Soil Under Siege: How Land Use Change is Accelerating Erosion in the Peruvian Amazon

Redacción HC
07/01/2025

In the heart of the Peruvian Amazon, the Neshuya sub-basin in Ucayali is facing a quiet but relentless crisis: soil erosion driven by deforestation and unsustainable agriculture. Between 2016 and 2022, changes in land cover have intensified the loss of fertile topsoil, a process with far-reaching consequences for ecosystems, water quality, and food security.

A new study, published in Geosciences (January 2025), applies geospatial modeling to assess how shifts in land use have impacted erosion rates. Using the Revised Universal Soil Loss Equation (RUSLE), researchers from Peru’s National Institute of Agricultural Innovation (INIA) and other institutions show that erosion in this Amazonian sub-basin has grown by 18% in just six years, revealing alarming trends that demand urgent action.

Mapping Erosion: Why Land Use Matters

Soil erosion is more than just dirt washing away — it’s the degradation of one of our most valuable natural resources. When forest is replaced with agriculture, especially without conservation practices, the land becomes vulnerable to heavy tropical rains, leading to gullying, sedimentation in rivers, and a decline in soil fertility.

The research focused on this key question:

To what extent has soil erosion increased due to deforestation and land use change in the Neshuya sub-basin from 2016 to 2022?

By comparing satellite data, field observations, and soil analyses, the study maps the progression of degradation — and identifies critical erosion hotspots.

RUSLE in Action: A Geospatial Lens on Soil Loss

The study employed the RUSLE model, a widely used tool to estimate soil erosion based on five interacting factors:

• R: rainfall erosivity
• K: soil erodibility
• LS: slope length and steepness
• C: vegetation cover
• P: conservation practices

Researchers conducted soil sampling and field validation, while satellite imagery helped assess changes in vegetation and land use patterns over time. They compared two key years — 2016 and 2022 — to quantify how erosion levels have changed.

“The average annual soil loss increased from 3.87 to 4.55 tons per hectare, highlighting the growing vulnerability of cleared lands,” the authors report.

Alarming Trends: Soil Loss and Landscape Transformation

1. Erosion Intensifying with Agricultural Expansion

The findings reveal an 18% increase in average annual erosion across the sub-basin. The main driver? Deforestation for agricultural expansion, particularly in areas with steep slopes and poor soil conservation.

• 7.65% of the total area, approximately 74.5 km², exceeded the critical threshold of 15 t/ha/year, indicating unsustainable land use.
• Areas of intense erosion correspond closely to newly deforested plots used for cropland or pasture, especially those lacking slope management or cover crops.

2. Spatial Hotspots Reveal Risk Zones

Erosion is not uniform across the landscape. The study highlights erosion hotspots where soil loss is concentrated due to a combination of steep topography and low vegetation cover.

“These areas require urgent attention for soil conservation interventions,” note the researchers.

3. Impact on Ecosystems and Hydrology

Soil erosion depletes not only agricultural productivity but also impacts watershed function by increasing sediment loads in rivers, reducing water quality, and damaging aquatic ecosystems.

What Needs to Be Done: Practical Responses

A. Policy and Planning Recommendations

To address the growing erosion problem, the authors recommend:

• Launching soil conservation programs, especially in erosion hotspots.
• Regulating deforestation, particularly on slopes and near waterways.
• Incentivizing agroforestry and contour farming, integrating vegetation into productive landscapes.

B. Improving Land Management

Sustainable land use must involve:

• Crop rotation and residue cover to reduce bare soil exposure.
• Terracing and buffer strips to slow runoff.
• Promoting farmer training on best practices and micro-watershed planning.

"The RUSLE model offers a low-cost tool for monitoring erosion over time and guiding site-specific interventions," the authors emphasize.

C. Involving Local Communities

Engagement with local farmers and indigenous communities is essential to develop culturally appropriate and economically viable conservation strategies.

“Soil conservation cannot succeed without the active participation of those who live on and work the land,” states the study.

Why It Matters: Soil Health is Climate Resilience

This study offers more than just maps — it provides a scientific foundation for climate-resilient land planning in the Peruvian Amazon. By linking deforestation and soil degradation, it underlines the importance of landscape-level strategies that conserve both forest and farmland.

From a national perspective, these findings could inform:

• Restoration programs in degraded Amazonian lands.
• Policies aligned with Agro Rural and other sustainable agriculture initiatives.
• Cross-sector coordination to integrate soil conservation into broader environmental policy.

Conclusion: Erosion Is Reversible — If We Act Now

The erosion crisis in the Neshuya sub-basin is a stark warning: deforestation and agriculture without safeguards can lead to lasting damage. But it also offers an opportunity.

By investing in scientific monitoring, adaptive land management, and community engagement, Peru can reverse these trends and protect the long-term health of its Amazonian landscapes.

Topics of interest

Biodiversity