Agroforestry may be easier to explain if we begin with forestry. Forestry is essentially the cultivation of trees for timber harvesting. On many timbered lands, it is frequently the sole enterprise.
Agroforestry, on the other hand, is the cultivation of trees in conjunction with other types of agriculture, such as pasture or crops. Agroforestry has numerous advantages over using land for a single purpose, whether it is forestry, livestock, or crops.
Advantages of agroforestry
The vegetation can capture sunlight over multiple layers and for a longer period of time, resulting in increased productivity and, ultimately, better soil.
Tree canopies can shield underlying crops and animals from the sun and wind.
Tree roots and herbaceous plants beneath can work together to reduce soil erosion caused by wind or water.
Increased plant diversity can reduce the risk that a disease or insect will wipe out the entire crop. At the same time, that diversity will attract a wider range of benign insects, which in turn will attract insect predators, which will control future pest insects.
The risk of a single enterprise experiencing low prices is reduced; the portfolio will be more balanced.
When compared to forest, grass, or cropland, the diversity of crop roots, as well as the extended duration and increased rate of photosynthesis, can improve the rate of carbon sequestration in the soil.
Types of agroforestry
Riparian buffers save soil by protecting the banks of streams and rivers from soil erosion. They also reduce pollution in water from soil particles, pesticides, and fertilizers. To fully protect soil and water, a properly designed riparian buffer should include trees, shrubs, and herbaceous vegetation.
You can choose tree species that produce a harvestable crop, such as maples for syrup or walnuts or pecans for nuts and timber. Riparian areas are home to many high-value trees, including black walnuts and pecans.
Windbreaks are useful in a variety of ways, including protecting homes, crops, and livestock. The location, spacing of trees, and a number of rows vary according to the intended purpose.
Home protection – Windbreaks can trap snow, reduce wind velocity around homes, and lower home heating costs in areas with cold winds and winter snow.
Animal protection – Windbreaks for livestock can significantly reduce winter feed requirements, improve comfort, and reduce animal mortality from blizzards. Make them perpendicular to the prevailing winter winds and on the animals’ windward side.
Crop protection – Windbreaks are typically placed on the windward side of prevailing hot summer winds for crops. Trapping snow is sometimes necessary for increasing moisture supply; for this, construct windbreaks on the windward side of the prevailing winter winds.
Forest farming refers to the cultivation of crops that thrive in a forest environment. Maple syrup is a well-known high-value forest product.
Many other trees, including birch, sycamore, walnuts, and hickories, can be tapped for sap that can be boiled down into syrup, each with a distinct flavor.
Other forest crops include medicinal plants like ginseng, black cohosh, and goldenseal, mushrooms like shiitake, and fruits like pawpaw and currants. Truffles are an extremely valuable underground fungus.
Alley cropping, which is common in tropical areas, is the practice of planting widely spaced rows of trees with rows of crops in between.
To protect small trees that can’t withstand livestock browsing or rubbing, it can be a long-term strategy or a transitional stage into silvopasture.
Alley cropping can benefit row crops by shielding them from wind, especially in areas where crop sandblasting is common due to windblown soil or where evapotranspiration is high due to frequent strong winds.
Alley cropping in tropical areas consists of leguminous tree rows alternated with annual crops. After the crop is established, the farmer cuts the tree branches and uses them as mulch between the crop rows to protect the soil and release nitrogen as it decays. This is an effective practice in areas where nitrogen fertilizer is expensive and difficult to obtain.
Alley cropping also provides numerous land management benefits. The basic configuration, a “corrugated canopy” of alternating tall trees and short crops, efficiently captures sunlight for high biological productivity.
Ground-level (often annual) crops produce quickly and help the land provide immediate returns, whereas trees are a long-term crop that may take several years to become profitable. Other advantages include livestock shade, windbreak capacity, and increased biodiversity.
Advantages of silvopasture
Silvopasture, which combines trees and pasture, resembles a savanna, an ecosystem that produces more animal biomass per unit of land area than any other on Earth. (The remaining African savannas support spectacular animal populations.)
A silvopasture can be created by incorporating trees into a pasture or by incorporating herbaceous vegetation (grasses, legumes, and forbs) into a forest. A silvopasture’s incredible potential productivity is due to a number of factors.
Together, trees and pasture can capture more sunlight than either can alone.
A field of evergreen pine trees with a warm-season grass understory, for example, will photosynthesize at a high rate both in summer (due to the efficient photosynthetic capacity of warm-season grasses) and in winter (due to the pine trees that retain their leaves or needles in winter).
A mix of deciduous trees and cool-season grasses takes advantage of the trees getting first use of the light in the summer, with shade-tolerant grasses beneath. During the winter, when sunlight is less direct and available, the trees shed their leaves, allowing more light to reach the grasses.
Animal population increase
Silvopasture can protect animals from extreme heat and sun in the summer, as well as wind in the winter.
