Humans should absolutely be vigilant about keeping soil healthy!
Soil pollution from industrial chemicals like dioxane, PCBs, or heavy metals is one serious problem. This can be fought by inspecting industrial facilities like factories or oil refineries and making sure they don’t spill these chemicals in the first place. Once the damage is done, it’s often very expensive to clean up, but solutions like bioremediation (putting certain microbes in place that will eat the chemicals) are getting better.
A lot of modern farming practices are damaging to soil. Soil gets tilled, disturbing soil organisms like worms, fungi, and insect larvae. Running large tractors over the soil can compact it, eliminating tiny air bubbles and pores in the soil that help those soil organisms survive. Tearing out roots, and leaving the soil bare for long periods of time increases erosion. Fertilizers and pesticides can damage soil organisms.
Fortunately, there are other ways to farm that damage the soil less! Using cover crops, not tilling the soil every year, and planting many species of plants (with different root systems) can keep the soil healthy while farming the land.
Besides not damaging soil through pollution or farming practices, protecting soil is mostly about keeping a healthy ecosystem in the area, and especially keeping plant root systems in place. Soil erosion, when the soil runs off the land due to wind or (especially) water, is very damaging and healthy plant roots can help keep the soil in place. Certain plant species that make partnerships with fungi and bacteria in the soil can help increase soil fertility.
That is a great question, and humans have already polluted many soils. Soil scientists and other scientists are looking for ways to help clean the polluted soils, a process we call remediation.
Some of the pollutants already in the soil include oil, gas and other chemicals from manufacturing that occur due to spills, leaks, and sometimes intentional releases (especially in the past century); garbage and food wastes; wastes from water treatment systems (you know, the stuff that goes down the toilet); excess nutrients from animals and food production; salts from many different sources; pollution resulting from mining and oil and gas production; pollution from burning fossil fuels that goes into the atmosphere, then settles back down to the soil; heavy metals such as lead that was used in pipes and paint, and chrome that is used in wheels; radioactive wastes from uranium mining and refining and use; and the list goes on.
And again, scientists already are working to help solve these problems and remediate the soil and water that have been polluted. But the problem did not happen in a day, and it may take years or decades to clean up some of the messes humans already have made.
So we absolutely need to be vigilant.
Our first step should be to stop doing the things that are polluting the soil, water, and atmosphere now. One of the best ways to start that is the 3Rs: Reduce, Reuse, and Recycle. But there are many places, even in the USA, and especially in small towns, where recycling is not available. If you wanted to recycle, you might have to haul your plastics 50 to 100 km, and glass as far as 500 km to find a collection facility.
What am I doing?
I teach people to be conservationists, to be better stewards of the soil and water resources we have, and to decrease the amount of fossil fuels we use. And soon, some of my research will focus on the connection between excess nutrients in soil and their connection with water pollution, and how to decrease nutrient loss from soils to improve water quality, while still maintaining the ability to produce adequate food for the growing population of the world.
And the whole world is not in the same place in addressing these issues. For wealthier countries such as the USA and those in the EU, we can afford to spend more money to help the environment, while in poor countries where people barely have enough money to grow enough food for their families, there is not enough money to invest in helping decrease pollution and cleaning polluted soils and water.
So, we also need to keep teaching people everywhere about the importance of protecting our natural resources and developing ways for them to do that without limiting their ability to feed themselves and their families.