Beyond the Bulb: Enhancing Onion Profitability and Shelf-life Using Reduced Fertility and Integrated compost and Biological Amendments in South Dakota

Commodities

Practices

Beyond the Bulb: Enhancing Onion Profitability and Shelf-life Using Reduced Fertility and Integrated Compost and Biological Amendments in South Dakota.

This project will evaluate five onion production systems in South Dakota to determine whether reduced synthetic nitrogen inputs can be supported by composted dairy manure and Holganix without sacrificing performance where it matters most to growers. Onion is a high-value but nutrient-sensitive crop, and producers need practical information on whether reduced-input systems can maintain marketable yield, lower synthetic input dependence, and improve storage outcomes under field conditions. This need is especially timely because growers are not only interested in how much onion a system produces, but also whether that system is affordable, manageable, and able to maintain bulb quality after harvest.

The study will compare a standard fertility treatment with reduced synthetic nitrogen alone and reduced synthetic nitrogen combined with composted dairy manure, Holganix, or both. The project will be conducted in field plots using a randomized complete block design with four replications. Onion transplants will be established in spring, managed under existing center pivot irrigation system with Lateral irrigator, and evaluated for total yield, marketable yield, bulb size, production costs, labor, storage performance, and soil health indicators. A major strength of the project is that it will not stop at harvest. Bulbs will be cured and stored under practical farmer-style conditions, then evaluated for rot, sprouting, weight loss, and marketable quality. This will help determine whether a system that performs well in the field also performs well in storage, which is essential for profitability and marketing flexibility.

Expected outcomes are that growers will gain clearer information on which nutrient management systems best balance yield, cost, labor, storage performance, and soil health outcomes. South Dakota specialty crop producers, including members of the South Dakota Specialty Producers Association, will be able to use these results to better judge whether reduced-input onion systems are worth testing on their farms. Results will be shared through presentations, outreach activities, social media and evaluation will include pre- and post-event surveys to assess knowledge gained. Overall, this project is expected to help growers make better nutrient management decisions while supporting NCR-SARE goals related to profitability, ecological stewardship, and quality of life.

Outcomes

The primary audience for this project is South Dakota specialty crop producers, including members of the South Dakota Specialty Producers Association (SDSPA).

Learning Outcomes:
Producers will gain knowledge about how reduced-fertility onion systems-utilizing composted dairy manure and Holganix microbial amendment-affect marketable yield, labor requirements, production costs, and soil health indicators. Currently, most similar research ends at the harvest gate; specifically, this project will help growers understand the trade-offs between conventional and reduced-input systems, with a focus on practical post-harvest outcomes such as rot incidence, sprouting, weight loss, and bulb marketability. At the end of this project, participants will be better informed on whether certain nutrient management strategies produce onions with better shelf-life and lower storage losses under South Dakota conditions.

Action Outcomes:
As a result of outreach activities, including a winter storage-focused workshop or presentation, growers will be better prepared to evaluate how reduced-input systems might fit their specific operations. We expect that some participants will indicate an intent to test or further explore reduced-fertility protocols, composted dairy manure, or microbial amendments on a limited, on-farm basis. Additionally, the project will encourage producers to consider the economic impact of storage stability when planning their seasonal marketing and inventory release.

Evaluation:
Success will be measured via pre- and post-event surveys at the SDSPA annual conference and our project-specific workshop. These surveys will measure knowledge gain regarding onion storage performance under different nutrient management systems and document whether participants intend to trial any of the studied practices on their own farms.