You can use organic fertilizer with a drip irrigation system so long as the fertilizer is water-soluble. If it isn’t soluble, it could block the injector's fertilizer passages and lead to the system malfunctioning. That is why it is so vital that you use a soluble fertilizer.There are several types of organic fertilizer that are water-soluble and will work well with your drip irrigation fertilizer injector. If you see any blockages, change out the fertilizer or apply it in smaller amounts.