Developing a fertility program for your forage crops may not be as simple as determining nutrient needs for row crops. In row crop production you apply nutrients with the simple goal of maximizing yield. While you would like to grow as much forage as possible, your real goal should be maximizing the utilization of the forage grown. Before developing a fertility program for your cool season grass pasture and hay fields, it is a good idea to evaluate your current forage species and stand health. Evaluating your current forage inventory will help determine seasonal production and times of excess or shortages in forage production. The goal should be to increase forage production or availability when forage is typically short and to increase utilization of forages when excess growth occurs.
You can use fertilizer, specifically nitrogen, to promote growth to meet seasonal needs. Grasses respond well to nitrogen fertilizer. Each ton of fescue produced requires 40 pounds of nitrogen. The soil will supply some nitrogen to the plant. The goal becomes to provide additional nitrogen to promote growth when needed. You can use nitrogen to promote growth of fescue in the spring and late summer. Determining when and how much nitrogen to apply will depend on your specific goals and should be evaluated on a field-by-field basis.
In order to get maximum benefit from nitrogen applications, soil-test levels for pH, phosphorus and potassium should be within recommended ranges. Apply lime, phosphorus and potassium according to soil test results.
Stockpiling tall fescue for fall and winter grazing Stockpiling is the practice of accumulating growth in the late summer and fall with the purpose of grazing the forage produced through the winter months. Nitrogen applications in early to mid-August will promote growth of tall fescue and increase total forage production. Target thick and healthy stands for nitrogen applications. It is best to graze or mow summer growth down to three inches before fertilizer applications.
Response to nitrogen fertilizer will depend on available moisture. Apply 40 to 60 pounds of nitrogen in early to mid-August for fall growth. Apply higher rates when excess forage is needed if moisture is adequate and yield potential is high. In order to maximize forage utilization and return on fertilizer investment for stockpiled forage, cattle should be managed with controlled grazing. Strip grazing will reduce waste and maximize forage intake. Research conducted at the University of Missouri has demonstrated that stockpiled tall fescue maintains quality throughout the winter months.
Spring applications of nitrogen to promote growth of tall fescue Spring nitrogen applications should be made to promote growth at the time of greatest forage need. If managing for hay or maximum tonnage, the nitrogen should be applied before grass greens up in early spring. Figure about 40 pounds of nitrogen per ton of growth desired.
If you have adequate forage early in the spring or can’t keep up with the early flush of growth, you can apply nitrogen after the first grazing cycle. Applying later in the spring will reduce overall tonnage but should extend the grazing season longer into the summer months.
Using fertilizer to promote forage growth to meet production goals and seasonal needs reduces waste and maximizes forage utilization. Steve Cromley is senior staff agronomist for MFA Incorporated.
Getting legumes into grass pasture is a time-honored way to make better grazing and hay. If you plan to interseed new legumes into an existing grass stand, consider following ideas to improve the success rate of your seeding.
Grass stands are commonly lower in nutrients than what will be needed by the legume. Soil fertility should be brought up to a level adequate for the interseeded legume. Phosphorus is commonly low in grass pastures unless animal manure has been applied regularly. Phosphorus encourages root growth and development as well as nodule production.
Soil pH generally needs to be higher for legumes than grasses. Apply lime several months prior to seeding the legume to adjust for proper soil acidity levels at the time of seeding.
Well-established grasses may make it difficult to get a legume going. There are several methods that can be used to weaken the existing sod, allowing the legume to become established. Grazing, mowing, light tillage, burning, chemical control, frost seeding and no-till drilling are all potential ways to aid in legume establishment in a heavily sod-dominated pasture. The thickness of the grass canopy and roots both need to be considered. If the existing sod has a thick vigorous root system, then a management practice such as light tillage will help weaken the stand to allow for legume establishment. A no-till drill used in combination with a sod-suppression management practice will help ensure good seed to soil contact and even emergence.
It is important to inoculate legume seed before planting. Even if the pasture has previously grown legumes inoculant should be used because Rhizobium bacteria populations necessary for good nodulation can vary across pastures. It is a relatively cheap practice to help ensure good legume establishment.
The benefits Successfully interseeding legumes can also reduce the need for nitrogen fertilizer. Legumes have a symbiotic relationship with nitrogen-fixing bacteria. As older legume roots die, grasses can take up nitrogen from their decaying roots, increasing protein content and yield. A good legume stand can fix between 50 to 300 pounds of nitrogen per acre and should comprise about 30 to 50 percent of the pasture. One way to look at the value of legumes is to consider that adding nitrogen fertilizer will increase total dry matter yield for the year it is applied, but a legume will improve the seasonal distribution of forage dry matter across multiple grazing cycles. Nitrogen fertilizer will also increase the competitive advantage of the grass over the legume.
Protein is in high demand for growing and developing livestock. Legumes have higher protein content than grasses and can be a great benefit to help meet livestock’s protein intake need. They can also improve the palatability and digestibility of the forage system. Improving the quality of feed has shown to directly benefit animal performance through increased gains, higher conception rates, increased milk production and higher weaning weight. Legumes also help decrease fescue toxicosis in fescue infected with endophyte.
