Earth and Space Science Soil

Soil _______________ is a mixture of bits of rock and once living parts of plants and animals. Soil covers most of Earth’s landmasses. Without soil, plants and animals wouldn’t be able to live on land.

weathering 2. The formation of soil starts with the ____________ of rock.

layers, soil horizons 3.Soil forms in ______________ that are called ____________ _______________.

humus, decayed 4. The A horizon, which holds the most nutrients, contains ________________ which is made up of ___________________ organic materials.

topsoil 5. The A horizon is also known as __________________. Most plant roots grow in this soil. The roots absorb nutrients and water from the humus.

subsoil 6. The B horizon is called the _________________. You will find less humus in subsoil and lots of fine particles of rock, such as particles that make up clay.

large, bedrock 7. Next is the C horizon, which is mostly made of _________________ pieces of weathered rock. All of these soil horizons rest on soild, unweathered ________________.

forest, desert 8. Soils in different places have different properties. Each type of soil supports different plant and animal life. Most of the United States is covered by three types of soil: ________________ soil, ______________ soil, and grassland and prairie soil.

thin layer, little humus 9. Forest soil has a ______________ _____________________ of topsoil with ____________ ______________. Frequent rainfall carries minerals deep into the ground, so plants with shallow roots do not grow well in forests.

sandy 10. Desert soil is _________ and does not hold much humus. Because deserts receive little rain, plants have special adaptations to grow there.

nutrients 11. Grasslands and prairies have soil rich with humus, which provides ___________________ for crops. Animals eat the grasses that grow naturally in this soil.

wasted, spoiled, eroded 12. Soil is a resource that can be used up, _____________, or _______________. It can be _____________________ by flowing water and wind.

Pollution,chemicals 13. __________________________ is the addition of harmful materials to soil, air, or water. Soil can be polluted by ____________________ placed in the ground. When people dump garbage on the ground, the garbage can also pollute the soil.

conservation 14. The preservation or protection of natural resources, including soil, is called ____________________.

Fertilization 15. ____________________ is a method of conservation by which nutrients are added to soil to replace the nutrients used by previous crops.

crop rotation 16. Farmers can alternate the type of crops they plant year to year. This is called __________ ___________________.

strip farming 17. Plant roots help prevent soil from being washed or blown away. For this reason, farmers may use ______________ ________________ method to plant grasses between rows of other crops.

contour, terracing 18. Farmers can conserve soil on hills when they use ____________ plowing and _____________.

A Horizon B Horizon C Horizon Solid Bedrock