Using regenerative agricultural practices in seed potato systems

Commodities

• Agronomic: potatoes

Practices

• Crop Production: cover crops, crop rotation
• Soil Management: soil quality/health

Montana is the nation's third-largest producer of certified seed potatoes, and most seed is shipped to major commercial potato growing states in the pacific northwest such as Idaho, Washington, and Oregon. The seed potato growers across the state work closely with the MT seed potato certification program housed in Montana State University to produce high quality, disease-free clean seeds. Approximately 47% of the seed potato growing acreage is in Gallatin County, where intensive agricultural practices have been continuing for over a century. Long-term intensive rotations and multiple tillage passes (3-4 per season) risk degrading soil structure, reducing microbial diversity, and increasing production costs. This project asks: (1) Can a diverse, two-year cover-crop rotation inserted between potato cycles, combined with minimal tillage, measurably improve soil and plant health? (2) Do these practices improve biodiversity while minimizing disease risk in seed potato systems?

We will conduct on-farm trials comparing the current potato-focused rotation with a regenerative approach using multi-species cover crops (legumes, grasses, and brassicas) for two seasons between potato crops, plus minimized tillage during field preparation and planting. Metrics include soil organic matter, aggregate stability, infiltration and compaction, microbial and insect diversity, and plant nutritional status.

Expected outcomes are field-tested guidelines and a simple decision tool that improve water infiltration and moisture retention, increase beneficial microbial and insect biodiversity, reduce tillage and fuel. The project advances sustainable agriculture by offering a practical, economically viable path to regenerate soils while safeguarding high-value seed markets. Findings will be shared through field days, the Montana Seed Potato Seminar, Extension newsletters, and Western SARE's database to support adoption across Montana and the Pacific Northwest.

Research Objectives

Objective 1: Soil health and microbial diversity

Our first objective will compare a two-year, multi-species cover-crop phase with min-till to the prevailing rotation for effects on soil health and microbial diversity over two growing seasons. Expected targets (by end of Year 2) are: faster water infiltration, increase in soil organic matter (SOM), lower soil penetration resistance, higher soil microbial activity, and higher soil microbial diversity vs. the prevailing rotation.

Objective 2: Plant quality

Determine whether the regenerative system maintains plant nutritional status and balance, and nutrient mobility within the plant.

Objective 3: Biodiversity and habitat co-benefits

Measure beneficial insect vs. aphid activity and field-edge habitat function associated with the cover-crop phase. Investigate microbial ecology by measuring the diversity of the soil microbiome using 16S rRNA, ITS, and 18S rRNA to capture bacterial, fungal, and protist diversity.

Education Objectives

1. Build farmer confidence to establish two-year, multi-species cover crops and practice minimal tillage in seed potato rotations.
2. Teach low-cost, repeatable field health measurements (infiltration, penetrometer) and simple biodiversity monitoring.
3. Provide decision tools (mix recipes, termination decision tree, equipment tips, and partial-budget templates) that shorten the path to adoption.