Why is it important to have high numbers of Rhizobium for each seed? Isn't one enough?

Inoculation is fundamentally a numbers game and one Rhizobium per seed is definitely too low of a number! The environment in the germinating root zone, especially at the root hairs, has many problems. It is a microscopic war zone, with many “enemies” that can get in the way of correct Rhizobium properly infecting plants. First, there are other Rhizobium residing in the soil. These compete to attach to the host plant. Second, other parasites (other microbes or fauna) prey on good Rhizobium inoculum. Third, a poor soil environment, low fertility or caustic pH or salts (very acidic or alkaline soils) will reduce Rhizobium population. High numbers of effective Rhizobium encased in a very good coating are needed in order to mitigate these problems. The Nitro-Coat® process is designed specifically to do just that. From the inception of its design to the execution of every coated pound of seed, the Nitro-Coat® process aims to provide the highest possible numbers of live Rhizobium to each seed at the time of planting.