Soil fertility can be regained short term by adding fertilizer and compost and incorporating into the soil. The compost needs to be aged. A dark brown beats bright green any day. Anything added to the soil needs to be consumed by what is alive underground. read more
Soils also regain fertility with time as plants live, grow, die and then decompose on and in the soil. Humans can help this along by adding organic materials, like compost and manure. Organic matter includes plant nutrients that include nitrogen, phosphorus, sulfur, magnesium, etc. read more