Increasing adoption of reduced tillage strategies on organic vegetable farms in the maritime

View the project final report

• 2015 annual report
• 2016 annual report

Commodities

• Vegetables: beans, broccoli, cucurbits

Practices

• Crop Production: conservation tillage
• Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research, participatory research
• Energy: energy use
• Farm Business Management: budgets/cost and returns
• Natural Resources/Environment: carbon sequestration, indicators
• Pest Management: mulches - killed, cultivation, mulching - vegetative
• Production Systems: agroecosystems, organic agriculture
• Soil Management: earthworms, organic matter, soil analysis, nutrient mineralization, soil microbiology, soil chemistry, soil physics, soil quality/health

Grower interest in reduced tillage techniques stems from concern over soil quality and energy use. Tillage decimates large-bodied soil organisms, reduces soil carbon storage and weakens the stability of aggregates. Yet, organic vegetable growers in the Pacific Northwest currently pass over their fields 10 to 20 times annually to incorporate cover crops and amendments, prepare the soil for planting and manage weeds. In response to the interest in tillage reduction, our syndicate of growers, researchers and Extension educators has worked collaboratively to develop and test reduced tillage strategies for organic vegetable production in the Pacific Northwest since 2009. Incorporating reduced tillage into organic vegetable cropping systems requires careful integration of cover crops with equipment. Cover crops for reduced tillage systems must be winter hardy, produce sufficient biomass to smother weeds, mature early and preferably add nitrogen to the system. Tools must effectively kill the cover crop without tillage and also prepare the soil to receive a transplant or seed.  Our goal is to increase organic farmer economic and environmental sustainability through soil conservation and reduced tillage. Through SARE Project SW11-072 we have carried out four on-farm experiments, carried out cover crop variety trials and initiated a long-term systems experiment. The proposed project will continue our systems-based work to develop and implement reduced tillage strategies for organic vegetable cropping in the maritime Northwest and other northern climates. Our future focus is to reduce risk for early adopters of reduced tillage by sharing successes and failures. We will also encourage more wide-spread adoption of reduced tillage by building on our previous experience to address specific obstacles and remaining questions, including: Which implements and strategies are most effective to manage residue in zone-tilled ground? (Objective 1) How does reduced tillage affect nutrient cycling and fertility management? (Objective 2) Which cover crops, mixes and termination strategies perform best? (Objective 3) What specific challenges and opportunities do continuous reduced-tillage present? (Objective 4) We will address these questions and extend our outreach (Objective 5) by: Facilitating research with seven commercial organic vegetable producers. We will improve residue management and compare cover crop termination strategies through on-farm trials and demonstrations. (Objectives 1, 3 and 5) Continuing an on-station long-term reduced tillage cropping systems experiment with three cash crops in rotation and adaptive management to include new cover crops and equipment improvements. Specifically, we will implement more aggressive zone tillage. (Objectives 1, 2 and 4) Executing six cover crop variety trials at two different research stations. (Objective 3) Reaching out to producers through field days, farm walks, articles, a video and presentations to state-wide, regional and national audiences. (Objective 5)

1. 1. Develop, trial and describe best strategies for cover crop residue management in zone tilled organic agriculture systems.

      1. 1. Zone tillage has thus far provided the most interest among cooperating growers. Our current zone till treatment will be modified to provide more aggressive tillage and a second zone tiller will be purchased to extend our ability to reach more farms. Cover crop degradation in the tilled zone will increase soil temperature and allow for in-row weed management. We will measure the success of zone tillage by comparing soil temperature and crop yield in zone-tilled and full-tilled treatments in on-farm trials and in our long-term reduced tillage systems trial.

      1. 1. Cover crops and cover crop termination methods are also integral to successful zone tillage. We will compare termination with the roller/crimper to termination with flail mowing and measure success by the occurrence of volunteer cover crops and weed management in the inter-row.

1. 1. Evaluate nitrogen cycling dynamics in reduced tillage organic systems.

      1. 1. Through our previous cover crop trials we have been able to identify a successful legume cover crop (Purple Bounty vetch) for inclusion in our long-term reduced tillage trial. We will focus our evaluation of nutrient cycling dynamics on the tilled and reduced tillage treatments following vetch by measuring both soil nitrate and total plant uptake by broccoli five times through the season each year of the trial.

1. 1. Select cover crops and termination strategies for reduced tillage organic agriculture.

      1. 1. Successful cover cropping is essential to reducing risk in adopting reduced-tillage organic vegetable production agriculture. The cover crop must produce enough biomass to effectively suppress weeds and also reach a late developmental stage to mechanically terminate while accommodating the relatively short growing season in the Pacific Northwest. One of the largest barriers to successful organic reduced tillage is termination of the cover crop. We will perform cover crop trials at two research stations (WSU Puyallup and WSU Mount Vernon) during each year of the project. We will measure above-ground biomass and carbon to nitrogen ratios of different varieties and mixtures and will also consider timing for termination and compare termination methods (roller/crimper vs. flail mower) for grain varieties.

1. 1. Develop trial, and describe strategies for continuous reduced tillage in organic agriculture.

      1. 1. To date we have not experimented with continuous reduced tillage methods in northwest Washington. However, we see this as an important next step to soil quality improvement. We will measure soil quality indices (e.g. penetrometer, bulk density, chemical properties and soil fauna) and weed populations in this treatment and the other five treatments in the long-term reduced tillage experiment.

1. 1. Help at least 15 western Washington organic producers adopt reduced tillage techniques on their farms.