Comparing Organic No till with Conventional Tillage methods when Direct Seeding Vegetables and Incorporating Cover Crops

View the project final report

Commodities

• Vegetables: carrots, greens (leafy)

Practices

• Crop Production: conservation tillage
• Education and Training: demonstration, extension, on-farm/ranch research, participatory research, workshop
• Natural Resources/Environment: biodiversity
• Pest Management: biological control
• Production Systems: holistic management, organic agriculture, permaculture
• Soil Management: earthworms, green manures, organic matter, soil analysis
• Sustainable Communities: public participation

We conducted a two-year experiment that was designed to demonstrate the potential benefits and viability of organic no-till for directly seeding market garden vegetables. In the first year, we planted a variety of salad greens and lettuce. In year two, we switched to carrots.

Our farm is located in the Pacific Northwest where extremely wet winters and springs can delay planting dates due to problems associated with wet soils. Our experiment clearly demonstrated that we could prepare the no-till beds as much as six weeks earlier than the tilled ones without harming the soil structure.

In year one, overall yields of salad greens was greater in the no-till beds due to earlier planting dates, which effectively increased the length of the growing season. In year two, the no-till carrot yields were significantly larger due to pest damage, as well as splitting of carrots in the first tilled bed.

Introduction

Soil and Climate

Growing conditions in the maritime Pacific Northwest present some unique challenges. Extremely wet winters and springs, as well as cool temperatures throughout the summer months, can promote a host of disease and pest problems, as well as having a negative impact on soil structure and fertility.

Problems with Tillage

The soil at our farm is shallow and has high clay content and an extremely hard glacial till subsoil. Most farms in our area have poor drainage that contributes to problems associated with spring tillage in wet soil, such as loss of soil aggregate, compaction, erosion, increased run-off, nutrient leaching and anaerobic conditions that promote soil born diseases. These problems contribute to reduced crop yields and increased production costs.

Increased erosion, run-off and nutrient leaching into our watersheds has become a major concern, especially in salmon spawning habitats. Government regulations regarding setbacks to streams and wetlands has started to have a serious impact on many farmers in our area.

In our site, tillage promotes the spread of quack grass, thistle and initiates the germination of many types of weeds when compared to continuous no-till.

Benefits of No-Till

Utilizing a fall-sown cover crop into a no-till system can greatly reduce run-off and nutrient leaching. Year-round cover cropping in a no-till system also reduces the need for manure and compost.

Without the use of herbicides, organic farmers tend to depend upon tillage as their main method of controlling weeds, as well as for incorporation of green manure into the soil. In a continuous organic no-till system that combines year-round cover cropping and proper crop rotation, weed pressure is reduced, as well as the need for soil amendments.

Amendment mix for salad greens and carrots cash crops

For our two-year experiment we compared the following four treatments, using Fava Bean cover crops, chicken manure and azomite mineral amendments.

1. No-till + manure amendments


2. Tillage + manure amendments


3. No-till + cover crop/manure amendments


4. Tillage + cover crop/manure amendments

The salad mix is composed of lettuce, Red Russian Kale, Arugula and a variety of Asian greens: Tokyo Bekana, Giant Red Mustard, Tatsoi, Mizuna. In our original proposal ,we planned to grow salad mix in both years in the same beds. Unfortunately we became concerned due to the large number of greens in the salad mix that are in the mustard family. In our region, club root is a major problem and affects all members of the mustard family. That is why we modified our experiment in year two and planted carrots.

1. Use no-till to build prime agricultural soil in a region that has no class 1 soils.

2. Develop innovative methods for direct seeded salad greens using a no-till system.

3. Effectively integrate cover crops/manure using a no-till system.

4. Develop planting/cover cropping schedules that allow earlier planting dates.

5. Compare soil quality and weed pressure between tilled and no-tilled plots.

6. Measure economic benefits.

7. Measure potential benefits to agriculture and soil improvement.

8. Encourage adoption of methods/educate wider public