Rodale: why a trial begun in 1981 still matters
Since 1981, Rodale has compared organic and conventional systems on the same plots. The Farming Systems Trial follows soil, yield and resource management across decades.
A continuing experiment
Started in Kutztown, Pennsylvania, it investigates barriers to organic transition using field measurements. Crops include maize, soybean and grains, with production, soil and input records.
Three fertility systems
The conventional system uses synthetic fertilisers and herbicides. One organic system uses legumes and rotations; another combines legumes, longer rotations and periodic composted manure. Since 2008, full and reduced tillage have also been compared. Nutrition, cover, rotation and tillage are studied as whole systems.
Yield, water and energy
Pimentel and colleagues’ 2005 assessment after more than twenty years reported comparable organic and conventional yields, higher soil organic matter and nitrogen in organic systems, and less fossil energy use. Better moisture retention mattered particularly during drought.
Organic management and structure
Littrell and colleagues analysed 2018 samples from three depths to 30 cm in a 2021 study, measuring carbon, microbial biomass and water-stable aggregates. Organic systems had more total and active carbon, especially with composted manure. Reduced organic tillage improved aggregation.
Lorenz and colleagues’ 2025 analysis after 34 years found higher organic-manure carbon stocks mainly in the top 20 cm. The difference was not significant for the whole 30 cm when compared on equivalent soil mass. Depth and calculation methods matter.
Microbial communities
Mo and colleagues examined communities at different depths in 2024. Fertility source was the strongest compositional influence, especially for fungi, diminishing with depth. Tillage affected mainly the top 20 cm. This adds biology to production and property measurements.
The value of time
Long trials follow transitions through varying years and weather. We adopt the logic of baselines, comparable interventions and observation over time, assessing production with biology, water and structure.
Our field work
We plan repeated olive grove measurements, recording microbiology, addressing deficiencies through liquid compost extracts and comparing microscopic outcomes.
Sources and further reading
- Rodale Institute, Farming Systems Trial
- Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems
- Long-term organic management combined with conservation tillage enhanced soil organic carbon accumulation and aggregation
- Soil organic carbon and total nitrogen after 34 years under conventional and organic management practices at the Rodale Institute Farming Systems Trial
- Agricultural practices influence soil microbiome assembly and interactions at different depths identified by machine learning