If by "waste" you mean things like horse manure, then it certainly does affect plant growth! Horse manure is commonly mixed in the soil to put on a variety of plants to help them grow better, as they use the nutrients from the manure to grow. Plants can also greatly benefit from other kinds of "waste," such as decaying plants, fruits, and vegetables. Compost piles, which you may have heard of, are actually a collection of all these "waste" materials, both plant and animal. Gardeners often put this compost on plants to help them grow better and make better fruit. For more information about compost, check out this website:

On a chemical level, many of these "waste" materials have specific chemicals that plants use to grow. For example, horse manure has high levels of nitrogen, phosphorous, and potassium, which are the three key chemicals plants need in the soil to grow well. As the manure dries, these chemicals become concentrated in the manure, so people often use dried manure instead of fresh manure. For more information on using manure to fertilize plants, check out this website: