I like the idea of transforming garbage into free mulch and fertilizer. It's a win-win situation when I can save money and keep my eggshells, coffee grinds and weeds out of landfills. Compost is the single best additive available for improving any soil. Soil too sandy? Add compost. Too much clay? Add compost. Lacking nutrients? Compost. No wonder gardeners call it black gold. And with all those crunchy leaves about to make their appearance, now is the perfect time to begin making your own.