Cover crops and the scrutiny on crop nutrients

Written by Adam Noellsch on .

Far from old-fashioned, cover crops are one tool to keep nutrients in the field.

Focus on crop nutrient use efficiency by the government and the agricultural industry is on the rise. In fact, nutrient use efficiency has earned its own acronym—NUE. With a new focus on NUE from the feds, it is important for producers to understand how to make sure applied nutrients end up where they’re supposed to—in the plant, not lost to watersheds. Nutrient programs like the 4 Rs (right rate, right timing, right source and right place) are backed by The Fertilizer Institute, The International Plant Nutrition Institute, The International Fertilizer Industry Association and the Canadian Fertilizer Institute. The focus on efficiency is here to stay.

Cover crops are an old method for increasing crop NUE, and they have been a hot topic for the past few years. USDA-NRCS and local conservation departments are encouraging cover crops. Cover crop meetings across the country feature farmer cover-crop success stories. Typically, the benefits of using cover crops are described in terms of soil health and quality. Improving soil health and soil quality should lead to a better overall crop-growth environment that increases efficient use of applied and available plant nutrients. These are good talking points, but understanding how cover crop systems can be used in a crop rotation to get these soil-improving benefits can be a challenge.

The first thing to do when planning a cover crop system is to set goals. Is reducing soil erosion your main goal? Or is weed control or nitrogen fixation by legumes? What about reducing compaction? A couple of years ago, the Conservation Technology Information Center surveyed 700 growers to see what goals farmers assigned to their cover crops. Farmers where also asked about the benefits they had experienced from cover crops as well as their biggest cover crop challenges.

Most respondents wanted to reduce soil compaction and erosion. Following that, in order, goals were: nitrogen scavenging, weed control, yield increases and nitrogen fixation.
According to farmers who answered the survey, the biggest challenges to using cover crops were establishment, time, species selection and seed costs. These surveys help whittle down what most people desire from using cover crops and the perceived challenges involved. Visit for more information on this survey and a full analysis.
It is important to use local extension and agronomists to help you implement a cover crop system. Also, talking to other producers with experience in cover crops can be beneficial. Attending cover crop conferences and trainings will help, but may also be an overwhelming informational experience. Be sure to focus on what your personal goals are. Talk to as many experts as you can.

Cover crop considerations:
1. Do not plant corn after a cereal rye cover crop. This is an issue that has been debated. Some growers have attested to growing corn after cereal rye. They say that as long as the cereal rye is killed at least two weeks prior to corn planting, they have seen no reduction in yield. However, others have had experience with cereal rye causing an allelopathic effect on corn that caused yield reduction.

My recommendation is to avoid cereal rye before corn. Use a different cover crop to avoid the risk of a yield hit. Additionally, if cereal rye is used before going into a non-corn crop, make sure the cereal rye is killed off at least two weeks prior to planting the crop.

2. Do not use annual ryegrass/marshall ryegrass/Italian ryegrass as a cover crop in a cropping system. Annual ryegrass is very good at reducing soil compaction and erosion; however, it is becoming resistant to glyphosate and can be tough to kill. While this may be an excellent choice for use in pastures, it is one to avoid in corn/soybean systems.

3. Inoculate legumes with the correct inoculum. Various legumes can be used as cover crops (crimson clover, berseem clover, alsike clover, red clover, hairy vetch, sunn hemp, etc.). Each legume needs a specific strain of rhizobia bacteria. Make sure to inoculate with the correct strain for the legume being used.

4. Make sure your soil test NPK levels are adequate to support growth of the cover crop and your regular crop. If soil test levels are not where they should be, the cover crop will not grow nor do the job you want it to. In turn, you may reduce nutrient availability for your cash crop by allowing the cover crop to take up nutrients that would have otherwise been used by your regular crop. In some cases, nutrient scavenging may be the goal, but you should still make sure you know your soil fertility to pick the best cover crop. 

5. In general, you will need 40 to 60 days of growth before a killing frost to maximize cover crop biomass production. Planting a cover crop too late may result in a poor or non established cover crop. Planting too early in some years may result in too much growth and nutrient/water uptake. Know proper planting timing for your cover crop mix and realize that not every year is going to be the same. A safe bet with cover crops is to plant species that will winterkill. If the winterkill mix is well-established and good growth is achieved for a couple of months, you will most likely add organic matter to the soil and provide cover to help reduce erosion. Additionally, you may see benefits from weed suppression and possibly improved soil health in general.

