Enhancing Sustainability of Organic Broccoli Production through Integration of No-tillage and Farmscaping
This project seeks to develop an improved organic production system for broccoli and other crucifer crops by integrating high-residue no-tillage (NT) systems to suppress weeds with farmscape plantings as food and habitat for beneficial insects. In 2004, two experiments (summer and fall) and eight on-farm demonstration trials (four summer and four fall) were conducted, using in-situ high-residue cover crop mulch and NT production systems to produce organic broccoli.
Research—Experimental plots were located at the Kentland Agriculture Research Farm, near Blacksburg, VA. Cover crops were established on raised beds (6-ft wide, center to center) for both crops. Winter rye and hairy vetch were seeded with a Tye drill on October 3, 2003, for the summer crop and foxtail millet and forage soybean were seeded on June 3, 2004, for the fall crop. Cover crops were killed with a flail mower and one-half of each plot was conventionally tilled (CT) and the remainder was left as a mulch (NT). Broccoli transplants were set with the Subsurface Tiller-Transplanter (SST-T) on June 9 (summer crop) and August 17 (fall crop). Both crops were irrigated as needed. Fertilizer consisted of the legume cover crops, Harmony Organic 5-5-3, and fertigation with Neptunes Harvest. In addition, the fall crop was sidedressed with 64 lb N/acre from a mixture of feather meal and sodium nitrate. Broccoli yields were 3.3 (summer) and 5.0 ton/acre (fall). Yield differences between NT and CT were not significant at P = 0.05. Insects were held in check using farmscape habitat plantings in the center of each plot and trap crops grown in field perimeters. Weed levels were highest in CT plots.
Outreach—Of the eight on-farm trials (four each in VA and NC), four were successful and four were ruined because of extreme weather (Hurricane Ivan) and deer damage to both cover crop and broccoli plants. Valuable lessons (principles) learned from the 2004 on-farm trials are (1) farmscape plantings and trap crops are effective in managing insect pests; (2) to be an effective weed-management tool, uniform thick stands of cover crops must be established and killed before setting broccoli; (3) to achieve high marketable yield, broccoli plants require abundant plant-available nutrients (especially nitrogen); and (4) site selection is very important—i.e. avoid using low-lying areas and weedy pasture or uncultivated fields such as fescue sods. In weedy fields, spend 1-2 years to improve soil quality and reduce weed and weed-seed levels before attempting organic NT systems.
Objectives—Our hypothesis is that by integrating farmscaping with NT systems, broccoli production can be economically feasible without application of chemical pesticides. We will demonstrate that high-residue cover crop mulch combined with farmscaping, augmentation with natural enemies (if needed) and timely use of the microbial pathogen Bt can suppress weed and insect pests to produce a profitable organic broccoli crop. Specific objectives are to (1) develop an improved prototype system for production of organic broccoli by integrating high-residue NT cover crop mulch to suppress weeds and supply organic nitrogen with farmscape planting to attract and sustain beneficial insects; (2) evaluate the need for application of Bt in farmscaped systems for broccoli to control insect pests; and (3) facilitate the adoption of high-residue NT production systems and farmscaping and other education and outreach methods.
Performance targets—By December 2005, four fact sheets and a comprehensive leaflet on organic NT-farmscaping broccoli production will be available in both electronic and printed form. Within one year after completion of the project, (1) two of the five organic growers hosting on-farm demonstrations will adopt NT-farmscape systems, and (2) ten of the 200 or more growers who will attend workshops and field days will explore NT-farmscape systems for production of organic broccoli or other crops.
Research—In 2004, uniformity and growth of cover crops were excellent for both broccoli plantings. Dry weight biomass of winter rye/hairy vetch was 3.9 and foxtail millet/forage soybean was 4.5 ton/acre. Marketable broccoli yield was 3.3 (summer crop) and 5.0 ton/acre (fall crop). Broccoli yield differences between CT and NT were not significant (P = 0.05). Higher yields in fall, compared to summer, are attributed to cooler temperatures and improved nitrogen fertility. Fall subplots sidedressed on August 31 with 64 lb N/acre outyielded subplots not sidedressed by 50%. Insect problems were kept under control with farmscape habitat plantings and trap crops. The microbial pathogen Bt was applied once per crop at 6 wk after planting. Weekly scouting broccoli fields showed relative little plant damage throughout the growing season for both crops and the ratio of beneficial to harmful insects was normally high. Although weed biomass was higher in CT than in NT plots (410 vs. 85 lb/acre, at canopy closure), probably weed-crop competition was held below yield-limiting levels in all plots. Weed suppression in all plots is attributed to release of allelochemicals from the high-residue cover crops grown.
