SoilsA chemical or natural substance added to soil or land.

5. The action of plowing along the contours of the land in order to minimize soil erosion.
6. The breaking down of rocks from erosion, water, and wind.
8. The top layer of soil.
11. A mixture of various decaying organic substances, as dead leaves or manure, used for fertilizing soil.
12. A chemical or natural substance added to soil or land.
13. An indication of the acidity or alkalinity of soil.
14. A diagram which shows how each of these 12 textures is classified based on the percent of sand, silt, and clay in the kind of soil.
15. Matter that has come from a recently living organism.

1. Make or form (sloping land) into a number of level flat areas resembling a series of steps.
2. A type of weathering in which surface soil and rock are worn away through the action of glaciers, water, and wind.
3. A dark brown or black colloidal mass of partially decomposed organic matter in the soil.
4. The flow of chemical elements and compounds between living organism sand the physical environment.
7. The disintegrated rock material usually unconsolidated and unchanged or only slightly changed that underlies and generally gives rise to the true soil by the natural process of soil development.
9. Cultivation in which different crops are sown in alternate strips to prevent soil erosion.
10. The separation of organic compounds.