Soils Study Questions: Horizons, Reflectance, Texture, and Moisture, Assignments of Environmental Science

Download Soils Study Questions: Horizons, Reflectance, Texture, and Moisture and more Assignments Environmental Science in PDF only on Docsity! Study Questions – Lecture 8 – Soils 1) What are ‘soil horizons?’ What causes them? Are they visible if you dig a large hole so as to view the soil in profile? How does the thickness of the ‘A Horizon’ vary with rainfall? 2) What are some of the factors that affect soil reflectance – and therefore potentially could be sensed by an RS instrument? 3) Soil type is determined by the properties of the soil profile. Are we able to use RS to determine soil type? Explain why not? 4) Describe how to estimate concentrations of iron in soil. What wavelength band would you use? 5) Two factors, soil moisture content and soil organic matter content, strongly affect soil reflectance. Describe how and why these factors affect soil reflectance; how do the effects vary with wavelength. 6) What is soil texture? How might a soil surveyor estimate soil texture while in the field? 7) How do you know if a soil particle is a sand, silt or clay? 8) You measure oven dried samples of pure sand, silt and clay. How would you expect the magnitude of the reflectance of each of these samples to vary with wavelength and, at any specific wavelength, which reflectance would probably be larger? 9) Repeat question 7) but now assume that the water content of each sample is at ‘Field Capacity’ (i.e. you have soaked each sample in water and then allowed the excess water to drain away) before measuring the reflectance of each of the three samples. Describe how you might use soil reflectance measurements to estimate the water content of a soil – and specify what wavelength bands you would choose. 10) Which provides the higher microwave return: wet soil or dry soil? Why? 11) Describe the logic behind using a thermal sensor to identify areas that might have higher soil moisture content. Describe the procedure – what data are collected - when are data collected – how are the data analyzed? This procedure takes advantage of the fact that moist soils have a higher ‘heat capacity’ or ‘thermal inertia’ than dry soils. What cover types might have a high thermal inertia and therefore appear to have a high moisture content? 12) How would you use RS to determine the parent material of a pure mineral clay?