While reducing fossil fuel burning is the main focus for mitigating climate change, lowering carbon emissions from land-use sources gets significantly less attention. For centuries people in tropical regions have relied on slash-and-burn subsistence farming, otherwise known as shifting cultivation to grow food in acidic rainforest soils. However, with the rise of cash crops, population growth and soils depleted of nutrients, the practice has not held up in the modern era, leading to social and ecological devastation, including elevated carbon emissions.

Mike Hands (left) and Abraham Martinez (right) in an Inga Alley in Los Flores, Honduras. Courtesy of the Inga Foundation

As rainforests serve as a significant carbon sink for the planet, their continued loss is another nail in the coffin for Earth’s habitability. Moreover, the exhausted soils combined with prolonged droughts under climate change have also severely threatened the food security of those who rely on subsistence agriculture, igniting a migration trend out of desperation.

Oxfam recently warned that over-reliance on tree-planting for carbon offsets could increase food prices, especially in the developing world. However, the claim assumes that reforestation and agriculture can’t work in tandem. Evidence of such potential lies in an agroforestry model championed by the Inga Foundation, founded by Mike Hands, who began research on alley cropping in Central America in the mid-1980s.

“We were able to test on the ground in a real environment, six different agroforestry systems and two bare soil systems for the prime production of basic grains — this is the fundamental problem of food security in Central America,” said Hands. “It’s the basic grains, maize and beans, that keep people alive.”

The research funded through the University of Cambridge ended in 2002, yielding the Inga alley cropping approach, which led to the creation of the Inga Foundation in 2007. The foundation’s Land for Life program uses the Inga Tree Model to address the vast deforestation on a range of mountainous areas in northern Honduras, where farmers have been practicing slash-and-burn for many generations. The model relies on the Inga tree’s nitrogen-fixing abilities, using cultivated rows of the tree with crops planted in between to replenish soils, shade out weeds and provide mulch. The system also yields lightweight, clean-burning firewood, which people use for cooking.

The method allows families to settle in one place and achieve food security with grain crops, and income with cash crops like turmeric and peppers. Farmers use a thinner planted version of Inga alley cropping to produce cacao. Meanwhile, the method results in reforested areas that also produce timber for local use.

According to Hands, the system is holding up to the stressors of climate change. For example, soil surface temperatures in degraded rainforest lands have become too hot to grow crops reliably. However, the mulch provided by the Inga alley cropping tends to keep the soils cool and moist.

“This is the only system that’s standing up to violent climate change,” Hands said, explaining that during a severe six-month drought in 2019, the Inga system was able to produce maize even without any rainfall.

The Inga Tree Model is also helping restore habitat to degraded lands by attracting biodiversity to the areas around the plantings. Hands said he’s even witnessed springs appearing, providing clean drinking water. However, despite the solid promise of the agroforestry approach, securing funding to expand the program has been a struggle.

Following the Inga Foundation’s inception in 2007, a film was made about the project, which attracted a few wealthy donors enabling the hiring of Director of Operations Abraham Martinez, Chief Agronomist Luis Miranda and the eventual scaling up of the program to about 300 families. However, as more Honduran families have become interested in Inga alley cropping over the years, the foundation has had difficulty keeping up with demand.

Inga Foundation founder and Director of the Land for Life program Mike Hands spoke with The Carbonic about the power of the Inga tree, including its carbon sequestration potential and how it’s transforming the lives of families in Honduras. The following interview has been edited and condensed for clarity.

Q: What are the main barriers to expanding this agroforestry model?

A: Well, there’s funding. And you can only convince people of a revolutionary way of growing food by demonstrating — they have to see it and feel it.

They have to see why the trees are there. They have to see the organic material in the soil, they have to see the crops thriving in the system, and the absence of weeds, because the system controls weeds. So, we have to demonstrate. To that end, we bought a 12-hectare demonstration farm, of which about four hectares are an arboretum for rare and threatened species and seed sources from the future; the rest is for agroforestry systems. We’ve been training people, including people who have come in from other countries. And the system now, as a result of that, is being replicated in 15 other tropical countries, including three or four in Africa and one or two in Southeast Asia and Hawaii, but mainly in Central and South America. Some are using the Inga tree, but we’ve also identified other genera that will perform as analogs for them as Inga does for us. But Inga is turning out to be quite an unusual genus. It’s a huge genus with 350 species. We have experience with probably about 15 different species.

