In my never-ending quest to figure out ways to help farmers help the planet, I came across this chart:

__2020 Agriculture Practices to Reduce Emissions.png

Alley cropping wins the remissions-reduction prize…but what is alley cropping? Turns out it’s an agroforestry practice that involves alternating field crops with rows of trees or shrubs, like so:

Source: USDA Forest Service

Source: USDA Forest Service

Besides soaking up emissions and storing carbon, alley cropping provides a host of other environmental services, including:

  • Enhances microclimate conditions to improve crop or forage quality and quantity.

  • Reduces surface water runoff and erosion.

  • Improves soil quality by increasing utilization and cycling of nutrients.

  • Enhances habitat for wildlife and beneficial insects.

  • Decreases offsite movement of nutrients or chemicals.

Alley cropping also provides farmers the opportunity to make extra revenue given that tree products like fruit and nuts generally fetch higher prices than many field crops. So why haven’t more US farmers adopted the practice? Short answer: time and money. Consider:

Per the USDA Economic Research Service (September 2020), total median farm household income in 2019 was $83,111 and is forecast to reach $89,674 in 2020.   Assuming an average of 1.5 earners per household, that’s less than the median household income of two dental hygienists -one full-time, the other part-time - earning the median income for their occupation.  

Alley cropping requires a lengthy time period to establish and realize a return on investment.  Trees can take 10-80 years to produce enough fruit, nuts, or timber to pay back the initial investment as well as to generate sufficient profit to compensate for reduced field crop yields.

Over 80% of US farms operate at a loss and depend on off-farm income to make ends meet. These farms simply don’t have the resources to invest in significant alley cropping.

The average US farmer is almost 58 years old. The average US farmer to too old to appreciate the long-term returns of alley cropping, especially when so many grown-up children are leaving the farm for work elsewhere.

Field crops may compete with trees for light, water, and nutrients. Many researchers have found that alley cropping reduces crop yield (up to 23%) due to competition with trees*. In time, tree yields may improve enough to make up for the loss - but as already noted, that may take a very long time.

So how can governments help farmers adopt planet-friendly practices such as alley cropping? Mainly through subsidies, training, and outreach. For more specific ideas, see:

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* This brings up the whole issue of whether to “share versus spare” the land. Sharing farmland with wild creatures (including insects and microorganisms) provides valuable ecosystem services. But if sharing reduces crop productivity, its environmental benefits may be offset by the extra farmland needed to make up for the lost productivity. In other words, trade-offs are involved and there is no one-size-fits-all way to farm.

References:

“Alley Cropping: An Agroforestry Practice” (PowerPoint) https://www.fs.usda.gov/nac/assets/documents/multimedia/presentations/Canned-PowerPoints/AlleyCropping2-18-12.pptx 

“Enhancing Resiliency in U.S. Agricultural Landscapes under Changing Conditions” Michele M. Schoeneberger, Gary Bentrup, and Toral Patel-Weynand, Editors/ U.S. Department of Agriculture Forest Service November 2017.

“Why Agriculture’s Greenhouse Gas Emissions Are Almost Always Underestimated” by Jeff McMahon/Forbes. August 14, 2020. https://www.forbes.com/sites/jeffmcmahon/2019/12/02/5-reasons-agricultures-greenhouse-gas-emissions-are-usually-underestimated/#436551776ac8

Xu, H.; Bi, H.; Gao, L.; Yun, L. Alley Cropping Increases Land Use Efficiency and Economic Profitability Across the Combination Cultivation Period. Agronomy 2019, 9, 34; https://doi.org/10.3390/agronomy9010034