Outreach/on-farm demonstrations—Of the eight on-farm trials, four were abandoned because of Hurricane Ivan and plant damage caused by deer. The remaining four trials were considered successful, even though broccoli yields were relatively low in both CT and NT plots. High weed-crop competition and inadequate nitrogen fertility probably accounted for the low broccoli yields. In 2005, more appropriate on-farm sites will be selected and weed management and soil fertility will be monitored more closely. Farmscape habitat plantings were successfully employed in 2004 to manage insect pests.
Outreach/increased grower awareness—Many organic growers in Virginia, North Carolina and elsewhere have expressed interest in our project. Examples of outreach activities by the project coordinator and outreach participants include:
Presentations were given by Ron Morse on organic NT vegetable production, at the annual conferences of (1) Maryland Organic Food and Farming Association (MOFFA) (January 8, 2005); (2) Southern Sustainable Agriculture Workers Group (SSAWG) (January 20-23, 2005); and (3) Richmond Area Vegetable and Fruit Program (February 1, 2005). Presentations were given by Mark Schonbeck on cover cropping systems for organic NT systems, at the annual conferences of (1) Southern Sustainable Agriculture Workers Group (SSAWG) (January 20-23, 2005); (2) Appalachian Sustainable Development (ASD) (February 5, 2005); and (3) Virginia Association for Biological Farming (VABF) (February 19, 2005). All presentations were well attended, totaling just under 300 participants.
A Grant was awarded to Mark Schonbeck and Ron Morse by the Organic Farming Research foundation (OFRF) to conduct supplemental experiments comparing cover crops as winter-killed mulch for spring organic NT broccoli and other crops (Award amount = $8,600).
Ron Morse has initiated a project to develop and evaluate NT planting aids (NTPAs) for small-scale farmers. This project is being undertaken to address a critical dilemma—small-scale organic farmers have the desire and need to adopt NT cropping systems; however, they lack the equipment and experience to make it succeed.
Information sheets were written and duplicated on (1) Farmscaping Techniques for Managing Insect Pests; (2) Selection of Cover Crops for Organic No-till Vegetable Production; (3) Integration of No-till Systems and Farmscaping for Production of Organic Broccoli: (4) Proactive Weed Management for Production of Organic Vegetables—Emphasizing Cover-Cropped No-till Systems; (5) Preliminary Evaluation of Cover Crops for Organic No-till Applications in Virginia and North Carolina; (6) Impacts of High-Residue No-till Systems on Soil Quality; (7) Developing Low-cost Equipment and Techniques for No-till Cover Cropping Systems on Small Farms.
Richard McDonald updated a organic transition website/manual for burley tobacco growers that is used to train growers and extension personnel. The website features organic broccoli production techniques, soil health basics, broccoli enterprise crop budgets, farmscaping plants for all four seasons, and organic pest management. The website is free and open to anyone (www.drmcbug.com)
Richard McDonald assisted transitioning tobacco growers who desire to explore organic broccoli production. In demonstration plots at the Mast store, he showed that incorporating cover crops doubled broccoli yield from 3,500 to 7,000 lb/acre. He provided BIPM expertise to the New River Organic Growers Association (NROG) to further their transition to organic broccoli production, as specified in the grant proposal. He also assisted the NROG members to become certified.
Richard McDonald conducted educational and demonstration projects for organic farmers. He helped establish NT/farmscaped plots for 2005 plantings at two sites. He assisted Lily Patch Farms in producing certified organic broccoli transplants. Richard presented eight farmscape training programs in which there were over 400 attendees.
Impacts and Contributions/Outcomes
Research data and grower experience have been positive thus far and we are very optimistic regarding future impacts leading to more sustainable and profitable methods of organic production of broccoli and other vegetables. We also anticipate that an impact will be development of NT equipment and associated technology for small (1-3 acres) organic farms. This equipment will include cost-effective light-weight (<800 pounds) roller-crimpers for killing high-residue cover crops and NT planting aids (NTPAs) to facilitate plant establishment into thick dead cover crop mulch.
Appalachian Sustainable Development
Department of Entomology
Blacksburg, VA 24061