Improving Orchard Management through Multi-Species Cover Crop Mo

View the project final report

• 2015 annual report

Commodities

• Fruits: cherries, general tree fruits

Practices

• Crop Production: cover crops, crop rotation, nutrient cycling
• Education and Training: farmer to farmer
• Pest Management: biological control
• Production Systems: holistic management, organic agriculture, permaculture
• Soil Management: green manures, organic matter, soil analysis, nutrient mineralization, soil chemistry, soil microbiology, soil physics, soil quality/health

The main objectives of this multi-year project were to: 1) Evaluate how planting times, seeding rates, and seeding equipment affected multi-species cover crop establishment. 2) Investigate three different cover crop multi species mixes and five single species mixes on the following parameters: soil compaction, tree nutrient uptake, fruit size and firmness, and fruit yield.  3) Quantify economics of cover crops, including cost of seed, cost of establishment, nutrient contributions, pest and disease influence, management costs, tree growth and fruit quality and yield. 4) Encourage the adoption of multi-species cover crop mixes amongst commercial orchardists in the region and beyond.

Currently, conventional management of the orchard floor in Pacific Northwest orchards involves using herbicides to keep a bare strip of soil directly under the tree rows and maintaining a perennial grass sod alleyway between the tree rows. The grass sod, predominantly creeping red fescue and perennial rye, does a good job of preventing soil erosion but provides few of the other benefits cover crops offer. The sod root systems are relatively shallow, don’t scavenge effectively for nutrients, don’t increase the soil microbial life beneficial to tree health, nor do they provide nectar or pollen to beneficial insects.  Planting cover crops in the alleyways could increase the sustainability of tree fruit orchards but this practice is not utilized at all in the Mid-Columbia region, according to our local Oregon State University Extension office.

Multi-species cover crop “cocktails” have been utilized more extensively in annual cropping systems and have been shown to improve soils and crop yields in ways that researchers still don’t fully understand.  Although it was not within the scope of this small project to understand all the mechanisms at play with respect to cover cropping benefits, we tried to identify the best cover crop mixes for our region and understand how they impact fruit quality and economic return to the grower. It was important to find out what works best in an orchard system, our local microclimate, soils, set of equipment, and other factors.  This way we can inform other growers about how to be successful with cover crops on their operation.  We understood if the cover cropping results were positive, it should lead to increased adoption of the practice by orchardists in the region and increased sustainability of the orchard cropping systems.  

The project was conducted in a mature cherry block (Chelan variety) at Omeg Family Orchards in The Dalles, Oregon. Single row alleyway treatments will be planted to cover crop mixes with multiple data points collected throughout their growing cycle.

The results of our study are contained herein.  Highlights include:

• An ATV with seeder mounted works well for sowing cover crops but requires more seed per acre. It is also the cheapest equipment to purchase.
• A no-till drill is effective but is the highest costs per acre to operate and the most expensive machine to purchase. Tillage is still required before planting to get the best stands.
• A power harrow with integrated pneumatic seeder does an excellent job establishing a cover crop in a single pass. The harrow has the lowest machinery and labor costs and a moderate price tag to purchase the machine.
• Fall is the most desirable time to plant. Spring and summer plantings suffer from equipment driving over the growing crop and shade from the canopy stunts the growing plants.
• A mix of ‘Bounty’ annual ryegrass, ‘Enricher’ radish, Phacelia, ‘Bayou’ kale and ‘Shield’ mustard performed the best for us. ‘Bounty’ annual ryegrass and ‘Enricher’ radish also did well planted as a single species.
• Soil nutrient levels were not different between treatments or the control.
• Soil quality in the alleyway improved with cover crops. Reductions were observed in compaction and infiltration rate was increased.
• There was no difference in tree leaf nutrient levels, shoot growth/caliper or fruit/size or quality from any of the cover crops.
• “Mow and blow” may be a way to make alleyway cover crops contribute to the tree crop. A follow-up project was funded and has been started investigating the benefits of mulching cover crops via mow and blow in orchard systems.

1. To research how planting times, seeding rates, and seeding equipment affects multi-species cover crop establishment.

2. To research three different cover crop multi species mixes and five single species mixes on the following parameters: soil compaction, tree nutrient uptake, fruit size and firmness, and fruit yield.  

3. To quantify economics of cover crops, including the following parameters: cost of seed, cost of establishment, nutrient contributions, pest and disease hotspots, management costs, fruit yield and quality.

4. To encourage the adoption of multi-species cover crop mixes amongst commercial orchardists in the region and beyond.