Soil pollution is often caused by the presence of chemicals or something similar in the natural soil. It's often done by those in industrial, agriculture or simply because you disposed your waste wrongly. Pesticides, accidental chemical spills and nuclear wastes are just some out of many examples of causes. 

Now besides degradation of the earth, how does this affect us humans? 

It simply affects our health. Midst process of wrongfully burning the wastes which degrades the quality of the soil, it will also cause air pollution by releasing carbon dioxide. Too much of exposure towards carbon dioxide means you will inhale less oxygen, which causes you to feel very nauseous and fatigue. In the long run, it could possibly lead to brain damage, muscle weakness and even potentially death. 

Besides respiratory issues, you could also lead to indigestion, food poisoning or other chronic health conditions. This could be caused by ingesting food or vegies grown in that contaminated soil. 

Now, how can this affect the ecosystem? The answer is simple. It could destroy habitats, the food chain and even diseases. 

We have finally understood as to why how crucial it is to take care of the environment with great love and care. Hence, we should always practice the 3R's as besides preaching, we can't do anything. 

Even the smallest change could be revolutionary. 

-kdj. 

reference : https://en.m.wikipedia.org/wiki/Soil_contamination