Some people have called it a magic tree, but I say no, it’s a useful tree. It has properties that we find useful managed in this way. It has a lot of tolerance for acidic soils. I’ve worked with botanists in Africa looking for an alternative there, and there are one or two promising species, but none of them perform there as Inga does for us.

 

Q: In discussions about climate change, there seems to be a tension between the need for reforestation and the demand for agricultural land. Is the Inga tree model evidence of a middle ground where you can have reforestation and agriculture?

A: Absolutely.

We’re told that the average holding in Honduras is about eight hectares. I’d say it’s somewhat smaller. Some have got a lot while others have considerably less. If you look at that land use, it’s been slashed and burned over many, many episodes. The soil is totally depleted; it supports only invasive grasses though it once supported a rainforest. So for every little plot where the farmer has to pour on expensive nitrogen fertilizer, you might get a crop, or you might not. And they’re struggling just to put food on the plate, and in some cases, they fail.

So you have eight hectares of wasteland that you can substitute with agroforest, only some of which are intensively managed for food. The only negative is the cost, which I say because the system sounds too good to be true. It resists climate change, it helps recreate springs for clean water, it takes people out of poverty, it reinvigorates the rural economy, it will re-green the landscape. It’s not cheap, it’s not quick, but it can turn around a family’s food security.

So, for us, we’re at year ten of the Land for Life project. It’s working out at roughly $2,000 per family to achieve this, but the costs will go down as soon as the system starts to go viral, neighbor to neighbor. So, this can be replicated — not at no cost but at very little cost. Because it’s a groundbreaking, revolutionary system, and we have to convince not only local farmers by demonstration but also decision-makers, we were determined to get the whole system at whatever cost to prove a point. And I don’t think that the next 350 families will cost anything like the first 350.

 

Q: With warming temperatures and changes in precipitation patterns due to climate change, how is this model holding up given negative impacts on forests and agricultural yields?

A: If you had previously asked about the use of Inga, I would have said that I don’t think it will withstand a very long dry season. With that said, what happened in 2019 was the worst drought ever recorded or known in Central America that was part of an El Nino event. We had between six and seven months of pure drought and searing temperatures. People were hoping to prune and plant in June of that year, but there was no way to touch the trees or plant. The Inga defoliated at about four months, but when it started to rain in September, it came back, and that was extraordinary. We hardly lost anything, and by December, the canopy was sufficiently dense that the families could prune and plant and grow crops. The system was working for them.

So that describes resilience to climate extremes. The model is a very powerful avoider of carbon emissions for the obvious reason that people stop slashing and burning and that can release hundreds of tons of CO2 in a single operation. But also the agroforestry system, the model as a whole is sequestering a lot of atmospheric carbon, particularly in the timber.

With eight hectares, assuming a family has a couple of hectares of alley cropping and the rest is a fruit tree, timber tree combination established at one hectare a year — the model assumes 40 families a year. By the end of last year, the avoided or sequestered CO2 was in the region of 300,000 tons of CO2. And that’s just the pilot project.

So it’s a powerful weapon in taking away a significant carbon source. Slash-and-burn or land-use change is thought to be contributing between 20 and 25% of all human carbon inputs into the atmosphere, and you hardly hear it mentioned. Everybody talks about flying aircraft, transport, fossil fuel burning, but they don’t talk about land-use change much, but it’s 20 to 25% globally.

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Q: Is the Inga tree itself central to the success of this method?

A: Rainforest soils typically are very weathered and acidic. By definition, the rain forest has at least 2,000 millimeters of rain a year, no month less than 100 millimeters, and you have a net passage of water down through the soil profile, which is not the case in Sub-Saharan Africa, which is sort of semi-humid and has a rising and falling water level. So this is different; you have a net-constant movement of water, which takes away the nutrients, making the soil more and more acid, up to a point. The limit is somewhere around pH four, and that’s pretty darn acid. But Inga can tolerate that.

