As the time of year comes to harvest warm season annuals, we have started receiving questions about adding fertility after taking the first cutting. Below are some answers…
Why you might need it -
Warm season annuals are efficient users of nitrogen, but they are still grasses that can require supplemental nitrogen when harvested. Even though nitrogen is the piece of fertility we focus most on for grasses, it is important to have your soil tests in mind to know what other amendments your soil may be looking for. Even if a warm season mix contains legumes, additional nitrogen may be needed. Those legumes are fixing nitrogen for you, but they are storing that as protein in the above ground growth that is removed as forage. This adds to the feed value, but not to the nitrogen content of the soil. Fertility after cuttings may not be needed if you have a lot of manure on the field ahead of time. It is also usually not necessary when grazing the forage as the livestock recycle the nutrients for you.
What to apply -
The type of fertilizer applied will vary from farm to farm based on your practices and what is available. Poultry litter can work well as a nitrogen source, but can be slower to release the nitrogen compared to others. Urea can be an option, but should be avoided in dry environments as it can be quick to volatilize. Ammonium sulfate and ESN (Environmentally Smart Nitrogen) are both stable forms that can work well to be applied after a cutting. A general recommendation for the amount of fertility needed is 30-50 pounds of actual nitrogen. We would not recommend any higher rates between cuttings
When to apply it -
The best timing for applying this fertilizer is directly after harvest in order to jump start you next cutting or grazing.
What other questions do you have about fertilizing warm season annuals?
As much as we would like it to be, rotational grazing is not an exact science. Many factors contribute to the way the season will go. We have some tips to answer the question of “What if the paddocks get ahead of you?”
One easy answer if you have too much grass is to harvest the excess! If you need hay, this scenario can work in your favor. You could harvest the paddocks that have gotten ahead of you as baleage or dry hay, depending on your needs. This not only provides additional stored forage, but also resets those paddocks to go into a vegetative state and recover. This creates higher quality forage that will be ready for livestock to graze. It is important to ensure adequate recovery time for the harvested paddocks in the same way you would if it was grazed.
If you are grazing a class of livestock that does not necessarily need that higher-quality, forage, you could just continue on your normal rounds of grazing. The forage in these paddocks that have gotten ahead of you can be lower quality as the grasses are most likely heading out. This may not be a concern if there are still species in the mix that are in the vegetative state. It is important to be aware of seed heads that may irritate cattle. Grazing these more mature paddocks could also result in uneven grazing, so clipping after may be necessary.
Having some paddocks get ahead of you is not the end of the world and can serve as a lesson for your next round of grazing. This may show you that you can increase stocking density or move livestock more often. Rotational grazing can be an ever-changing system as you meet weather challenges and other factors that affect your rotation.
In a perfect world of grazing, your warm season annual, or blend of annuals, would be grazed when the grasses are in boot stage. This is when the quality is highest for most warm season species. However, as you rotationally graze, the paddocks at the end will be far past the boot stage and much poorer quality. There are a few ways to overcome this. One way would be to stagger planting of the warm seasons to allow different paddocks to be at the boot stage when you need them to be. That may help in planning for next year, but what about for what is already growing this year?
Our recommendation would be to start grazing warm season annuals once it reaches at least 24 inches. This allows you to rotationally graze through your stand and hopefully never have livestock reach a past-prime paddock. Another benefit to this method is easing livestock into the high-quality forage that warm seasons provide at boot stage. As they move through paddocks that are increasingly closer to boot stage, it allows the rumen to adjust to this new forage. Switching to warm seasons directly from hay or pasture can be a shock to their system in some cases.
Stubble Height -
Rotational grazing warm season annuals will result in increased utilization of the forage, but leaving an adequate stubble height is key. Sorghum sudangrass and sudangrass can be grazed down to 4-6 inches and still have adequate regrowth for multiple grazing passes. When grazing millet or blends of millet, warm season legumes, and brassicas, maintain a higher stubble height of 8-10 inches in order to have productive regrowth. We know that every grazing move will not be perfect, but it will be beneficial to try to stick to these guidelines for stubble height.