The last thing to think about when implementing cover crops is to remember that it is probably not going to be a one-year fix. Increasing soil organic matter and improving soil structure take many years. Some benefits like fixing nitrogen and scavenging nutrients may be achieved in the short term, but for overall soil health and quality improvement, long-term strategies for using cover crops and cash crop rotation will be required. The best thing to do is keep learning and keep experimenting with different mixes to see what works best on your farm.

Keep nitrogen where you put it

Written by Dr. Jason Weirich on .

Nitrogen inhibitors have a financial and environmental benefit. 

By now I am sure you have heard that MFA will no longer handle ammonium nitrate. In light of that news, let’s talk about nitrogen management. 

Nitrogen can be lost from the crop system through volatilization, leaching and denitrification. To increase nitrogen use efficiency, you can employ enhanced fertilizer products to delay or stop these losses. Here is how it works.

Urea-based fertilizer products are subject to volatilization losses if surface-applied and not incorporated by rainfall or mechanically. The risk of volatilization loss increases with high residue, warm weather and high soil pH levels. Sources subject to volatilization losses include dry urea and UAN solution. 

Urease inhibitors can be used to temporarily block the urease enzyme from converting urea to ammonia (NH3). The only proven urease inhibitor on the market today is NBPT, which is marketed as Agrotain. 

Leaching and Denitrification 
Ammonium (NH4+) sources in the soil go through a process called nitrification. Ammonium is converted to nitrite (NO2-) by nitrosomonas bacteria, and nitrite is further oxidized to nitrate (NO3-) by nitrobacter bacteria. A majority of the nitrogen taken up by the plant is in the nitrate form, however most plants can also take up ammonium (NH4+). Once in the nitrate form, the nitrogen is subject to leaching and denitrification losses. Nitrate moves freely throughout the soil profile with moisture. In coarse textured, well-drained soils, nitrate can leach below the root zone and become unavailable to the crop. Nitrate is also subject to denitrification losses. Denitrification occurs in soils that become waterlogged. It’s a biological process that converts nitrate to gaseous forms of nitrogen that are lost to the atmosphere. 

Nitrification inhibitors reduce the rate at which ammonium is converted to nitrate by killing the nitrosomonas bacteria in the soil. Nitrification inhibitors are designed to keep the nitrogen in the ammonium form longer so plants have the opportunity to take up the nitrogen before excessive moisture occurs and nitrogen is lost from the system.

Currently there are two proven nitrification inhibitors on the market. Nitapyrin has been used since the 1960s. Nitrapyrin is marketed as N-Serve and most recently as Instinct, an encapsulated product for dry and liquid fertilizers. Instinct can also be used in liquid manure. 

The other proven nitrification inhibitor on the market is dicyandiamide (DCD). DCD is the nitrification inhibitor in Agrotain Plus and Super U. Research has shown that DCD activity is shorter than nitrapyrin (Bronson et al., 1989). Proven products that contain both a nitrification and urease inhibitor include Super U and Agrotain Plus.

From a cost perspective and environmental perspective, you need to protect all sources of nitrogen from loss. In next month’s crop section we’ll cover the importance of N-Serve use in fall and spring applications of anhydrous ammonia. If you have any questions please contact your local MFA location.

Put back what you take

Written by Dr. Jason Weirich on .

Removal rates aren’t the same across your field

As we wrap up another cropping season, I hope that your year has been a success. As I write this in late August, for publication in October, I am hopeful for a record corn and soybean harvest. With record yield potential comes some management decisions you need to make prior to planting next year’s crop. Management decisions regarding soil fertility are critical to give your crop the potential for great yields again next year. In that sense, I believe MFA’s Nutri-Track program has a fit on all acres across our trade territory.

Nutri-Track is is designed to manage, maintain and track fertility levels across operations by combining GPS-based soil testing and yield monitoring. Whether you raise corn, soybean, wheat or forage, your soil’s nutrient levels are a critical factor in maximizing production. Nutri-Track has three unique stages that will fit any operations.

Stage 1: Intensive soil sampling
Nutri-Track’s 2.5-acre grid-sampling program will provide a baseline for your field’s nutrient levels and soil properties. This is essential to correct any underlying problems so that you can maximize yield. We also use this program for range and pasture ground to maximize forage production and grazing capacity.

