Alley cropping is known to be one of the methods of farming wherein the various trees are placed in wide spaces. In between, the trees are various crops.
Doing this has shown some benefits such as the following: the production of crops have been greatly improved; farm income has diversified as there are different trees, shrubs, and crops that can be great sources of income for the farmer; certain crops, especially those that are more sensitive can be protected because of the trees.
Alley cropping will allow more fragile crops to be placed in between the trees so that they can grow and flourish in spite of the harsh weather conditions that they may face.
In agroforestry, when lines of trees are planted room is left for compatible plants to be grown. These will improve the soil, providing nutrients for the trees, especially valuable nitrogen. You can regard the lines of plants between the lines of trees as 'alleys' and this is what alley cropping means- the cultivation of food, forage or specialty crops between rows of trees.
It is a larger version of intercropping, which is a similar planting of compatible plants between trees, but conducted over a longer time scale. Alley cropping provides profitable opportunities for farmers, not just for their crops, neatly in rows, but for growers of hardwood timber, nuts and Christmas trees.