Adding legumes to an established grass pasture provides many benefits. A substantial and healthy legume component in your pasture delivers increased nutritional quality, reduced need for nitrogen fertilizer and a longer grazing season. These benefits all mean lower input costs per pasture acre and increased animal performance through grazing better quality forages.
Adam Noellsch is a staff agronomist for MFA Incorporated.
There is a trend across MFA’s trade territory—a shift of acres away from CRP ground back into crop production. When brought back into production, most CRP acres will go to soybeans the first year. In some cases growers prefer corn the first year. Most of the CRP acres that are coming back into production haven’t seen a crop in 10 to 15 years, some fields have been out of production even longer. I have had the opportunity to visit with several producers about their plans to establish soybeans across these acres. Most of the conversations have revolved around weed control and the planning to fight weeds present in the CRP and ones that might emerge with the crop. But one thing producers sometimes overlook is the importance of inoculating soybean seed. I’ve visited with some producers who plan on planting soybeans into CRP land who were not concerned or didn’t plan on inoculating. That’s a recipe for less than optimal yield.
Inoculants are very important to soybean production. Soybeans are a member of the Leguminosae family and this family has the ability to live in a symbiotic (beneficial to both) relationship with Bradyrhizobium japonicum. This bacterium is specific to soybean and cannot inoculant any other legume.
For the relationship to exist and be beneficial to both, B. japonicum must be present in the soil in relatively high numbers at planting time. In fields where soybeans haven’t been planted for three to five years, it is essential to inoculate your soybeans. Studies from some of the Midwest universities show a benefit from inoculating your soybeans every year while others say you only need to inoculate when soybeans have been absent for several years. I suggest that you do a study on your own farm to determine what best fits your operation. A simple side-by-side evaluation of both practices can help you determine what system to use.
When B. japonicum is present in the soil, it attaches and colonizes on the soybean root hairs immediately behind the growing root tip. Sometimes people confuse the nodules produced by B. japonicum with soybean cyst nematode. SCN are white to yellow in color and the B. japonicum is a wart-like structure. B. Japonicum will grow rapidly and start producing nitrogen around the V2 to V3 stage. If you are curious if your nodules are producing nitrogen you can cut one of the nodules in half. The inside of the nodule will have a pink or red interior. This color doesn’t define the nitrogen efficiency of the nodule or plant. Nodules will fix nitrogen for six to seven weeks.
Soil moisture, soil temperature, soil pH, diseases and micronutrient availability are some of the factors that influence the ability of B. japonicum to fix nitrogen.
Soybeans get about 35 percent of the nitrogen they consume from the soil. The rest of the nitrogen that the soybean plant needs comes from the symbiotic relationship of soybean and B. japonicum. Most of the 35 percent comes from organic matter or fertilizer that has been used in previous crops. If the soil nitrogen level is very high it will inhibit nodules and the B. japonicum will shut down until the soybean utilizes the soil nitrogen. Soybeans can require more than 300 pounds of nitrogen per acre, and most of it is needed during the initial flowering through seed set stages. During pod fill it is not uncommon for the soybean to produce three pounds of nitrogen per acre per day.
Several companies are selling inoculants with growth promoters. One of the common growth promoters on the market is LCO. These promoters are nutrients or chemical enhancers that stimulate root growth or enhance the communication between bacteria and roots to make the nodules form quicker than normal. We are evaluating these growth promoters and other products at the MFA Training Camp site, and will provide the results of these studies when they are available.
I hope that if you are putting a soybean crop on first-year removed CRP ground that you will inoculate your soybeans. Contact your local MFA agronomist to develop a plan for your inoculant needs.
Now that grower meetings have slowed down and you gear up for field work, let me review a frequently asked question about weed control options for 2013. My first response to questions about what to do this year is a question in itself. I ask what weed control program was used the previous year. The common response is: a preemergence herbicide applied at planting followed by glyphosate and an in-season contact herbicide. Of course, the drought had major effects on the performance of your preemergence herbicides in 2012. But whatever let-downs we might have suffered last year, we have to recognize that managing herbicide resistant weeds in the future will rely heavily on the proper use of preemergence herbicides. So if your preemergence herbicide was a flop in 2012 please don’t give up in 2013.
For weed control in 2013, I have a few themes for you to consider. With corn or soybean we must start clean with herbicides or tillage. If you plant your crop into weeds you will have weeds all year. Our options for weed control after the crop is planted are limited. Controlling annual weeds like marestail and giant ragweed before we plant our crop can save you a headache during the growing season. To combat these two problematic weeds, 2,4-D or Dicamba can be used prior to planting either corn or soybeans. 2,4-D or Dicamba provide challenges in themselves. Plant back restrictions following these herbicide range from 7 to 30 days (consult label for specific restrictions).
If you are not willing to use 2,4-D or Dicamba in a burndown situation, there are a few other options. Paraquat can be effective on small weeds. Paraquat is a contact herbicide and needs to have excellent coverage of the weeds to get control. Sharpen (BASF) herbicide can also provide excellent control of marestail and giant ragweed. The organic matter of your soil affects the plant-back intervals following an application of Sharpen. Regardless of what herbicide or tillage option you choose, make sure that you start clean.
