Paulownia agroforestry

Paulownia agroforestry in France.

Agroforestry. A perfect agriculture.

Agroforestry is an agricultural system on the same land that combines cultivation and/or animal husbandry with trees and shrubs. The resulting biological interrelationships offer many advantages, including diversification of income sources, increased organic production, improved water quality, and enhanced habitat for people and wildlife.

Agroforestry practices currently in use in the United States and elsewhere in the world include alley cropping, silvopasture, windbreaks, shelterbelts, riparian buffers, and forest farming (production of specialized forest products). Below is a brief overview of each of these main systems.

ADVANTAGES:

  • significant climate improvement,
  • temperature reduction of 20% in the shade of trees,
  • complete improvement of previously eroded and depleted soils,
  • emergence of humus in sandy and depleted soils,
  • Diversification of income sources in agricultural production,
  • Rapid recovery of large areas of degraded and dried-out soils,
  • An increase in biological production of 190%,
  • the appearance of moisture and a humid microclimate,
  • improvement of ecology, habitat for people and wildlife,
  • improvement of biodiversity,
  • water retention and use,
  • increased precipitation.

ALLEY CROPPING
Alley cropping involves growing plants (grains, coarse fodder, grasses, vegetables, berries, etc.) between trees planted in rows. That is, between rows of trees, everything normally grown in fields is grown: grains, grass, vegetables, berries.

When crops are grown, this approach is called "wooded"; when fodder grasses are grown, it is called "wooded pasture."

The space between rows is organized to accommodate mature trees, while leaving room for the crops planned in the alley. If light-loving plants, such as grains or grasses, are planted in the alleys, the alley paths must be wide enough to allow light access even when the trees mature.

Unexpected facts about agricultural productivity

Another solution is to plan to change the order of crops and harvests when tree growth reduces light access. For example, soybeans or grains can be grown when trees are very small; as the tree canopy closes in, coarse fodder can be harvested for hay; when trees are mature and the land is shadier, alleys can be occupied by grazing animals or shade-tolerant crops.

As with all complex systems, alley cropping requires skilled and careful planning. Crops and trees have requirements that sometimes necessitate intercropping between them. The design must provide enough space for the machinery needed to maintain each activity.

In most alley cropping systems, trees are planted in straight rows, sometimes without regard to slopes and topography.

Trees are planted in strictly oriented rows, along meridians in the northern hemisphere to minimize shade, and perpendicularly closer to the equator for more shade.

However, there are advantages to planting trees in an arc or along the contour. These include slowing surface water movement and reducing soil erosion. Trees can be planted in single rows or in blocks of several rows between alleys. The first row of a block is planted on the contour line; subsequent rows are planted below the initial line depending on the slope of the terrain. The last row of the block is planted parallel to the contour line where the next tree block will begin. The width of tree blocks can vary, but the boundaries of the alleys where crops are grown are parallel. This arrangement helps prevent the formation of nodal rows in the alleys, thus facilitating the maneuvering of agricultural machinery. The width of the alleys is determined by the size of the machinery.

If contour planting is not feasible, another solution is to plant trees in curved zigzags, so as to capture water flowing down slopes, or at least slow it down. Tree islands will offer some of the same benefits if they do not interfere with agricultural operations.

In some regions, fast-growing hardwoods or pines (auxiliary tree species) are planted as markers to ensure that the main tree species to be harvested develop straight trunks without any branches. Another solution is to plant trees to be felled in more frequent rows, then thin and prune them as they grow. Although these early harvested trees have low market value, their presence during the early years of growth increases the value of the main crop. The goal is to produce long, straight logs with few lower branches to maximize profit from the final harvest. Regardless of how a plantation is designed, trees on the outer edges of groups will develop more lateral branches, or even a crooked trunk, resulting in lower value for sawn timber.

Thinning and pruning trees, as well as debranching and pruning branches and the lower story of branches, increase the soil fertilization process, strengthen the symbiotic relationship (relationship) of trees with bacteria and fungi, and increase nutrient production. Pruned trees have higher photosynthetic efficiency than unpruned trees. Faster photosynthesis means more carbon and more sunlight are consumed, which lowers ambient temperature. A cooler environment means more water.

Calculations also showed that nitrogen and other compound leakage is reduced by 50% compared to a plot of land without trees. In addition, tree roots intercept nutrients not used by field crops, which would otherwise leach into groundwater. Subsequently, the nutrients intercepted by the trees are returned to the soil as fallen leaves.

