The replacement of nutrients and other micro-nutrients is necessary in order to continue using your soil. In conventional farming simple chemical components are applied.
Although these basic components contain the necessary nutrients (N, P and K), these are rapidly absorbed by the plant and not much goes into the soil. Therefore your soil is not improved and will degrade slowly and surely.
Other materials are necessary in order to enrich your soil as well in order to provide a complete “meal” for your soil. Using too much raw organic material or unstable materials such as cow manure can harm your soil over a period of time. Compost or organic fertilizer is the best material you can apply either as a complement or on its own as a fertilizer.