Is It Time to Consider Agro-forestry Practices?
Oct 26, 2018
Back in the 1930’s, farmers in the Great Plains were encourage to incorporate trees in the form of windbreaks and shelter belts on their farms, to reduce the wind-driven erosion that was devastating the countryside in the years-long natural disaster known as the Dust Bowl. The shelter belts constructed near waterways, featuring trees, shrubs, and grasses, also helped to address water quality by filtering groundwater runoff, even though it was not a primary program objective at the time. One of the main responsibilities of the young men and women employed under the Civilian Conservation Corps (CCC), established by President Franklin D. Roosevelt in 1933, was to plant trees on public lands in the states between Oklahoma and Montana that bordered streams and rivers. By the time the project was completed in the 1940’s, an estimated 220 million trees had been planted, some of which still survive today. My grandparents’ farm in southwest Iowa had a row of majestic willow trees near their home when they sold it in the early 1980’s, which likely were planted to serve as a windbreak decades earlier.
At the time, few American farmers thought of their trees as part of an agro-forestry practice, but now ecologists and scientists view windbreaks and riparian shelterbelt buffers as key pieces of the suite of agro-forestry practices used commonly around the world to both protect natural resources and enhance farm income. Agroforestry has long been used in Asia, Central America and parts of Africa, where some trees were left in place to provide shade for other crops such as squash or maize, and generate additional plant residue to keep the soil fertile. The trees themselves can also be a source of income, especially if they bear fruit or nuts which can be harvested and sold over a period of many years.
In addition to shelterbelts/windbreaks, other key agro-forestry practices include silvopasture, in which livestock graze on grass under a canopy of trees, alley cropping, under which rows of trees are planted with wide spacings with a companion crop grown in the alleyways between the rows, multi-story cropping, where existing or planted stands of trees or shrubs are managed as an overstory with an understory of woody and/or nonwoody plants that are grown for a variety of products, particularly horticultural crops. Restoring or renovating windbreaks established in earlier decades is also considered to be a critical agroforestry practice.
All of these practices are included in the NRCS National Handbook of Conservation Practices (NHCP), and at least one of them is eligible for adoption under the two major working lands conservation programs, the Environmental Quality Incentives Program (EQIP) and the Conservation Stewardship Program (CSP) in each of the 50 states. Between 2009 and 2017, farmers enrolled in EQIP installed these practices on the following numbers of acres:
- Windbreak establishment-222, 385
- windbreak/shelterbelt restoration-55,970
- Riparian forest buffer-12,432
- Alley cropping-694
By contrast, conservation practices such as residue management (including no-till cultivation) and integrated pest management (IPM) have been installed on 6.2 million and 4.7 million acres under EQIP respectively over the same period. Clearly, agro-forestry practices have not yet been widely embraced by American farmers.
In the face of climate change and stagnant agricultural productivity in much of the developing world, agro-forestry practices are being strongly promoted by the development NGO community and their governmental partners as a way for small-holder farmers to diversify and improve their farm incomes while preventing deforestation and pulling carbon dioxide out of the atmosphere. A 2010 study reported in the journal Advances in Agronomy found that while the amount of carbon that can be stored in soil depends on silt and clay content and soil quality, long-term agroforestry systems tend to store equivalent or higher amounts of soil organic carbon (SOC) than neighboring natural forests.
In a recent study by a professor at Illorin University in Nigeria, 200 farm households in north central Nigeria were surveyed to evaluate the impact of their adoption of agroforestry practices. In the study, 70 percent of the households had adopted at least one such practice, and such adopters had experienced significantly higher productivity growth in recent years than non-adopters in the same region. One of the factors that the study found discouraged adoption of agroforestry was the weak land rights available to farmers in the region.