This one comes from the results from our first soil tests:
On November 22, extension agents Mack Raper and Creig Kimbro from the Soil Conservation District visited the future pasture site to assist with some soil sampling. We divided the 67 acre area into three parcels. Here is the basic methodology we used.
We split up into 2 groups to cover more ground, Mack went by himself and I went with Crieg. We each carried a soil probe for collecting the soil.
After pushing the probe into the ground, the collected column was extracted. The upper and sections of the column were discarded to give us a better rating on the majority of the soil. The middle section of each column was then put into a bucket. For each parcel of the property, between 20 and 40 samples were put into the buckets. The clumps of soil in the buckets were then broken up manually and mixed thoroughly. The well mixed soil was then poured into a box that had been specifically crafted for this sampling technique. We ended up with 1 of these boxes for each of the three parcels of the property. The boxes were labeled and mailed to the Soil, Plant and Pest Center of The University of Tennessee in Nashville. A few days ago I got the results in the mail.
Here they are:
Zones
|
Water pH
|
Buffer Value
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P (phosphorus)
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K (potassium)
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Ca (calcium)
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Mg (Magnesium)
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1
|
5.0
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7.4
|
4 L
|
36 L
|
126 S
|
21 D
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2
|
5.0
|
7.4
|
5 L
|
44 L
|
161 S
|
26 D
| ||||
3
|
5.0
|
7.3
|
3 L
|
32 L
|
260 S
|
25 D
| ||||
Recommended applications of Nitrogen/Phosphate/Potash (N/P2O5/K2O): 0/90/90 lbs/acre
L = Low
S = Sufficient
D = Deficient
Because we will be growing plants that are referred to in the literature as Native Warm-Season Grasses (NWSG), our recommendations pertain to those particular species. Please see the earlier blog post on NWSG for details, but here is a list of the 5 species generally used in these plantings:
Switchgrass (Panicum virgatum L.)
Indian Grass (Sorgastrum nutans L.)
Big Bluestem (Andropogon gerardii Vitman)
Little Bluestem (Schizachyrium scoparium (Michx.) Nash)
Eastern Gammagrass (Tripsacum dactyloides L.)
I will briefly go through some of the parameters mentioned in the table above.
Water pH: This test is specific to the pH value of the water in the soil that is directly available to the plants. It is sometimes referred to as “active” acidity (vs. “stored” acidity, which I will explain next). The “H” in pH stands for Hydrogen, the most abundant element in the Universe. Hydrogen is the 1st element on the Periodic Table in Chemistry as it contains only one Proton and a corresponding single Electron. Not being an isotope, Hydrogen also contains a single Neutron. Thus, it is the most fundamental element. Water is generally thought of as 2 Hydrogen atoms combined with 1 Oxygen atom, the molecule H2O. When this rule is absolutely true in a sample of water, it is actually referred to as “neutral” H2O. In actuality, water in liquid (aqueous) form is a dynamic combination of H+ ions and OH- (Hydroxide) ions in the entire spectrum of proportions between the 2 ions. If there is more H than OH the solution is considered acidic. If more OH than H, it’s basic. The rating for pH is a 0-14 logarithmic scale with a rating of 7 being neutral – having equal amounts of H and OH. Our given rating of 5.0 means that water in our soil water is about 200 times more acidic than “neutral” H2O. Most plants for which the soil lab gives recommendations need pH to be between 6.0 and 7.0. However, NWSG, according to the literature and unpublished research, do not seem to have affected growth rates under a pH at our level of 5.0. Moreover, it is to our benefit that the soil water is so acidic because the weeds that generally compete with not yet established NWSG will not grow as well. For this reason, it was not recommended by the soil lab to add lime, typically added to raise the acidity of low pH soils, to our soils…Great!
Buffer Value: This value is a bit more complicated and specifically applies to soils that have a pH that is too low to grow recommended plant communities. Because NWSG will grow at the pH of 5.0, this value does not fit into our management plans; so I will not describe it in detail. One thing I will say is that the value has to do with the “stored” acidity and not the “active” acidity mentioned in the above paragraph, meaning that there are other aspects of the soil are holding a certain level of nutrients that, if they were released, could change the pH.
P and K: I’m going to talk about these together since so much of the things I want to say apply to both nutrients. P and K are the elemental codes for Phosphorus and Potassium respectively. These elements, along with Nitrogen, are the most needed and thus limiting nutrients that plants need. The ranges given in the above table for P (3-5) and K (32-44) represent the pounds per acre of these nutrients present in the soil at the time of the sample. All of the values for our project area are low, so it was recommended that we add 90 lbs/acre of each of these two nutrients. P and K can be added at any point during NWSG establishment, but if conditions allow, we might add these nutrients prior to our planned Spring burn. Both P and K are used in a number of ways in plant growth. Both are used during energy transformation. P is particularly important in nucleic acid formation, thus cellular division, thus new tissue growth. P is especially important during the early stages of plant growth, an also important to a plants growing roots. These two mentioned aspects of Phosphorus importance are especially important for NWSG. We need successful and bountiful early plant growth for the NWSG to out help compete with fast-growing weeds. Because NWSG are long-lived, large-rooted perennials, it is important that they develop robust root systems to reach moisture and nutrients deep in the soil. Potassium (K) is important to regulate water, enzymes, and ions (charged particles) in the plants. The details are too detailed to go into here. Nonetheless, plants are dependent on the presence of K. These nutrients are not added in pure form but as molecules – Phosphorus pentoxide or Phosphate (P2O5) and Potassium Oxide (K2O).
