As mentioned above, compound fertilizer has two or more nutrients. Taking npk compound fertilizer as an example, it main contains nitrogen, phosphorus and potassium. They basically correspond to the leaves, roots and stems of plants. If you just need one of fertilizer elements, you just need to fertilize it to your plants. But what if you want to use different fertilizers for plants? Obviously, it will take you lots of time and energy to fertilize different fertilizers each time, and the final result may not be very good.