An air cart for use in an agricultural air seeding system is provided. The air cart includes a first storage compartment for holding a first granular product type. The air cart also includes a second storage compartment for holding a second granular product type different from the first granular product type. The air cart further includes a common conduit configured to receive the first granular product type from the first storage compartment and the second granular product type from the second storage compartment to enable simultaneous flow of the first granular product type and the second granular product type. The air cart even further includes a multi-product particle flow rate sensing system configured to monitor respective flow rates for both the first granular product type and the second granular product type during simultaneous flow of the first granular product type and the second granular product type through the common conduit.