Scientific Research, Honduras

Our Inga Alley Cropping method is based on extensive scientific research undertaken over a number of years with the support of the University of Cambridge. The main focus of the Inga Foundation is now outreach and the introduction of Inga Alley Cropping methods to slash-and-burn farms. However, holding true to our scientific roots, we believe that continued research is essential to ensure we can provide the very best advice and support to the farmers we work with. In Honduras, we have an area of mature Inga alleys for research purposes located within the grounds of the Centro Universitario Regional del Litoral Atlantico (CURLA University), in La Ceiba city.

New Long Term Research Project

The research plots at CURLA, comprised of six Inga species, were planted in 1996 and serve as a demonstration and research center for Inga Alley Cropping. The easily accessible location adjacent to the city allows us to reach as many people as possible and showcase our techniques in practice. Due to lack of funds, the CURLA alley plots were neglected for several years up until 2011, when we were able to secure the funds to restore the plots to viable status with the two most effective species, Inga edulis and I.oerstediana. 18 months after the replanting took place, the site made a spectacular recovery, and was ready for use once again.

These plots have now been used for Inga Alley Cropping for 17 years, making them the oldest area of continuous Inga Alley Cropping in the world. As such, they are an invaluable resource for research into the long-term effects of this model.

In partnership with CURLA University, we are undertaking a long term research experiment into the soil nutrient benefits of our Inga model. The experiment began in March 2014, using 4 crop species; Maize, Chili Tabasco, Pineapple and the Datil Banana, all of which could become key cash crops for use with Inga Alley Cropping. We have been applying varying levels of two key nutrients – phosphorus and potassium – to different sections of the plots in order to determine the minimum level of these nutrients that a farmer would need to add to ensure good yields over the long term.

Previous research tells us that Inga Alley Cropping is highly efficient in retaining nutrient inputs, recycling them within the system. By contrast, in traditional agriculture, soil supplements are often rapidly lost from the soil, especially on the very steep slopes which most farmers in Honduras are forced to cultivate. Hence, we know that the soil supplements required for good harvests is likely to be significantly lower in the Inga Alley system than traditional models.

However, to be able to give the best and most accurate advice to farmers, we need to quantify this difference. This experiment aims to generate reliable, accurate data in relation to key cash crops regarding the minimum level of inputs needed to sustain good harvests year on year. With this information we will be able to fine-tune our advice to local farmers, so they can get the very best value from the Inga alley system.

The Biological Corridor

Planted in 1999, the mini-biological corridor in CURLA serves as an example of how Inga can be used in conservation to reconnect areas of forest.

The aggressive grasses which typically dominate slashed and burned sites can often make reforestation difficult and costly as the rainforest seedlings are easily outcompeted and smothered by the grasses. However, Inga can help to control the grasses and weeds, allowing the rainforest trees to survive and grow.

In this system, Inga are planted four metres apart to begin the process of reclaiming the site from the grasses (in this case mainly Rottboellia cochinchinensis and Digitaria swazilandensis). Each fourth Inga was replaced by one of fifteen native rainforest tree seedlings for which the Inga would act as a “nurse” tree.

Fifteen years on, the biological corridor is now performing exactly as intended. Some of the trees have reached 70 feet or more in height and have begun to form buttresses. The corridor is full of all kinds of birds, from owls to woodpeckers and hummingbirds, as well as insects and other animals and the soil’s physical appearance is beginning to resemble that of a rainforest. The corridor is now a highly valuable educational resource for teaching Forestry students about Inga’s potential for restoring links between isolated forest blocks.

Guayabon-Guapinol-canopy (1)
The elegant ivory stem of a 20-metre individual of Terminalia oblonga (Combretaceae)

Now that the forest canopy has been successfully established, the Inga are beginning to be shaded out as the natural process of succession moves forward and the forest matures.

Spondias mombin-sm-pic
Spondias mombin (Anacardiaceae). Probably redistributed by nocturnal mammals.
Right: Xylopia frutescens (Annonaceae) almost certainly brought in by Toucans which are commonly seen in the trees.

Pictured above: Saplings of rainforest tree species, germinated from seeds that were transported here by birds and animals, who use the corridor for its protective feeding environment