Management Practices and Cover Crops for Reduci...

Management Practices and Cover Crops for Reducing Tillage, Enhancing Soil Quality, and Managing Weeds

Management Practices and Cover Crops for Reducing Tillage, Enhancing Soil Quality, and Managing Weeds

collins

The Challenge

The USDA National Organic Program rules stipulate that certified organic growers must implement tillage and cultivation practices that maintain or improve the physical, chemical, and biological condition of their soil and minimize soil erosion. Yet, many of the approximately 255 certified organic farms in western Washington passed over their fields 10 to 20 times annually with tillage equipment to manage plant residue, control weeds, and prepare the seed bed for planting. According to Douglas Collins, Washington State University, tillage decimates large-bodied soil organisms, reduces soil carbon storage, and weakens the stability of aggregates. Thus, many organic growers wished to integrate reduced till systems onto their farms to improve soil quality, while maintaining adequate weed control.  However, there had not been much research conducted on no- and reduced-till systems in organic agriculture, especially vegetable crops. When Collins brought together a research and producer group, they identified a “lack of successful examples of reduced-till practices for systems similar to theirs and in the maritime Northwest climate” as a critical gap to making this system change. Producers were specifically interested in identifying species of cover crops to use in organic reduced-till systems; planting and termination timing for cover crops; weed management techniques; and field equipment necessary to adopt these systems.” Consequently, Collins and his team developed the project “Selecting Management Practices and Cover Crops for Reducing Tillage, Enhancing Soil Quality, and Managing Weeds in Western Washington” with the long-term goal to increase organic farmer economic and environmental sustainability in western Washington through soil conservation in reduced tillage systems.

Searching for a Solution

This project’s objectives were:

1) Identify production methods that effectively integrate cover crops and reduced tillage technologies to improve soil quality while reducing in-season weed pressure and seed bank populations on western Washington organic farms;

2) Evaluate profitability and greenhouse gas impacts of reduced tillage cropping systems on these farms;

3) Facilitate adoption of reduced tillage technologies and ideas by a wide audience and identify tools and strategies most effective at encouraging behavior change.

Collins led this project toward meeting its objectives by conducting a multi-year reduced-tillage cropping systems experiment at the WSU Puyallup Research and Extension Center; conducting cover crop trials at the same site, leading to selection of winter crop varieties for the long-term systems experiment; and conducting six replicated on-farm trials and one un-replicated on-farm demonstration.

What was Learned

In reports and materials developed from this project, Collins describes its key findings: 

Selecting Cover Crops and Termination Strategies

  • Barley matured more quickly than rye.
  • Because rye matures less rapidly during the critical stages of termination, it was easier to manage termination at the desired time than barley.
  •  Common’ vetch matured more quickly than ‘Purple bounty’, ‘Lana’, and hairy vetch.
  • ‘Purple bounty’ and ‘Hairy’ vetch were the slowest maturing of the vetches and did not reach full flowering until mid-June 20. ‘Common’ vetch reached full flowering around May 24. ‘Lana’ was slower maturing and reached full flower around June 1.
  • Based on the variety trial, ‘Aroostook’ rye and ‘Lana’ vetch were included as cover crops in the reduced tillage cropping systems rotation in fall 2012.

Crop Yield 

  • Cover crop termination and reduced tillage combinations did not affect broccoli yields during any of the three years of the trial.
  • Full tillage (flail spader) bore greater squash yields than reduced tillage treatments in both 2012 and 2014.
  • Flail mowing produced greater squash yields in 2012 and 2014, among reduced tillage treatments.
  • Strip tilling yielded more squash in 2012, but plant aid yielded more in 2014.

Reduced Tillage Broccoli On-Farm Trial

  • Strip tilling following flail mowing common vetch produced broccoli yields equivalent to roto-tilling at one farm, though hand weeding took longer.
  • Grower experiments with high-residue cultivation were promising and will be explored further.

Economic Analysis 

  • From an economic perspective, there was no significant difference among treatments in broccoli.
  • Yield and time spent weeding were monitored on a plot level. Treatments were not significantly different in any of the three years studied.
  • Harvesting, irrigating, fertilizing, and planting also utilized hand labor, but these activities were consistent across treatments. Both tractor-labor and fuel usage were greater in the spader treatment than in the reduced tillage treatments. Treatments utilizing the roller/crimper utilized about 0.5 hours less labor/acre than treatments utilizing the flail mower. Treatments utilizing the planting aid used about two gallons/acre less fuel than treatments using the strip tiller.
  • In 2013, hand weed control in squash fields was not adequate, and the spader treatment performed worse than the other treatments.
  • In 2012 and 2014, weed management was better and the spader treatment yielded the most.
  • As with broccoli, treatments utilizing the roller/crimper utilized about 0.5 hours less labor/acre than treatments utilizing the flail mower. Treatments utilizing the planting aid used about two gallons/acre less fuel than treatments using the strip tiller.

Greenhouse Gas Impacts of Reduced Tillage

  • Insitu soil respiration was consistently higher in the full-tillage treatment than in the reduced tillage treatment for the first seven days after tillage.

Facilitating Adoption

  • During the three year project, 210 producers and professional were directly reached in six field-based events.

Want more information? See the related SARE grant(s) SW11-072, Selecting Management Practices and Cover Crops for Reducing Tillage, Enhancing Soil Quality, and Managing Weeds in Western Washington .

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Location: West
 

2016 Annual Report

For the first time, we are sharing a yearly snapshot of our work. The stories provided here typify the creative, participatory and integrated research Western SARE annually funds – led by land grant institution researchers and graduate students, Extension and other ag professionals, and nonprofit leaders in full partnership with producers.