Nutrient level tune-up

On page 8 of this issue, Dr. Weirich discussed the importance and techniques for collecting a proper soil sample. The next step in developing a nutrient management plan for your farm is interpreting the soil test results.
Soil testing and nutrient management is not an exact science. Do not get lost in the numbers on your soil test report. Instead, pay attention to the soil test ratings or levels of each nutrient. If a nutrient level is very low on the soil test report there is a high probability that a positive yield response will occur from applying that nutrient to the planned crop. Likewise if a nutrient rating on the soil test is very high there is a low probability that the planned crop will respond to fertilizer applications of that nutrient. Soil tests are more accurate at determining pH, phosphorus and potassium levels then secondary or micronutrient levels. If a secondary or micronutrient is low on the soil test report consider using a plant tissue test to confirm a deficiency. You may also consider on farm trials by applying the secondary or micronutrient in question to a small area in the field.

Once you have determined which nutrients need to be applied to maximize yields, the next step is to determine an application strategy. Most fertilizer recommendations including MFA’s are based upon a build-plus-maintenance approach. The goal of a build-plus-maintenance strategy is to increase low-testing nutrients to optimal levels. If a nutrient level is below optimal the fertilizer recommendation, we’ll recommend more then is being removed by the crop. The idea is to build the soil test level up by applying more than is removed. Once the soil test is in the optimal range the recommendation will be to only apply maintenance or crop removal rates. This strategy works well on land that is owned or in a long term lease.

Another nutrient application strategy is the sufficiency approach. The goal of the sufficiency approach is to apply enough fertilizer to maximize yields in the year of application. This strategy may be appropriate for short-term lease farms. This approach requires annual applications of fertilizer, especially if soil test levels are below optimal. The lower the soil test level the more fertilizer is going to be needed in order to maximize yields. Some factors that will affect fertilizer rates required for optimal yield will be cropping history, soil type, nutrient placement and timing of application. Consult with your local MFA Agronomist to help fine tune nutrient applications.

With the drought and low yields this past year it is going to be tempting to reduce or eliminate fertilizer applications for the 2013 crop. I strongly recommend utilizing your soil test results to determine your nutrient application rates and not 2012 yields. If soil test levels are low, continue to apply recommended rates, you will be ahead of schedule and reach optimal levels sooner. If a nutrient is in the optimal or higher range then you can probably get by without applying a full rate or no fertilizer containing that nutrient.

Soil testing and interpretation is only a portion of a well developed nutrient management plan. A nutrient management plan should consider the 4R best management practices for each field. The 4R nutrient stewardship concept is to apply the right source of plant nutrients at the right rate, at the right time and in the right place. Visit with an MFA Agronomist to help develop a nutrient management plan that is tailored to your farm.

Steve Cromley is senior staff agronomist for MFA Incorporated. See related story about soil testing.

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Ten scouting tips

Scouting fields for weeds, disease and insects is one of the best investments you can make to maximize profits. We can expect to see more pests in our crops this year. The mild winter gives concern to the increased insect and weed pressure. I hope you consider evaluating every field in May—and I don’t mean the “windshield” scouting. Make sure evaluations are done thoroughly, it is a bottom-line consideration.

1.    Be proactive. A lot of information is available on the Web. It isn’t always the case, but you can often follow in-season situations occurring south of you and know these issues might be heading your way.

2.    Know the weather conditions. Mother nature can influence when weeds emerge, disease is present or insects arrive.

3.    Be thorough. The standard pattern for walking your field is a W. While you won’t walk every acre, this pattern will allow you to get a uniform sample from across your field. Be consistent in sampling methods. I like to see a sample point for every 2 to 4 acres.

4.    Keep good records. These records can help you make a prescription for your field. The notes will also help you make decisions next year. Before evaluating a field, know field history, cropping history, crop rotation, yield potential, pesticide application type, rate and history, variety/hybrid planted, planting date, planting rate, row width, tillage system, tillage timing, seed treatments, weather patterns, fertilizer and lime rates, previous pest problems, and other agronomic factors.

