Managing Nitrogen as a System in Corn

By Dale Cowan

Crop planning by customer by farm by field by crop by product continues on with even more urgency as spring like weather in late February and early March lingers. One of the input areas of interest with challenging crop prices is Nitrogen on corn. Determination of the “right” rate of nitrogen continues to be somewhat elusive as many factors compound the choosing of the right rate. Is the right rate something that is realistic? At some point we need a “number” to set up an applicator to apply the targeted rate of nitrogen. The reality is most decisions we make in farming are from a systematic process of trade offs with consideration given for risks associated with each decision step. Add in field variability the complexity increases.

One of the tools we can use to understand the complexity of making a nitrogen recommendation is the Ontario Nitrogen Calculator (ONC)( found on our website)

The calculator ask for input on soil texture, soil organic matter, yield goal, price of corn, price of nitrogen, any other nitrogen sources and previous crop. It is an interactive spread sheet so you can enter different scenarios to see how that impacts on the nitrogen rate. 

It allows for a pre-sidedress nitrate soil test to be used prior to side-dressing UAN as final check in adjusting N rates which overrides the preplant and side-dress application rates calculated previously. In this example a PSNT test of 11 ppm taken in early June adjusts the N recommendation to 180 lbs. of N. The spread sheet also provides for an interpretation of an ear leaf tissue sample.

Once you have the spread sheet filled in it is easy to change the price of corn and see how that changes the nitrogen recommendation. Under this scenario dropping the price of corn from $5.75 to $4.75 only drops the nitrogen rate by 12 Lbs. of actual N per acre. Changing soil texture from loamy sand to heavy clay increases N recommendation to 214 lbs. of actual N. Changing soil organic matter from 3% to 5% decreases N recommendation by 24 lbs. of N. Changing the previous crop from corn to red clover ploughed down decreases the N recommendation by 73 lbs. to 126 lbs. of actual N.

What’s the right rate of nitrogen?

It is situationally specific.

Download the spread sheet and contact your AGRIS Crop Specialists to learn more on managing nitrogen application risk. Including the use of nitrogen stabilizers to further protect the nitrogen investment and reduce any environmental risk of N loss.

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Assessing Winter Wheat Stands This Spring

By Jordan Sisson

Evaluating winter wheat stand in the spring is crucial for assessing the crop's health and to ensure there is a viable crop. As soon as winter breaks and the snow melts we should be out in our fields doing those assessments to make informed management decisions. Although some could have been fooled that spring had already arrived with the recent warm temps we’ve experienced. Safe to say this hasn’t been a typical winter, with minimal snow fall or any snow to see at all currently in southern Ontario. All the more reason to get out and do these assessments when the time comes.

Walking your field(s) in the spring here are some things you should be looking at:

• Plant population -Use a square-foot or row-foot method to count the number of plants in several locations and compare that to your target planting rate
• Winter survival – how has the wheat held up through the winter? Are there dead or damaged plants? Winter injury or kill can be cause by environmental factors such as iced over fields or lack of snow cover, which we haven’t had much of the latter this year.
• Uniformity – are there gaps or uneven stands? This could be cause by issues with equipment at planting, soil variability or uneven emergence.
• Plant vigor/root health – If you are unsure if the plant is still alive dig up a few plants to examine the root system. If you’re worried C&M seeds says to place them inside your home in a pail of dirt. In 3 days you should see new white roots starting to form indicating that your wheat is alive.
• Tillering – be able to identify number of tillers, adequate number of tillers is essential for maximizing yield potential. this will also help when using the tool listed at the bottom of the article.
• Early weed pressure – identifying any weed pressure early can help in deciding how timely your herbicide application needs to be.

Thankfully aside from a visual inspection C&M seeds also has a tool to take the math out of it for you and help us make decisions with their STAND ASSESSMENT CALCULATOR that can be done on the web or saved to your cellphones home screen (https://redwheat.com/stand-assessment-calculator/) scroll down and click on the “check out our stand assessment calculator” link.

All the info you will need is the number of plants per ft of row, stems/plant and seeder row width. It is recommended to make multiple assessments in different areas of the field to get a good average for these values. Once filled in you should get prompts based on your results.

If you are unsure reach out to your local AGRIS Crop Sales Specialist who have the right tools and knowledge to help assist with the stand assessments in field with you.

SCN management in Soybeans

By Mike Veenema

One of the biggest yield robbing pests, could be one that we don’t see. Soybean cyst nematode (SCN) can reduce yield up to 30%, and starts to infect roots long before you see visual symptoms, by then it’s too late. Above ground symptoms aren’t always obvious, but yellow, stunted plants, often in headlands, and patches scattered throughout the field are an indicator. If high populations and susceptible varieties coexist in the same field, the entire field may look stunted and yellow. These aboveground symptoms often don’t appear until mid to late season, at which point all you can really do is consider future management. Mild pressure may go undetected and could still be causing yield loss that isn’t realized.

Below ground symptoms of SCN infected roots are discoloration and stunting. The most obvious sign of a SCN problem is on the roots and can be seen within 2 months after planting, before above ground symptoms are present. Above ground symptoms are similar to other diseases and so digging is the best way to confirm. Other diseases, like sudden death syndrome and brown stem rot, will have much worse effects on plants that are suffering from SCN pressure as well.

Dug plants with intact roots will allow female cysts to be seen. They would be small, white, lemon shaped objects on the roots. As they mature, they will change from white, to yellow, to brown, as they form a protective layer (cyst) to protect their hundreds of eggs. Those eggs can be viable in the soil for years, and each one can contain a new juvenile SCN.

Unfortunately, optimum conditions for SCN development are also favorable conditions for growth. Sandy drought prone areas or those with pH issues accelerate SCN damage as well as reproduction. A long-term management strategy is the best approach to reduce this pest;

• Soil test for test every five years. A soil sample sent to the lab for egg counts to identify the level of SCN pressure in each field. This will give a starting point to determine where increased management is necessary.
• Genetic Resistance, the most common is PI 88788, followed by Peking. Most soybean cultivars grown are resistant to SCN, but not all of them. When growing soybeans more often or year after year, gene selection should be considered, in an effort to switch it up to prevent resistance. Know what type of resistance is present in the beans you are growing, and when possible, a different source should be used than the previous soybean crop.
• Crop rotation is absolutely critical, as there are few host crops for soybean cyst nematode. Egg counts can be reduced by 50% by rotating to a different crop. Corn soy rotations will have more pressure than corn soybeans wheat, and adding additional crops to the rotation to will further reduce populations. When crops are grown that do not host SCN, eggs will hatch but the juveniles that emerge will starve.
• Weed management. Some weed species, such as henbit, field pennycress, and purple deadnettle can host SCN populations, so avoiding infestations of these annual weeds, particularly early in the spring, will eliminate potential favorable conditions in which this pest can thrive.
• Nematicides. Seed treatments can help with early season protection from pests, and may add to yields, but are not a silver bullet to dealing with SCN.

In conclusion, yield matters, and to capture the most potential from every seed we sow, we have to pay attention to the small details that can make a big difference. The details may be as simple as field history and genetic selection. SCN management is similar to weed and fertility management, a multi-year strategy is required. Contact your AGRIS Crop Sales Specialist to assess your fields for SCN and discuss management strategies to maximize your soybean yields.

Ref. A Farmers Guide to Soybean diseases; Mueller, Wise, Sisson, Smith, Sikora, Bradley, & Robertson

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