, but this remains an option. It seems that a good deep frost has a part in the improvement of the overall tilth of the ground in lower tillage programs. I’m not convinced that putting cows on it can help reduce compaction.
• Talking about compaction, the fewest trips possible over the ground, especially in the winter and when the ground is wet, is a must. While old root structure provides some channel to store water, as it rots it disappears. Running machinery over the ground when it’s still too wet will just close those channels to the subsoil. The moisture in those channels also plays a part in the frost to help open the soil up in following years of reduced tillage. In following years of corn on corn, the numbers of these channels increase, and allow the ground more of these channels for water. This is one of the keys to improving corn on corn yields.
• There are things I want to try, but budgets and fancy new tools don’t always pay off in our sized operation. Our ground is somewhat stony, so chisel-type equipment only finds more. The frost still pushes enough to the surface, and a moldboard only seems to make them come out faster than a disk or coulter. The trash on top and just mixed in has helped to reduce the amount of surface stone as the years have passed or has at least hidden them and seems to help the soil rebuild rather than recede.

But corn on corn can work if these simple common sense ideas are used, and yields don’t suffer. You just have to treat the soil to build it up and keep it fertile. Corn takes a lot out of the ground, and it needs that winter break. Treat it right in the spring, feed it well and it will produce a great crop the following year."