From Forest to Farm: Can Agroecological Practices Restore Amazonian Soil Health?

Redacción HC
10/06/2025

As tropical forests in the Amazon Basin continue to be cleared for agriculture and pasture, critical ecosystem services—such as carbon sequestration, water regulation, and soil fertility—are rapidly deteriorating. But a new field study published in Forests (2025) offers compelling evidence that agroecological practices like organic fertilization and biofertilization could help reverse some of this damage, particularly in the deeply weathered oxisols of the Amazon.

Conducted by researchers from the Federal University of Paraíba, Brazil, the study examined how different land uses—agroforestry, pasture, and natural forest—combined with soil treatments affected ecological functions. The question at its core: Can we make degraded farmland function more like a forest again?

A Region Under Pressure

The Amazon Basin, a global biodiversity hotspot and climate regulator, is under immense strain from deforestation and unsustainable land use. Converting forests to agriculture often leads to depleted soils and weakened ecological resilience. But alternatives exist.

Agroecological approaches that blend ecological principles with traditional farming may offer a solution. The researchers focused on two key interventions: organic fertilization using manure and biofertilization using microbial inoculants. They tested these in both agroforestry and pasture settings to see if the land could recover vital functions.

Field Experiment: Methods That Mirror Complexity

Over a three-year period (2022–2024), field plots were established in Amazonian oxisols—soils known for low natural fertility but high weathering stability. The experimental design included:

• Three treatment types: control (no input), organic fertilization (manure), and biofertilization (microbial consortia)
• Two land uses: agroforestry and pasture systems
• One benchmark: a nearby intact natural forest

Soil samples were analyzed seasonally for key indicators:

• Physical: bulk density, porosity, root density, and aggregate stability
• Chemical: pH, soil organic carbon (SOC), total nitrogen, phosphorus
• Biological: microbial biomass, respiration, and gene abundance (archaea, bacteria, fungi)

The researchers applied robust statistical methods (ANOVA, regression modeling) to identify how treatments and seasonal factors interacted to influence ecosystem services.

Key Findings: Organic Fertilization Stands Out

1. Boost in Biomass and Litter

The intact forest naturally had the highest aboveground biomass and litterfall. However, plots receiving organic fertilization showed a 19.3% increase in plant biomass and a 30.3% rise in litter production over two years—approaching forest-like levels.

2. Improved Soil Structure and Moisture Retention

Organic inputs enhanced soil porosity and reduced compaction, leading to better water retention. In contrast, biofertilization and control plots showed little to no structural improvement, highlighting the importance of organic matter inputs in rebuilding degraded soils.

3. Enhanced Nutrient Content and Microbial Activity

Soils treated with organic fertilizer recorded significant gains in:

• Soil pH
• Organic carbon and nitrogen
• Phosphorus availability
• Microbial biomass (carbon and nitrogen)

Biofertilization yielded moderate benefits, but the control plots experienced progressive nutrient depletion, reinforcing the urgency of active soil restoration.

4. Microbial Diversity and Root Development

• Organic fertilization supported higher fungal abundance and root density, critical for soil structure and nutrient cycling.
• Biofertilization increased archaeal populations but reduced bacterial and fungal diversity, suggesting possible ecosystem imbalances if not managed carefully.
• The natural forest maintained stable and diverse microbial gene abundances throughout the study.

5. Ecosystem Service Modeling

Modeling revealed:

• Provisioning services (e.g., biomass, litter) were tied to aboveground growth and root development.
• Regulating services (e.g., nutrient cycling, soil structure) depended on physical and chemical improvements in the soil.

Service contribution scores were:

• Forest: 47%
• Agroforestry: 22%
• Organic fertilization: 10%
• Biofertilization: 5.6%
• Control: −42%

These results suggest that organic fertilization within agroforestry systems best mimics forest functions, though not fully.

Practical Implications: From Research to Action

For Policy

The study underscores the need for national policies that support agroecological transitions:

• Incentives for using organic amendments
• Long-term soil health monitoring
• Support for agroforestry development in tropical regions

Such measures could help reverse deforestation trends, boost carbon sequestration, and improve rural livelihoods.

For Farmers and Communities

• Organic fertilization allows productivity without dependence on synthetic inputs
• Improved soil moisture and structure boost resilience to extreme weather
• Agroforestry offers biodiversity benefits and diversified income sources

With appropriate technical support, these strategies could empower smallholder farmers across the Amazon Basin and beyond.

For Researchers

The study calls for:

• Long-term studies beyond three years to capture carbon sequestration trends
• Exploration of optimal combinations of organic and microbial treatments
• Greater focus on species diversification in agroforestry to enhance multifunctionality

Conclusion: Toward a Regenerative Amazon

While no intervention matched the ecological performance of intact forest, the evidence is clear: agroforestry systems enriched with organic fertilization significantly improve degraded soils. These findings offer a hopeful path forward—one where productivity and restoration coexist.

As the Amazon faces mounting threats, integrating agroecology into land management could become a cornerstone of regional sustainability. And with the right investment and education, these practices could be scaled to benefit both people and the planet.

Topics of interest

Biodiversity