Grazing Schedule -
As you are moving livestock through your warm seasons, be sure to move in a timely manner as they graze. This will help achieve the stubble height goals mentioned above, but also helps avoid concern of nitrates. As plants take up nitrates from the soil, they store some within their tissues. The concentrations of nitrates are high in new growth, drought-stressed plants, as well as the lower portion of the plant’s stem. Keeping livestock moved quickly enough to avoid grazing of the paddock’s regrowth will keep nitrate concerns very low.
Let us know what other questions you have about grazing your summer annuals!
If you have planted warm seasons this year, then hopefully they are up out of the ground soaking up the sun! Now comes the time to decide when you will be harvesting these forages. Depending on what you have planted, you may be planning to graze, make multiple cuttings, or one cutting to harvest the forage. Below shows the various times these cuttings and grazings could occur and the benefits of each:
Vegetative Stage - Early in the development of warm season grasses before any seedhead development. If you need to graze your summer annuals early, this can be a useful time for that. Dry hay may need supplemented to increase the overall dry matter content of the forage.
Earliest harvest time
Boot Stage - Seed head has formed, but still remains inside the stem. A flag leaf will be visible and you will be able to feel the seed head inside of the stem towards the top. This is an ideal time to harvest a multi-cut sorghum sudangrass or millet.
Soft Dough Stage - Seedhead is developed and beginning to harden. When you press a seed between your fingers, it will squish and feel doughy. This is the timing to aim for when doing a single cut harvest of a forage sorghum.
Low protein (corn silage)
When you have cool season pastures, you know the intense, lush growth that occurs in the spring. You also know that your stands are cringing thinking about the summer heat that is about to set in. With summer comes slowed growth and multiple stressors like drought and heat being thrown at your stands of grasses and legumes. How can we minimize the stress on the plants? How does grazing have to change for this?
Rest, Rest, Rest
With all of the stress cool season pastures undergo in the summer, giving paddocks sufficient rest is the least you can do! Recovery in the summer months will be much slower than in the spring and fall as the grasses are less active, see the “Cool Season Perennials” line below:
This slow in growth is even more drastic in extremely dry or abnormally hot periods. With a slower recovery comes a need for longer rest periods. Take a look at the plants instead of your calendar when planning moves during the summer and plan ahead accordingly. Observe the density of the stand and take that into consideration as it will likely be thinner than when you grazed it earlier in the spring. In general, stands of grasses and legumes should be allowed to regrow to anywhere from 12-24 inches before being grazed again and always leave adequate stubble.
Did someone say stubble?
To ensure that longer rest and recovery period actually produces growth, a suitable stubble height must be left when a paddock is grazed. This can vary from species to species and can effectively be summed up by the “take 50, leave 50 method” shown in the first image below:
That being said, a critical height that should be left regardless of how much is grazed is at least 4-8 inches. That surface area that is left will allow quicker recovery when a hot or dry spell ends. This allows plants to pull less from their root reserves (days of stopped growth in image above). This makes your stand more tolerant when hot and dry weather conditions occur again and protect pastures from all the detriments of overgrazing.
In the same way that a stressed person or animal is more susceptible to illness and death, this summer's stressors can be damaging to plants. Providing adequately rest, recovery and stubble height can minimize damage from the hottest driest summers where cool season pastures exist.
Imagine this, when our established cool season pastures slow during mid-summer (as seen below) we can have our warm season annuals there just in time to provide grazing for livestock in our rotation. A combination of warm season grasses, legumes, and broadleaves emerge perfectly. Livestock are happy to graze the high quality, highly digestible forage all summer. Fall comes and the cool season pastures pick back up while the warm seasons slow and stop growing. *rewinding sound* There are a few hurdles we have to face to get close to achieving this goal and making it at all comparable to planting to warm season annual in its own paddock.
As you can see above, cool season pastures will slow, but not go completely dormant during summer months. They will still be competing for sunlight, water and soil minerals (Gerrish, 4). This is where adequate fertility is important, especially when putting a grass (warm season) into a grass (cool season). There are a lot of nitrogen needs there. Also, the existing pasture already has an established root system that is a pro at grabbing all of the nutrients, and not to mention moisture, that it can. These new seedings of sorghum, sudangrass, millet, etc. may be fast to establish, but can have trouble competing with the root systems already in place. Shattering the soil and breaking up those root systems around where that seed will go in the ground is key to give it a less competitive area when establishing. This is where a very effective no-till drill is important, as well as the next guidelines mentioned.
