Sunn hemp pasture in Walton County. Photo Credit: Jennifer Bearden
Sunn hemp is a fast growing, warm season, annual legume. It grows 6-7 feet tall. Sunn hemp can tolerate a wide range of soil pH (5.0-8.4). It is native to India and Pakistan. The University of Hawaii and USDA NRCS, together, released the variety called “Tropic Sun” in 1982. This variety only makes seed during periods of short day length and a certain range of temperatures. These factors limited seed production. Recently, however, Auburn University released AU Golden and AU Darbin varieties that are able to produce seeds in more temperate climates. Since sunn hemp is a legume, it fixes more than 120lbs of nitrogen from the environment per acre, per season. It can yield 3,000 to 10,000lbs of forage per acre. It can be grown in a wide range of soil types, but is most productive in more fertile soils. Sunn hemp has traditionally been utilized as a cover crop, but has recently been evaluated as a forage for livestock as well for wildlife food plots.
The advantages of using sunn hemp as a cover crop are the large amount of biomass produced per acre, nitrogen fixation, nematode suppression, and weed suppression. Because it can grow in a wide range of soil types and pH levels, and because of its drought tolerance, hunters have tried it for wildlife food plots. Research has shown that Sunn Hemp is an acquired taste, and that livestock and wildlife need time to become accustomed to it, but the nutrient quality of the leaves is very high with crude protein (CP) ranging from 25-30%.
Sunn hemp is an interesting option for livestock warm season annual grazing. Plant sunn hemp once soil temperatures have reached 65°F. Use a seeding rate of 25-30lb per acre and planting depth of 1/4” to 1”. Don’t forget the cowpea type inoculant. Because this is a legume crop that fixes its own nitrogen (N), N fertilization is not required. Soil test for pH, phosphorus and potassium prior to planting, and apply the recommended nutrients based on the soil test results.
Grazing management is very important for Sunn Hemp. The goal is to keep the plants in a vegetative growth stage with a high percentage of leaves compared to stalks. The leaves are 25-30% CP with TDN of 65-71%. The stems are much lower quality (8-10% CP and 22% TDN). Grazing and forage management should focus on maximizing leaf-to-stem ratio. Start grazing approximately 45 days after planting when the sunn hemp reaches 1.5-3 feet tall. If you wait too long, sunn hemp can reach a height of over 6′ and livestock will break off the plants and prevent regrowth. Stop grazing when stubble is 12-18″ to allow regrowth. Overgrazing or mowing below 12″ can kill the plant and prevent regrowth. Because of its high quality, sunn hemp works well using limit grazing (1-3 hours/day) to compliment traditional perennial pastures.
Sunn Hemp is an annual legume that is not related to industrial hemp or marijuana. It is actually in the Crotalaria family, but unlike other species in this plant family that are toxic, sunn hemp contains much lower levels of alkaloid compounds. Sunn hemp seeds do contain small amounts of toxic alkaloids, so seeds should not be fed in livestock diets. Small amounts of seeds consumed while grazing are not enough to cause acute toxicity. The leaves and stems are not toxic to livestock.
For more information on using sunn hemp as a forage, use the following link to a recently published Alabama Extension fact sheet:
105 cattle and hay producers, industry representatives, extension agents, and researchers from three states took part in the Forage Legume Conference in Marianna, FL. Credit: Doug Mayo
Jose Dubeux, Forage Management Specialist, North Florida Research and Education Center, lead the team that organized the Forage Legume Conference, that was held on March 15, 2018, in Marianna, Florida. There were 105 cattle and hay producers, industry representatives, as well as extension and research faculty, and students from the University of Florida that participated in the event. The morning session featured presentations from five forage experts from Florida, Georgia, and Alabama. The morning session concluded with a panel of four forage producers, who have successfully integrated legumes on their operations. The afternoon session featured a tour of forage legume research at the Marianna Beef Research Unit, at the UF/IFAS North Florida Research and Education Center.
Legumes are plants that are able to secure their own nitrogen from a symbiotic relationship with specific beneficial bacteria. Adding legumes to forage grass systems offers many benefits, such as increased soil nitrogen availability for the grass, higher nutrient quality for increased animal performance, and increased production from extension of the grazing season. The six invited speakers provided the most current research-based recommendations for integrating legumes into grazing and hay operations. Many of the participants at the Conference asked for a copy of the presentations that were provided, so the purpose of this article is to share them in a printer friendly PDF format.
1. Alfalfa in the South
Dennis Hancock, UGA Forage Extension Specialist.
