Question

1. directions: the suggested time for answering this question is about 22 minutes. where calculations are required, clearly show how you arrived at your answer. where explanation or discussion is required, support your answers with relevant information and/or specific examples. suppose that you have just started a summer internship working for a cooperative extension service, where you will collect soil samples, conduct laboratory and field tests, and make recommendations on soil conservation and agricultural practices. a. identify and describe one chemical soil test and one physical soil test that could be performed and explain how the results of these tests will allow the cooperative extension service to make specific recommendations for sustainable agriculture. b. explain one advantage and one disadvantage to using inorganic commercial fertilizers. c. describe two soil conservation practices that are designed to decrease soil erosion. d. identify one biome that is characterized by soil that is rich in humus. describe how humus originated in the soils of this biome and two ways that humus improves soil conditions for plant growth.

Explanation:

Part a

• Chemical Soil Test: pH Test

A soil pH test measures the acidity or alkalinity of soil. Soil pH affects nutrient availability (e.g., phosphorus, iron, and manganese availability varies with pH). For example, if soil is too acidic (low pH), lime may be recommended to raise pH, improving nutrient uptake for crops like corn or soybeans.

• Physical Soil Test: Texture Analysis

Soil texture (percentage of sand, silt, clay) is determined by methods like the hydrometer method or feel method. Texture influences water-holding capacity, drainage, and root penetration. For instance, sandy soils drain quickly but have low water retention, so recommendations might include adding organic matter or using irrigation systems to support crops like lettuce, which need consistent moisture.

• Advantage of Inorganic Commercial Fertilizers

They provide nutrients (e.g., nitrogen, phosphorus, potassium) rapidly, addressing specific nutrient deficiencies quickly. For example, a nitrogen-deficient field can be treated with urea to boost crop growth (e.g., wheat) in a short time.

• Disadvantage of Inorganic Commercial Fertilizers

Overuse can cause soil degradation (e.g., acidification, loss of organic matter) and environmental pollution (e.g., nitrogen runoff into water bodies, causing eutrophication). For instance, excess nitrogen fertilizer in a corn field may leach into groundwater or runoff into streams, harming aquatic ecosystems.

• Practice 1: Contour Plowing

Plowing along the contour (perpendicular to slopes) slows water runoff, reducing soil erosion. It traps water and sediment, allowing better water infiltration and soil retention. Used on sloped fields (e.g., hillside farms) to grow crops like potatoes without excessive erosion.

• Practice 2: Cover Cropping

Planting cover crops (e.g., clover, rye) during off-seasons. Cover crops protect soil with their roots and foliage, reducing wind and water erosion. They also add organic matter when tilled under, improving soil structure. For example, a farm may plant rye after corn harvest to prevent winter erosion.

Answer:

• Chemical Soil Test: Soil pH Test – Measures soil acidity/alkalinity. If pH is too low (acidic), lime is recommended to improve nutrient availability (e.g., phosphorus) for crops like corn.
• Physical Soil Test: Soil Texture Analysis – Determines sand/silt/clay percentages. For sandy soils (fast drainage, low water retention), recommend adding organic matter or irrigation for crops like lettuce.

Part b