Agroforestry: The future of a hybrid practice

The first day of the workshop, held at the Russell E. Larson Agricultural Research Center, was led by Eric Burkhart, Plant Science Program Director at Shaver’s Creek Environmental Center.  Here are some of the concepts presented by Burkhart.

Agroforestry is the integration of row crops and forest trees and sometimes even livestock into one ecosystem. Although this idea is far from being new, it is not as radical as some may think. From pest control to energy conservation and overall environmental health, there are a wide range of benefits that come with agroforestry.

One agroforesty practice is riparian forest buffers.  Riparian forest buffers allow vegetation to establish along waterways to ensure a structurally sound bank.  These buffers also can filter out nutrients and sediment in runoff from adjacent fields, protecting water quality. Generally, the wider the buffer, the better, but finding a balance between a growing a healthy buffer and reserving land for harvestable crops is necessary.

Another form of agroforestry, called silvopasturing, is the integration of livestock and tree production.   Livestock graze on forages growing under the canopy of the trees.  Silvopasturing can improve the overall health of the animals by placing them in a more comfortable environment. Farmers practicing this in the southeastern United States have been finding that using the right mix of tree species and livestock species is necessary.  Do your homework to understand which species of trees grow well together and which allow for animal grazing.  Although providing shade and a more inviting environment for livestock is certainly a benefit, researchers have not determined if there are any benefits to the tree crops.

Windbreaks are another way to utilize agroforestry. This is a practice where forests are established to modify the wind flow and microclimate to surrounding harvest fields and land. Most times, these are seen as borders along plots of land. Although they look like property lines, they have many more applications such as pesticide barriers, snow fences, and even odor-drift barriers. Usually a minimum of three rows of different tree and shrub species are used to gain maximum control of wind on fragile crops. The three row minimum may threaten the land space otherwise used for extra rows of crops, but most farmers agree that the net benefit of higher quality crops without wind damage outweighs the loss of shaded crops right next to the windbreak.

Alley cropping is yet another form of agroforestry.  In alley cropping, tree crops are planted in a wide row spacing so that annual crops can be planted in the alleyways between the trees. It is most commonly practiced with fruit trees or among vineyards to maximize the crop output for the land, but sometimes crops are simply planted in existing forests. Orientation must be intentional in order to allow for enough sunlight for both the trees and crops.

A final type of agroforestry is forest farming, which is when specialty crops are introduced and husbanded in forests.  This is more or less taking advantage of what naturally grows well in a forest environment and harvesting it for profit. Mushrooms, sugar maples, ginseng, and goldenseal are all examples of profitable crops that can be found naturally or cultivated in forests.

One project that was featured in the afternoon session was the use of agroforestry techniques to reduce emissions from poultry houses.  Dr. Paul Patterson, Professor of Poultry Science, has found that densely vegetated windbreaks situated downstream of poultry house ventilation fans can scrub ammonia out of the air and can prevent dust, odor and even virus particles from polluting the air too. (See http://www.lancasterfarming.com/news/southeedition/Odor-Eaters for a more detailed story).

As you can see, this daughter of agriculture and forestry has many practical uses. Agroforestry as the integration of row crops, forest trees and livestock seems so natural that it is curious as to why it hasn’t been implemented since the beginning of the agricultural revolution. But inefficiency and time loss are two factors that have to be overcome before the use of agroforestry will be widely adopted.  However, by introducing the idea and sharing successful strategies, workshop organizers hope this naturally logical practice will quickly catch on.

By Sydney Laudenslager, Agricultural and Biological Engineering Department