Choosing the right preemergence herbicide for your farm will depend on the weed spectrum you have in your fields. Just because you have a program that works on one field doesn’t mean that it will be the right program on another field. Programs need to be developed on a field-by-field basis. The Today’s Farmer Agronomy Guide can be very useful for determining which preemergence herbicide you would like to use in corn or soybean based off of the weed spectrum in your field. However, our local agronomist can help you develop a whole-farm weed resistance plan, which will be tailored to your needs.
When we talk about soybeans we must talk about overlapping our residual herbicides to get ahead of the glyphosate-resistant waterhemp and Palmer amaranth. We must get in the mindset of applying our herbicides on bare ground. Generally, most of the commonly used preemergence herbicides will be effective for around 30 days. There are a lot of factors that influence the degradation of herbicides and can vary their effectiveness. So we need to have another preemergence herbicide applied before the first residual herbicide is ineffective. For example: if we apply our first preemergence herbicide on May 1, by June 1 we need to have our next preemergence herbicide applied and hopefully activated by a rain before the first preemergence herbicide is no longer effective. This will provide weed control further into the growing season giving you a greater chance of success.
In corn, a lot of growers talk about using a one-pass program. That is fine if you are scouting your fields and willing to come back with another postemergence application. However, I find that a lot of people plan on a one-pass program and never scout their fields. We had several calls last fall that corn was clean for eight weeks, but when the combines pulled in the field it was weedy. This could have been avoided by scouting. If you are planning a one-pass program scout your fields every seven to 10 days for escaped weeds and other pests that may be present. I like a two-pass program: a preemergence herbicide applied at planting and, 30 days later, another preemergence herbicide applied to extend weed control further into the season.
Regardless whether it’s a corn or soybean crop, it is critical that we keep the crop weed-free early in the season. Early season weed completion is detrimental to your yields. Scouting your fields every seven to 10 days can save you a lot of headaches later into the season. Getting in the field means you see weed escapes and can treat for them, but it also means you see the disease and insects that can really affect yield. There is no replacement for scouting your fields. MFA’s CropTrack is a scouting program that helps you determine pests that are present and when crop management tactics are needed. Visit your local MFA and see if this program is a fit for your operation.
Dr. Weirich is director of agronomy for MFA Incorporated.
Each year we get a lot of questions regarding sidedress applications of nitrogen. Sidedress applications allow growers to maximize profits. However, each growing season has varying precipitation and different environmental conditions that can prohibit producers from applying nitrogen in-season.
For each bushel of corn removed, 1.5 pound of nitrogen is required. However, one pound of nitrogen is in the corn and half a pound is in the stover. For example, you want to grow 200 bushels of corn, you would need 300 pounds of nitrogen. Some of the nitrogen would come from a credit from previous crop and nitrogen from the soil to reduce the total amount of nitrogen needed for application.
If the corn crop were following soybeans, a 20- to 30-pound nitrogen credit would be applied. Depending on soil type and cropping history, 60 to 70 percent of your nitrogen should be applied at or before planting if you are planning on sidedressing your corn crop. This allows you to evaluate growing conditions and maximize profit.
When corn is in its early vegetative stages to V5, little nitrogen is needed. The largest portion of nitrogen uptake occurs during the V8 to VT (tasseling) development stages. Corn takes up very little nitrogen after pollination.
Thus, it is critical to apply your sidedress nitrogen application before the V8 development stage. Most research indicates that if the nitrogen application is made around the V6 stage, yield loss due to nitrogen stress is rare.
Soil injection or dribbling nitrogen between the rows is the best ways to sidedress nitrogen. This type of application can reduce volatilization of urea and protect the crop from foliar damage. If you are sidedressing with ammonia, it is critical that you watch soil conditions and make sure the knife track closes properly to avoid foliar damage from the ammonia escaping.
Applications of ammonium nitrate, SuperU and urea “over the top” can result in foliar damage. However, this damage is an aesthetic concern and rarely result in any yield loss. For broadcast applications, UAN can be applied up to one-foot plants, ammonium nitrate up to two-foot plants, and urea or SuperU up to four-foot plants or the V8 stage. Broadcast applications of UAN or ammonium nitrate are the least desirable way of applying N due to the cosmetic burn. You can reduce this cosmetic burn by applying the dry nitrogen sources when the foliage is dry.
Sidedressing corn can help you apply nitrogen when the crop needs it most. Also, sidedressing allows you to evaluate current-growing conditions to determine yield potential and the proper amount of nitrogen needed to reach your yield potential. When it comes to sidedress applications, apply earlier than later in crop development. By waiting until later in the season, you have the risk of wet weather. Wet weather can sometimes delay timely applications of nitrogen and cause significant yield loss.
Visit your local MFA location for more information on sidedressing corn or to visit with an agronomist about sidedressing corn on your farm. Dr. Weirich is director of agronomy for MFA Incorporated.
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