Integrating Cacao into “El Cafetal Puertorriqueno”: A Farmer-Led Agroforestry Model for Native-Shade Coffee Farms in Southern Puerto Rico

Commodities

• Additional Plants: coffee, trees

Practices

• Crop Production: agroforestry

The proposed solution to the challenges identified in this farm system is to integrate cacao as a complementary perennial crop within a scientifically structured, research-only block and to evaluate four nutrient management strategies that are realistic and accessible to small farmers. This approach directly aligns with the Congressional definition of sustainable agriculture by improving environmental quality, enhancing the natural resource base, increasing farm profitability, and strengthening the quality of life for rural communities. The project's design, using cacao as experimental units within a native shade coffee system, allows the farmer to address long-standing challenges related to economic instability, and soil degradation while generating new knowledge that can be shared across the Southern region.

The core of this project is the establishment of a one-acre cacao research block under the farm's existing canopy of native and endemic shade trees. This planting is not intended as a commercial orchard but as an experimental system that enables a controlled comparison of four nutrient management strategies: an on-farm bioferment made from recycled coffee grounds, a commercially available organic fertilizer (10-10-10), the farmer's current synthetic fertilizer (20-20-20), and a low-cost coffee-based foliar spray prepared from coffee leaves or spent coffee grounds. By testing these treatments side by side, the project will generate clear evidence about how each nutrient strategy affects cacao establishment, soil health, microclimate conditions, and labor and cost requirements. These outcomes directly support the farm's transition toward lower chemical dependency, reduced input costs, and more ecologically aligned nutrient cycling.

This solution is specific and measurable through a structured experimental design using 300 cacao seedlings spaced at 12 feet in all directions. The acre will be divided into four equal plots of 75 trees, and each treatment plot will be further divided into three subplots of 25 trees to increase replication and statistical reliability. Measurements including plant height, basal diameter, canopy width, and leaf number will be recorded every 60 days. Plant nutrient status will be assessed through laboratory leaf tissue analysis conducted at the University of Puerto Rico Agricultural Experimental Station, allowing precise evaluation of how each treatment influences nutrient uptake over time. Soil parameters such as pH, electrical conductivity, organic matter content, compaction, and macronutrient levels will be measured at baseline and at key intervals throughout the two-year trial. Tracking microclimatic variables and noting pest and disease presence will further support the project's ability to evaluate treatment effects. Together, these standardized laboratory and field measurements will produce a robust dataset capable of informing both the participating farmer and others in the region.

The solution is achievable because it builds directly on the farmer's existing knowledge and management practices. The farmer already maintains perennial crops under a native shade canopy, manages shade levels carefully, applies organic matter to the soil, and understands the biological rhythms of tree crops. None of the four nutrient strategies requires specialized equipment, capital investment, or advanced technical skills. The bioferment relies on materials already available on the farm, such as used coffee grounds and brown sugar. Commercial organic and synthetic fertilizers are affordable and widely accessible, and the coffee-based foliar spray uses inputs generated on-site. The scale of one acre is manageable and realistic for the farmer's labor capacity and is well suited for conducting meaningful, farmer-led research.

The solution is also realistic for the ecological and socioeconomic context of southern Puerto Rico. Cacao is well suited to the filtered light and moderated humidity found under native shade trees such as guamá, yagrumo, and maga. Planting cacao in these conditions requires no new infrastructure, no irrigation, and no modification of the forested overstory. Additionally, because cacao and coffee share similar management rhythms, nutrient needs, and shade requirements, integrating cacao does not increase management complexity beyond what is feasible for a smallholder farmer. Instead, it extends existing practices and enhances the system's biodiversity, economic resilience, and ecological function.

