> For the complete documentation index, see [llms.txt](https://sexytrees.savimbo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sexytrees.savimbo.com/trees/agroforestry/inga-agroforestry.md).

# Inga agroforestry

<mark style="color:$danger;">This is a</mark> [<mark style="color:$danger;">bricolage</mark>](/foundations/bricolage.md) <mark style="color:$danger;">protocol; which means we are building it in public! Some pages are under construction — but check back soon its updating fast!</mark>&#x20;

Inga alley cropping is the perfect system to provide a real-world anchor to the 'order' end of the [good-agroforestry spectrum](https://sexytrees.savimbo.com/trees/agroforestry#figure-c-agroforestry-spectrum-from-healthy-chaos-to-healthy-order) (see [Fig. C](/trees/agroforestry.md#figure-c-agroforestry-spectrum-from-healthy-chaos-to-healthy-order)).&#x20;

We were first introduced to the system by an NGO working in Ecuador. Nicola Peel from [Rainforest Saver](https://sexytrees.savimbo.com/practice-guide/community/field-schools#jose-abel-in-lago-agrio-ecuador) mentioned Inga alley cropping, developed over 37 years of iterative field testing by Mike Hands from Cambridge, working with the [Inga Foundation](https://sexytrees.savimbo.com/practice-guide/community/field-schools#inga-foundation-in-honduras). What caught our attention is that 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) (See [Fig. I)](https://sexytrees.savimbo.com/trees/agroforestry/pages/5HR7WHMxgdwgEhsE3fCQ#figure-i.-inga-alley-cropping-photo-collage).&#x20;

We have strong respect for the [pragmatism and economic decision-making](https://sexytrees.savimbo.com/foundations/grassroots-economics#characteristics-of-grassroots-economies) of smallfarmers. If they have adopted a new protocol, it's for a reason.&#x20;

It turns out Latin American small farmers and Indigenous communities *really* like Inga. A 1997 region-by-region farmer-priority survey across three areas of the Peruvian Amazon: Yurimaguas, Pucallpa, and Iquitos — ranked Inga as one of the top five preferred species for agroforestry ([Sotelo et. al. 1997](https://repositorio.catie.ac.cr/handle/11554/6701)). In ⅘ of our pilot sites, communities were already intercropping with Inga trees (*Guamo* in Latin America).&#x20;

We chose the classic hedgerow conformation, [Inga alley cropping](/practice-guide/inga-agroforestry/plot-dimensions.md#alley-or-hedgerow-architecture) (see Fig, as the systematic end of the evaluation spectrum, although there are some fascinating [matrix conformations](/practice-guide/inga-agroforestry/plot-dimensions.md#matrix-or-nurse-species-architecture) that are well tested and hold equal promise. &#x20;

### **Systematic agroforestry — Inga alley cropping**

We have encountered much more complex and structured systems for polycropping. Perhaps the best example of this is the well-researched academic work done by Evert Thomas and the team at [Alliance Bioversity International - CIAT](https://alliancebioversityciat.org/tools-innovations/diversity-restoration-d4r) in Peru and Colombia ([Fremout et al. 2021](https://doi.org/10.1111/1365-2664.14079), [Tscharntke et al. 2023](https://doi.org/10.1111/conl.12936)).&#x20;

However, these ecosystem-tailored systems are often not easily accessible to the average smallfarmer. Do they work better? We think so. Are they easy to teach to a beginner? Probably not. For agronomists serious about industrial-scale production, we recommend the spatially explicit, climate-adjusted species-selection tools developed by Bioversity/CIAT — [Diversity for Restoration](https://www.diversityforrestoration.org) and, for agroforestry design specifically, [CacaoDiversity](https://www.cacaodiversity.org).