Stage 2: Intensive soil sampling with yield monitor crop removal
MFA Nutri-Track techs combine the information they receive from the 2.5-acre grid samples with yield data to give you a tailored recommendation for your nutrient removal and build program. By using yield monitor data, you will no longer have to use a flat yield removal rate. Thus, in the future, you can apply the right amount of fertilizer to the right areas of your fields. You won’t be over-applying in low-producing areas of the field. You will boost production in areas that can support additional yield goal.

Stage 3: Yield monitor crop removal
This is perfect for fields that already have optimum fertility. You maintain those levels by replacing exactly what you have removed. This program is also a good fit for rented ground.

The question that I most often get is, “Why should I enroll in this program?”
We all know that each field has areas that out-yield the rest of the field. By employing the data analysis along with precision application, you can apply fertilizer with true variable-rate technology. You will get your nutrients to right spots in the field. The practice has proven itself.

The next question that I get is, “Through this program I will spend less money on nutrients, correct?”

That is not always the case. When I look at composite data from our precision techs, I see that growers are under fertilizing areas of the field and sometimes over fertilizing other areas. Cost might be a wash, but putting the nutrients where they are most efficiently used has the potential to boost yield.

This year looks to be one of the best we have seen in several years across our trade territory as a whole. I understand that there are parts of our trade territory that won’t see record yields. This program is still a fit for those acres. At MFA we support the 4 R’s: The Right fertilizer source,

Right rate, Right time, and Right place. As an industry, this is an important concept. Regulators and environmentalists scrutinize agriculture more each year. We need to manage our inputs and be good stewards.

MFA can help you develop a plan for all of your acres and make sure we are using your nutrients to the best of their ability for maximized profit.
Contact your local MFA location to make a nutrient management plan. It’s a good practice.

Learning in the East

Written by Dr. Jason Weirich on .

ALOT Class XV is back from China

In July, I traveled to China with Agricultural Leadership of Tomorrow. ALOT is a two-year program that teaches its members leadership along with a deep exploration of Missouri agriculture and how it fits into the larger world. Members travel extensively in the state as well to Washington D.C. to visit with friends and foes of agriculture. The international trip is a capstone of sorts. ALOT is a great program, and I encourage anyone willing to commit the time to apply.

China wasn’t my first choice of countries to visit, but after our trip, I am glad that I did. I can’t believe some of the things I saw, heard and smelled on the trip.

We visited several production agriculture farms. Particularly interesting was a rice farm. It was a demonstration farm for rice production with fish and crab intercropping. The farm had a polywire fence around the field to keep the crabs in. Labor for a 2,000-acre rice farm had numbered about 1,200 workers, but with the new practices on demonstration there, managers have reduced the number of employees to 300. It may be a harbinger of things to come in rural China.

The most shocking thing I saw at this location was duck production. An elevated duck pen was situated above a water canal. Waste from the ducks dropped into the canal, which drained directly into the Yellow River. I don’t think this practice would survive long in the United States.

Our group visited a government-built community designed to house farmers. As a way to accommodate rural-to-urban migration, the government builds these communities along with schools and hospitals for the residents. As residents move into the community, they are given a small parcel of land to farm and one dairy cow. These farmers are also asked to work in a local factory or plant to provide additional income for their family.

We visited a prairie restoration site. Here, the Chinese government restored an over-grazed and wrecked prairie to its native vegetation. It was amazing to see the restoration job with the prairie back to green vegetation, but now there is no grazing on any of the land because officials do not want to destroy plants that have been re-established. Thus, animals are kept confined in this region. I would compare the area to southeast Colorado, a dry, short grass prairie.

One thing that I will remember from the trip was an explanation about chicken cage sizes. We were on an egg-layer farm. Because of the recent regulation changes in California for chicken cages, the plant manager for the facility reminded us that the number one goal of production agriculture in China is to feed the people. He said that obviously China has a lot of people to feed, so the regulations cannot be like those of California. Another interesting fact about this plant is that they use the waste to produce natural gas.

The Chinese are hard workers. On a number of occasions, our group saw workers sweeping interstates and roads with hand-made switch brooms. However, “The Company,” the Chinese government, is in control of everything. Citizens there would actually reference “The Company,” but we knew what they meant. At times we couldn’t help but wonder if it was all a planned and rehearsed tour. Either way, it was an eye-opening experience.

Overall, it was an educational trip for my ALOT class. I hope we can leverage it and our entire ALOT experience into a positive influence for agriculture in Missouri and the United States.

