Midterm Study Guide Flashcards
How was soil fertility managed during the Neolithic?
Slash and burn
What fertility theory dominated the Middle Ages?
Humus theory
What characterizes Humus Theory?
The idea that plants “eat” soil particles.
How does the practice of tillage relate to Humus Theory?
It was believed that finer soil particles facilitated plant root ingestion of soil for fertility.
What fertility theory arose in the 19th century?
Mineral plant nutrition; NPK
Who discovered that plant carbon comes from the atmosphere, not soil?
Justus von Liebig
Who discovered N-fixation?
Hellriegel and Wilfarth
Approximately half the yield increases from the Green Revolution were from _____.
Fertilization
Fertilizer use efficiency is generally ____% or less.
40
Sustainable agriculture is related to alternative/organic agriculture. (T/F)
F
Sustainable approaches can be incorporated into any agricultural system. (T/F)
T
Sustainability of a farming system is only marginally related to fertilizer (organic/inorganic) or other inputs. (T/F)
T
Intrinsic soil factors, rainfall or irrigation practices, and management related factors have a greater influence on farm sustainability than soil amendments or other inputs. (T/F)
T
What legislation provided for land-grant state colleges and universities for agriculture and mechanical arts?
Morrill Act 1862
What legislation gave federal land grants to states in order to create a series of agricultural experiment stations to study soil minerals and plant growth?
Hatch Act 1887
What legislation assisted states in carrying on a program of forestry research and for purposes of developing/utilizing resources from forests and related rangelands?
McIntire-Stennis Act 1962
Major agricultural research drivers in the last century:
-Food supply and safety
-Land expansion
-Population growth
-Limitations on renewable resource availability
-Maintaining productivity
Most funding for research now comes from the ____ sector.
Private
The relationship between essential nutrient concentration and plant growth:
As nutrient concentration increases towards critical range, plant yield increases. Above the critical range, the plant contains sufficient levels for normal growth and can continue to absorb nutrients without increasing yield (luxury consumption). Excessive absorption can be toxic and reduce yield.
The technological innovation that provides inorganic nitrogen for fertilizers.
The Haber-Bosch process
What factors of precipitation affect plant growth?
Quantity and distribution
What is the thesis of the Malthusian Population Trap?
Population expands geometrically, food production increases arithmetically
What is Liebig’s Law of the Minimum?
Plant yield is directly related to the minimum or limiting nutrient; yield will not increase if more nutrients other than the limiting one are added.
What are micronutrients?
Nutrients required in smaller amounts and may only be required by certain plants.
What are the essential macronutrients?
NPK, Mg, Ca, and S (also C, O, and H)
What are the essential micronutrients?
B, Cl, Mn, Fe, Ni, Cu, Zn, and Mo
Mg is a (macro/micro) nutrient.
Macro
Ca is a (macro/micro) nutrient.
Macro
S is a (macro/micro) nutrient
Macro
Fe is a (macro/micro) nutrient.
Micro
P is a (mobile/nonmobile) nutrient.
Mobile
Mg is a (mobile/nonmobile) nutrient.
Mobile
Cl is a (mobile/nonmobile) nutrient.
Mobile
Mo is a (mobile/nonmobile) nutrient.
Mobile
K is a (mobile/nonmobile) nutrient.
Mobile
N is a (mobile/nonmobile) nutrient.
Mobile
Ni is a (mobile/nonmobile) nutrient.
Nonmobile
Zn is a (mobile/nonmobile) nutrient.
Nonmobile
B is a (mobile/nonmobile) nutrient.
Nonmobile
Fe is a (mobile/nonmobile) nutrient.
Nonmobile
Ca is a (mobile/nonmobile) nutrient.
Nonmobile
Mn is a (mobile/nonmobile) nutrient.
Nonmobile
S is a (mobile/nonmobile) nutrient.
Nonmobile
Cu is a (mobile/nonmobile) nutrient.
Nonmobile
What are the general plant symptoms of mobile nutrient deficiencies?
Older leaves will display deficiency symptoms before younger leaves.
What are the general symptoms of immobile nutrient deficiencies?
Younger leaves will display deficiency symptoms first, and symptoms may be localized.
The most concentrated nutrients in plants are ___ and ___.
O and C (about 45% each)
H concentrations in plants are ____%
6
N concentrations in plants are ___%.
1.5
K concentrations in plants are ___%.
1
P concentrations in plants are ___%.
0.2
Ca concentrations in plants are ___%.
0.5
Mg concentrations in plants are ___%.
0.2
S concentrations in plants are ___%.
0.2
Micronutrient concentrations in plants are less than or equal to ___%.
0.01
Macronutrient concentrations in plants are greater than or equal to ___%.
0.2
What is the Steenberg effect?
A rapid yield increase with added nutrients can cause a small decrease in nutrient concentrations in the plant.
What are essential plant nutrients?
Mineral elements required for plant growth and development
The criterial for essential elements:
-Required for growth and reproduction
-Specific (can’t be replaced)
-Acts directly
Silica is an essential nutrient (T/F).
F (beneficial)
Na is an essential nutrient (T/F).
F (beneficial)
Co is an essential nutrient (T/F).
F ( beneficial)
Se is an essential nutrient (T/F).
F (beneficial)
B is an essential nutrient (T/F).
T
Cl is an essential nutrient (T/F).
T
Mn is an essential nutrient (T/F).
T
Fe is an essential nutrient (T/F).
T
Ni is an essential nutrient (T/F).
T
Cu is an essential nutrient (T/F).
T
Zn is an essential nutrient (T/F).
T
Mo is an essential nutrient (T/F).
T
In the inorganic components of soil, (primary/secondary) minerals provide the greatest ion exchange capacity.
Secondary
How to minerals contribute to nutrient availability?
Ion exchange; weathering.
The hydrolysis of feldspar yields ____.
Kaolinite
The oxidation of biotite yields ____.
Iron oxides
The hydrolysis of biotite yields ____.
Vermiculite
How is CEC defined?
meq/100g soil
1meq/100g = __ cmol/kg
1
Equivalent weight =
grams/equivalent
For a monovalent ion, equivalent weight =
Atomic weight
For a divalent ion, equivalent weight =
1/2 atomic weight
How does pH affect CEC?
Low pH decreases; high pH increases