For a week, you are given the option to eat your favorite sweet treat or broccoli (without any thought of which is healthier). When there is a steady supply of that sweet treat that you love, why would you choose the broccoli if you didn’t have to?
This is a way to imagine the life of a cow in a set stocked pasture. When given free-rein to a large area, the first thing that cattle will eat is the most succulent, digestible grass they can find. This includes young and mid-maturity grasses. They will leave behind any roughage that is more mature and less palatable. What is grazed first will come back again highly palatable and digestible, so that is what the cattle will go for right away again. This cycle leaves room for problems...
Overgrazing of the individual grass plant induces a detrimental chain of events...
Young succulent plant is grazed very low to the ground – very little leaf surface area is left for the grass to photosynthesize and regrow – plant is forced to pull from any root reserves it may have to spark above ground growth – new root growth is put on hold because of this – above ground growth increases enough for cow to notice again – young succulent plant is grazed very low to the ground
This cycle is extremely hard on the plant. All of the stressors combined make the plant vulnerable to disease, drought, and pests. Eventually, this all ends with the tragic death of the plant, which leads to the next point!
The death of these species that cattle overgraze, lessens the diversity throughout that pasture. Surely you don’t want the diverse mix that you seeded to go from a 7-way blend to a 2-way blend. Diversity in a pasture is important not only for forage quality, but also soil health. Varying root and growth types improve the soil, increasing the longevity of your pastures.
Where there is a will, there is a way for weeds. Overgrazed pastures that become less diverse create a thin stand that makes weeds’ job easy. Thin stands leave room for bare soil. With the addition of moisture and heat, that bare soil will quickly fill in with weeds from the seed bank that have been patiently waiting for their time in the spotlight. These undesirable species can be difficult to rid from your pastures and take up space that could be producing valuable forage.
Aside from the detriments to the pasture itself, this doesn’t even begin to touch on the ding to forage quality for the cattle’s diet, but that is a different topic in itself... So, what is the solution for this unproductive cycle? A grazing rotation that fits your operation. This can look different for many, but see the tips for getting started here!
So, you know how legumes fix nitrogeninto their tissues, but how does that nitrogen get back into your soil? That takes other friends in the soil known as the microbes...
The Terminator -
When the nitrogen that your legumes fix leaves the soil and enters plant tissues, imagine it saying “I’ll be back.” (Come on, do the voice.) When your cover crop is terminated, whether that be from winterkill, chemical, or tillage, it is then exposed to soil microbes. Those critters go to work on the residue and break it down into inorganic N for the plant. The peak time that this occurs is 5-6 week after termination. This is why it is beneficial to seed legumes the season before a grass crop (hence, the usual corn and bean rotation).
Maximizing Nitrogen -
We know we need to terminate the legume, but when is the best time to do that? Minnesota State studies have found that when the plants are at 50% flowering, the nitrogen content is the highest. Any earlier than that, and we have not reached the peak. Any later than that, and the legume will be more mature and have a negative effect on nitrogen increase because it will use some up to be able to break down in the soil.
How much nitrogen will my legume supply?
This can be estimated by getting a biomass measurement and popping some numbers into a formula, or you can use this Nitrogen Calculator and it’s even easier. When we get our pounds of biomass per acre, we can multiply that times a constant to get an estimate of how much nitrogen those plants created for us per acre. The amount of this that we actually capture in the soil depends if it is incorporated or not. We retain 50% of this fixed nitrogen when the cover crop is incorporated, we hold on to 40% of it when the cover crop remains on the soil surface. This is mainly to volatilization from the surface of the cover crop exposed to the air and sunlight.
Moral of the story is consider using legumes to grow your nitrogen!
Visuals created by Associate Professor Julie Grossman and her team of grad students at the University of Minnesota Department of Horticulture Science.