I’ve always pushed back at it being called a magic tree because it’s not; it’s a useful tree. Having done a lot of work with botanists in Africa especially, I have reluctantly concluded that there is something about Inga that I don’t fully understand. I think it’s about a symbiotic relationship between organisms and the roots — the fungi and the bacteria that are symbiotic with the Inga.

 

Q: With heightened concern about sustainability and the push for greener cities and urban agriculture, do you think the Inga tree model could be replicated in urban environments on a small scale?

A: Yes, in the humid tropics. You can put it in a backyard, and it will work. We worked with one NGO that was training in the system. They’re running an orphanage up in the highlands, and they’re essentially doing Inga Alley Cropping in their backyard.

There’s a quasi-government group that has an example of Inga Alley Cropping in the city of La Ceiba in the old Botanical Garden of La Ceiba, which is about two hectares of land with some lovely old trees. So there’s no reason why you shouldn’t do it.

 

Q: What else is essential to know about the Inga tree model and the Inga Foundation?

A: The model ticks 11 of the 17 United Nations Sustainable Development goals. I think it’s almost unique in doing that. The reason it’s possible to claim that is that we’re working with degraded ecosystems. So what we’re doing is remedial and regenerative; that’s why it’s possible to claim 11 of the SDGs without negatively impacting the remaining six.

 

Q: What’s the outlook for expanding this?

A: We are struggling. We are inundated with families wanting the system. Mainly as a result of seeing the system in 2016 and 2019 stand up to violent climate change with long ferocious droughts — I think that’s what has tipped it.

There’s nothing more fundamental than how you eat and how you achieve that. So there’s an initial reluctance on the part of farmers, which is entirely understandable. An adventurous handful will go for it in a given community, while others will sit on the fence for a bit. But now that’s changing because we’ve just persisted in what we’re doing, and we have a consistent message. So they trust us now, and it’s gathered momentum as one factor.

There’s one community with 50 families in a deforested basin in the mountains. When we went in in 2014, 18 of the 50 families signed up. There was some reluctance to what we were doing, as project after project had come in and promising things that had failed.

That has now changed. We now have all 50 families on board, and among them are 12 men who had initially decided to go to the States, migrating with the caravans. However, they decided not to go when they saw their neighbors with a successful Inga system and saw that they had a future.

I want the message to get to Joe Biden that funding this will keep people on the ground; I think it’ll revive the rural economy. It will mitigate the climate, stop soil erosion. People can get clean water. All of these things — the environmental, social, economic benefits, and people not migrating. People don’t migrate because they want to, but because they feel they have no choice.

https://www.thecarbonic.com/post/the-inga-tree-model-stands-up-to-violent-climate-change

How the Inga Tree Can Combat Climate Change, Fight Hunger and Reduce Rainforest Loss

A technique developed by ecologist Mike Hands provides a means for regenerative agriculture — one that restores land, draws carbon out of the atmosphere and offers long-term food security. The technique, called Inga Alley Cropping, can help subsistence farmers and rainforests, and is being pioneered by the Inga Foundation, an NGO founded and directed by Hands.

Abraham Martinez and Luis Miranda in an Inga alley in Las Flores, Honduras. Credit: Inga Foundation

Calls for regenerative agriculture have been ringing for decades; however natural resource depletion and food insecurity remain pressing issues. As millions of people still survive on the food they grow themselves, small-scale regenerative agriculture is an essential tool for feeding the world and restoring natural ecosystems.

Subsistence farming is the primary source of food and income for more than 250 million people. However, crop cultivation can be unpredictable as harvests vary year to year, and maintaining a healthy plot of cropland is difficult. For centuries, people have been using slash-and-burn techniques to grow crops. Slash-and-burn can be productive, but it depletes tropical soils and exacerbates rainforest depletion at its current scale. Fortunately, more farmers are choosing regenerative techniques.

Shifting Cultivation in Subsistence Farming

Agriculture often strips the land of nutrients, especially when the same crops are continuously planted. A popular technique to combat this nutrient loss is shifting cultivation, where a farmer changes the plot of land they use to avoid worse harvests. In the tropical rainforests of the Western Hemisphere, slash-and-burn has been a dominant technique for shifting cropland to utilize the most healthy soils. Farmers cut down sections of rainforest, then burn all the organic material, which fertilizes the soil. The burn also eliminates weeds and pest species.

