OSC Activity C.8

1. Adjust nitrogen and water supply according to plant physiological stage, soil biological activity (mineralization rate) and greenhouse climate;
2. Reduce nitrogen and water emission into the environment by better nutrient and water management adjusted to plant needs;
3. Evaluate the suitability of different cultivars for organic growing systems;
4. Improve fruit quality by better fertilization and irrigation management;
5. Characterize and assess compatibility of available certified organic fertilizers;
6. Evaluate mineralization rates and nitrogen availability of those available certified organic fertilizers in the growing medium;
7. Evaluate the sustainability of this organic growing system

Even though some organic growers have achieved high yields, the main problem for most remains irrigation management and the relatively low mineralization rate in soil in terms of plant needs. Little information and few tools for irrigation and fertilization management are available for organic growers. The objective of this project is to characterize the nutrient release availability of various certified organic fertilizers and to improve irrigation and fertilization management in an organic growing system to fulfill, in real time, plant requirements.

The experiment, conducted over a three-year period (two growing seasons; December 2009 to March 2012) at the Productions Horticoles Demers (St-Nicolas), will compare three growing media: a third-year peat-based growing medium, a peat-based growing medium containing clay and a muck soil. In the first year of the experiment (1st crop: December 2009 to November 2010), two different rootstock cultivars (Beaufort and Maxifort) will be compared to identify the cultivar most suited for organic growing systems. Organic fertilization will be based on growing medium and soil solution analysis of each growing system. Greenhouse effluents will be collected and will be recirculated directly without being treated. In the greenhouse, climate parameters, plant growth, fruit yield and fruit quality will be monitored. In the second year of the project (December 2010 to November 2011), the experiment will be repeated in the same media with the two cultivars.

• Defining Irrigation Set Points Based on Substrate Properties for Variable Irrigation and Constant Matric Potential Devices in Greenhouse Tomato
  • HortScience (2012) 47: 1141-1152
• Greenhouse Tomato Plant Development Under Organic Growing Conditions: A Case Study of Six Organic Soils
  • Acta Horticulturae (2011) 915: 83-89
• The Northern Tomato: A Hot Topic in a Cold Climate [PDF - 3.6 MB]
  • The Canadian Organic Grower. 2012
• Organic Greenhouse Tomato Production in a Closed System [PDF - 29 kB]
  • Canadian Organic Science Conference. 2012
• Organic Greenhouse Tomato Production in Raised Bed Containers: A Two Year Study
  • Acta Horticulturae (2011) 915: 69-74
• Organic Greenhouse Tomato Production in Raised Bed Containers under Commercial Conditions: Conclusion of a 3-Year Study
  • 28th International Horticultural Congress. 2011
• Soil Salinization of Organically-grown Greenhouse Tomato [PDF - 67 kB]
  • Canadian Organic Science Conference. 2012

• Microbial biomass content and enzymatic activities after application of organic amendments to a horticultural soil
  • Bioresource Technology (2000) 75: 43-48
• Nitrogen and Carbon Mineralization Rates of Composted Manures Incubated in Soil
  • Journal of Environmental Quality (1994) 23: 1184–1189
• Organic production of greenhouse tomatoes utilizing the bag system and soluble organic fertilizers
  • Acta Horticulturea (2004) 659: 707-719
• Soil microbial biomass and activity in organic tomato farming systems: Effects of organic inputs and straw mulching
  • Soil Biology & Biochemistry (2006) 38: 247-255

• Agriculture and Agri-Food Canada
• Les Productions Horticoles Demers