a plant requires nutrients for survival & soil provides nutrients for plants ->  plants require nutrients in soil for survival  plants require nutrients in soil for survival & if something requires something else then that something else is important to that something ->  nutrients in soil are important to plants  nutrients in soil are important to plants & plants are a part of an ecosystem ->  nutrients in soil are important for an ecosystem  decomposition is when a decomposer recycles / returns nutrients / nitrogen from dead organisms to the soil by eating those dead organisms & decomposition is when a decomposer breaks down dead organisms ->  a decomposer breaks down dead organisms to return nutrients to soil  nutrients in soil are important for an ecosystem & a decomposer breaks down dead organisms to return nutrients to soil -> decomposers breaking down dead organisms to return nutrients to soil is important for an ecosystem