by Elizabeth A. Tomlin
Central New York’s Cornell Cooperative Extension presented their 2018 Corn Day with CNY CCE Field Crop Specialist Kevin Ganoe, and speakers Emeritus Distinguished Professor of Agronomy, Penn State University, Dr. Douglas Beegle; Field Crops Specialist, CCE North Country Regional Ag Team, Mike Hunter, and Dr. Eric Young, Agronomist / Soil Scientist, Miner Institute.
“Corn is a major crop in this area,” stated Ganoe. “We have about 120,000 acres of crops of corn grown in the eight counties that our team serves. It’s our largest annual crop.”
Ganoe reminded attendees of last year’s rainfall that added extra stress to nitrogen supplies.
“Nitrogen behavior is very dynamic,” said Dr. Beegle during his presentation on nitrogen (N) management. “A lot of things happen once you apply your nitrogen, almost all of them are bad. Once you apply it you’re going to start losing it, I don’t care how much you paid for it.”
N surrounds us in the atmosphere, but is not available to crops unless applied during critical periods. Applying it too soon or too late does not benefit the crop and costs you money.
“Timing is critical,” emphasized Beegle.
N is lost quickly when exposed to the air and washed away by rain.
Beegle said problems occur when applying N when temperatures rise above 40 degrees F.
“That’s about when the N cycle ‘wakes up’, we’ve got our highest rainfall of the year, we don’t have any crop growing or very little uptake at that time of year; so there is a huge potential for loss there.”
Apply a small amount at planting, while reserving the rest for application through side-dressing when the crop requires it.
“There’s nothing magic about it; it’s just avoiding potential loss. Don’t have it out there until you have to.”
Urea-containing fertilizers convert to gaseous ammonia and are lost when left exposed. However, if it is incorporated, loss is dramatically reduced as ammonia is then converted to ammonium and able to be absorbed.
“Moist soil promotes more volatilization than dry soil,” Beegle said. “It’s much better to put urea on very dry soil before it rains. The worst thing you can do is put it on moist soil right after it rains.”
Manure should be incorporated immediately.
Aerators and shallow disc incorporation use minimal soil disturbance.
“These are things we have been looking at to reduce nitrogen losses and at the same time conserve the benefits we get out of no-till.”
Spreading manure in colder temperatures provides N retention due to much less volatilization.
“When we chop the silage, plant the cover crops, wait until temperatures are down to the 40-50 degree range and then spread the manure, we see some real benefits from that from two points of view. One, we get less volatilization loss from manure when we do that, and second, we’re getting our cover crops planted a lot earlier, so, we’re getting a better cover crop. That’s helping us in the spring, because now we have a good cover crop there when it warms up and the nitrogen cycle wakes up. We’ve got a nice vigorous cover crop growing and it’s taking that nitrogen up — and we recover nitrogen.”
Soil testing and leaf chlorophyll meter testing for corn are options to help determine requirements.
“Everyone should be making basic adjustments to their N recommendations for manure applications and legumes in the rotation,” said Beegle. “These adjustments can be significantly improved by using in-season tests like the Pre-sidedress Soil Nitrate Test (PSNT), the chlorophyll meter test, or using N/weather models. Tools like the Late Season Corn Stalk Nitrate test can provide invaluable feedback on N management.”
Although these tests may not be 100 percent accurate, they greatly improve decisions in whether or not to make applications.
“The key word is ‘improve’,” said Beegle. “Using tests about doubles the accuracy of our nitrogen recommendations, and if I can double the accuracy, to me that’s great.”
Dr. Young updated attendees on measuring impacts of feeding hybrids to dairy herds and correlating milk production rates.
Corn silage components and quality were discussed.
“To talk about corn silage quality, we have to talk about fiber quality,” explained Young. “Two of the most important forage quality measures for milk production potential are, starch content and fiber digestibility. Two important fiber quality measures are NDF digestibility (i.e., NDFD) and undigested NDF (i.e., uNDF).”
Studies show in greater than 40 percent corn silage rationed, for each 1 percent increase in NDFD number, one-third lb./milk/D/ per cow was increased. “That is not insignificant,” Young said.
Young pointed out that responses to forage quality in corn silage depends on what the cow is already producing.
“Higher producing cows respond to a greater degree to those increases in corn silage digestibility.”
Studies of cell wall components’ impact on forage digestibility and rumen function were investigated.
Results show that BMR corn hybrids contain less lignin and have a higher rate of fiber digestibility than non-BMR corn, with BM3 corn at 34 percent less lignin.
“Lower lignin means greater digestibility,” said Young.
Cows processing corn silage faster eat more, producing an increase in milk.
“When selecting corn hybrids for dairy cows, make sure to evaluate both yield and forage quality,” said Young. “Ideally, a farmer would combine yield measures with forage quality measures to obtain inventory estimates based on quality — what’s actually in their bunker/silo to feed out.”
Seed cost should be evaluated in relation to corn silage quality and cow performance.
In addition to correct hybrid selection for specific growing regions, harvesting management is a priority in achieving high nutrients in corn silage.
Mike Hunter reported on important changes in restrictions on dicamba that can result in large fines if not followed.
“Seed companies are selling dicamba-resistant soybeans — or Xtend soybeans — for growers to plant in New York State,” said Hunter. “If you are a soybean grower, you may have planted dicamba-resistant soybean varieties in 2017, or may be considering planting some in 2018. In either case, there are new revisions to the herbicide labels that are important for growers to review. It is also important that you understand where this technology best fits, as well as, the stewardship guidelines associated with these new crops.”
A “major driver” for dicamba-resistant soybeans is an increasing spread of glyphosate (Roundup) resistant weeds.
“Dicamba tolerant soybeans can offer growers another technology to aid with the post-emergent control of many herbicide resistant weeds such as marestail (horseweed), tall waterhemp and Palmer amaranth. Glyphosate resistant marestail and tall waterhemp are now found in areas of New York.”
Hunter reported that the Weed Science Society of America (WSSA) ranks Palmer amaranth as the most difficult weed to control in the U.S., causing a devastating impact on crop yields. It is extremely prolific — a single Palmer amaranth plant may produce a million seeds per season — and has stems tough enough to damage farm equipment. Not documented in New York State at this time, Hunter advises, “Be on the lookout.”
Dicamba-resistant technology can improve control of these weeds. However, drift from the herbicide has caused severe crop damage and yield loss.
“Switching to dicamba-resistant soybeans is unlikely a long term solution, as selection for resistant weeds will begin with the increased use of these new herbicides.”
Preserve this technology for future use by providing good stewardship. Obtain updated label restrictions at http://bit.ly/2fEk1sh.
Hunter also advised on non-glyphosate herbicide programs for conventional corn.
“Regardless of a growers’ reason to plant conventional corn, preemergence weed control programs are almost a necessity for a conventional weed control program.”
Total reliance on post-emergence conventional weed control programs is inadvisable.
“There is a high risk of yield loss if the post-emergence application is delayed.”
Select a solid, one-pass pre-emergence corn herbicide program.
“It is especially important to use a very good soil residual grass herbicide because it is difficult —and costly — to control certain emerged annual grasses with conventional post-emergence herbicides. In conventional corn, a post-emergence annual grass rescue treatment will cost around $24 per acre.” Hunter said many pre-emergence herbicide programs contain acetamide (s-metolachlor, metolachlor, acetochlor, dimethenamid-P) products, or premixes containing one of these active ingredients.
CNY CCE 2018 Corn Day
by Elizabeth A. Tomlin