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Planning the Design of Alley Cropping and Its Benefits

Imagine a farm where trees are integrated into the crops and are considered just as important as the annual crop, if not more important. An impossible scenario? Not with alley cropping. In this agroforestry practice, trees and crops are integrated into a farming operation to create a diversity of income sources. Alley cropping is broadly defined as "planting rows of trees at a wide spacing which creates alleyways where agricultural forage or horticultural crops can be produced." Alley cropping provides a variety of benefits to farmers.

Some of the benefits of alley cropping are we get annual income off the ground while the trees are getting established. Also, we see a lot of wildlife out here with the trees – while those crops are growing we see deer, turkey, and quail utilizing this ground and the trees.

There are four benefits to alley cropping

  1. The diversity enhances or adds income to your practice
  2. Alley cropping improves crop product as trees contribute organic matter
  3. In alley cropping, trees create a windbreak that can protect crops 
  4. Alley cropping provides conservation benefits. In order to receive the benefits you desire from an alley cropping practice, thought should go into the design.

Planning the design of your alley cropping practice starts with

  • Identifying your production objectives;
  • Determining tree spacing;
  • Orienting your rows to obtain maximum sunlight; and
  • Creating a maintenance plan

The design of an alley cropping practice begins with identifying your objectives. Are you implementing an alley cropping practice to grow timber, nuts, or other products? For erosion control or to provide more wildlife habitat? Your objectives will determine how you plan your alley cropping practice.

Tree spacing is critical if you want to use trees to control erosion, trees within the rows need to be close together for a more immediate effect. Trees grown for timber may also benefit from closer spacing so they grow straight with less branching. However, for the best nut production plant trees on a wide spacing. This allows for the development of a full broad crown how closely you plant these rows of trees will be determined by the crop you want to plant in the alley. If you want to grow a sun-dependent crop or forage, you need wider spacing, because as the trees grow, the crowns get larger and begin to shade the alley. The more narrow the alley, the faster the tree canopy will close over it, creating shade. Once the alleys are fully shaded, you may have to shift to a more shade-tolerant crop or forge. Your equipment may also dictate the widths of your alleys. You will want to make full passes up and down the alleys during planting and harvesting.

Another factor to consider is orientation of the rows. That is, what direction do they run? To take full advantage of the sunlight, usually east-west is most desirable. However, if you have hilly land, planning on the contour will help prevent erosion.

Trees will also require some maintenance:

  • Weed control. Especially in the establishment stages, to give the seedlings a better chance to compete. This is most commonly done using an herbicide around the tree base before the buds break dormancy in the spring.
  • Fertilization. If you are growing your trees to produce nuts such as walnut and pecans, then fertilization is a very important part of the maintenance process. If you are growing trees for timber production it may be less important but can still be very beneficial.
  • Pruning. When pruning for nut production, prune just high enough for your equipment to pass below the large crown. However, if you're a growing trees for timber, you will need to prune to a greater height to produce a high-quality saw log. 
  • Thinning. How much you thin the trees and an alley cropping practice varies with species, site conditions and management objectives. However, since growing low quality wood is not a goal in alley cropping, timely thinning is critical.

Once you have a design for your alley cropping practice, you need to decide on the tree species best suited for your objectives and for the site conditions. When deciding on what trees to plant, ask yourself. The following question what trees do well in my area consider growing conditions such as soil and climate as well as the potential markets for your product. Ideally, the tree species you select should be marketable. This includes both the wood itself and other products such as nuts or fruit which would give you another source of income. The trees should also be compatible with the companion crop or forage you choose. Some trees produce growth inhibiting chemicals which affects what you can grow.

It is also important that the trees be high quality and fast growing or of such high value that a medium growing species is acceptable. Another consideration is the trees be deep-rooted so that they don't compete with the crops or forage for moisture.

Site tolerance, or how well a tree is suited to either a wet or dry site, needs to be taken into account.
Ideally, the leaves should produce a light rather than a heavy shade. This will be especially important as the trees mature and the canopy closes: the light of the shade that is produced, the longer you can grow crops or forages.

And finally you need to make sure that the trees are capable of providing the products you desire. For example, if you plan to grow trees for nut production, in most instances you will be using grafted stock.

The choice of companion crops varies, depending on the type of trees selected. There are five major groups of crops that can be grown in any alley cropping practice.

  1. Cereal or row crops. 
  2. Forages
  3. Specialty or medicinal crops
  4. Horticultural crops
  5. Biomass crops.

Alley cropping is a useful practice for farmers seeking income diversity and conservation benefits. Income is provided in the short term by production in the alleys. Longer term income is provided by the trees and tree products. Trees also have a positive conservation effect. In other words alley cropping is an ideal practice for production and conservation benefits.