Good fertilizers help ensure that your soil stays healthy. Yet applying too much, especially at the wrong time of year, will cause runoff, leading to groundwater pollution. Additionally, nitrate-based fertilizers (which are synthetic) often contain a high salt index that can cause root burning and dehydration.
The alternative is to use organic gardening products judiciously. (To gardeners, the terms "organic" and "natural" mean products derived from a plant, animal, or mineral source, not those containing USDA-certified organic materials.) Organic fertilizers won't dry or burn your soil; they will rehabilitate soil quality and improve the general health of your garden.
Buy natural fertilizers with ingredients such as bonemeal, kelp meal, and alfalfa meal. Natural fertilizers break down in the soil slowly, which is more beneficial to plants. Avoid natural fertilizers with peat moss, which is harvested from swiftly disappearing bog habitats.
In the fall, rake leaves into a pile and mulch with them in the spring; they'll enrich the soil and reduce the need for fertilizers. When buying fertilizers, look for those with a seal from the Organic Materials Review Institute, which means they can be used on USDA-certified organic farms.
Start composting and make your own compost tea to fertilize with (see Composting).