The downside to slash-and-burn is it leaves the plot of land infertile after three to five years, meaning the farmer must move to another plot of land. This causes deforestation, leaving behind hectares of depleted soils. It’s estimated that 300 million farmers practice slash-and-burn agriculture globally. The patches of land degraded by the practice could once again be used for plant life, but it takes a long time to regenerate the soils. This means that as soil fertility dwindles, subsistence farmers face increased food insecurity. Other consequences include loss of habitat for wildlife, mudslides, greater damage from flooding and the loss of trees that capture carbon.

Yet land areas home to tropical rainforests continue to be in high demand. Deforestation for development and agriculture, both subsistence and commercial, threatens some of the most biodiverse habitats on the planet. Only 10% of the world’s population uses shifting cultivation for food but operates on 30% of the world’s most exploitable soils. As demand for tropical land increases, subsistence farmers’ livelihoods are put in danger.

Deforestation is also exacerbating climate change, with portions of the Amazon rainforest now functioning as carbon sources rather than as carbon sinks.

 

The Inga Tree Model

Hands developed a new tactic for regenerative agriculture after studying crop management in Costa Rica, which serves as the basis for work done by The Inga Foundation, a registered non-profit tasked with imparting regenerative agriculture techniques to subsistence farmers and tracking their progress. Inga Alley Cropping relies on nitrogen-fixing qualities of the Inga tree and cultivating rows of the tree to provide food without forcing subsistence farmers to move plots constantly. The practice restores degraded lands, provides long-term food security, creates sustainable livelihoods and protects tropical rainforests.

Inga Alley Cropping is agroforestry performed by growing alleys of Inga Trees on depleted farmland with crops placed in between. The trees fix nitrogen, a necessary nutrient for plant growth that’s often depleted by agriculture, into the soil. Although industrial agriculture relies on chemical fertilizers, traditional farming often harnesses other techniques. For example, as the Inga trees grow, they shade out weeds, cutting them off from the solar radiation necessary for growth. Farmers then strip the branches for mulch, which further protects the soil and prevents weed invasion. Branches can also be used for firewood, especially for families who cook with wood stoves.

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Inga Alley Cropping is beneficial in many ways. First, the Inga trees fix nitrogen to the soil, which can maintain soil fertility for years. Since soils remain fertile, subsistence farmers can stay on one plot of land while preserving adequate harvests. The ability to stay and farm over one area also reduces deforestation.

 

Regenerative Agriculture

Inga Alley Cropping is part of a larger movement towards regenerative agriculture. Regenerative agriculture relies on the principle that food growing techniques should enrich the soil, not deplete it. The regenerative practices conserve and rehabilitate soils, an attribute crucial for subsistence farmers who may not be able to access more land or chemical fertilizers. Regenerative farming can improve water quality, sequester carbon, and provide more resilience against natural disasters such as flooding and drought. Sustainable land management is a vital tenet of sustainable development.

Inga trees, like all plants, can remove carbon dioxide from the air and store it in their cells. The Inga Foundation derived a mathematical model showing the carbon sequestration potential of the technique. In 12 years, one family adopting Inga Alley Cropping can sequester 712 tonnes of carbon per hectare.

Food security remains a critical issue for millions of families all over the world. Many of them must grow their own food, with little support from governments. Instead of relying on slash-and-burn for crop management, regenerative approaches like Inga Alley Cropping boosts food security without drastic changes to livelihoods. In addition to helping fight climate change by capturing carbon, using the Inga trees produces better quality food for less work while restoring the land and protecting rainforests.

Over the last nine years, four million Inga trees have been planted, empowering over 300 families in Honduras.

“We’ve demonstrated that a family with a few hectares of this can not only achieve food security — of number one importance, but can also produce cash crops for an income,” said Hands.

Agroforestry work done through the Inga Foundation has produced 4,500 pounds of organic turmeric, with plans for more cash crops underway. The organization operates on grants and donations, and launched a Crop without a Drop campaign to help spread the Inga Tree Model to more subsistence farmers.

https://www.thecarbonic.com/post/how-the-inga-tree-can-combat-climate-change-fight-hunger-and-reduce-rainforest-loss