This approach leads to a more sustainable outcome because it addresses the three pillars of sustainability. Environmentally, integrating cacao increases biodiversity, adds a new vegetative layer to the agroforestry system, improves soil structure, enhances microbial activity, and reduces erosion on sloped land. By evaluating organic and regenerative nutrient treatments, the project supports the reduction of chemical inputs and fosters healthier, more biologically active soils. Economically, adding cacao provides the farmer with the opportunity to diversify future revenue streams and buffer against the volatility of the coffee market. Even though these research plantings are not for commercial production, the knowledge gained will guide future diversification efforts and reduce the risk associated with adopting a new crop. Socially, the project enhances community sustainability by creating a demonstration site where farmers can observe real-world outcomes, learn from nutrient comparisons, and adopt practices that align with their own goals and capacities. Outreach and dissemination will allow the results to benefit the broader agricultural community in southern Puerto Rico.

In summary, the proposed solution integrates cacao into a native shade coffee system through a controlled, farmer-led research design that is specific, measurable, achievable, and realistic. By evaluating four nutrient management strategies and measuring ecological and economic outcomes, the project advances farm sustainability, protects natural resources, and provides region-specific knowledge that can help other small farmers diversify and stabilize their production systems. This research-driven approach supports long-term resilience for both farmers and the wider rural community.

This project aims to test four nutrient management strategies to determine how cacao performs as an understory crop in a native-shade coffee agroforestry system. The goal is to understand how each nutrient treatment influences cacao establishment, soil health, microclimate regulation, and the practicality for small-scale farmers. The one-acre cacao plot will serve as a temporary research area explicitly designed for experimentation and data collection, not for long-term commercial farming.

Cacao trees will be planted 12 feet apart in rows, resulting in about 300 trees on the acre (Bentley et al., 2004). The plot will be divided into four equal sections, each with 75 trees, and each section will be further divided into three smaller blocks of 25 trees to improve the reliability of results and account for spatial differences. The layout will form a grid with four quadrants, each assigned a different treatment. Within each quadrant, trees will be planted in neat rows under a consistent native shade provided by species like guamá, yagrumo, and maga.

Before planting, soil samples from each quadrant will be taken to measure pH, organic matter, nitrogen, phosphorus, electrical conductivity (EC), and soil compaction with a penetrometer. This baseline data will help us track changes and compare treatments over time.

Treatment Descriptions:

1. Coffee-ground bioferment compost tea: Used coffee grounds and brown sugar will be fermented without oxygen in a 1:3 ratio of solids to water for 7 to 14 days. After fermentation, the tea will be diluted 1:10 for planting and 1:20 for ongoing maintenance, applied as a soil drench every 2 to 4 weeks. This method explores a closed-loop system that recycles waste into nutrients.

2. Commercial organic fertilizer (10-10-10): An accessible organic fertilizer will be applied at about a quarter of a pound per plant every 6 to 8 weeks. This will test how well a standard organic fertilizer performs and its practicality.

3. Conventional fertilizer (20-20-20): The farmer's usual practice of applying one tablespoon mixed in a gallon of water every 6 to 8 weeks will be used as a baseline for comparison.

4. Coffee-based foliar spray: Fresh coffee leaves or used grounds will be simmered in water, strained, then diluted 1:4 and sprayed on the leaves every 2 to 3 weeks to see if coffee extracts can serve as a low-cost, nutrient-rich supplement.

Monitoring and Measurements: Cacao performance will be checked every 60 days, with measurements of height, basal diameter, canopy width, leaf count, and leaf chlorophyll levels using a SPAD-52 meter from the Agricultural Experimental Station in Rio Piedras, Puerto Rico. Soil health will be assessed seasonally through EC readings, soil compaction tests, and visual checks of organic matter and structure. Additional observations will include pest and disease presence, microclimate conditions such as temperature, humidity, and shade levels, and storm resilience. Economic factors such as labor, input costs, and ease of applying treatments will also be recorded.

Data Analysis: The effects of treatments will be analyzed using one-way ANOVA at each time point in R. Since trees are measured repeatedly, a linear mixed-effects model will be used to account for variation across subplots and over time. This approach ensures rigorous analysis, aiming to support farmer adoption of effective practices.