Establishment Challenges –
We have seen many producers try to establish warm season in pasture stands and meet some challenges. Sometimes the larger seeds were not put deep enough to produce a healthy root system, or smaller seeded species were sunk too deep to establish. Another issue we have seen is conditions that are too wet when the warm season are planted. This leads to sidewall compaction that does not let the root system get established or the planting slot stays open and the seed to soil contact is not adequate. What is the answer to all of this? Be very mindful of seeding depth and soil conditions when planting (and remember to use an effective no-till drill). Giving the warm season plants a fair chance to germinate and establish a strong root system is a vital step.
In late spring, soil temperatures have to be 65 degrees and rising before planting any warm season annuals. Before that, they will not have proper temperatures to germinate or form a healthy root system. This stunting only allows the existing pasture to get further ahead. Timing of grazing is key to make sure you do not damage your perennial pasture. A successful, thriving establishment of these warm season needs to be rotationally grazed in a timely manner as to not shade out your pasture. If your warm seasons take off and get ahead of livestock in a rotation, this is where you could chop or make baleage from these species. So versatile!
Planting warm season forages alone will always be the most reliable way to have a successful establishment anf forage yield, but this can be an option if it matches your goals better. Overall, the key guidelines for establishing warm season into pastures are fertility, seeding method and depth, and planting and grazing timing. If these are followed properly (and Mother Nature cooperates), the dream mentioned at the beginning could become a reality!
Gerrish, Jim. "Using Annual Forages to Beef Up Perennial Pastures." The Stockman Grass Farmer, 2017, pp. 1-4.
Have you ever heard about warm season annuals and wondered where they can fit in your rotation? Here are a few ways these versatile annuals can be used:
Warm Season Forage
Warm season annuals like sorghum sudangrass, sudangrass, millet and cowpeas make excellent forage over the summer months. These species do best in the heat of the summer and can be harvested multiple times. Harvest method depends on which species or blend of species you use. Forage sorghum can be harvested standing similar to corn silage while sudangrass and millet work best harvested in multiple cuttings as baleage. A mix like Summer Blend, shown below, can also provide grazing throughout the summer to give you perennial pastures a rest. Soils have to be at least 60 degrees and rising to be planted, so these species work well after a small grain or spring cover crop.
Prevent Plant or Emergency Forage
Although we hope this does not happen, warm season annuals can work well in prevent plant situations as well as providing emergency forage. When conditions do not cooperate to get your planned cash crop in, warm season annual blends can be planted as a cover crop or as a forage. If it is the beginning of summer and you are in need of more dry hay, Teff can act as an emergency forage and provide dry hay while growing in during the hottest part of the year.
Fall Seeding Opportunity
Planting warm season annuals early summer can set land up perfectly for a fall seeding of alfalfa or pasture. Warm seasons planted as a cover crop and terminated before this planting can contribute to soil building. Planting a blend of warm season provides varying root systems to kickstart soil biology. Warm season legumes will also fix nitrogen in the plant tissues that can be released to the next plants being seeded. Using a summer or two of annuals to improve soils that were previously row cropped is an important step in transitioning to perennials. Using annuals to condition the soil prepares it well for the smaller seeded, slower establishing perennials. The dense vegetation of warm season annuals also does wonders for weed control leading up to the perennial seeding.
If one or more of these uses stands out to you, consider warm season annuals in your rotation!
Forage sorghum is a viable complement to or replacement for corn silage, yes, we said it, replacement for corn silage! Read on to see how forage sorghum could fit in your operation.
Forage sorghum is designed to be a good fit in areas with historically low corn silage yields and is available in maturities ranging from 85 to 108 days (approximate) from emergence to soft dough. Forage sorghum will benefit producers most if they can harvest the forage standing, like corn silage, saving time and money by eliminating the swathing process. When forage sorghum is intended to be harvested standing, variety selection is important. Various sorghums are better suited for different geographies and management styles.
Advantages of planting forage sorghum for silage:
- Forage sorghum will generally be higher yielding than corn silage in drier and tougher conditions. In better fields or conditions, corn silage will likely have a 10- to 15-percent yield advantage, but can have higher input costs (see the next points!)