Dr. Dennis Hancock, UGA Forage Specialist, provided an update of several years of research and on-farm testing for interseeding alfalfa into Bermudagrass hay fields. The main idea of this project was to evaluate use of alfalfa to reduce nitrogen fertilization, and also increase hay nutrient quality. In addition to the presentation below, Dr. Hancock also has a web page with links to more information on this topic: Alfalfa in the South
2. Integrating Rhizoma Peanut in Grazing Systems
Dr. Lynn Sollenberger, UF Agronomy Department, shared the results of several years of research on techniques to integrate rhizoma peanut (aka perennial peanut) into bahigrass pastures. The main concept was to develop a management system which could reduce or eliminate nitrogen fertilization, with equal or improved animal performance. His team’s research has been focusing on variety selection, timing of planting, and the challenges with the grass suppression and weed control needed to establish strips of rhizoma peanut in existing bahiagrass pastures.
3. Using Clovers in the Southern Coastal Plains
Dr. Don Ball, emeritus Alabama Forage Extension Specialist, shared some of his vast knowledge from a career of research and on-farm work with integrating clovers into grass based grazing systems. In his presentation, Dr. Ball answers the key question of, “Why grow clovers?”
4. Warm Season Annual Legumes: Past, Present, and Future
Dr. Joe Vendramini, Forage Specialist, UF Range Cattle Research and Education Center, provided a presentation summarizing research that his team has conducted on three warm season annual legumes: aeschynomene, cowpea, and sunn hemp. Aeschynomene is a proven reseeding annual legume that grows better in wetter, poorly drained soils than other legumes. Cowpea can be utilized as a cover crop, or temporary grazing, but was not competitive when integrated into grass pastures. Sunn hemp has shown real potential, so current research is focusing on the best varieties and management techniques to integrate it with grass pastures.
5. Economics of Forage Legumes vs. N Fertilization
Chris Prevatt, UF Livestock Economist, shared a presentation that analyzed comparison of past research on grazing systems that included legumes, versus grass systems for stocker cattle performance. He is also currently contributing to the ongoing research with Jose Dubeux’s team by calculating the cost/benefits of rhizoma peanut/bahiagrass systems, as compared to traditional nitrogen fertilized grass only systems.
For more information on forage legumes, contact your local County Extension Agent, or use the links to fact sheets on the following topics:
Hay producers have a free marketing tool from FDACS to help them connect with customers to sell their hay. Photo taken at Cone Farms, Madison County. Credit: Doug Mayo
Chris Denmark and Emily Hetherington, Florida Department of Agriculture and Consumer Services, Division of Marketing and Development
The Florida Department of Agriculture and Consumer Services’(FDACS) Division of Marketing and Development has redesigned the Hay Suppliers web page to provide more utility for both hay producers and consumers. FDACS recognized the need for the update when, in December 2016, it was contacted by the Alabama Department of Agriculture that was looking for hay for drought stricken producers. The enhanced website now enables hay seekers to search for Florida hay supplies by hay type, region, and bale type.
The Marketing Team continues to build the database and encourages producers to go online and submit hay listings. The goal is to make the Hay Supplier Database the first choice for consumers and producers who are seeking hay in Florida. Visit www.freshfromflorida.com/haylist for more information.
The Division of Marketing is always looking to help Florida producers with their marketing needs. The newest team member, Emily Hetherington, has a background in dairy and beef cattle production in Australia, Florida, and Georgia. She comes from a family of dairy farmers and beef producers. Please feel free to contact Emily to introduce yourself or if you have any questions about livestock and hay marketing endeavors. She looks forward to working with you and helping our Florida hay and cattle producers.
For more information, contact Chris Denmark or Emily Hetherington – (850) 617-7291.
Cheryl Mackowiak, UF/IFAS NFREC Soils Specialist
As producers near the end of cover crop and cool-season forage planting in the Southeastern U.S., it is time to focus on fertilization. Depending upon your state, extension professionals have establish guidelines for how much and when to apply nitrogen (N), phosphorus (P), and potassium (K) fertilizers to meet crop demands. For example, annual ryegrass and small grains (i.e., wheat, oat, rye, triticale) planted on tilled land often benefit from split N rates such as 30 lbs N/acre at or near planting and another 40 to 50 lbs N/acre after establishment. Overseeded pastures may get by with an initial 30 lbs N/acre, but often 50 lbs N/acre is applied once the cool-season grass has emerged with another 50 lbs N/ac applied after repeated grazing to help support regrowth in spring, when winter forage is the most productive. In comparison, P and K applications are based upon soil sampling and your soil report recommendations. These nutrients are typically applied only once in the fall (if needed), and combined with your first N application.
