Cover Crop Innovation in Oregon: OSU Organic Extension Collaborates with OGC Grower Partner Siri & Son Farms

Long used by organic farmers, the application of cover crops such as Vetch, Rye or Red Clover help to supply plant available nitrogen, prevent erosion, manage weeds and contribute to vital soil regeneration.  

Often applied to whole fields to transition acreage between one planting and another by enriching the soil, they can also be planted among established crops. In a process called interseeding, cover crops are sown into fall plantings as the crops grow and before the start of the rainy season. Interseeded crops enjoy the added benefit of reduced mud splatter on the plants; a welcome advantage for the workers responsible for picking and washing the harvest. 

Two large hoppers deliver Vetch seeds down hoses attached to five seed spreaders that distribute them to the ground among the cabbage. Two sets of black tines on each side of the row drag along the dirt to disturb weeds.

A typical alternative to cover cropping has been the application of a nitrogen source such as chicken manure, which helps feed the plants, but doesn’t offer the same soil-building and carbon-capturing benefits as over crops. Chicken manure is also an expensive input that must be handled carefully, can only be applied after all crops have been harvested and before the rain comes. While interseeding can often make the difference between getting a cover crop established or not in fall vegetable fields, the device itself, which needs to deliver cover crop seeds from a tractor into established rows without harming the plants, can run up to $50,000. 

These prohibitive costs had Nick Andrews, an Organic Extension Agent from Oregon State University who focuses on organic vegetable production, wondering if he couldn’t create accessible solutions to encourage more cover-cropping not only by organic growers, but all growers looking to incorporate the beneficial practice. Utilizing the same hardware many growers already use to apply fertilizer, Nick began tinkering.  

With his hybrid device still in prototype, Nick reached out to one of Oregon’s largest producers of organic fresh vegetables, Joe Siri of Siri & Son Farms seeking collaboration on field tests in his expansive acreage of late-season crops. An intrepid farmer and keen businessperson, Joe was happy to coordinate with Nick to test his device. 

On a sunny day in early September, Nick and Joe made the trial run of the interseeder device over a planting of fall cabbage with great results. Pleased by what they both saw, and with a few notes taken on best timing for interseeding cabbage, now it’s time to wait and see how the cover crop seeds will perform.  

Nick Andrews , Joe Siri and Siri & Son Farms’ Equipment Operator, Adrian

To support and track the success of the interseeding project, Nick will be working with Joe to utilize another tool he developed several years ago, the cover crop calculator. The calculator considers all the inputs involved in cover-cropping, from fuel to equipment depreciation and cost of seed, to determine the cost of creating the greatest amount of Plant Available Nitrogen (PAN). Joe is no stranger to the cover crop calculator. He and Nick used it to assess the economics of several of last year’s cover-cropped fields and were able to determine that the PAN he received from the cover crop came in at half the cost of the equivalent amount of nitrogen from chicken manure. Joe and Nick are expecting to see similar financial results from this season’s interseeded cabbage fields.  

A win-win from every angle, and an exciting innovation from the mind of Nick Andrews and OSU’s Organic Extension Program that we look forward to keeping track of!  

As cooler weather starts to tease its impending arrival, and with it a slowing of annual harvest season, OGC would like to extend our thanks to the organic researchers, scientists, growers and their crews for all their hard work. It’s this type of exciting effort behind the scenes that not only keeps Oregonians well fed with delicious organic produce, but also helps keep this beautiful state’s soil, water and wildlife as healthy as possible.