AY Honors/Agriculture/Answer Key
1. List the components of soil. Why is soil important to plants?
Soil Components
Soil has three components: solid, liquid, and gas. The solid phase is a mixture of mineral and organic matter. Soil particles pack loosely, forming a soil structure filled with voids. The solid phase occupies about half of the soil volume. The remaining void space contains water (liquid) and air (gas).
Soil texture refers to sand, silt and clay composition. Sand and silt are the product of physical weathering while clay is the product of chemical weathering. Clay content is particularly influential on soil behavior due to a high retention capacity for nutrients and water.
Importance to Plants
Soil provides minerals and water to plants. Soil absorbs rainwater and releases it later thus preventing floods and drought. Soil cleans the water as it percolates. Soil is the habitat for many organisms.
2. Explain the difference between clay, sand, and loam soils. List three crops that grow well in each.
- Clay
- Clayey soils are made from very fine particles which stick together easily. Water does not easily soak through clayey soils, but once it penetrates, the clay holds it well. It must be broken up before it can be used for agriculture. This can be done by mixing it with sand, sawdust, wood chips, lime, or manure. Crops that grow well in clayey soils include celery, (need two more).
- Sand
- Sandy soils are made from coarse particles. Water soaks into sand quickly, but will not remain there for very long. This can be addressed by adding clayey soil to it. Crops that grow well in sandy soil include melons, cucumbers, peaches, peanuts, and beans.
- Loam
- Loam is soil composed of sand, silt, manure, and clay in relatively even concentration (about 40-40-10-10% concentration respectively). Loams are gritty, plastic when moist, and retain water easily. They generally contain more nutrients than sandy soils. In addition to the term loam, different names are given to soils with slightly different proportions of sand, silt, manure and clay: sandy loam, silty loam, clay loam, sandy clay loam, silty clay loam, and manural loam. Loam soil is ideal for growing crops because it retains nutrients well and retains water while still allowing the water to flow freely. This soil is found in a majority of successful farms in regions around the world known for their fertile land.
3. Test the germination of three varieties of seeds, 100 seeds in each variety. Record germination percentage after three, four, and five days.
First, wrap each variety seeds in a paper towel. Then dampen the paper towels and place them each inside their own clear plastic bag (such as a sandwich bag or a freezer bag) so that they retain moisture. Do not seal the bags. Place the bags in a warm place. After three days, carefully remove the paper towel from each bag, open it, and count the number of seeds that have sprouted. If you started with 100 seeds as per this requirement, the germination percentage will equal the number of seeds that have sprouted. Write this percentage down for each variety.
Do not remove the sprouted seeds. Rewrap the seeds in the paper towels, place the paper towels back in the bags, and return them to the warm place. Repeat after day four and day five.
4. Explain how plants obtain nutrients and convert them to food. Explain the differences between primary, secondary, and micronutrients.
5. Name and identify ten common weeds of your community and tell how to best eliminate them, using cultural or chemical methods.
6. Identify six common insect pests or diseases. Tell what plants they usually affect and how to eliminate or prevent their occurrence.
7. Locate two sources of agricultural weather information. How is this information helpful to the farmer?
8. Assist in planting, cultivating, and harvesting at least four different crops. Maintain a log of work done and problems encountered from seeding to harvest.
9. Know the purpose of the following:
- a. Plowing
- b. Disking
- c. Cultivating
- d. Irrigation
- e. Harvesting
10. Name and identify ten common birds of your locality, and state their value to the farmer.
11. What is erosion? How can it be prevented?
Erosion is the displacement of soil by wind, water, or ice by downward or down-slope movement. It can occur quickly on steep ground - especially if there is nothing growing there. It can be slowed by minimizing the amount of time the land has nothing growing on it. When plowing, discing, or planting, it is best to make furrows perpendicular to the slope of the ground. Plowing straight uphill will cause furrows to act as ever-widening ditches that channel the water quickly away, carrying soil with it. Plowing across a hill instead slows the descent of rainwater and allows it to drop the sediments it picks up rather than carrying it off.
