Soil restoration is the process of improving the structure, microbial life, nutrient density, and overall carbon levels of soil. Many human endeavors – conventional farming chief among them – have depleted the Earth to the extent that nutrient levels in almost every kind of food have fallen by between 10 and 100 percent in the past 70 years. Soil quality can improve dramatically, though, when farmers and gardeners maintain constant ground cover, increase microbe populations, encourage biological diversity, reduce the use of agricultural chemicals, and avoid tillage.