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It’s time to fight resistant pigweed

Residual herbicides should become a part of your weed-control

If you have attended a grower meeting recently, you have probably heard a lot about herbicide resistance—whether you wanted to or not. Herbicide resistance is not going away any time soon. As we move in to the growing season, we should all ask ourselves one question, “Do I want to be proactive or reactive?”

Since the introduction of Roundup-Ready crops in the mid- to late-1990s, glyphosate made weed control too easy. Farmers were able to plant crops, follow with one, or sometimes two, applications of glyphosate, and then they were finished.

In 2005, we started seeing and hearing about reduced control and weed escapes resulting in yield loss and reduced profit. Things got worse. And now, the days of efficient glyphosate-only weed control programs are gone.

If you don’t have glyphosate-resistant weeds yet and continue to use only glyphosate, it is a matter of time before resistance reaches your farm. And when that happens, residual herbicides will become a part of your weed-control program, if they aren’t already. Make sure to choose a residual herbicide that fits your weed spectrum. The MFA agronomy guide provides an excellent breakdown of each herbicide by weeds controlled.

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Late fall tillage could mean big spring weed flush

I know its February and weed control for the upcoming field season is probably the last thing on your mind. It is not uncommon to already have your plant food and seed inputs planned and purchased by now. Even though integrated pest management is reactionary by nature, planned pest management is often a very good idea.

Over the past several years, weed control systems have changed appreciably. Now is the perfect time to address those changes and prepare for the field season. Let’s discuss a few key components of a planned progressive weed control program.
Fall weed-control strategies have increased over the past decade. Many of these programs use residual products designed to keep weed pressure low through spring planting. We noticed a large downturn in fall herbicide use in 2010. The main reason given for less fall herbicide use was that the early harvest combined with dry weather allowed some much needed fall tillage to be done. Environmental conditions in 2008 and 2009 were not conducive to tillage.

As a result, many fields were severely rutted. Additionally, terrace work, grass waterway construction/maintenance, and drainage improvement projects, which were put on hold for several years, were finally initiated. All the ground work kept fall weeds in check. Don’t be lulled into a false sense of weed control security, as we often experience a weed flush following tillage. I expect to see that flush in full force this spring.

Be prepared to use an aggressive burndown program. In many cases, that burndown should include a full-rate residual product. If a residual is not used in the burndown, I recommend a planned residual as a preemerge or early post-emergent application.
Even with a residual herbicide, plan on an additional post application of glyphosate on tolerant crops once the weeds reach a height of 4 to 6 inches. Where resistance is an issue (almost everywhere in Missouri), the glyphosate needs to be applied with an appropriate tank-mix partner.

I am a big supporter of agronomy programs designed to slow weed, insect and disease resistance. I have discussed resistance as the key message in this column many times in my tenure. For obvious reasons, glyphosate resistance has received the most attention. However, as of 2010, the Weed Science Society of America lists 348 herbicide resistant weed biotypes present in over 50 countries. The United States alone accounts for 123 of those biotypes. To fine-tune those numbers, they represent 194 weed species and have been documented in over 400,000 fields.

Weeds developing resistance to glyphosate is part of a long list that includes resistance to seven other herbicide modes of action. In Missouri, 12 weed species have developed resistance to herbicides since 1992. They include common cocklebur, barnyardgrass, common sunflower, horseweed/marestail, common ragweed, Palmer amaranth, giant ragweed, annual bluegrass and most impressively, common waterhemp, which has developed resistance to four different herbicide families.

The society lists the following general principals of weed resistance management as:
•    Apply integrated pest management practices. Use multiple herbicide modes-of-action with overlapping weed spectrums in rotation, sequences or mixtures.
•    Use the full recommended herbicide rate and proper application timing for the hardest to control weed species present in the field.
•    Scout fields after herbicide application to ensure control.
•    Monitor site and clean equipment between sites.
For annual cropping situations they also suggest you consider the following:
•    Start with a clean field and control weeds early using a burndown treatment or tillage in combination with a preemergence residual herbicide as appropriate.
•    Use cultural practices such as cultivation and crop rotation where appropriate.
•    Use agronomic principles that enhance crop competitiveness.
Weed control strategies are constantly evolving. Even when the most aggressive herbicide programs are required, the return on investment is very positive, especially with today’s commodity values. Don’t let the season sneak up on you. Take time during a cold February day to visit with your local MFA Certified Crop Adviser. They can help develop a custom weed control program for each of your fields.
Dr. Paul Tracy is director of agronomy for MFA Incorporated.