Frequently, a call comes in that a farmer’s winter grass forage does not seem to be responding to N fertilizer. They have met or exceeded the N fertilizer recommendations and yet, the plants remain faded looking and stunted. The first question I ask: “How much sulfur (S) was applied?” Sulfur deficiency can often be mistaken for N deficiency in both, summer and winter grasses. We typically see more problems in winter grasses, because of where the grasses are planted and the previous season land-use. If none of your N fertilizer was applied as ammonium sulfate, or your K fertilizer did not contain potassium sulfate, SolPoMag, or a similar sulfate fertilizer, your grass may be suffering from S deficiency. The good news is that many grass species respond quickly to S fertilization, and an application rate as low as 10 lbs S/acre is often all that is required for recovery. An application of 10 to 20 lbs S/acre will hardly be noticed in your fertilizer bill.
Fig. 1. Nitrogen deficiency due to a faulty fertilizer applicator. Areas of stunted growth are relatively large and plants in the deficient areas appear more uniform than under S deficiency. Credit: Cheryl Mackowiak
Fig. 2. Mechanically induced N deficiency (strips of ample growth alternating with growth suppression). Credit: Cheryl Mackowiak
Both, N and S nutrient deficiencies will result in stunted growth, and a yellow color. However, if it is N deficiency, it is more typical that the field canopy will appear uniformly yellow over large areas, or you will observe straight line streaks where the fertilizer truck may have overlapped with the previous pass (Figs. 1 and 2). Upon closer inspection, the lower (older) leaves of N deficient plants will be lighter green or even yellow (Fig. 3).
Fig. 3. Close-up of N deficiency, with older (lower) leaves lighter or sometimes yellow, compared to more recently emerged leaves. Credit: Cheryl Mackowiak
With Sulfur (S) deficiency, the field will have a splotchy or mottled appearance, and sometimes the affected plants are intermixed with healthy looking plants (Fig. 4). Upon closer inspection, the newer leaves on individual plants may be lighter green than the older, or more basal leaves (Fig. 5).
Fig. 4. A small grains study site displaying classic S deficiency symptoms. Credit: Cheryl Mackowiak
Fig. 5. Individually affected plants will appear uniformly lighter green, or younger leaves may be lighter colored than older leaves. A visually healthy plant may grow adjacent to an impacted plant. Credit: Cheryl Mackowiak
Conditions that may lead to S deficiencies include, the lack of at least 10 lbs S, in sulfate form, as part of your fertilizer blend (elemental S will not provide a quick enough response), planting on row crop land, or planting on new land that had been forest or pine plantation (often locations for wildlife food plots). Well-managed pastures are less likely to suffer from S deficiencies, since livestock excreta contributes S to the soil. Not all labs analyze for soil S, so the safe bet is to include a small amount (10 to 20 lbs S/acre) of sulfate S in your fertilizer blend. Check the fertilizer label if you purchase bags, or make the request when you hire custom fertilizer spreading. If you have to apply the S fertilizer yourself (small areas), you can purchase SulPoMag, potassium sulfate, calcium sulfate (i.e., gypsum), or magnesium sulfate at many feed and seed stores. Remember, cool-season legumes (clovers, vetch, peas, etc) benefit from 20 lbs S/acre fertilization, as well!
For more information related to this subject, use the following UF/IFAS publication links:
Jose Dubeux and Liza Garcia, University of Florida – North Florida Research and Education Center
Figure 1. Honeybee on white clover at UF-IFAS Citra. Photo credit: Jose Dubeux
Improved forages are not only good for livestock, but they can also help feed bees! Managing grasslands to enhance bee habitat requires similar management practices to those needed to enhance pasture for grazing livestock. Diversification of pasture species, management to increase the flowering period, and proper grazing management (no overgrazing) are key practices to enhance habitat for bees (Figure 1), and other native insects that also provide plant pollination. These practices are also important to improve livestock performance and sustainability of grasslands.
Bees are the primary pollinators and they benefit 1/3 of the world’s crop-based production. Bee populations are declining, affecting plants that rely upon them. Reasons for bee decline are diverse, and include land-use change leading to loss and fragmentation of habitats, agriculture intensification, pesticide application and environmental pollution, decreased resource diversity, alien species, the spread of pathogens, and climate change.
Both livestock and bees benefits from forage legumes. Cattle perform better on grass-legume mixtures compared to grass monocultures, because of the greater digestibility and crude protein found in legumes when compared to grasses. Legumes also add nitrogen to pastures via biological N2-fixation (BNF), enhancing forage productivity, and ultimately, stocking rate and gain per area. Bees benefit from legumes because of the flowers they feed on (Figures 2 and 3). Bees do benefit from grass flowering as well, however, diversifying the forage species also improves bee diet, providing opportunities for selection and improved nutrition.