You probably read our post about cool season legumesand how they can fix you nitrogen, but how do legumes actually give you a nitrogen credit? Is it their leaves? Roots? Magic? Kind of! It is actually a symbiotic relationship that legumes can form with rhizobia in the soil. Let see how that works…
It starts with the air -
The air we breathe is around 78% nitrogen. Wouldn’t you save a lot on fertilizer costs if plants could use that atmospheric nitrogen? The reason they can’t is atmospheric nitrogen is tightly connected by a triple bond that can only be disconnected by high pressure and heat or... Bacteria!
Remember those rhizobia that I mentioned? Those are the happy little bacteria that legumes allow to attach to their roots and make a trade (see below). The deal is, the rhizobia take nitrogen from the air in the soil and break it apart to make it useable for the plant to uptake into leaves and stems. In exchange, the plant provides the other means of life that the rhizobia need. Pretty good deal, right?
When the deal is done -
So, your rhizobia have attached and your legume is full of nitrogen. It is a common misconception that at this point your legumes are directly feeding your grasses and broadleaves that may be growing nearby. Unfortunately, the amount of this that happens is very small. I repeat, legumes do not feed your grasses a large amount in season. That being said, they can feed a grass that is planted after the legume is terminated, but Beyond Agronomy will get into that in the next post; Come back on Thursday for The One where the Nitrogen is Released to see how this atmospheric nitrogen truly gets back into you soil!
Visuals created by Associate Professor Julie Grossman and her team of grad students at the University of Minnesota Department of Horticulture Science.
At Prairie Creek Seed, we know the value of continually learning and sharing information. The following methodology comes from Associate Professor Julie Grossman and her team of grad students at the University of Minnesota Department of Horticulture Science. We love the way this process was put together and look forward to seeing what estimates you can all get from your cover crops!
1. Sample your biomass
1. Create a square to measure a known area
2. Take off the above ground growth in that area a few times throughout the field.
3. Dry the sample until it is crunchy and weigh it
2. Convert to biomass lbs per acre
3. Calculate how much nitrogen is in that material using this table:
Hairy Vetch, Clovers, Peas
4% at flowering
3% as seeds are maturing
Cereal Rye, Oats, Sudangrass
3% at flowering
2% as seeds are maturing
Buckwheat, Radish, Turnip
Similar or less than grasses
4. Estimate how much will be available in 1 year. We retain 50% of available N when residue is incorporated and 40% when unincorporated.
Lbs N 0.50 = Lbs available in 1 Year
Lbs N 0.40 = Lbs available in 1 Year
You can also skip the last three steps and get an estimate using our Nitrogen Calculator Tool. All you need there is your dry sample weight and area measured! Do keep in mind that these are estimates and many factors go into to N fixation and release including variety, weather, nitrogen applications, and geographical location.
Laid out here are the top 3 (but not the only) reasons new pasture seedings can fail. Pastures are a long-term investment and getting them established is the biggest hurdle. Let’s see how to jump it…
Like many people, small grass seedlings do not like crowds. They strongly dislike shade when trying to establish. Desirable or undesirable species that grow faster than newly planted grass can cause too much shade for the seedling to overcoming. Having just formed, the seedling will not have enough root reserves to pull from to outgrow lack of sunlight for an extended period of time.
When interseeding into existing pasture, a similar problem can occur with the already established species. This is why our recommended formula for interseeding into an existing stand is: Graze/Cut → Drill in new species → Graze/Cut when established stand begins to fill in. This sequence gives new seedlings the highest amount of light to establish and boost your pasture stand.
Seed Bed Prep –
Not giving a proper seed bed for new plants to establish in is a great way to start your new seeding off poorly. Treat it like the cash crop it is! No one would broadcast their corn, would they? Even in no-till situations, shattering a small section of that topsoil where the seed is places is crucial for giving that plant a strong start. That seed needs a tilthy soil area to send new roots down and healthy shoots up.
