Capitão Poço, Brazil — A multidisciplinary research team led by Marluce Reis Souza Santa-BrÃgida from the Universidade Federal Rural da Amazônia, together with Lucietta Guerreiro Martorano of Embrapa Amazônia Oriental, Carlos Augusto Cordeiro Costa of the Universidade Federal Rural da Amazônia, LetÃcia Moura da Silva of the Universidade Estadual de Campinas, Marcos Cesar Danhoni Neves of the Universidade Estadual de Maringá, Marcelo Moreira de Oliveira of the Universidade Federal do Pará, and Flávia Cristina de Araújo Lucas of the Universidade do Estado do Pará, reported in 2026 that the IrrigaPote subsurface irrigation system strengthens soil quality and water-use efficiency in Amazonian agroforestry systems. Conducted between August 2023 and August 2024 in the Cristo Rei rural community in Pará State, the study provides scientific support for expanding low-cost irrigation solutions for climate-vulnerable family farming systems.
The findings are significant because Amazonian agricultural soils are naturally acidic, nutrient-poor, and highly susceptible to leaching under heavy rainfall. These conditions limit crop productivity and increase vulnerability to climate variability. By combining agroforestry management with localized irrigation technology, the study demonstrates a practical pathway toward improving soil fertility and strengthening rural resilience.
Why Soil Quality Matters for Amazon Family Farming
Family farming plays a central role in food production and rural livelihoods across Brazil, especially in the Amazon region. However, agricultural sustainability in this environment depends heavily on soil management. Tropical soils in the region typically contain low levels of available phosphorus and limited cation exchange capacity, making nutrient retention difficult.
Agroforestry systems—where crops grow alongside trees—have emerged as an effective strategy for restoring degraded land and improving ecological stability. These systems increase organic matter inputs, support biodiversity, and enhance nutrient cycling. The research team evaluated whether such systems could also support the adoption of IrrigaPote, a low-cost social irrigation technology designed to improve water efficiency under variable rainfall conditions.
How the Study Was Conducted
The researchers carried out a mixed observational study in an agroforestry production area combining lemon cultivation with native tree species in the Cristo Rei community of Capitão Poço, Pará. Soil samples were collected at depths of 10, 20, and 40 centimeters and analyzed in specialized laboratories at Embrapa Amazônia Oriental and the Soil & Plant Laboratory in Paragominas.
The evaluation included chemical indicators such as pH, organic matter content, nutrient availability, and cation exchange capacity; physical indicators such as soil texture; and biological indicators such as microbial enzymatic activity. Mineralogical analysis using X-ray diffraction helped identify dominant soil minerals affecting fertility and water retention.
This integrated assessment allowed researchers to determine whether soil conditions were suitable for implementing the IrrigaPote irrigation system within sustainable agroforestry production.
Key Findings: Organic Matter and Microbial Activity Drive Soil Improvement
The study confirmed that agroforestry management gradually improves soil quality even in highly weathered tropical environments. Several important results stand out.
Soil acidity remained moderate, with pH values between 5.26 and 5.30, consistent with typical Amazon soils. Available phosphorus levels were low, measuring 1.43 mg per dm³ in surface layers and 0.72 mg per dm³ in subsurface layers.
Despite these limitations, surface soil showed strong enrichment in organic matter and carbon. Organic carbon reached 20.02 g per kg in the upper layer, while organic matter reached 34.5 g per kg, demonstrating the impact of litter deposition and root activity in agroforestry systems.
Biological indicators revealed especially strong ecosystem functioning. Arylsulfatase enzyme activity reached a very high value of 97, while beta-glucosidase activity reached 63, indicating active nutrient cycling supported by soil microorganisms.
Synthetic soil quality indices confirmed these trends. The biological soil quality index reached 0.91 and the nutrient storage index reached 0.96, both classified as very high. These values indicate that the soil can effectively recycle and retain nutrients despite mineralogical constraints.
Mineralogical analysis showed dominance of quartz and kaolinite, minerals typical of highly weathered tropical soils with low natural fertility. Under such conditions, organic matter becomes the primary driver of nutrient retention.
IrrigaPote Improves Water Efficiency and Climate Adaptation
One of the study’s most important contributions is its evaluation of the IrrigaPote irrigation system as a climate adaptation tool. Unlike surface irrigation methods, IrrigaPote delivers water slowly below ground near plant roots, reducing evaporation losses and deep percolation.
This localized subsurface irrigation stabilizes soil moisture levels and supports microbial activity responsible for nutrient cycling. Stable moisture conditions also help maintain soil organic carbon, which plays a critical role in sustaining fertility in tropical soils dominated by low-activity minerals.
The researchers observed that improved moisture stability contributes to stronger nutrient retention and reduced leaching, particularly under high rainfall conditions common in the Amazon.
According to Marluce Reis Souza Santa-BrÃgida of the Universidade Federal Rural da Amazônia, the interaction between agroforestry management and IrrigaPote irrigation creates “a functional synergy capable of compensating for the natural limitations of tropical soils and improving both environmental stability and productive resilience.”
Implications for Sustainable Agriculture in Tropical Regions
The study highlights how integrating agroforestry systems with low-cost irrigation technologies can strengthen climate resilience in smallholder farming systems. These findings are especially relevant as climate change increases rainfall irregularity and drought frequency across tropical regions.
By improving water-use efficiency, supporting soil biological activity, and stabilizing nutrient cycles, IrrigaPote offers a scalable solution for sustainable agricultural intensification without increasing environmental pressure.
The results also demonstrate that organic matter management is essential for maintaining fertility in tropical soils dominated by quartz and kaolinite. Policies supporting agroforestry expansion and decentralized irrigation technologies could therefore play a strategic role in improving food security in climate-sensitive regions.
Author Profiles
Marluce Reis Souza Santa-BrÃgida, researcher at the Universidade Federal Rural da Amazônia
Lucietta Guerreiro Martorano, researcher at Embrapa Amazônia Oriental
Carlos Augusto Cordeiro Costa, researcher at the Universidade Federal Rural da Amazônia
LetÃcia Moura da Silva, researcher at the Universidade Estadual de Campinas
Marcos Cesar Danhoni Neves, researcher at the Universidade Estadual de Maringá
Marcelo Moreira de Oliveira, researcher at the Universidade Federal do Pará
Flávia Cristina de Araújo Lucas, researcher at the Universidade do Estado do Pará
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