Systems of Transition from Conventional to Organic Agricultural Production

Systems of Transition from Conventional to Organic Agricultural Production

Summary

The objective of this project is to evaluate cover cropping versus compost as methods to convert market garden and field crop/livestock farming systems from conventional to organic farming. This project emphasizes the transition phase, in which growers converting to organic farming employ practices to build soil organic matter, sol fertility, and soil microbial communities suppressive to pests.

The project began in 1999 when the WVU Horticulture Farm began the transition to organic practices. Replicated field trials in vegetable (market garden) and field crops were established using a randomized factorial design. Plots receiving compost have been amended with 10 tons per acre each year to enhance soil fertility. A four-year crop rotation has been established in both market garden and field crop farming systems. In addition, in the field crop system, livestock production (sheep) and pasture have been integrated into half of the field crop systems. Results are being communicated to growers, extension staff, and the public through field days, internet web pages, and other media outlets.

Objectives/Performance Targets

The objective of this proposal is to compare intensive cover cropping and use of compost as methods to convert market gardening and field crop/livestock farming from conventional to organic. In addition, soil quality and organic matter fate are being evaluated in an intensive compost rate trial, and weed management practices are also being compared to identify optimum practices during the transition phase.

Accomplishments/Milestones

Plots for the farming systems trials were established in fall, 1999, and winter cover crops were established in all systems. During the 2000 growing season, plots receiving the intensive cover crop treatment were planted to rye/vetch in spring. This was tilled in and a mid-season crop of buckwheat was planted. A fall cover crop of rye and vetch served as winter cover. Plots receiving the compost treatment were tilled and 10 tons per acre of composted dairy manure were applied. A vegetable rotation of legumes (beans and peas), solanaceous crops (tomato and pepper), cucurbits (pumpkin and zucchini), and leafy vegetables (spinach and lettuce) was established in the Market Garden. The field crop plots receiving compost were planted to potato, soybean, wheat, and brussel sprouts. A red clover/orchard grass pasture was established on designated plots in the field crop rotations where livestock were part of the farming system.

All plots were planted to cash crops, vegetables or field crops as appropriate, in 2001 and 2002. Sheep were introduced to the field crop rotation. Data on yield, pest densities, and soil quality parameters were collected, and economic inputs and income were recorded.

Yields for most crops were generally at or above conventional averages, although disease and insect pressure reduced yields of spinach, cucurbits, and potatoes in 2001 and 2002. Compost amendments did not significantly increase soil organic matter compared to the intensive cover crop treatments, however, enhanced soil nutrition from compost resulted in improved yields of potato, wheat, lettuce, spinach, pumpkin and pepper in 2001. Sheep and lambs gained weight about equally on cover-crop and compost treatments, and few problems with intestinal parasites were observed as rotational grazing gave excellent suppression. Yield data from 2002 are still being analyzed, and will be integrated with economic returns and expenses to compare the three-year economic values of the transition systems.

Insect pest populations were similar in both the cover crop and compost treatments. Cucurbits receiving compost treatments showed slightly earlier onset of bacterial wilt, but differences were not significant by the end of the season. Compost treatments appeared to suppress seedling diseases in spinach and peas, resulting in better stands and higher yields than in the cover crop only treatment. Earthworm populations tended to be higher, and earthworm biomass was significantly higher, in plots receiving compost. Soil populations of plant parasitic nematodes did not differ among treatments and remained low throughout the period. Populations and activity of soil-borne biocontrol agents also remained low and did not differ among treatments, thus the cause of nematode suppression remains unknown.

Weed management trials in 2001 evaluated plastic versus straw mulches in pepper production. Straw mulch gave satisfactory weed suppression but tended to result in nitrogen deficiency symptoms. Best yields and weed suppression were obtained with black plastic mulch. Trials in 2002 compared acetic acid sprays with use of corn gluten as a soil amendment. Neither treatment gave satisfactory, season-long weed suppression.

Grower outreach occurred through field days held Aug. 2, 2001 and on July 18, 2002. Over 120 people attended both events and favorable comments were received in participant evaluations. Three student interns were registered in 2001 and four students in 2002. A WVU student field day Sept. 8, 2002 was held, with about 12 students attending. A one-semester course in organic farming and gardening is being offered at WVU and had 28 students in 2002. A webpage on the organic farm project was established in 2001 and is available at: www.cafcs.wvu.edu/plsc/organic. Presentations to growers also occurred at annual meetings of organic growers, at extension field days, and through news media reports. Organic growers have responded enthusiastically to the project.

Impacts and Contributions/Outcomes

Production performance for organic transition farming systems were demonstrated and evaluated for two years. Grower participation at field days and in on-farm application of management practices has increased and student participation in the project is resulting in an increasing pool of trained pratcitioners. Scientific papers reporting results from the project were presented at meetings of the International Federation of Organic Agriculture Movements (IFOAM), the American Phytopathological Society, and the Agronomy Society of America (Northeast Branch). Fact sheets are in preparation, with assistance and support from the West Virginia University Cooperative Extension program.