Chapter 37: Soil and Plant Nutrition

Question 1

soil

Answer 1

composite of organic and inorganic matter that accumulated in layers over time

Question 2

defining features of soil

Answer 2

texture and compositions

Question 3

soil horizons

Answer 3

stratified soil layers

Question 4

a horizon

Answer 4

topsoil; mineral particles, living organisms and humus; most important for plant growth

Question 5

b horizon

Answer 5

less organic matter and less weathered that horizon a

Question 6

c horizon

Answer 6

mainly partially broken-down rock

Question 7

clay

Answer 7

soil texture that retains too much water and not enough oxygen

Question 8

sandy

Answer 8

soil texture that is unable to retain enough water for plant growth and to access soil minerals

Question 9

loam

Answer 9

ideal/most fertile topsoil; equal amounts of sand, silt, and clay

Question 10

soil solution

Answer 10

water and dissolved minerals retained in pores between soil particles

Question 11

topsoil composition

Answer 11

inorganic and organic chemical components; mostly particles are negatively charged

Question 12

leaching

Answer 12

anion plant nutrients that cannot bind to soil particles are lost from the soil

Question 13

cation exchange

Answer 13

cations (K+, Ca+, Mg+) that adhere to negatively charged soil particles are displaced by H+ to be absorbed in the soil solution and taken up by the roots

Question 14

soil pH

Answer 14

affects mineral availability; slightly acidic soils are usually preferred

Question 15

Humus

Answer 15

prevents packing of clay particles by forming a crumbly soil

Question 16

Macronutrients

Answer 16

Carbon, oxygen, hydrogen, nitrogen, potassium, calcium, magnesium, phosphorus, sulfur

Question 17

micronutrients

Answer 17

chlorine, iron, zinc, manganese, copper, nickel, boron, molybdenum

Question 18

magnesium deficiency

Answer 18

white stripes along veins and purple underside of lower leaves

Question 19

nitrogen deficiency

Answer 19

yellow at leaf tip continuing along the middle of the leaf

Question 20

potassium deficiency

Answer 20

drying at tip and edges of the lower leaves

Question 21

phosphorus deficiency

Answer 21

reddish-purple coloring of leaves

Question 22

epiphyte

Answer 22

plant that grows on another plant and obtains water and minerals from rain; does not use hosts for sustenance

Question 23

hemiparasite

Answer 23

absorb water, minerals, and sugars from living host plants, still photosynthesize

Question 24

holoparasite

Answer 24

rely entirely on host plant for sustenance

Question 25

carnivorous

Answer 25

have adaptations for trapping insects and other small animals to obtain nitrogen; photosynthetic

Question 26

rhizosphere

Answer 26

layer of soil closely surrounding a plant’s roots

Question 27

rhizobacteria

Answer 27

live in close association with plant roots or in the rhizosphere

Question 28

nitrogen cycle

Answer 28

series of processes that transform nitrogen and nitrogen-containing compounds; plants can absorb nitrogen as NO3- or NH4+

Question 29

Nitrogen fixation

Answer 29

conversion of nitrogen from N2 to NH3

Question 30

crop rotation

Answer 30

takes advantage of agricultural benefits of symbiotic nitrogen fixation

Question 31

sustainable agriculture

Answer 31

farming methods that are conservation minded, environmentally safe, and profitable

Question 32

fertilizer

Answer 32

combats depleted nutrients and reduced crop yields by replacing nutrients lost from soil

Question 33

commercial fertilizer

Answer 33

N, P, K

Question 34

natural fertilizer

Answer 34

manure, fishmeal, compost

Question 35

algae blooms

Answer 35

fertilizer runoff can kill aquatic life and create dead zones

Question 36

irrigation

Answer 36

drain on freshwater resources

Question 37

aquifers

Answer 37

primary source of freshwater for irrigation; underground water reserves

Question 38

salinization

Answer 38

concentrating of salts in soil as water evaporates

Question 39

drip irrigation

Answer 39

reduces water use and salinization by releasing water slowly and at the root

Question 40

phytoremediation

Answer 40

uptake and concentration of soil pollutants in plant tissues that are removed for safe disposal to reclaim contaminated areas