gave this very good answer:
"HUMUS is the brown jelly like material that acts as a glue to hold our soils together
Organic matter is added from crop residues, animal manure and green manures, which then decompose in the soil.
An important part of soil organic matter in the HUMUS.
Earthworms and soil microbes live on organic matter and turn it into humus, which then helps feed the plant.
Organic matter improves soil structure (tilth), reduces erosion, increases aeration and improves water intake and retention.
A large percentage of our nitrogen can come from humus, earthworms and microbes.
Our main goal is to provide the proper environment for soil life and to discontinue using toxic fertilizers that destroy soil life."
What is a toxic fertilizer? Short answer is any fertilizer that kills soil life to give off nutrients to the soil and thus, the plants it feeds.
Anhydrous ammonia grows great corn but it kills everything in about a 6 inch or so circle where it is knifed in the soil. Really healthy soil can tolerate this once a year or once a crop rotation but I would classify it as a toxic fertilizer. Much safety has to be exercised just to apply it.
Potash would be less toxic than anhydrous but it's still toxic. Does that mean I shouldn't use it? No. It is still the most used source of potassium for crops. If you want a less toxic source, you would need to apply potassium sulfate which is more expensive and difficult to source from most fertilizer dealers.
How can I learn more about such things? Here is a note from my friend Joe Glassmeyer:
"I attended another excellent program and field tour at The OSU South Center in Piketon Ohio.
Dr. Rafiq Islam hosted a Soil, Water, and Bioenergy Field Night. The first objective was to explain currently developing technology to absorb excess phosphorus and remove it from water run off from agricultural fields. It could than possibly be reused as fertilizer in subsequent years. His research is sponsored by Battelle and The Ohio Soybean Council.
The process is to chemically treat soybean hulls to enable them to capture phosphorus. Then they are processed into pellets and placed into long socks. These are installed to the sources of phosphorus runoff to absorb that material.
Phosphorus runoff has been a horrendous problem for certain bodies of water in Ohio. After the soybean hulls deteriorate they could be land applied the next year as a fertilizer source.
Dave Brandt was next on the program. His talk was on cover crops and how to plant, nurture and terminate them for the benefit of the cash crop to follow. He had numerous pictures of various cover crops in different stages of growth. He truly is the guru of cover crops and combines a keen sense of humor in his presentation to keep the audience tuned in. If you have a chance to take in one of his presentations do so by all means.
After the presentations it was onto wagons for the field tour.
Rafiq showed and explained the structures to collect and analyze water from the test plot areas. There were also test plots of cover crops in various mixtures. Dave explained the benefits and drawbacks of these mixtures and how to properly manage each."