Ca: The levels of Calcium in our soils ranged from 126-260 lbs. per acre, which is considered sufficient for growing NWSG. We will not need to amend the soil for this element. Ca plays roles in a plant’s biochemistry as a structural component, an enzyme activator, nutrient transporter, and plays a role in photosynthesis.
Mg: Our levels of Magnesium were considered deficient, with a range of 21-26 lbs. per acre. Being a component of chlorophyll, Mg plays an important role in the production of the energy source ATP (adenosine triphosphate). Mg also assists in the transportation of the ATP molecule in plant tissue. Because we are deficient in this nutrient, we might have to amend our soils appropriately. However, I have not found specifics on this nutrient in the NWSG literature as of yet.
Thanks to Debby Joines (Soil, Plant and Pest Center, Manager), Creig Kimbro (UT Extension Agent), Mack Raper (NRCS, UT Extension), Dewitt Simerly (UT Extension), and Michael Mccord (TWRA Biologist) for their contribution of so much useful knowledge that is helping us to understand the soil aspects of our bison project.
This blog post was also posted on the Cove Creek Farm Blog. If interested, please check it out at www.covecreekfarm.com/news
This was the first post on Native Warm Season Grasses (NWSG):
One of our primary objectives in establishing our bison herd is to simultaneously establish natural habitats for the bison to forage. Bison are ruminants, like cows, having 4 stomachs, but they are obligate grazers. Cows will naturally browse a lot more broad-leafed vegetation than most people would expect. Grazing is an interesting phenomenon from a botanical perspective because it is specific to pretty much one family of plants – the grasses (Poaceae). That being said, Poaceae is one of the most diverse families of plants in the world, 5th most diverse to be exact, with over 10,000 described species.
A physiological difference between the grasses (along with their monocotyledonous relatives) and most other plants is that they grow from the bottom of the plant instead of the top. In consequence, they can be continuously grazed very low to the ground and then bounce right back. Broad-leafed plants grow from the buds that are situated at the base of each leaf. Eat away the buds, and they will not be able to grow the following season.
While planning our pastureland for bison, we are very interested in growing species that are native to our area. There has been much research focused on growing native grasses for forage in our area through the University of Tennessee Extension Agency. Their main research and management focus in the literature has been on species collectively known as Native Warm-Season Grasses or NWSG. There are 5 species that dominate the NWSG literature.
They are:
Little Bluestem (Schizachyrium scoparium)
Big Bluestem (Andropogon gerardii)
Indiangrass (Sorgastrum nutans)
Switchgrass (Panicum virgatum)
Eastern Gammagrass (Tripsacum dactyloides)
These 5 species will most likely be the ones we will be planting in our pastureland.
There are many reasons why NWSG are preferred to non-native forage grasses.
1) They are native. We want to support and establish a native ecosystem for it’s intrinsic and ecological value.
2) They are clumping. The fact that they form clumps instead of spreading means that there is ample room between the plants for small wildlife to move about. These wildlife include rabbits, wood rats, Northern bobwhite (quail), and other birds. Of all the native bird communities in North America, grassland birds are the most imperiled. We want our bison habitat to help struggling bird communities as well.
3) They lack pest problems that often dominate the management of other non-native species.
4) They have local adaptation. Because they are adapted to the local climate they are much less affected by occurrences like droughts than non-native species. Their roots can dig up to 12 foot deep into the soil, tapping into nutrients and moisture that are unavailable to most non-native forage species.
5) They are perennial. Once established, stands can last up to 15-20 years.
6) They grow during the Summer. Most forage growth of non-native forage grasses is during the Spring and Fall months, leaving the livestock without good forage for the warmer months. These early and late growing non-natives are typically referred to as the cool-season grasses. The NWSG not only provide good forage for the Summer months, but ungrazed areas can be hayed to provide food for the remaining, cooler months.
7) They don’t mind poor soil. Being locally adapted, they can handle low-nutrient, acidic soils that are common in our area. These poor soils are especially common in areas where forest cover has recently been cleared. Our plot was cleared last Summer (2013) and has these nutrient-lacking soils. In fact, we are perfectly poised for NWSG establishment, as research has shown that recently cleared areas with low-nutrient, poor soil are the best sites because weeds, and their seeds, have not had time to dominate, and because species that are not adapted to the local conditions have had a harder time establishing themselves.
8) They need less soil amendments. Once again, this is a feature of native species with localized adaptations. As I mentioned above, NWSG roots dig deep into the soil, obtaining nutrients that are unavailable to many weeds. Also, because they are adapted to deal with low soil nutrient and pH, NWSG can out-compete aggressive weeds in these harsher environments.
We are still deciding on the species out of the 5 mentioned that we will be growing. The two species of Bluestem and Indiangrass are generally grown together as a community. Both the Gammagrass and the Switchgrass are typically grown as single species monocultures. The reasons for this difference are two-fold. First, the equipment used for planting the seeds is different. For example, Eastern Gamma is planted with a corn-planter, which will not work with any of the other seeds. The second reason is that both the Gamma and the Switch will outcompete and shade-out the Bluestems and Indian. Though we still have some considering to do, the ecological benefits of the Bluestem/Indiangrass community seems a more robust option than the monocultures of either Switchgrass or Eastern Gammagrass.
This post is also posted on the Cove Creek Farm blog. Please check it out if yo are interested.
http://www.covecreekfarm.com/news/
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