Soil Health and Management in Organic Systems: Identifying Pathways to Resilience
Project Director
Jodi Johnson-Maynard
Year Funded
2020
Award Number
2020-51106-32358
Funded Institution
University of Idaho
Grant Program
ORG (Organic Transitions)
USDA NIFA Report (alternate)
Project Overview
Replicated trials were conducted at two sites in the Palouse region and two sites in the Magic Valley region of Idaho to evaluate the efficacy of organic soil amendments and tillage on soil health. Alfalfa + orchardgrass were planted in 2021 and terminated in Fall 2023 or Spring 2024, followed by feed barley in 2024, and amended with compost or processed organic fertilizer. Three levels of tillage intensity were applied before alfalfa/grass planting and at termination. Treatments were compared for total soil organic carbon (TOC), microbially active (permanganate oxidizable) carbon (POxC), phosphorus (P), soluble nitrogen (N), bulk density and infiltration rate, earthworms, and crop yield.
Farmer Takeaways
(1) Compost, together with a soil building cover crop like alfalfa-grass, can mitigate adverse effects of tillage during the organic transition.
(2) Soil aggregate stability, phospholipid fatty acids (PFLA, an indicator of microbial biomass), permanganate oxidizable carbon (POxC), and total soil N may be more reliable indicators of management effects on soil health in the interior Pacific Northwest.
(3) Total soil organic matter (SOM) responds slowly to tillage and amendment type.
(4) Water infiltration rate, soil respiration, earthworm populations, and water extractable carbon and nitrogen may be too variable to reliably indicate management effects.
Project Outputs
Temmen, D. 2022. Variation in soil health indicators across certified organic farms in the Inland Pacific Northwest. ASA, CSSA, SSSA International Annual Meeting. Baltimore, MD.
Romano, A.W., L.R. Schott. Soil health in organic systems of the western high desert. ASA, CSSA, SSSA International Annual Meeting, Baltimore, MD.