Use the drill, coulters, and seed depth that are right for the conditions you are seeding into and type of pasture species that you are planting.
Heavy rain, no rain, cold snap, hot streak. All of these situations can be detrimental to your new seedlings trying to germinate, root down, and produce above ground growth. At the end of the day, there really is no way to foresee some of these conditions unless you have a really good weather reporter or have a direct phone line to the Big Guy – if that’s the case, we would love to do a conference call before every planting season! (563-852-3192)
Keep following Beyond Agronomy for more take-away tips on how to successfully establish pastures!
Compromise happens everywhere in life from picking where to have dinner to how long you want to stay at the in-law's place. Compromises also happen in cover crop and forage blends...
While it may seem great to plant the full rate of everything in a mix to get as much in as possible, that often is not realistic agronomically or economically. Creating a balance of rates in a blend will ensure that nothing competes and everything shows up. This is especially important in pasture blends when it comes to that desired ratio of grasses and legumes. For cover crop and forage blends, we like to use our Cover Crop Calculator to put together a mix for you based on rate or budget needs to get the best of both worlds. Contact the office or your dealer for them to put one together for you! (Here are some guidelines for cover crop planting rates)
In general, large seeds are happier planted deeper and small seeds prefer to be kept shallower. In a blend of various species this can be difficult. The answer is compromise. In a blend planted too deep, only the larger seeded plants will establish. Planted to shallow, a stand will only consist of the smaller seeded plants. We like to pick a mid-range depth based off of what is in the mix. This ensures that everyone will show up to the party. (Check out ourPerennial seed depth toolandannual seed depth tool)
When to seed and when to terminate are two very important questions when making decisions about your blends. With blends that are all cool season or all warm season, the timing of planting is generally unanimous and no compromise is needed. For blends with both, you have to find mid-ground. Deciding when to terminate a cover crop or forage blend may take more discussion. Do you terminate when the grass components are young and lush so that they break down quickly? Or do you let the blend continue to grow so that the legume component can fix you as much nitrogen as possible? Again, a balance is best. In the case of crops like cereal rye, you have to look at forage quality and tonnage when deciding termination timing.
The answer to most questions when balancing these compromises is usually is “it depends.” Stay true to the goals of your cover crop or forage blend and you can achieve the balance that is right for your operation.
We know the benefits of rotational grazing. We know what it does for the pasture productivity, soil health and forage quality. Now, we need to start! So, I asked Karl “What is your advice for beginning rotational grazing?”
The day the decision to begin rotational grazing is made go out and document what is there. Get counts and photos of plant stands and various species. Dig around and get an idea of your soil structure across pastures. (This will be important in five years because you won’t remember what it was like when you first started.) There are multiple ways to accomplish rotational grazing, but not a one size fits all method. Determine what will be best for you, and start there. The physical items you need are polywire, a reel, and some step-in posts (plus some grass and livestock, of course). Bonus: Do not spend a lot on interior fencing and infrastructure. With polywire and step-in posts you can be creative.
The next step is figuring out what forage you have and how much you need:
1. Pasture sticks can be used to measure pasture height and a different side of the stick gives us a table that can be used to estimate the density of various pastures by counting visible dots.
For the 4 dots visible in this mixed pasture, the table gives a range of 150-250 lbs DM lbs per inch, so we will use 200#/Inch to estimate. We know they will graze the 10-inch grass to a 4-inch stubble with 6 inches eaten. (Stubble height can change and vary, and sometimes getting too specific can overcomplicate things.)
