# Agroforestry
There is a dizzying array of possibilities for agroforestry. We spent six months with a rolling workgroup for this methodology, and arrived at some core conclusions.
* **Native trees are a pretty good rule**. It doesn't *always* hold; there are some strong arguments for non-native nurse trees in some sticky bioremediation, contamination, or sterile food production situations (e.g., breadfruit, or ) But some of the most useful plants (water hyacinth has immense bioremediation properties, bamboo is a miracle solution for paper and construction materials) are truly invasive outside of their ecosystem.
* Agroforestry does have a basic theme. The agroforestry enthusiasts all have different ecosystems, and their enthusiasm reflects a place-specificity that makes it easy to both argue like the blind men and the elephant, and
#### Standardized agroforestry cultivation with Inga Alley Cropping
The systematic solution for Savimbo came in a chance observation from an NGO working in Ecuador. Nicola Peel from Rainforest Saver mentioned Inga Alley Cropping developed by Mike Hands from Cambridge. Specifically, she mentioned that smallfarmers in Ecuador were adopting it with no funding, because they liked the results (Nicola Peel, Rainforest Saver, pers. communication, 5 December 2023).
Now, the Inga system is not the most esoteric or elegant AFS we have encountered. Our study of the Indigenous chagras in Sibundoy, Colombia over the last year has convinced us that far more sophisticated biological systems exist for food production. Furthermore we have seen sophisticated designs for large-scale site-based production systems from Bioversity/CIAT operating with tailored plots in Putumayo — designed using the Cacao Diversity planning tool.
The chief ecological, economic, and pragmatic benefit of Inga Alley Cropping is that it uses a widespread native tree, and the system has proven to be both effective, and simple enough to learn and implement rapidly for a grassroots smallfarmer to have food security anywhere in Latin American.
This agricultural system is not an Indigenous system. It is the result of systematic academic fieldwork that crossed into local adoption — because it works. Originating in the humid tropics of Honduras and Costa Rica, the modern Inga systems were co-developed by Dr. Mike Hands from the University of Cambridge working in local communities in Honduras and Costa Rica over 37 years. Now taught and researched at the Inga Foundation in Honduras and used across diverse ecosystems, altitudes, and climates. As Mike said “This is new science, because it has to confront a new situation.” (Mike Hands, Inga Foundation, pers. communication, 6 March 2026).
In comparison to other permaculture designs, Inga-Alley cropping has a stable history of rigorous field-testing with measurements for soil chemistry, yields, and long-term productivity [(Hands 1998)](https://sciwheel.com/work/citation?ids=18617781\&pre=\&suf=\&sa=0). Briefly, as we defer to the Inga Foundation as the proper source for updated work, the system involves planting fast-growing Inga spp. trees in rows, with crops grown in the alleys between them, either single or in polyculture (e.g., maize, beans, cacao, and pepper) [(Hands 1998)](https://sciwheel.com/work/citation?ids=18617781\&pre=\&suf=\&sa=0).
The system offers a regenerative alternative to slash-and-burn agriculture, a common cause of deforestation in the humid tropics. Farmers burn new fields to temporarily increase nutrient availability due to the soil´s acidic, nutrient-leaching nature [(Juo and Manu 1996; Bezerra et al. 2024)](https://sciwheel.com/work/citation?ids=18625101,18626643\&pre=\&pre=\&suf=\&suf=\&sa=0,0). Hands et al. ([(Hands et al. 1995)](https://sciwheel.com/work/citation?ids=18617847\&pre=\&suf=\&sa=0)) described the fertility pulse to be caused by phosphorus, commonly low in humid tropical soils, leaching from forest biomass through soil macropores once the soil is exposed after burning, as a short term effect. In contrast, alley cropping mobilizes and cycles phosphorus through dense networks of fine roots and mycorrhizal associations concentrated in the upper soil and mulch layers. The nutrients are taken up from decomposing organic matter and returned to the soil through pruned biomass and leaf litter, approximating nutrient cycling in highly weathered tropical soils, reducing dependence on external inputs over time. That way, the same plots can sustainably be cultivated over time without resorting to further deforestation.
Inga edulis was identified superior to other tested alley species such as Gliricidia sepium and Erythrina fusca which decrease in productivity and thus produce insufficient mulch cover in the long term [(Hands 2021)](https://sciwheel.com/work/citation?ids=18625117\&pre=\&suf=\&sa=0). In turn, I. edulis trees maintain productivity and tolerate repeated pruning or pollarding, allowing the branches to be converted to mulch.
After seven years of research in Honduras and Costa Rica, Inga alley cropping, particularly I. edulis and I. oerstediana, had outperformed all alternatives in the trial sites in pruned biomass production, yield and seemingly in weed control capacity [(Hands 1998)](https://sciwheel.com/work/citation?ids=18617781\&pre=\&suf=\&sa=0). Also, Inga was found to concentrate large densities of root biomass in the top 10 cm soil layer [(Hands 1998)](https://sciwheel.com/work/citation?ids=18617781\&pre=\&suf=\&sa=0), showing how Inga-alley cropping mimics nutrient cycling in tropical forest systems, where fine roots are concentrated in the upper few centimeters of soil and are largely absent below \~20 cm depth [(Hands et al. 1995)](https://sciwheel.com/work/citation?ids=18617847\&pre=\&suf=\&sa=0). At this time, the idea of Inga planting for soil regeneration in degraded cattle ranges was introduced, followed by trials in Honduras [(Hands 1998)](https://sciwheel.com/work/citation?ids=18617781\&pre=\&suf=\&sa=0).
Over time, the research evolved into the “Guamo model”, an integrated rural livelihood model based on Inga-alley cropping with more than 300 Honduran families who have validated the system under real farm conditions [(Hands 2021)](https://sciwheel.com/work/citation?ids=18625117\&pre=\&suf=\&sa=0). The model comprises 4 components focused on 1) production of basic grains (through Inga-alley cropping), 2) cash crops (through Inga-alley cropping), 3) fruit trees (through Inga in orchards), and 4) reforestation with tropical hardwoods [(Hands 2021)](https://sciwheel.com/work/citation?ids=18625117\&pre=\&suf=\&sa=0). Besides Honduras, Inga alley cropping is nowadays used in Guatemala, Costa Rica, Colombia (recent expansion), Ecuador, Cameroon, Kenya and other parts of Africa, and at pilot sites in Southeast Asia [(Rainforest Saver; Inga Foundation 2026)](https://sciwheel.com/work/citation?ids=18625090,18626662\&pre=\&pre=\&suf=\&suf=\&sa=0,0).
Because of its multiple ecological and social benefits, standardized agroforestry cultivation and restoration with Inga contributes to 10 of the UN Sustainable Developmental Goals (SDGs; [(Hands 2021)](https://sciwheel.com/work/citation?ids=18625117\&pre=\&suf=\&sa=0). It supports a green transition by promoting local biodiversity, enhancing carbon sequestration in both soil and tree biomass, enhancing water retention, and helping filter and purify water. The system thus has the potential to generate revenue from biodiversity, carbon, and water credits, potentially providing income earlier than harvest returns.
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