During my recent trip to West Sumatra, we organized a day to present our findings from the belowground biodiversity work done in collaboration with Malang University to the farmers. A team of five (staff and two students who conducted the fieldwork) joined to explain the importance of worms, trees, and ground cover in promoting soil health. 🐛

The day was structured with a full morning of interactive sessions, followed by practical activities in the afternoon. We demonstrated how tree roots and worms develop vital pores for water infiltration, which also help loosen the soil. We also explained the importance of leafy biomass, both for adding carbon to the soil and providing nutrition for worms. 🌿💧

Planar cages were created using different types of biomass, showing how worm activity varies according to the type and quantity of biomass used. These ranged from intensive horticulture (with little to no biomass) to mixed agroforestry with coffee and Leucaena biomass.

A particular attention was paid to the biomass of Leucaena leucocephala. This nitrogen-fixing tree, known as lamtoro in the Indonesian language, is is not very popular with many of our farmers, as they perceive no direct economic benefits from it. We explained how it can substitute many kilograms of urea fertilizer, provide necessary shading for tree crops, reduce evapotranspiration, sequester significant amounts of carbon, and offer high-quality forage for worms, allowing them to grow faster and thus speed up soil health processes. While farmers weren’t fully convinced after hearing all these “indirect” economic advantages, by the end of the day, our nursery manager had already received several requests for Leucaena seedlings. 🌱

One thing that surprised us was the limited attention the planar cages received. Farmers commented, 'I see this every day when I dig a hole.' However, they all took a moment to walk by and glance at them, so we hope it sparked some reflection.

An interesting discussion revolved around which worms are best to have in the soil. The team explained that all three ecological groups of worms are equally important, as each group performs different functions to improve soil health and water infiltration. The farmers concluded that they would protect the worms and avoid using salt on the soil to kill them, as some had done in the past. 🙅🏾

The afternoon session proved to be the highlight for the farmers, as they were able to directly observe the morning’s concepts in the field. Using methylene blue, they visualized water infiltration in soils under vegetable fields and coffee agroforestry systems, clearly highlighting the differences in how water moved through the soil.

This was followed by a “rain test,” where farmers used watering cans to observe water passing through three types of soil cover: bare soil, soil covered with leaves, and soil with both leaves and woody biomass. The results were striking, clearly demonstrating the critical role of soil cover in enhancing water infiltration, preventing erosion, and providing nutrients to the soil, as well as offering valuable forage for worms. 💚

This final activity caused a lot of laughter and jokes among the participants, leaving them delighted as they went home. Many farmers realized that they had been practicing the wrong management approach by always trying to keep the soil clean. Reasons for this were to reduce fire risks from the dry biomass and to avoid unseen snakes. They now understand it is more beneficial to keep the soil covered with fallen leaves and other green materials, as it directly benefits their tree crops. They were excited about this new knowledge for at least two reasons: it will improve soil health and quality, which is good for their trees, and it will also require less work. 😊

Paul Burgers