Large scale agriculture drains nutrients from the soils faster than biogeochemical cycles can replenish them. Adequate nitrogen, phosphorous, and potassium, as well as many trace minerals like sulfur, are critical to plant growth and productivity. If any of these nutrients are in short supply in a soil, they can be limiting factors to the successful growth of a plant crop and the production of fruit, grains, and vegetables.

Farmers add fertilizers that contain N-P-K (nitrogen-phosphorous-potassium) to crop fields to encourage more plant growth than would be possible otherwise, and to increase crop yields. Particularly where crops are removed and fed to livestock instead of being turned back into the ground, soil bacterial can't replace nitrogen as rapidly as needed for the growth of the next crop, nor is phosphorous in adequate supply to promote optimal crop growth. Thus, supplementation of these nutrients in soils is necessary.

Even in organic farming, organic wastes from animals or discarded plant parts are used to replenish the fertility of the growing soils. the growth of decomposer bacteria is encouraged to help maintain soil fertility at sustainable levels.