182 exam 4
The soil moisture tension of a soil is 4 atmospheres. The matric potential of this soil would be ______ atmospheres.
-4
After a rain when water stops moving into a tile line, the soil immediately adjacent to the tile line has a SMT of _____ atmospheres.
0
Matric potential describes the movement of water held between ________ atmospheres soil moisture tension.
0-30
A soil has 36% water by volume and 30% water by weight. What is the bulk density of this soil?
1.2 g/cm3
For the past several decades nitrogen recommendations for most of Iowa have been based upon applying ________ # N for each bushel of corn expected.
1.2#
A column of soil 60 cm high was wetted half way down and allowed to drain for 3 days with no evaporation. The approximate soil moisture tension at the top of the column will be:
1/3 atm
A soil at pH 6.0 contains ________ H+ as it would have at pH 7.0.
10 times as much
Given the data at the Wt. at field capacity 150 g. right, what is the Wt. at wilting point 138 g. % available water Wt. air dry 135 g. in this soil? Wt. oven dry 120 g.
10%
One ton of 5-20-10 would contain ________ pounds of nitrogen.
100
How many pounds of pure calcium carbonate are required per acre furrow slice to replace 1 milliequivalent of hydrogen per 100 g?
1000
The ECCE of a lime sample is 96% and the percent available based on fineness is 92%. What must the CCE of this sample be?
104%
What is the neutralizing value of a liming material containing 75% CaCO3 and 24% MgCO3?
104%
A liquid fertilizer with a volume of 55 gallons and a weight of 550# had a guaranteed analysis of 30-10-10. How much dry fertilizer with a guaranteed analysis of 15-5-5 must be applied to give an equivalent fertility level?
1100#
A soil sample from a greenhouse bench was taken to determine if the soil conditions were favorable for root penetration by plants. If the sample has a bulk volume of 95 cm3 and an oven dry weight of 171 grams, the bulk density of this soil is:
112#/ft3
A soil contains 8 meq of K per 100 grams of soil. This equals _______ lbs/1000 square feet.
143
What is the % Na+ saturation, if the following are held on the cation exchange sites: 3 meq H+11 meq Ca++1 meq Mg++2 meq K+3 meq Na+
15%
One soil sample sent to the lab from a 10 acre pasture for soil testing should contain:
15-20 cores
In a soil the Pw at saturation is 35%; at field capacity = 24%; at wilting point = 8%, and at air dry = 3%. The available water in this soil is
16%
If a soil contains 7 meq of magnesium/100 g of soil, then how many lbs of magnesium per acre does this soil contain?
1680 lbs/acre
An average loamy soil was dry to the wilting point to a depth of more than 3 feet. How deep would a 3.0 inch rainfall penetrate if it falls slowly enough for all of the water toenter the soil?
18"
A moist soil sample collected in the field weighed 213 grams. After being oven dried the sample weighed 180 grams. What was the original moisture content of the sample?
18%
The following data were obtained from a soil sample: SMT % H2O 0 atm 40% 1/3 atm 24% 15 atm 16% 30 atm 6% The % capillary water is
18%
A soil has a bulk density of 1.2 g/cm3, a particle density of 2.6 g/cm3 and Pw values of 10% at 15 atmospheres tension, 30% at 1/3 atmosphere and 5% at 30 atmospheres. This soil will contain ________ inches of available water per foot of soil.
2.88
A soil sample weighed 640 g. moist, 560 g. oven dry, and occupied 400 cm3. What is the percent moisture by volume?
20%
Consider the following data: SMT=0 Pw=40% Field Capacity Pw=30% Wilting Point Pw=15% Hygroscopic Point Pw=10% Bulk Density = 1.2 g1cm3 The percent capillary water is:
20%
What is the % Mg++ saturation in a Histic epipedon having the following exchangeable ions: Ca++ = 37 meq/100 gMg++ = 12 meq/100 gK+ = 3 meq/100 gNa+ = 1 meq/100 gZn++ = 1 meq/100 gH+ = 7 meq/100 g 16%
20%
A producer has a fertilizer recommendation of 160 + 96 + 120. Which of the following is the best choice of a mixed fertilizer to meet this recommendation?
20-12-15
One-half cubic foot of soil removed from a field site weighed 47.6 pounds. It is oven dried and then weighs 41.2 pounds. What is the initial percentage of water by volume (Pv) for this sample?
20.5
A soil sample weighs 144g when wet and is shown to contain 20% water on an oven dry basis. How many grams of water was present in the wet sample?
