True or False Flashcards
Mineralization increases the inorganic nutrients in the soil
True
Actinomycetes dominate acidic cold dry soils
F
Sodic Soils have good structure
f
Fe and Mn are commonly deficient in very acidic soil
False (very available in acidic soils)
Soil Acidifications increased by fertilizers
true
Saline soils have high ECE measurements > 4dS/m
true
Sodic soils form white crusts
False (saline soils do)
CEC increases in humus with higher pH
True
Sulfur can be used to increase soil acidity
True
Ammonium can be fixed on clays
True
diffuses slowly in soil with a high cation exchange capacity (high clay or organic matter content) because the ammonium is attracted to the negatively charged sites
Water moves from a low to high energy state
False (high to low)
As decomposition of added organic material proceeds, the C/N ratio in the remaining undecomposed material increases
F
Water moves from one site in a soil (water potential of -5 kPa) to soil with a water potential of -40 kPa
True
Iron and aluminum hydrous oxides are characteristics of soils that are highly weathered chemically
true
Most nitrogen leaching to groundwater is in the form of ammonium
false - nitrates
Saline soils are characteristic of arid and semiarid areas with poor internal drainage
true
Sodic soils generally have better physical conditions than either saline or saline-sodic soils
false
In the early stages of plant N deficiency, the most obvious symptoms are yellowish colours in the youngest leaves
false
Most anaerobic microbes in the soil are bacteria
true
Cruciferae family do form mycorrhizal relationships
false
Define field capacity
when soils stop draining due to gravitational forces
water films are thin enough to hold against gravity
Why is plant growth rapid at field capacity?
there is enough air, yet water is held loosely at high potential
the higher the CEC of a soil, the higher its buffering capacity
true
although kaolinite particles are larger than other silicate clays, their SA is much smaller than other clays
true
ammonium fixation would be expected to be greatest in soils containing high amounts of ____________
clay
Phosphorous availability in soils is constrained by the presence of significant quantities of ___________
iron and aluminum oxides
in order for nitrate to form from soil OM, __________ must be present in the soil
Nitrosomonas
Nitrobacter
one would expect well drained soils to have the higher OM contents where the climate is _____________
cool and humid
