Which chemical property most contributes to soil formation

Humus increases the soil's porosity and water-holding capacity and helps to buffer rapid changes in soil acidity. Humus also helps the soil to hold its nutrients, increasing its fertility. Fertile soils are rich in nitrogen, contain a high percentage of organic materials, and are usually black or dark brown in color.

Explanation:

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b) the inside picture would look at a very high temperature in a very low ph