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Agronomy 2010

Calendar year 2010 was filled with environmental stresses, new product releases, non-traditional pest invasions—but more importantly—great opportunity for our farming community.
For the third straight year, excessive early season rainfall dominated our spring. Like last year, the wet spring forced delayed planting or caused many fields to be replanted. Unlike last year, our dry September and October created excellent harvest conditions.

The open fall allowed us time to start replenishing the negative nutrient balance that has occurred via a combination of plant food prices, high crop yields and restrictive application weather over the past several years. If you haven’t already addressed this issue, please plan to do so before spring planting.

How did our crops respond to the weather patterns? Generally, corn yields were more adversely affected than soybean yields. Aside from the obvious flooded areas, much of the lost yield this year came in the form of nitrogen deficiency. Preplant nitrogen just couldn’t hold up to the loss pathways associated with the wet weather. Once again, split nitrogen performed much better than applying all nitrogen up front. Slow release or nitrogen stabilization products helped, but for the third straight year, they were inferior to a planned split nitrogen program.

If decades of preaching the benefits of sidedressing nitrogen onto corn, combined with environmental conditions over the past three years doesn’t generate interest in this management operation, then I guess nothing will. I fully understand the equipment, logistics and timeliness issues associated with sidedressing, but still highly recommend considering it as a planned, standard component of your corn production system.

Unlike corn, I was pleasantly surprised with soybean yields this fall. Obviously, nitrogen loss is not critical with beans, but other factors like adequate moisture, improved genetics and better adoption of residual herbicides, foliar fungicides and foliar insecticides played a role.

Soybean fields that received foliar fungicides, insecticides and fertilizers applied between growth stages R1 (flowering) and R3 (pod set) performed very well. A common denominator with yield increases was the positive response to the fungicide. The insecticide and foliar fertilizers increased crop growth and yield in some situations. Late season disease pressure, thick canopies and high humidity conditions stimulated diseases like Septoria brown spot, Frogeye leaf spot and Cercospora blight.

I believe that soybean insect pressure was much higher than normal and response to insecticides was from insect control and not a function of plant health, that is so often claimed as a benefit.

We had high podworm pressure in several areas. One hundred percent yield loss was reported at some western and northern Missouri locations. I have not seen this in 24 years of walking soybean fields in our region.

We had mid-season garden webworm and late season stinkbug problems this year. Both required treatment and the stinkbugs led to “green bean syndrome” and appreciable yield loss.
Soybean aphid pressure was much less than last season. These insects have been known to cycle in large numbers every other year. Therefore, we need to be prepared to address them next season.

Foliar fertilizers have been the rage the past few years. Higher commodity values and increased crop yields have driven these phenomena that cycle through about every 7 to 10 years. What, if anything, is different this time around? First, crop yields are much higher. A shot of needed plant food mid-season may help top-off a good crop. Second, since we are already going across fields with mid-season fungicides and insecticides, a good situation for piggy-backing crop nutrients is already present. Third, is the glyphosate-chelation theory that has generated quite a buzz.

With increased demand, comes misinformation. It also generates a myriad of new products, many of which are unproven. My advice to anyone considering foliar fertilizers is to check out the products thoroughly and buy them from a reputable source.

Forage yield (especially tall fescue) was down this year. With adequate moisture, this should not have happened. I believe in many situations, that years of neglect in plant food applications and weed control strategies were the primary causes. As commodity prices continue to stay high, pressure on forage will continue. Let’s not overlook the management required to reap the most benefit from our forage acres.

The optimist in me predicts a strong agronomic 2011. As we enter the holiday season, remember the important role we play in feeding, clothing, and fueling the world. It is a mission to be proud of.

Paul Tracy is Director of Agronomy for MFA Incorporated.

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