There’s more that I would like to tell you about ALOT and China than space allows here. If you see an ALOT class member, be sure to ask them about their experience. We all have important information to share. Applications for Class XVI of ALOT are due Sept. 15.

To keep the benefits, manage resistance

Written by Dr. Jason Weirich on .

Weed resistance isn’t the only threat; let’s take care of fungicides

Fungicides grow more popular. Over the winter you probably had the opportunity to attend producer meetings in your area. And, you probably heard a company representative or an agronomist talk about the use of fungicides to increase yield. Most of the presentations promoted “plant health” or stress reduction as a way that fungicides help increase yield on your farm.

Interest in the use of foliar fungicides has increased since the highly publicized arrival of rust a few years ago. Until recently, use of fungicides had been limited to fields where diseases were known to be present as well as soybean and cornfields used for seed production.

The market introduction of strobilurins, a broad-spectrum fungicide registered for control of a number of foliar diseases across a number of crops, increased the adoption of fungicide use in our trade territory. However, the current trend in our trade territory and through the Midwest is toward an increased use of fungicides for “plant health.” That general description covers improved stress tolerance and growth efficiency to increase yields instead of simply disease management.

From my perspective, it might be useful to discuss what university research tells us about fungicide use on corn and soybeans and what strategies the row-crop industry is adopting.

Disease management
The highest probability of seeing an economic response from an application of a fungicide is in the presence of disease or when conditions are favorable for disease. Fungicide use in this scenario increases yield by eliminating or controlling yield-limiting diseases in your field when conditions are favorable for disease development.

Some of the factors that are favorable for diseases in corn include: susceptible hybrid, continuous corn, no-till, late planting, high plant population, high-yield scenarios, irrigation, disease activity at tasseling, disease favorable weather conditions, or a history of disease in the field.
Some of the factors that are favorable for diseases in soybean include: susceptible variety, early planting, historical disease presence, dense crop canopy, favorable weather conditions, irrigation or a continuous no-till soybean field.

With the factors listed above, you will see there is some overlap between the two systems, but there are also several differences listed for corn and soybean production. While decisions for fungicide use based off the two cropping systems cannot provide 100 percent accuracy, they will provide a baseline justification for use of fungicides.

Just as I have recommended in the past, you must be able to see if it works on your farm. When you are applying fungicides to a field with low risk it is always a good idea to leave a portion of the field untreated as a comparison to evaluate the use of fungicides on your farm.

“Plant health”
We have all heard the discussions about the use of fungicides for plant health. We have seen applications of fungicides on corn or soybeans stay greener longer. Does that always result in higher yield? I don’t believe it does 100 percent of the time. I have seen significant yield increases from applications of fungicides, but on the flip side, I have seen cases where there was no yield responses.

Some of the potential plant health attributes include, but are not limited to, greening effect, corn stalk strength and drought/stress recovery.
Most claims about the greening effect suggest if it is greener longer, its healthier. Yet, this effect can have a negative impact as well. It can slow or even delay harvest, and it may require grain drying after harvest.

Stalk quality appears to improve with the use of strobilurin fungicides. Some university research shows improved stalk strength after strobilurin use, even where disease pressure was low. More research is being conducted to validate industry claims.

Fungicide resistance
I wouldn’t be doing my job if I didn’t talk about fungicide resistance. The use of any fungicide increases the risk for resistance. Anytime a fungus is exposed to a fungicide, even when fungal activity is low, the selection pressure on the fungus is increased toward resistance.
While there is no way to prevent every case of resistance to strobilurins and DMIs, we can hope to delay the development of resistance by minimizing the use of at-risk fungicides.

Factors that increase potential for fungicide resistance might include: repeated/overuse of fungicides of the same mode of action; applying half-rates of fungicides and applying fungicides when disease pressure is already high.

Most of the products on the market include two modes of action. Also, when you read the label of most fungicides, you will see it covers resistance management and the importance of utilizing resistance management strategies. Always read and follow the label.

I believe proper use fungicides are going to help us reach the full potential of our crops. If you have other yield-limiting factors eliminated on your farm and are looking for ways to potentially increase production, fungicides might be an option for you.

Scouting can be another way to avoid loss from diseases in your field. Again, leave a check strip on your farm so you can see the result in your fields. If you are looking for a proper fungicide program or a field scouting program, contact your local MFA retail location.

Dr. Jason Weirich is the MFA's director of agronomy. READ MORE by Dr. Weirich HERE.



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