Fallen leaves from deciduous plants promote the development of fungi (their symbiosis with the root system of plants - mycorrhiza), which significantly accelerates the growth of agricultural plants. Proper tree selection eliminates competition for moisture (this primarily involves choosing species with a taproot or lobed root system). The sunlight in the forest is slightly lower than in open fields, but other favorable factors as well as direct benefits from trees (honey, nuts, etc.) increase the yield of the plot by up to 190% and add diversification in case one of the components does not yield.

The presence of trees multiplies the number of bird species, which are effective in killing harmful insects.

Three species of linden (small-leaved, large-leaved, and Manchurian) and field maple can also be used as trees. These powerful melliferous crops yield up to 1000 kg of honey per hectare in continuous plantings.

FORESTRAINING

Combinations of trees and pastures are called silvopasture. Hardwoods (sometimes walnuts) and/or pines are planted in single or multiple rows, and animals graze between them.

The forest protects animals from wind and the soil from erosion, fertilizes and improves it. In addition, animals have the opportunity to hide in the shade in hot weather, which they are deprived of when grazing in fields. Trees also reduce the number of horseflies, which greatly bother animals (horseflies have visual orientation and dislike shade).
 
WINDBREAKS OR SHELTERBELTS

Trees are planted in single or multiple rows at the edge of a field to reduce the impact of wind on crops or livestock. Windbreaks have been shown to reduce wind forces in the horizontal direction, which is equivalent to at least ten times the height of the trees. Wind and water erosion are reduced, while creating a more humid and favorable microclimate for crops. In winter, windbreaks retain snow, and winter crops or livestock are sheltered from icy winds. Beneficial insects in windbreaks find a permanent habitat there, which strengthens crop protection.

Although trees compete for available water along the boundaries between windbreaks and crop rows, potentially reducing yields next to the windbreak, the net effect on productivity is positive. In fact, even on land well-suited for high-quality crops, windbreaks can increase the yield of the entire downwind field by 20%, even when windbreaks are included in the total cultivation area.

Windbreaks can be specifically designed to shelter livestock. Studies have demonstrated the economic benefits of protection from wind chill, a major stress experienced by outdoor livestock in winter.

Windbreaks help reduce feed bills, increase milk production, and improve calving success.

In addition to protecting crops and livestock, windbreaks offer other benefits. They help wildlife, especially by serving as a long corridor along which animals can move safely.

Windbreaks can be developed into additional income centers: hunting leases, selective logging, firewood trade, and special forest products are just some of the possibilities.

All types of trees can be used as windbreaks. However, deciduous trees, even in multiple rows, will lose their effectiveness as soon as they lose their leaves. For year-round use, some selected species must be evergreen. Fast-growing trees should be included; non-competitive species with deep root systems are best planted along the borders. Regular deep hoeing along the borders will prevent roots from spreading into crop rows. If some trees are regularly felled, new trees can be planted in their place, thus organizing a long-term rotation of the windbreak.

RIPARIAN STRIPS

Trees, grasses, and/or shrubs planted along streams or rivers are called riparian buffers or infiltration strips. These plantings are designed to delay the sliding of soil, excess nutrients, and chemical pesticides on the surface of the earth before they reach watercourses. They also strengthen riverbanks. On arable land where a tile drain is installed to improve drainage, polluted water can flow directly into watercourses. Wetlands organized as buffers can capture and treat this drainage water before it enters the watercourse.

Wooded areas along watercourses meet other community needs largely by storing water and helping to prevent bank erosion, which reduces siltation downstream. These areas also protect and improve the aquatic environment. Shade on the water makes it cooler, which is a prerequisite for many desirable aquatic species. Buffer strips at the same time provide habitats for wild flora and fauna and can be used for special forest products.

FOREST FARMING. OBTAINING SPECIAL FOREST PRODUCTS

When natural forest land is used for both wood products and auxiliary agriculture, it becomes an agroforestry system.

In addition to producing logs and balance wood, forest land can generate income from many other products. Established forests offer many non-timber "special forest products" that provide cash flow without requiring a single harvest of old trees.

The number of products forests can produce is limited only by the imagination of landowners and their ability to identify and tap into this lucrative market. Here are some examples:

  • fruits, nuts, berries,
  • honey and other bee products,
  • mushrooms,
  • herbs and medicinal plants,
  • materials for making baskets or weaving chairs,
  • pine needles, branches, cones,
  • plant materials as dried or fresh ornaments,
  • aromatic substances,
  • fence posts, firewood, wood for smoke,
  • ornamental or unusual forest materials, for example,
  • dyeing substances,
  • tree and shrub seeds, seedlings, and forest residues,
  • charcoal.