- Forage sorghum requires 33% less water than corn. Helpful on sandy ground, right?
- Forage sorghum seeding rates are quite low— 6 to 9 pounds/acre—reducing seed costs to around $16 per acre.
- Forage sorghum at soft dough will have low starch but high sugars and NDFd. This gives forage sorghum a high starch equivalent on a forage test closer to corn silage.
- Forage sorghum is flexible for harvest, which can be important with variability in weather throughout the season. It can be cut and wilted for harvest if needs or conditions warrant earlier harvest.
- Forage sorghum requires less nitrogen than corn. Nitrogen should not exceed 110 pounds actual N, including soil-available nitrogen.
- Energy will increase with forage sorghum heading because of continued sugar formation in the stalks and leaves, not to mention the additional carbohydrate deposition in the grain.
What do you think?
Not interested in the sorghum family for warm season options? Here are some other alternative forages for this summer:
Do you like the sounds of the sudangrass, but want to avoid the prussic acid concern in the fall or experience slightly cooler summers? This millet may be the answer! Millet can provide multiple baleage cuttings or grazing passes. Millet will also provide fast establishment and quick recovery after harvest or grazing. Dry matter tonnage will generally be 4-5 tons per acre. It is important to leave an 8 inch stubble height in order for millet to properly regrow.
So much talk of silage and baleage. If you are thinking “I have to make dry hay out of my annuals” then it is good that you made it to teff! From the plains of Africa, teff is a warm season cereal that provides excellent forage as dry hay. With very fine stems and leaves, teff can be mowed and baled dry reliably. Teff will provide multiple cuttings in a season and also has no prussic acid concern in the fall. Dry matter yields of 4-5 tons can be expected. The key with teff is seedbed preparation. At 2.4 million seeds per pound, teff requires a bare, firm seed bed for even establishment.
Looking for additional diversity with your summer annuals? Consider a blend of some of the above annuals with some warm season legumes and brassicas. Prairie Creek Seed often combines warm season grasses with cowpeas, mung beans, berseem clover and forage brassicas like rapeseed and radishes. These blends provide excellent forage quality while also benefiting soil biology with their varying root systems.
As the time to plant warm season forages approaches, it’s time to start thinking about the specifics of planting these annuals. Having proper soil temperature, seedbed preparation, seed depth, seeding rate and fertility is important!
Soil Temperature -
We have already gone into why you should not plant warm season annuals too early, so when should you plant? Soil temperatures need to be at a minimum of 60 degrees and rising. Meaning you should check your soil temperatures at the coldest part of the day and it needs to be at least 60 degrees.
Seeding Depth -
The importance of accurate seeding depth tends to be overlooked with warm season annuals. For the most part, treat it as important as your corn seeding depth! Proper depths are as follows:
Millet = ½”-¾”
Teff = 1/8"
Similarly to seeding depth, the seedbed should be prepared the same way as your corn. A firm, but tilthy soil will provide the best environment for warm seasons to establish. For some farms this may include tillage to prepare the seedbed, or a really good no-till drill can also do the trick. The key is making sure to create a strip of loosened soil for the new seedlings to get started.
Seeding Rate -
Depending on your use of the warm season annual, seeding rates can vary from a set range. In most cases, a higher seeding rate will give you a thinner stem on warm season grasses and a lower seeding rate will increase the stalk size. Also, these rates will be lower when combined in a blend. The ranges we recommend for warm season planted alone are listed below:
Forage Sorghum = 5-9 lbs per acre
Sorghum Sudangrass = 20-25 lbs per acre
Sudangrass = 35-45 lbs per acre
Millet = 15-25 lbs per acre
Teff = 5-7 lbs per acre
Summer Blend = 20-25 lbs per acre
Warm Season Combo = 20-25 lbs per acre
Decisions for fertilizing should generally be based on a soil test. Without a soil test, a recommendation for a multi-cut crop would be a balanced fertilizer applying 30-40 units of actual nitrogen per cutting. For a single harvest crop, like forage sorghum, we would recommend 80-100 units of actual N applied at planting. This includes all forms of nitrogen such as soil available nitrogen, any N additions from previous crops, and manure applied.
Feel free to contact the office with any additional questions on warm season planting!