2007 Cornstalk Nitrate Test Results Available

ISA On-Farm Network is providing county-by-county nitrogen stalk test results online for farmers this fall.

What can you do to cut your costs of production for corn and soybeans and yet keep your yields rising? Tracy Blackmer, director of research for the Iowa Soybean Association, has some suggestions. One of them is to look at nitrogen management. Are you applying too much N, too little or just the right amount for your corn? Another suggestion is to run some strip trials in your fields to find if you can get a yield increase by using foliar fungicide on soybeans?

The 2007 yield results of on-farm research trials conducted by Blackmer and his colleagues in the fields of farmers participating in ISA's On-Farm Network, are starting to come in this fall. Here's a look at what they are showing.

Cornstalk nitrate testing program

"We collect stalk samples in the fall on farms of cooperators in our nitrogen trials around the state and we test these samples for nitrate content," explains Blackmer. "That gives us an idea of how much nitrogen was available to the crop this year. We find out whether the corn had an adequate amount of N available or whether it had too much or too little nitrogen."

Farmers want to know if their corn ran short of nitrogen, or if they had more nitrogen available than was needed. This fall stalk test is a good way to find out, says Blackmer. "Our On-Farm Network has research being done on 1,000 fields all over Iowa this year."

More samples marginal-to-low this year

What are the results showing this year? Where there were heavy rains, did the nitrogen leach away? Did the corn run short of N? "We are seeing some differences in nitrogen availability within the state this year," says Blackmer. "Overall, we have more samples in Iowa this fall that are testing in the marginal- to-low category than we have in the optimal and excess category. That's true for the state in general this year."

Are these results due to good planning of nitrogen application rates this year on the part of farmers? Or did they simply not put enough N on and with all the rain did their corn crop eventually run out of N? "It depends somewhat on each situation as to how much N the farmer applied per acre," he says. "We had a wet year in Iowa, so people lost more N than they usually do. But what we are seeing in a lot of the fields is there are ways these farmers have reduced their risk of loss. The amount of N loss depends on how you manage your nitrogen."

Expensive N is an incentive to sidedress

With 50 cents per pound as cost for N fertilizer in the spring and consequences of having your corn run short of N, you certainly want to target your nitrogen application rate and do what is right. "We've been able to identify some practices that have done very well. We see that with many of the anhydrous ammonia applications don't necessarily lose as much N, especially if the applications are made in spring or if they are applied later on as side-dress applications."

Liquid N applied as a sidedress worked pretty well in 2007. The preplant liquid N, however, did leach away in some cases in Iowa where there was a wet spring.

With the On-Farm Network results coming in this fall, "We have data from farmers in every county in Iowa," says Blackmer. "We look at management practices - the difference between amount of N applied by no-tillers vs. farmers who do tillage. Also, there's a difference in how much N is applied to first-year corn and second year or to continuous corn. Some of these fields in our statewide testing are in their fourth or fifth year of continuous corn."

Cover crop trials worked well in 2007

"The cover crop trials this year have shown that when we plant a cover crop in the fall ahead of planting beans in the spring, it does a really good job in the spring of tying up nitrogen that was available in the soil," says Blackmer. "We killed the cover crop with a herbicide spray about the time of planting the beans in the spring. The cover crop took up all the N that was available in the soil. Thus, there was very little N left in the soil for a loss."

Blackmer adds, "We pulled nitrates out of the soil with the biomass. We pulled up about 30 to 40 pounds of nitrogen per acre. It doesn't look like we had a real impact on corn or bean yields by planting the cover crop. We'll need to finish up those numbers this week. So it looks like planting cover crops in the fall on bean stubble ground are a good thing for farmers to be doing to help save soil over winter and to soak up some of the nitrogen and keep it from being lost.

Foliar fungicides look good in bean trials

"We've seen yield results all over the board this year from our foliar fungicide trials," he says. "We had some bean fields that responded quite well with yield increases and we had some with no response to the spraying of foliar fungicide."

Sometimes farmers call him and they're excited after seeing a big yield number on a yield monitor or they hear a report from another farmer who tried a foliar fungicide on soybeans and had success. "But when they compile the final yield report after harvesting the entire plot it is often different," adds Blackmer.

"However, we clearly have some fields and test sites within fields this year where we've seen positive yield increases where we applied a foliar fungicide to soybeans," he points out. "One key consideration for farmers is that it doesn't take much of a yield increase to pay for the fungicide and application when you have a $9- to $10-per-bushel market price for soybeans, like we have today."

For more information about this year's nitrogen rate, fungicide use and other On-Farm Network trials - go to www.isafarmnet.com. The Web page will pop up on your computer screen and you can click on your county and see the results.

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