According to research conducted in Kentucky, shade can significantly improve animal performance in humid areas during the summer, increasing average daily gain on beef steers by 1.25 pounds of live weight.
Furthermore, wind protection can improve animal performance in the winter. In the fall, specific tree species can provide dropped leaves, fruit, or nuts as supplemental livestock feed.
A wide variety of plants can provide numerous benefits:
- Diversity reduces disease and insect pressure on a single plant species.
- Returning roots, root exudates, and vegetative material to the soil promotes soil development and productivity.
- Woody debris and fallen leaves are especially beneficial to the development of soil fungal populations, while herbaceous perennial plants are also extremely beneficial to the soil.
- A mixture of grasses, legumes, forbs, and trees can build soil much faster than any of the individual components.
Some tree species, such as oaks and pines, host ectomycorrhizal fungi, which differ from the endomycorrhizal fungi that most herbaceous plants host; the former can bore into the rocky soils that characterize many pastures and extract water and nutrients from them. This explains why oak and pine trees dominate many rocky areas.
The cycling of nutrients extracted from needles, leaves, and acorns can help enrich soils beneath them, benefiting other plants.
How to manage a silvopasture
Silvopasture management necessitates more thought than most land uses because it must consider the needs of pasture, trees, and animals. This requires more careful planning, closer monitoring, and ongoing maintenance.
Animal protection for trees
When trees are small, protective structures may be required to keep animals from browsing and rubbing on them. Rotational grazing may also be necessary to protect trees and tree roots. Incorporate tree lines into paddock subdivision electric fence lines to manage the fencing and reduce livestock eating and rubbing on trees.
Select shade-tolerant forages (that are fairly non-competitive with the trees). Eastern gamagrass is more shade-tolerant than most other warm-season grasses.
Virginia wild rye is shade-tolerant among cool-season grasses, but it may be less productive than other species, such as low-alkaloid reed canarygrass or orchard grass.
Kura clover (or AberLasting clover, a hybrid of Kura and white varieties) is a standout legume, as is the subterranean clover.
Plant species that are competitive must be controlled
Tall fescue and smooth brome are notorious for competing with trees, especially in their early stages of development. This is not to say that these species cannot be used in a silvopasture. In fact, they may offer advantages that other forage species do not, but they must be managed.
Maintain a grass-free zone around the tree bases, for example, or plant shallow-rooted white clover (or currants, ginseng, or goldenseal) for a higher-value, shade-tolerant crop.
If the landowner is not allergic to herbicides, grass can be selectively removed from broadleaf plants or legumes using the herbicide Clethodim.
How to make your own silvopasture
If you want to plan your future silvopasture farm, which will include three distinct pasture types, here are my suggestions. You can use these plans to get ideas for your own silvopasture.
Silvopasture for the warm season
With a willow and mulberry overstory, the understory would be dominated by Eastern gamagrass, alfalfa (lucerne), chicory, plantain, Maximillian sunflower, Korean lespedeza, crabgrass, and a slew of other native warm-season grasses, wildflowers, and legumes.
The grasses would provide summer grazing for livestock, while the high protein willows would provide browse and pick up the slack in late summer as the grasses’ productivity declined.
The trees would be planted north-south so that the prevailing summer wind could blow between them and provide shade all day.
Mulberries would provide pigs with summer fruit and excellent browse for beef animals. Other summer fruits, such as gooseberries, currants, goumi, Lodi apples, apricots, and wild plums, could help the pigs extend their fruiting season.
Silvopasture for the winter
To block the cold north wind, friendly endophyte tall fescue, red clover, bird’s-foot trefoil, and small burnet — all of which retain their quality well into the winter months — would be planted under east-west lines of pines. Winter-hardy bamboo and shrubs with winter leaves, such as four-wing saltbush, could also be included.
Widely spaced, thornless honey locust trees would produce high-sugar pods that would survive the winter with little deterioration, providing a high-energy supplement for wintering cattle. Plant blocks of pines in the southeast corner of each paddock would provide blizzard shelter.
Silvopasture for the spring-fall
A blend of cool-season grasses, forbs, and legumes, such as low-alkaloid reed canarygrass, meadow brome, orchardgrass, smooth brome, red clover, white clover, alfalfa, bird’s-foot trefoil, chicory, and plantain would be planted under a diverse blend of oaks and chestnuts for high-carb nuts, as well as hazelnuts, walnuts, and pecans for high protein.
For high-energy fruits, additional trees could include autumn olives, apples, pears, and persimmons.
This field can be pastured primarily in the spring and fall, with plenty of pig food and fruits for cattle in the fall. The leaves of deciduous trees will supplement the cattle feed supply in the fall.
These three pastures provide nearly year-round grazing for cattle, even when there is heavy snow cover, as well as fruits and nuts for pigs (or poultry). There will be no diesel, no fertilizer, and no work other than that done by cows and pigs. The entire farm runs on sunlight, and the soil improves year after year.