The best way to fertilize with a drip system is to ensure you know the amount of fertilizer you need before mixing it with the water. You will have to ensure you get it right in the mix before linking the injector to the irrigation system.By wetting the soil with drip irrigation, fertilizing will be easier. It will also enable the roots to take up more nutrients from the fertilizer. It will also reduce the chances of leaching as well as having your water.