Inga alley cropping offers three converging advantages — ecological, economic, and pragmatic. It is built on a widespread native tree, it restores degraded land into food production at low input cost, and it is simple enough for a grassroots smallfarmer to learn and deploy rapidly — making food security achievable across much of the humid tropics of Latin America.&#x20;

#### Figure I. Inga alley cropping photo collage

<figure><img src="/files/D2uY1DeHlZXmlsTYy5bz" alt="Multi-strata tropical agroforestry in action: a Savimbo field team walks an Inga alley between rows of young cacao with banana plants in the mid-canopy at a SexyTrees pilot site in Putumayo, Colombia. The brown mulch path is freshly pruned Inga biomass — the leaf-mulch mechanism that suppresses weeds, cycles phosphorus, and replaces slash-and-burn on degraded humid-tropical soils."><figcaption><p><em>Inga edulis</em> alley cropping with cacao and banana in mature plot at <a href="https://rainforestsaver.org/">Rainforest Saver</a> site in Sucumbios, Ecuador — Savimbo staff training in <a href="https://sexytrees.savimbo.com/practice-guide/community/field-schools#jose-abel-in-lago-agrio-ecuador">José Ramírez training program</a>.</p></figcaption></figure>

<div><figure><img src="/files/2SidMnT1PrHfZwmLpLeK" alt="Juvenile seed pods of Inga edulis, the ice-cream bean tree, hanging in clusters from a branch"><figcaption><p><em>Inga edulis</em> — the ice-cream bean (guama) — fruiting (juvenile pods). Photo: <a href="https://www.flickr.com/people/92252798@N07">Dick Culbert</a>, CC BY 2.0.</p></figcaption></figure> <figure><img src="/files/UlxsOEg3sybaMt7uiv2q" alt="Mature seed pods of Inga edulis, the ice-cream bean tree, hanging in clusters from a branch"><figcaption><p><em>Inga edulis</em> fruiting (mature pods). Pods like these feed families between harvests. Photo: <a href="https://www.flickr.com/people/92252798@N07">Dick Culbert</a>, CC BY 2.0.</p></figcaption></figure> <figure><img src="/files/wIkHGQWGK0Ea8HbveKjl" alt="Glossy pinnate leaves of a young Inga edulis, the ice-cream bean tree, grown as a specimen at a botanical garden"><figcaption><p><em>Inga edulis</em> foliage — evenly pinnate, dark-green leaves. This nitrogen-fixing legume is the workhorse species of Inga alley cropping, prized for fast growth and a dense, weed-suppressing canopy. Photo: <a href="https://commons.wikimedia.org/wiki/User:Daderot">Daderot</a>, CC0.</p></figcaption></figure></div>

For clarity, we defer to the [Inga Foundation](https://sexytrees.savimbo.com/practice-guide/community/field-schools#inga-foundation-in-honduras) as the ideal source for foundational science and updated planting protocols. But we've done our best to summarize what we've been able to retain — as we learn it.

Inga alley cropping is not an Indigenous system. It came out of systematic academic fieldwork that smallfarmers adopted because it worked. Dr. Mike Hands at the University of Cambridge co-developed the modern protocol over 37 years of trials with local communities in Honduras and Costa Rica, work documented across three foundational papers ([Hands et al. 1995](https://www.scopenvironment.org/downloadpubs/scope54/); [Hands 1998](https://shop.kew.org/the-genus-inga-utilization); [Hands 2021](https://doi.org/10.1098/rsos.201204)) and continued today through the [Inga Foundation](https://sexytrees.savimbo.com/practice-guide/community/field-schools#inga-foundation-in-honduras). The system has since been successfully deployed across diverse ecosystems, altitudes, and climates.

