In 2026, five students from Sokoine University of Agriculture (SUA) in Morogoro, Tanzania, carried out three research projects on APOPO Syntropic Agroforestry demo sites. In one trial, plots planted with legume cover crops had 71–82% fewer weeds than unplanted plots. Other studies found higher levels of some soil indicators in agroforestry plots than on nearby conventional farms.
Syntropic Agroforestry imitates natural forest succession. It layers trees, shrubs, and food plants so that each species contributes to the whole system. The APOPO HeroTREEs program uses this approach with smallholder farmers in Africa and Southeast Asia. Demonstration farms show how the system works in practice. To help more farmers and organizations adopt it, we need evidence.
Where the research took place
The studies took place at two sites: the APOPO HeroTREEs demonstration farm at SUA main campus and the demonstration plot at Lugala Farm. APOPO HeroTREEs and SUA are developing the Lugala site for research, training, and practical learning. The plan is to expand the cultivated area each year, reaching 10 hectares by 2029.
The studies explored different questions around soil health, soil fertility, moisture, weed suppression and sustainable farm productivity.
The cover crop trial: Maliha, Amina, and Carolina tested three legume cover crops (jack bean, cowpea, and lablab) against an unplanted control in the cocoa-based syntropic plot at SUA. Each treatment was repeated three times, giving 12 plots. Over eight weeks, they measured how well each crop established and grew, how many weeds appeared, and how soil nitrogen, phosphorus, and potassium changed.
What the studies found
- Weeds: Eight weeks after planting, plots with cover crops had 42–67 weeds per square meter, compared with 231 in the unplanted control. That is 71–82% fewer weeds. Cowpea did best, at 42 per square meter.
- Soil nutrients: Nitrogen, available phosphorus, and potassium rose in every plot, and rose more under cover crops than in the control. Under cowpea, nitrogen rose from 0.14% to 0.29%, compared with 0.10% to 0.14% in the control. Available phosphorus under cowpea reached 64.7 mg/kg, compared with 29.9 mg/kg in the control.
- No single crop did everything: Jack bean grew the tallest (104 cm) and covered the most ground (72%), but cowpea suppressed weeds best. Some weeds, including species of Bidens and Malvastrum, were more common under cowpea. Differences in leaf number were not significant at four or eight weeks.
- Comparison with conventional farms: Other student studies found higher soil pH, nitrogen, and available phosphorus in APOPO syntropic agroforestry plots than on nearby conventional farms. Some other indicators showed no clear difference.
These results come from one season at one site. Soil changes slowly, so a single season cannot show the full picture. Soil nutrients also rose in the unplanted plots, so the trial cannot separate the effect of the cover crops from other factors. It compared cover crops with unplanted ground in a syntropic plot, not with conventional farms. This is why long-term monitoring is part of our approach.
From student researcher to intern
Maliha Issa Hamid recently completed a bachelor’s degree in Crop Production and Management at SUA. With fellow students Amina Peter Kingupa and Carolina Gregory Rafael, she studied how cover crops suppress weeds and improve soil.
Maliha joined APOPO HeroTREEs for a six-month internship starting in October 2026. She is collecting baseline information from participating farmers, including their current farming practices, income, and food security.
This baseline lets us follow the same farmers over a period of time. It will show what happens to their soils and farms, and whether syntropic agroforestry improves their income, food security, and livelihoods.
“Syntropic agroforestry is more than growing trees and crops together. My research on cover crops showed me how plants, soil, and farm management work together over time. Now I’m learning from farmers and seeing these systems in practice. I want to help develop farming that works for both people and the environment.” Maliha Issa Hamid, SUA graduate and APOPO HeroTREEs intern
Why Tanzania needs its own evidence
Our HeroTREEs team has found very little published scientific research on syntropic agroforestry in Tanzania. Studies from West Africa point to potential. In Ghana, for example, researchers from Bern University of Applied Sciences compared young cocoa on 20 dynamic agroforestry fields and nine monoculture fields. They concluded that dynamic agroforestry shows potential for cocoa health, and that good field management strongly influences it. Findings like these cannot show how syntropic agroforestry performs in Tanzanian soils, climates, and crops. At Lugala, students can run studies, and farmers and agricultural organizations can see the system at work.
International Syntropic Agroforestry Research Workshop
APOPO HeroTREEs will host an International Syntropic Agroforestry Research Workshop from 26–30 October 2026 at SUA in Morogoro, Tanzania. Researchers and practitioners will agree on indicators and methods for long-term syntropic agroforestry research. The aim is comparable data on soil regeneration, biodiversity, climate resilience, farm productivity, and livelihoods.
Learn more about the upcoming HeroTREEs Research Workshop.
Student research, farmer data, and shared methods all support the same goal: evidence that helps farmers make informed decisions about syntropic agroforestry.
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