Unit 4 Free Response

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.

A chemical test could be a pH test measures the acidity or alkalinity or hydrogen ion concentration. A physical test could be a soil texture test that would test for the percent/proportion of sand, silt, and clay sized particles that make up the solid inorganic phase of soil. This physical test could help sustainable agriculture by know whether to add soil additives such as sand, clay, or humus to affect ion-excahgne capacity as well as moisture content and water-holding capacity.

Describe two soil conservation practices that are designed to decrease soil erosion.

Conservation tillage decreases erosion by disturbing the soil as little as possible when planting crops. Terracing or division terrace decreases erosion by shaping the land to create level shelves of earth to decrease soil and water runoff.

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.

Deciduous forest: tropical/seasonal and temperate. Humus originated here because of plant and animal materials decomposition. Humus improves soil conditions by providing nutrients/fertility for plants and soil organisms and helps topsoil hold water.

Describe one economic advantage and one economic disadvantage of using GM crops.

Decreased health care costs due to reduced worker exposure to pesticides and better-nourished people. Higher yields per acre often lead to greater soil depletion, requiring higher costs of mitigation.

Identify and describe one environmental advantage and one economic advantage of consuming locally grown produce.

Decreased transportation of food, which results in decreased fossil fuel consumption, decreased greenhouse cases, climate impacts, and carbon footprint. Lower cost associated with transportation and storage.

A healthy soil ecosystem is of primary importance in sustainable agriculture. Describe TWO viable agricultural practices that farmers can use to maintain or improve soil quality.

Fertilizing or supplementing which is the application of nutrients. It makes for optimum nutrient availability and less soluble/mobile nutrients in organic fertilizer. Windbreaks which is planting rows of trees or shrubs. This lowers soil loss to wind erosion and traps moisture of winter snows.

Identify one likely cause for the difference between the projected land area for GM crops in industrialized countries in 2004 and the actual land area for GM crops in industrialized countries in 2004.

Genetically modified crops faced increased public resistance toward perceived risks, due to increased awareness following labeling of products.

Describe TWO viable strategies for reducing the amount of land needed for agriculture.

Increasing crop yield through the use of more effective pesticides and fertilizers. Decreasing the demand for agricultural demand through switching from cotton to hemp for textiles which would provide more material per acre.

Describe one method to prevent or remediate soil salinization.

Irrigate with sufficient water to leach the salts down through the soil, or wait for rain to flush the salts out of the soil.

Explain on advantage and one disadvantage to using inorganic fertilizers.

One advantage is that it is easily obtained, transported, stored, and applied. A disadvantage could be that it adds no humus or organic matter to soil which decreases water-holding capacity.

Describe one environmental advantage and one environmental disadvantage of using GM crops.

Permits low tillage agriculture which reduces soil erosion, energy consumption associated with farm machinery, and evaporative water loss. Native plant diversity may be impacted by the spread of genes to non engineered crops.

Describe how salinization occurs.

Salinization can occur when irrigation water evaporates, leaving the salts behind in the soils.

Soil quality is a critical factor in agriculture. Identify TWO physical and/or chemical properties of soils and describe the role of each property in determining soil quality.

Water-holding capacity shows how much water is needed by plants for survival. Water cannot be used by plants if it leaches away from plant roots. If soil cannot retain water within reach of plant roots, crops will need frequent rains or irrigation. Aeration shows oxygen that is needed by plant roots/soil organisms for respiration.