We can calculate our forage amount using those measurements:
(200# Density/Inch x 6 Inches) = 1200# DM/Acre
2. Now, take a look at your livestock and get rough idea of dry matter intake per day. An example is a 1000# cow eating 3% of her body weight in dry matter forage (30#/day). Calculate the need for your entire herd:
50 Cows x 30#/Day = 1500# DM Need/Day
3. How many acres will give them 1500# of forage? Use the Dry Matter/Acre estimate and the DM Need/Day that we found:
Knowing this, Karl recommends giving them enough for 2 days, so 2.5 acres (accurate acre measurement is important). The reason for two days when starting is it gives you wiggle room. If you underestimated, it won’t be grazed to the dirt before the next time you check on them. If there is more that 2 days’ worth, it can be adjusted to leave them on that longer or tighten that paddock. Eventually you will get an eye for what your cattle will eat and how long it will take them. Some may say that overgrazing at the beginning by accident will wreck pastures forever, but it won’t. If that does happen, it’s okay. It’s just the beginning and you will perfect it over time.
With your forage estimates made, walk all your pastures and see how much you have to get a big picture idea of your grazing plan. Parts of the pasture will all be at different stages, so some estimating will be needed. There are many opinions on the timing of when cattle should be moved, but this can be flexible. Generally, as long as they are not left for longer that 4-5 days, the pasture will not be damaged. With cow calf pairs, Karl has his cattle in the same paddock for 2-3 days. If his schedule allows, he will move more often, but the system has to work with your lifestyle to an extent.
Dairy and grass finished beef are a different story. Both need the best forage quality to be highly productive, so they would need moved as often as possible. Karl has finished cattle on grass and would move them 1-2 times per day. The movement encourages higher forage intake and the lack of fluctuations in forage quality throughout the time they are in paddocks will improve performance.
Your final task is determining a water source. One central location can require creativity in how they get there. You want to avoid creating a permanent lane where the cattle will form trails and dead areas in the pasture. Karl has been there done that and those areas can be difficult to heal. A hydrant at a high point of the operation can serve well as a water source with the addition of a garden hose or water pipe to start. The initial expense of that option will be made up for in being able to make the paddocks wherever you want and having that improved management.
The main point of beginning rotational grazing is improving soil health, plant health and animal performance. Get basic skills in place then look at what additional improvements you can make in seed options, genetics, and infrastructure.
If you or anyone you know has used warm season annuals for forage, you made a very good choice! But you have also probably heard of the concern of prussic acid. What is prussic acid and why is it a topic of discussion this time of year?
What is Prussic Acid?
Prussic Acid is a compound that exists in warm season forage plants such as forage sorghum, sorghum sudangrass, and sudangrass. While these are often harvested and grazed during the summer, this time of year can also be common. The concerns with prussic acid arise when we start having killing and non-killing frosts. When these types of plants are killed from a frost, the cells rupture releasing the prussic acid as a gas that will be harmful to livestock. Here are some procedural guidelines to follow this time of year if you have these crops:
Grazing: After a killing frost, keep livestock from grazing for 10-12 days
Mechanical Harvest: At, or before, a killing frost, the forage can be chopped or baled at any time the moisture is correct for the harvest type; however, do not feed forage for 30-40 days after harvesting.
What happens during those wait times?
Since it is released as a gas, the forage dries and the prussic acid dissipates through volatilization. This makes the concentration levels in the tissue safe for livestock consumption. It is important that the killing frost we are speaking of is truly killing to the entire plant. If the frost only kills part of the plant, it can attempt to regrow by sending out new shoots that can also higher prussic acid concentrations.
Still have concerns?
Forage samples can be sent in and tested for prussic acid concentrations at most forage sampling facilities. The cost of these can range from $50-$60, but can serve as insurance and be helpful in relieving worries about what you are feeding. Simply ask for a Prussic Acid Test. Keep in mind that since prussic acid volatizes as a gas, this is a time sensitive test that often needs overnight shipping to the testing facility.
Overall, the likelihood of prussic acid poisoning is very controllable by using the guidelines above. Feel free to give the office a call if you would like any additional information!
Bean, Brent, and Kim McCuistion. "Avoiding Prussic Acid." Sorghum Checkoff, 1 Nov. 2017.
