Closing the Loop: Nutrient Balances in Organic and Conventional Coffee Agroforests

Abstract

Agroforests are a primary example of ecologically sustainable agroecosystems due to their efficient use of natural resources and ability to buffer against ecological and socioeconomic stresses. We constructed nitrogen (N) and phosphorus (P) balances to examine the ecological sustainability of conventional, organic, and unfertilized coffee agroforests. A similar percentage of applied nutrients were recovered in conventional and organic coffee yields. However, nutrient excess (inputs minus outputs) was higher in conventional farms, suggesting they may be more prone to nutrient loss. Nutrient pools were large overall, with unfertilized farms tending to store nutrients aboveground, and fertilized farms belowground. Future research should investigate the fate of excess nutrients to develop specific strategies promoting nutrient optimization in agroforests.

Keywords:

• agroforestry
• coffee
• nutrient cycling
• nutrient balance
• organic agriculture

ACKNOWLEDGMENTS

We would like to acknowledge the financial contributions of The Jefferson Scholars Foundation, the Raven Society, The Bankard Fund for Political Economy, and the Center for Undergraduate Excellence, all at the University of Virginia, to this research. Gabriela Soto and Buenaventura Gamboa introduced us to farmers and helped with the logistics of the fieldwork. Our sincerest thanks go to Laura Bonner for her help in the field and laboratory. Finally, we would like to acknowledge the farmers of San Juan Norte, Colorado, Tres Equis, and Grano de Oro for giving us access to their farms and welcoming us into their homes and hearts.