S06 - Session O8 - Comparison of organic, conventional and compost fertility source effects on media microbiome and plant health.

Authors: Melodie Floom *, James Altland, Frederick Michel Jr.

Sustainable and resilient food production methods are necessary to sustain a growing human population. Food crops are increasingly being grown in container media to address these problems. However, little is known about the microbiome within growing media or how it may impact plant health. The objective of this project was to understand how organic and conventional sources of substrate fertility affect microbiomes in container media. In the first experiment, three cultivars of lettuce; Salinova Green Butter, Black Seeded Simpson, and Romaine lettuce were sown into an 85:15 sphagnum peat moss: perlite blend. One conventional (Jack's 20-10-20) and three organic fertilizers; Miracle Gro Performance Organics All purpose, Alaska Fish Emulsion 5-1-1, and Espartan 2-3-2 were used as fertility sources. Espartan 2-3-2 organic fertilizer produced lettuce yields that were similar to those with conventional fertilizer. In the second experiment, five different composts formulated with dairy manure, food scraps, sawdust and yard trimmings were tested for their efficacy as fertility sources for Romaine lettuce. The composts were mixed at 30% total volume with the peat perlite blend. Conventionally and organically fertilized plants were grown alongside the compost treatments as positive controls. Dairy manure compost produced the highest yields and quality with an average dry weight and 4.66g, compared to 8.48g and 6.45g for the Jack's 20-10-20 and Espartan 2-3-2. The media microbiomes within the conventional, organic, and dairy manure compost fertilized substrates were then compared. Romaine lettuce was sown into the three different substrates and grown for 6 weeks. Growing media was sampled for microbial analysis after 0, 3, and 6 weeks. DNA was extracted, purified and PCR amplified using bacterial 16S rDNA gene and fungal ITS targeted primers. The amplified sequences were identified using Greengenes 16S gene database along with R 4.0. software. Results of this microbial community analysis will be presented.