Optimizing substrates, composts, and fertilizer additions for organic transplant production

View the project final report

• 2004 annual report
• 2005 annual report

Commodities

• Agronomic: soybeans, wheat
• Vegetables: broccoli, cabbages, cucurbits, peppers, sweet corn, tomatoes

Practices

• Crop Production: conservation tillage
• Education and Training: demonstration, display, extension, farmer to farmer
• Pest Management: allelopathy, biological control, chemical control, cultural control, integrated pest management, mulches - killed, mulches - living, mulching - vegetative, mulching - plastic, physical control, trap crops, weed ecology
• Production Systems: agroecosystems
• Soil Management: earthworms, green manures, nutrient mineralization, organic matter, soil analysis, soil quality/health

The goal is to provide guidelines for producing healthy and vigorous organic vegetable transplants as the first and most critical step in successful field production. Organic transplants required by National Organic Program are rarely available commercially, so they must be produced on-farm. Although ‘recipes’ and anecdotal information are available, most growers develop their mixes through trial and error, as few guidelines and even fewer published experimental reports are available. Commercial organic mixes are expensive, and not always locally available. Previous work at NCSU and elsewhere with organic transplant and other mixes suggests that the limiting factor in organic mixes is the timing of nutrient availability. Initially pH and salt levels may be above optimal, but over a period of 6-8 weeks, nutrient availability declines, and plants may become nutrient-limited. Adding more organic fertilizers without burning the seedlings is then difficult. The goal of this project is to provide guidelines on the type of composts, growing media and fertilizers that will provide sustained nutrition over the transplant production period, without creating initially excessive levels. Specifically, we will investigate the time-course of nutrient availability in different types of mixes. This will allow us to develop general guidelines for materials to be included and also to determine if a pre-conditioning period would be useful. Beginning with recommendations from local organic growers, we plan to utilize low-cost, locally available material whenever possible. The best performing commercial organic mixes, as identified in a previous study, will be included as controls.

The goal is to provide guidance for growers in terms of an efficient and cost-effective combination of ingredients for an organic growing media and the period of time over which these mixes should be able to support seedling growth without the costly addition of soluble organic fertilizer. Various organic amendments will be examined in terms of their effectiveness for seedling production and in terms of the period in which mineral nutrition is provided to the plant by that particular amendment. Possible amendments to be investigated include: compost, vermicompost, bloodmeal, and feathermeal. Some organic fertilizers, such as soymeal and alfalfa meal require a moist preconditioning period of 2-4 weeks before seeding. The effects of various periods in which the mixed ingredients are left to 'settle' after mixing and moistening, but before planting will also be investigated. Specifically, we would look at the effect of a preconditioning period on germination, pH, EC, and plant performance. the performance target is to provide guidelines for successful transplant production with a minimum of expense to the grower.