Figure 2. Bumblebee on Crimson clover at UF-IFAS NFREC in Marianna. Photo credit: Jose Dubeux
Figure 3. Bumblebee grazing on crimson and white clovers at UF-IFAS NFREC in Marianna. Photo credit: Liza Garcia.
At the UF-IFAS North Florida Research and Education Center in Marianna, researchers are assessing the bee population on grass monocultures and grass-legume mixtures, under grazing conditions. For the grass-legume system, they are evaluating a bahiagrass-perennial peanut mixture during the warm-season, overseeded with rye, oats, and a blend of crimson, red, and ball clovers in the cool-season. The grass monoculture system they are comparing is bahiagrass during the warm-season, overseeded with rye and oats during the cool-season. Over the last two years, they have been putting out traps for 24 hours and collecting bees every 28 days in these contrasting grazing systems (grass vs. grass-legume pastures). Thirteen bee species were already identified, including 11 native bee species. Native bees are extremely important, since they are generally better pollinators than honeybees. Wild native bees are mostly pollen collectors and help pollinate many of our agricultural crops, maintain productivity, and plant diversity. Adding forage legumes increased the flower density (flower number per unit area). As a result, some of the bee species occurred more frequently in the grass-legume system as compared to the grass monocultures (Figure 4).
Figure 4. Number of Melissodes communis per trap in grazed paddocks of grass monoculture and grass-legume mixtures.
Figure 5. Honeybee on perennial peanut flower. Photo Credit: Jose Dubeux.
Take home message
Bees and livestock might have more in common than you think! They both need a diverse forage diet, so adding forage legumes to the pasture benefits bees and livestock. Adding forage legumes extends the flowering period benefiting native bees. Legumes enhance cattle performance because of greater nutritive value. Enhancing bee habitat will also have a positive cascade effect on crop pollination over the long-term, enhancing crop productivity as a result. This win-win situation also benefits the environment. Cool-season forage crop planting time is here, so this is a good opportunity to integrate clovers into your grazing system. Perennial Peanut is the most productive warm-season perennial legume for Florida. Researchers at UF/IFAS are developing techniques to integrate perennial peanut into bahigrass pastures as well. The investment to add legumes into your grazing operation is worth making just for the improved animal performance, but it will also enhance the habitat for pollinators that are so important for the environment and our food systems.
More information related to this topic:
Useful information is provided on every bag of certified seed. Make sure you know what you are buying by reviewing the seed tag before making the investment. Photo credit: Doug Mayo
Fall is here so it is time to prepare for winter grazing. Once you determine the variety(s) you will be planting (2017 Cool-Season Forage Variety Recommendations for Florida), the next step is to order and purchase the seed. However, not all seed is equal. While most cattlemen are familiar with reading feed tags, you may not be as familiar with the information provided on the tags of seed bags. Just as the feed tag provides vital information about the product in the bag, so too does a seed tag. Like many other purchasing decisions, it is important to know the details before you make the purchase.
Many legumes seeds are bagged with a coating that contains the correct inoculant for that variety. Based on the information provided on this seed tag, only 25 lbs are actual seeds. Credit Dr. Jose Dubeux
The following are commonly found on all certified seed tags: Name, Lot Number, Purity, Other Crop, Inert, Weed Seed, Noxious Weeds, Germination, Dormant or Hard Seed, Total Viability, Origin, Date Tested, Net Weight, and the Name and Address of the Seller. Full definitions of these can be found in the NRCS Factsheet: A Guide to Understanding Seed Tags. Most of these components are easily interpreted, however there a few key points to keep in mind:
- Purity, inert, other crop and weed seed are reported as a percentage, while noxious weeds are reported as total number of weed seeds per pound of seed.
- Total Viability is the combination of immediate and dormant or hard seed germination. Example: if germination = 76% and dormant = 6%, the total viability would be 82%. This means that the vast majority of the seed will germinate right away, but a small percentage will sprout some time later. The hard seed provides some insurance of a stand, if conditions immediately after planting become unfavorable.
- If other crop is over 5%, the crops it contains must be listed on the tag.
- The Test Date gives you an idea how fresh the seed is. The Southern Seed Certification Association requires retesting of germination and purity for re-certification of seed carried over from the previous season.
Keep in mind that state law requires each bag of certified seed to be tagged, and include a lot number. It is a great practice to save at least one seed tag for your records until the end of the growing season. This allows for traceability of the seed, if there is a major stand issue, or a question about the crop that was planted.
More information on seed certification standards and procedures, and the noxious weed list can be found in the following fact sheet: