May 10, 2013
Here in the U.S. people call it silvopasture when they graze under the forest canopy, and where the forest is not edible but for wood.
Edible silvopasture is where the cows graze the trees (edible trees are planned for) and we have trees for shade, fodder, microclimate, temperature equilibrium, recycling of nutrients, reducing evapotranspiration, drought reserve, nitrogen fixing, windbreaks and other benefits.
Trees are an essential part of a ranch/pasture and their value has been largely underestimated by ranchers.
On my ranches in Mexico I developed a no-till way of planting the trees which you will see in the pictures which accompany this story. They are Leucaena leucocephala trees on bermudagrass pasture. The leucaena are planted 5.5 feet apart with one row allowed to grow into trees for shade every 100 feet. The rest are kept relatively short to add to grazing quantity and quality.
At work: Elizondo's tropically adapted Mexican dairy cows graze both trees and grass in a high-stock-density rotation.
The protein content of these trees is around 24% and they have high digestibility for their environment, making this the highest-producing pasture per acre for pounds of beef produced in the world. It has an average daily gain over two pounds per animal per day and with stocking rates of up to three steers per acre.
With the inclusion of Leucaena into my common bermudagrass pastures total forage production (carrying capacity) went up to around double and the milk production went up around 40% per cow without any fertilizer and with much less irrigation.
I like to graze these silvopasture paddocks in a leader-follower way, with the dairy cows as leaders and dry cows as followers.
In a real silvopasture the air temperature difference on a hot day is up to 20 degrees lower, compared with the temperature just a few feet away where there are no trees.
In cold weather it would be the opposite: warmer near the trees and colder farther away.
This is very valuable for the comfort of cows and humans.
For shade you need five to 30 big trees per acre besides the windbreak rows, depending on the size and species of the tree.
For edible silvopasture you need around 30,000 grazeable trees per acre, managed like brush. They are planted very densely and the stems stay thin so they are easy to cut with a rotary mower anytime it is needed, which is around every two to three years in my environment in Mexico.
Here's how I established Leucaena leucocephala on my ranches in Mexico.
They should be planted by seed as to be economical and feasible. Here's how I prepare the grassland before I plant them.
First step is to cut or graze the grass as short as possible to weaken the stand.
Second step is to use the keyline plow to aerate the soil where the seed will be planted every 5.5 feet.
Third would be to set back the bermudagrass with close grazing or round up.
Fourth would be to plant the seed with a normal no-till planter.
Fifth would be to control the bermudagrass for three months so the little seedling can establish. Normally I did this with a weed cutter powered by gasoline motor and some Fusilade herbicide. Use a low concentration of the herbicide. This is the most important step because if the bermudagrass gets higher than the seedlings it will be a failure.
After three months the trees will be high enough to stop controlling the bermudagrass and when they reach six to eight feet tall we start grazing.
This planting is expected to last 30-50 years and as the roots touch underground the mycorrhiza and nitrogen-fixing bacteria benefit the bermudagrass as well as the trees.
Moisture evaporation is reduced with the dense canopy and irrigation needs are much lowered by at least half.
Since this species produces a diffuse shade the bermudagrass grows very well under it and becomes more palatable, with lower fiber and higher protein. When there is too much shade the energy of the grass goes down and energy is sugar. Cows don't like sour grass.
Also, horn fly problems were reduced to almost nonexistent by the birds and microorganisms attracted by the microenvironment.
No fertilizer has been used and it doesn't seem we will need it.
I try to not use any chemicals but the herbicide is essential at establishment. Since this occurs only once in 30 to 50 years it should not be a big problem.
I have to mention I also used the keyline plow for the first two years after establishment to help the roots go deeper. After two years the change in the color of the common bermudagrass was noticeable due to the 300 pounds of nitrogen fixed per acre per year.
The planting of any leguminous tree for grazing on the whole ranch has to be done in stages as you cannot put your cows there till the trees are established and it will take from six months to a year.
It's very important the roots of the leguminous trees touch in between the rows so that the full benefit is realized for the grass from the mycorrhiza and nitrogen-fixing rhizobia in the soil.
Mycorrhiza, which is the symbiotic relationship of plant roots, helps the grass roots access more moisture and nutrients through shared nutrients with the trees.
You need to have a complete rotation, meaning enough area or acreage, of the Leucaena trees so the cows and their rumen bugs won't be without the Leucaena forage because it takes about two weeks for them to get used to it.
Once they get used to it they love it! But if you go on and off they will never get adjusted, as it contains mimosine, which is detrimental. However, there are rumen bacteria which degrade it into a non-toxic compound. By the way, it is a native bacteria in Mexico but was "discovered" in Hawaii some 30 years ago, so it may be more widespread than once thought.
In my pictures of before and after grazing you can see the 100% defoliation on the Leucaena trees. We come back for grazing in 35 days in summer and up to 65 days in winter. After the milk cows take the best we follow up with the dry cows to take the common bermudagrass down as in that environment it would hamper future regrowth of the grass if left ungrazed.
You will need to find species adapted to your environment. There are many in all environments.
There are other species like black walnut that would work in more temperate areas. I would love to find them and try them out.
For example, here in Florida I believe we could use Mimosa (Chinese empress) which should give the same production that leucaena does, with more frost tolerance.
Maybe it's time to seriously consider this in the US, of course with adapted species. We should not try to grow what wants to die and not try to kill what wants to live.
Jim Elizondo is a ranch manager and management consultant in Florida. He and Johann Zietsman are teaching courses this summer on sustainable ranching. He can be reached at [email protected] or (832) 776-0886.
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