Ectomycorrhizal are the fungi that form a sheath around the root tip of the plant. See beneficial fungi for a full definition.
Microbial inoculants are products that introduce beneficial bacteria and/or fungi to the root zone (or rhizosphere) of your plants. They assist your plants in building up root mass, which results in greater nutrient uptake.
Seaweed (specifically kelp varieties) is a naturally occurring, nutrient-rich algae containing amino acids. Nutrients found in this extract include potassium, calcium, magnesium and many trace elements. Powders and extracts from seaweed are often used as garden supplements to improve overall growth and plant health.