S15 - Session P3 - Response of potted herbs to different solid organic fertilizations

Authors: Annie Brégard, Thi Thuy An Nguyen, N. Zyromski, Martine Dorais *

The growing consumer demand for fresh and pesticide-free food is driving the development of organic controlled-environment agriculture worldwide. In organic cultivation systems, the fertilization management and the growing media are the main determinants of the crop performance and product quality. The objectives of this study were to evaluate, in a commercial greenhouse, the impact of different combinations of solid organic fertilizers (1. Poultry pellets [PP], 2. PP + alfalfa meal [AM], 3. Soybean hydrolysate [SH], 4. SH + AM, 5. PP + SH, 6. Blood and feather meals + PP, 7. Frass, 8. PP + frass, 9. PP + shrimp meal, 10. Conventional liquid fertilizer [CLF]) on the growth of six potted herbs (basil, coriander, mint, parsley, rosemary, thyme). The growing medium was a mix of peat and wood fiber and a control with peat only (11. CLF control). The experiment was conducted at a commercial greenhouse (Serres Frank Zyromski Inc., Riviere-Rouge, QC, Canada) using a randomized complete block design with 10 replicates. Total nutrient composition was similar for all treatments. After 42 days of cultivation, the effect of fertilizations on plant height, photosynthetic performance (PEA, SPAD), fresh and dry biomass, soil biological activity (FDA), pH, EC, and N levels were measured. Highest fresh or dry plant biomass were generally measured under the control liquid fertilization treatment compared with poultry pellets, while the lowest values were obtained under fertilization treatments containing soybean hydrolysate. Plant growth was not related to the biological activity of the growing medium or its N concentration. The control treatment without wood fiber and fertilized with liquid fertilizer performed better in general. Results will be discussed in terms of the best sustainable organic fertilization strategy for potted herbs. Further studies are, however, needed to establish the optimal proportion of solid organic fertilizers that could be incorporated into the growing media to limit the use of liquid fertilizer, while ensuring the appropriate nutrient needs of herbs during their short growth cycle.