soil properties

Question 1

soil minerals?

Answer 1

ineral = sand, silt, and clay

Question 2

soil texture?

Answer 2

Coarse= loose, more sand, less clay
Fine = heavy, more clay, less sand
Loamy= mixture

Question 3

what acts as glue? pores?

Answer 3

rganic matter and clay act as glue to hold together aggregates
Pores are the spaces between aggregates that affect water and air movement

Question 4

what odes porosity impact?

Answer 4

he porosity changes the rate of water and nutrients leaching through which changes the
concentration of them through the soil profile
Size of pores and total pore space in influenced by soil texture

Question 5

describe coarse soil

Answer 5

Course soil: large pores but less total space affecting water infiltration, percolation, and
aeration

Question 6

describe fine soil

Answer 6

Fine soil: small pores but more total space affecting water infiltration, percolation and
tends to waterlog

Question 7

sandy loamy vs clay loamy?

Answer 7

Sandy loamy – fastest to percolate
Loamy
Clay loamy – slowest to percolate which can be beneficial to allocate water to top layer
where it may be limiting

Question 8

permeability?

Answer 8

how fast air and water moves through soil (sand is more permeable than clay)

Question 9

saturated soil?

Answer 9

pores are full of water, water drains b/c of gravity until field capacity (no more
free drainage)

Question 10

unsaturated soil?

Answer 10

flow until wilting point (water held tightly by soil to be removed by plant)

Question 11

what is field capacity? when is it low vs high

Answer 11

Field capacity – no more free draining
-Sand has lower field capacity because its drains better with gravity and had smaller total
space and has a lower wilting point because grains don’t hold water well
- Clay has enhanced field capacity and higher wilting point because although having
smaller pores, they have more percentage of pores thus can hold more water

Question 12

5 organic content functions?

Answer 12

1. Importance as nutrient
2. Holds water (field capacity and wilting point)
3. Cation exchange capacity: ability of soil to hold onto nutrients (cations) for plant use and
   prevent leaching beyond roots
4. Decomposition
5. Mycorrhizae – fungi symbioses with plants, increases plant water and nutrient absorption

Question 13

what is soil solution?

Answer 13

the soup of dissolved chemicals available for plants and soils organism, containing
ions
-input from atmosphere and transformations and output through plant uptake,
transformations to solids

Question 14

what is CEC

Answer 14

Cation Exchange Capacity
The ability of soil to hold onto nutrients (cations) for plant use and prevent leaching beyond roots
-Indicator of soil fertility, quality, and productivity
-Weaker cations are removed first

Question 15

what is CEC influenced by?

Answer 15

1. Soil texture (meq/100g) the number of ions that can be held:
   Sand (light) 3-5
   Sand (dark) 10-20
   Loam 10-25
   Clay 20-50
   Organic 50-100
2. Strength of absorption (AL3+ strongest, Na+)
3. Relative concentration of cations

Question 16

AEC?

Answer 16

Anion Exchange Capacity
-Phosphate, Sulfate, Chloride, (Nitrate is weakly held to soil thus leaches)
-Most soils are negative

Question 17

when is AEC high

Answer 17

A low pH = high AEC (more positive charge)

Question 18

pH affects?

Answer 18

pH affects:
1. Nutrient availability
2. Organisms

Question 19

pH is affected by?

Answer 19

1. acids from plants and soil microbes
2. plant litter
3. Parent materia