> *"The opposite of deforestation is not necessarily simple 'reforestation'. Restoration of the landscape has to imply the reversal of soil degradation; the restoration of SOM and the restoration of the microbial populations that formerly retrieved, retained and recycled essential nutrients."* — [Hands 2021](https://doi.org/10.1098/rsos.201204), *R. Soc. Open Sci.*

Inga alley cropping has been field-tested over decades, with measurements for soil chemistry, yields, and long-term productivity ([Hands 1995, 1998, 2021](https://doi.org/10.1098/rsos.201204)). The system is straightforward in description: fast-growing *Inga edulis* trees planted in rows, food crops grown in the alleys between them — maize, beans, cacao, pepper, alone or in polyculture. The science behind why it works is less obvious.&#x20;

The system is specifically designed to replace motivators and cycles of 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](https://doi.org/10.1016/0167-8809\(95\)00656-7); [Bezerra et al. 2024](https://doi.org/10.3390/su16229994)).&#x20;

Slash-and-burn farming gets its productivity from a one-time fertility pulse: phosphorus, which is otherwise scarce in highly weathered tropical soils, leaches from burned forest biomass through soil macropores and briefly becomes available to crops ([Hands et al. 1995](https://www.scopenvironment.org/downloadpubs/scope54/)). The pulse is short. Within a few seasons, the phosphorus is gone, and the farmer clears more forest.&#x20;

Inga alley cropping intentionally replaces this with a continuous cycle. It concentrates large densities of root biomass in the top 10 cm soil layer, forming dense networks of fine roots and mycorrhizal associations in the upper soil and mulch layers, and mobilizes phosphorus from decomposing leaf litter and pruned biomass. Thus approximating the nutrient cycling of an intact tropical forest (where fine roots are concentrated in the upper few centimeters of soil and are largely absent below \~20 cm dept). The same plot stays productive. No new burning required.

Species selection was explicit and concrete. *Inga edulis* outperformed other tested alley species — *Gliricidia sepium* and *Erythrina fusca* — which lost productivity over time and produced insufficient mulch cover for long-term use [(Hands 2021)](https://doi.org/10.1098/rsos.201204). Trials measured biomass production, weed control, and tolerance to pollarding. The genus *Inga* contains over 300 species [(Hands 1998)](https://www.kew.org/kewbooks/the-genus-inga-utilization); *I. edulis* is the current recommended workhorse, though the science continues to evolve. It maintains productivity under repeated pruning, and the pruned branches become mulch. There is an elevation limit: native to Amazon basin lowlands, *I. edulis* reportedly performs best below 1,600m, with a biological ceiling near 2,200m [(NFTA 1993](https://winrock.org/factnet/fact-net-fact-sheets/inga-edulis-a-tree-for-acid-soils-in-the-humid-tropics/); [Rainforest Saver)](https://rainforestsaver.org/how-to-and-the-science/step-by-step-guide-to-inga-alley-cropping/). Other Inga species — *I. densiflora*, *I. oerstediana, I/ punctata* — extend into Andean foothills, and some pilot sites use these, although we haven't found any good research on them as yet.

Many sites we interviewed had analogs of Inga trees, nitrogen-fixing trees they swear by. We are fairly rigid on the [policy of using native trees](https://sexytrees.savimbo.com/trees/agroforestry) for the SexyTrees protocol. Therefore, we have been neutral on the selection of analogs for other ecosystems in Nepal, Asia, and Kenya. Not every ecosystem can afford rigorous field-testing for trees that locals report work. Besides Honduras, Inga alley cropping is nowadays used in Guatemala, Costa Rica, Peru, Colombia, 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).&#x20;

It's of note that Inga Foundation has evolved to a more sophisticated economic model, which they call the “Guamo model,” based on real-world experience with >300 Honduran families [(Hands 2021)](https://sciwheel.com/work/citation?ids=18625117\&pre=\&suf=\&sa=0).&#x20;

1. Production of basic grains (Inga-alley cropping hedgerows),&#x20;
2. Cash crops (hedgerow),&#x20;
3. Fruit trees (matrix), and&#x20;
4. Reforestation with tropical hardwoods (matrix)

This is an interesting evolution and points to expanded income generation beyond food security. We think it's worth studying for sites looking at [EUDR-compliant crops](/markets/tree-unit.md) and engaged in collective market negotiations for cash crops.&#x20;

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