Landscape Design Soil Science and Irrigation 1 — Questions and Answers
Question 1: What are the three primary macronutrients found in most commercial fertilizers, represented by the NPK ratio?
- Nitrogen, Phosphorus, Potassium (Correct answer)
- Nitrogen, Phosphorus, Calcium
- Nitrate, Potash, Kelp
- Niacin, Phosphate, Kieserite
Correct answer: Nitrogen, Phosphorus, Potassium
NPK stands for Nitrogen (N), Phosphorus (P), and Potassium (K), the three primary macronutrients essential for plant growth and the basis of fertilizer labeling.
Question 2: Which soil texture has the highest water-holding capacity?
- Sandy soil
- Loamy soil
- Clay soil (Correct answer)
- Gravelly soil
Correct answer: Clay soil
Clay soil has the highest water-holding capacity due to its tiny particle size and large surface area, though this can also lead to poor drainage and aeration.
Question 3: What is the 'field capacity' of soil?
- The maximum amount of soil a site can hold before erosion occurs
- The amount of water soil holds after excess drainage has occurred (Correct answer)
- The total weight of plants a soil can support
- The depth at which soil temperature remains constant
Correct answer: The amount of water soil holds after excess drainage has occurred
Field capacity is the amount of moisture soil retains after gravitational water has drained away, representing the optimal moisture level for most plant growth.
Question 4: What does a soil percolation test measure?
- Soil nutrient levels at various depths
- The rate at which water drains through the soil (Correct answer)
- The compaction level of the soil surface
- The presence of soil-borne pathogens
Correct answer: The rate at which water drains through the soil
A percolation (perc) test measures the rate at which water drains through soil, critical for determining irrigation scheduling and suitability for features like rain gardens or septic systems.
Question 5: Which irrigation system type delivers water directly to the root zone, minimizing evaporation and runoff?
- Overhead spray system
- Drip irrigation system (Correct answer)
- Rotary sprinkler system
- Flood irrigation system
Correct answer: Drip irrigation system
Drip irrigation delivers water slowly and directly to the plant root zone, reducing evaporation, runoff, and foliar disease by keeping foliage dry.
Question 6: What is 'organic matter' in soil and why is it important for landscape planting?
- Synthetic nutrients added to improve fertility
- Decomposed plant and animal material that improves soil structure, fertility, and water retention (Correct answer)
- The living microbial population in the soil
- Rock minerals that release nutrients slowly
Correct answer: Decomposed plant and animal material that improves soil structure, fertility, and water retention
Organic matter consists of decomposed biological materials that improve soil structure, increase water and nutrient holding capacity, and feed soil microorganisms essential for plant health.
Landscape Design Soil Science and Irrigation 1
What are the three primary macronutrients found in most commercial fertilizers, represented by the NPK ratio?