Here are the primary components that you would require -
1. Organic Matter: Compost and mulch enrich soil and improve structure.
2. Microorganisms: Bacteria, fungi, and mycorrhizae break down organic matter and enhance nutrient uptake.
3. Soil Fauna: Earthworms, insects, and arachnids aerate soil and mix organic matter.
4. Nutrients: Macronutrients (N, P, K) and micronutrients (Fe, Mn, Zn, etc.) are essential for plant growth.
5. Soil Structure: Aggregates and porosity improve aeration and water retention.
6. Water Management: Proper irrigation and drainage ensure optimal soil moisture.
Item 3 is important in more ways than most people realize. Last year many farmers in my area that planted soybeans early had a problem with slugs eating the sprouting beans and were forced to replant multiple times. This spring I went to a growers conference and heard a presentation by a Prof. Tooker from Penn State Ag about the slug problem, which he has been researching for several years. Turns out that the slug infestation can be directly traced to the use of insecticides used in seed treatments. The insecticides kill beetles (and other beneficial insects) that eat the slugs but don't kill slugs because they aren't insects (they are mollusks). No beetles more slugs. Take away is don't use treated seed. However, standard practice at seed companies is to treat seed with fungicides and insecticides, thus creating a problem rather than solving it.
We just need to add a mollusk treatment!