Exam 2-Chapter 11

Question 1

What are the four different horizons

Answer 1

OAEBC - O Horizon-top most layer (detritus,humus, high organic content), A-Topsoil below O-mixed humus and leached mineral soil. E-Zone of leaching/less humus. B-subsoil-leached minerals. C-partly broken down minerals.

Question 2

Differences between organic and inorganic fertilizer?

Answer 2

Organic fertilizer has plant and animal waste. Inorganic fertilizer is nutrients with no organic compounds so it cannot support soil organisms or build soil structure, so it leads to soil degradation, less water retention, nutrients without replenishing soil (can lead to eutriphication)

Question 3

4 soil classes - characteristics

Answer 3

mollisols-prairie soils, fertile, dark. alfisols-high-nutrient soils, widespread, moderately weathered. oxisols-tropical forest soils, leached minerals, resist cultivation. aridisols-desert soils, unstructured, thin, light.

Question 4

What generally makes up soil?

Answer 4

sand-40%, silt-40%, clay-20% (gravel, loam which holds nutrients and water)

Question 5

What are the four major classes of soils important for agriculture, animal husbandry, and forestry?

Answer 5

Mollisols, alfisols, oxisols, and aridisols

Question 6

Why is soil important to us?

Answer 6

For food production and sustainability (90% of all food comes from land-based agriculture)

Question 7

what aspects of soil matter for plant growth?

Answer 7

root environment to supply mineral nutrients, water, oxygen, soil fertility, tilth (ability to support and plant growth).

Question 8

What are some major causes or erosion?

Answer 8

over-cultivation, plowing, overgrazing, deforestation, nutrient mining, inorganic fertilizer, desertification

Question 9

what are some techniques to reduce soil erosion?

Answer 9

contour plowing, shelterbelts, no-till farming