a product that often gives carbon-rich soils their characteristic dark color (Fig. 2). These various forms of SOC differ in their recalcitrance, or resistance to decomposition. Humus is highly ...

(a) Soil in central Iowa with dark, organic-matter-rich topsoil. Iowa's average topsoil depth decreased from 35-45 cm to 15-20 cm during the 20th century due to farming. (b) Severe gully erosion ...

Without sufficient organic material, your soil can become barren and less capable of supporting healthy plant growth. I've noticed that gardens with rich, dark soil loaded with compost tend to ...

Chalky soil is a light brown soil. Water drains through it quickly. Peat does not contain any rock particles. It's made from very old decayed plants and is dark, crumbly and rich in nutrients.