Cover crops – they work! (When managed properly)Here are the general benefits of cover crops that we should all know:
1. Improving Soil Structure & Water Infiltration
Roots are your best friend when it comes to cover crops. Whether they are fibrous and spreading or a taproot that drives deep to pull up nutrients, varying root structures create channels that facilitate aeration and water infiltration. Beyond the physical abilities of roots, the biological magic that they induce is the real money maker for the soil life. Which leads us to the nutrient cycling that soil biology sparks!
2. Increase Nutrient Cycling
Your soil is the transforming factory that turns nutrients into a form that is able to be taken up by the plant. The biology in the soil is what facilitates this process. The previous mentioned root systems of cover crops give off exudates into the soil that the microscopic biology love to live in. A high population of soil life around the root system creates a zone that feeds the plant versions of the necessary nutrients and minerals in a form they can use.
3. Reducing Erosion
Everyone has seen the rainfall simulator, right? That is a perfect visual to show that it is a fact that something growing (or even dead) on the soil surface reduces erosion. In a rotation, cover crops protect the soil and keep it where you need it. This is especial important for highly erodible soils or areas with shallow top soil. You need to keep every bit that you have! Keep in mind the carbon to nitrogen ratio and rooting type of cover crops when choosing one specifically for erosion control. (We have some erosion control ratings of common cover crops here)
4. Managing Moisture
This benefit can go both ways: holding moisture in or getting rid of it. Need something to retain soil moisture? You need a low growing, ground covering option. Living or terminated cover crops can protect the soil moisture form evaporating away. Need a little less moisture in the spring (don’t we all…)? A living cover crop can uptake that moisture and transpire it away for you. Obviously, the extremes of both of these would not be beneficial, but when used correctly cover crops can be your moisture risk management.
5. Provide Forage
This one is a no brainer for those with livestock (or if you have a neighbor with livestock that might pay you to graze your cover crop *wink wink*). A cover crop can provide many of the benefits listed above and you don’t have to feed as much hay! Selecting the right cover crop for forage is important as well as the seeding rate. Higher rates are often needed to produce the maximum amount of tonnage.
And what do all of these combined have the potential to do? Increase yields and, more importantly, profits! Think about the examples above and consider what cover crops could do for your operation.
Cover crops are generally user friendly and successful with little stress, but there are a few things that shouldn’t be overlooked...
“Prairie Creek Seed, who do you give such a wide range for recommended seeding rates on your cover crop blends?” Good question! Different seeding rates have their place. Want a thick, full stand to achieve maximum forage for livestock? You better stick to the higher end of our scales. Looking for a cover crop that will not be harvested? Then it is more economical to stick to the lower end. There is such a thing as too low of a seeding rate, and that is the first way cover crops can be sabotaged. A seeding rate that is too low will result in not enough cover to establish and will not gain you any benefits.
Another way to mistreat your cover crops is not giving them a proper seeding method. While there are many cover crops that can be broadcast, not all of them can take that! Many large seeded cover crops need to be drill or incorporated in some way to have a strong establishment. Taking the extra time, and sometimes added expense, of drilling your cover crop will pay for itself. The establishment of many cover crops will be sped up by around 2 weeks when drilled. Getting seeds in the ground also makes them more tolerant of weather extremes by having a healthier established root system (this will be important later).
If you are planting a cover crop without the goal of harvesting, then this point is not as critical, but is still important! Growing anything desirable with low fertility is next to impossible. If you want your cover crop to get large enough for forage (or even just large enough to provide adequate erosion control) it does not hurt to provide some fertility as it fits into your operation.
Remember how cover crops that are drilled have a stronger root system to handle weather better? This leads us to the ways that good ol’ Mother Nature can sabotage cover crops. The same way that drought and heavy rain effect your cash crops, those events can also be damaging to your cover crop. While this point is out of your control, it is important to remember that cover crops are not indestructible.
Keep these points in mind to set your cover crops up for success!