24
If the fertilizer law were changed so that analysis must be on the elemental basis, a bag of 24-24-24 oxide will be labeled
24-10-20
A moist sample of soil weighed 40 g. After drying, it weighed 32 g. The Pw of this soil was
25%
The molecular weight of MgO is 40 and that of CaCO3 is 100. The CCE of pure finely ground MgO is:
250%
To change the soil pH from 5.0 to 6.0 requires an increase in the % base saturation from 55 to 70%. If the cation exchange capacity of the soil is 20 meq/100g, how many milliequivalents of H must be replaced?
3
How many inches of water are contained in a foot of soil with a bulk density of 1.5 g/cm3, a particle density of 2.6 g/cm3, and contains 20% moisture by weight?
3.6
How many milliequivalents of lime per 100 grams of soil must be added to a soil with a CEC of 27 meq/100 g, a pH of 6.1, and is 76 percent base saturated, to raise it to a pH of 6.9 or 90 percent base saturated?
3.78 meq/100 g
You have a recommendation of 4 lbs. of nitrogen for a 1000 sq.ft. lawn. Phosphorus and potassium can be added with no harm done but no benefit would be expected. Your fertilizer dealer has the following materials on clearance at very low prices all in 20# bags. Which would you buy?
33-0-0 at $6.00 per bag
A soil sample has a particle volume of 25 cm3 and weighs 100 grams when oven dry. What is the particle density?
4 g/cm3
It is recommended that the average Iowa farmer should soil test each field about every
4 years
A soil contained the following ions on its cation exchange in 100 grams of soil 20 meq Ca 3 meq K 5 meq Mg 5 meq H 7 meq Na What is the CEC of this soil?
40
A golf course owner has a soil tested that gave the following results: Ca = 15 meq/100g, H = 7 meq, K = 5 meq, Na = 2 meq, Mg = 11 meq. What is the cation exchange capacity of this soil?
40 meq/100g
If a liming material is 50% available over a 3-year period based on fineness of grind and has 90% calcium carbonate equivalent, the overall effectiveness of this material would be
45%
To change the soil pH from 4.5 to 5.5 requires an increase in the % base saturation from 50 to 70%. If the cation exchange capacity of the soil is 24meq/100g, how much CaCO3 lime is required to do the job?
4800#/A
In soils, the hydrogen-base balance influences soil pH most strongly between:
5.5-7.0
Most of the world's productive agricultural soils are found in the pH range of _______.
5.5-8.0
A soil with a pH of 6.0 requires 5 meq/100g of CaCO3 to improve the soil pH. One should therefore apply _______ #/A of CaCO3
5000
A soil had a lime requirement of 3 tons of CaCO3. If pure, fine MgCO3 were used instead, how many pounds would be required?
5040
It takes 3 tons of 100% ECCE material to neutralize a soil. How much pure, fine MgC03 would it take to do the same job?
5040#
A soil had a lime requirement of 5300 lbs/A. How much lime with an ECCE of 91% should be applied?
5824 lbs/acre
You want to increase the base saturation of a soil from 50% to 80%. How many meq's of H+ must be neutralized if the soil has a CEC of 20 meq/100g of soil?
6
How many pounds of pure calcium carbonate are required per acre furrow slice to replace 6 meq of H per 100 g of soil?
6000
Analysis for exchangeable ions indicate that a soil contained the following amounts of exchangeable cations in terms of meq/100 g of soil H = 4 Ca = 10 Mg = 2 K = 1 all others = 1 What is the % Ca plus Mg saturation?
66%
What is the ECCE of a liming material which is 83% pure, has a size reactivity of 77%, and the neutralizing value is 104%?
66%
What is the percent base saturation, if a soil contains: Ca++ = 10 meq/100 gMg++ = 4 meq/100 gH+ = 5 meq/100 gNH4+ = 1 meq/100 gAl+++ = 2 meq/100 g
68%
The following data were obtained from a soil sample. SMT %H2O 0 atm 32% 1/3 atm 14% 15 atm 7% 30 atm 5% The % available water is:
7%
A soil had a bulk density of 92 pounds per cubic foot and contained 30% water (by weight) at field capacity and 16% at the wilting point. How many inches of water would be required to bring a 3 foot root zone from the wilting point to field capacity?
7.4
A soil with a pH of ________ would probably have the highestpercent base saturation.
7.5 (highest number)
Calculate the percent base saturation of the following soil Ca = 11.2 meq/100g Mg = 4.0 K = 3.0 Na = 0.8 H = 8.0
70%
A producer has a soil test which shows a cation exchange capacity of 28 meq/100gms and a base saturation of 75%. He asks you how many pounds of limestone are needed per acre (pure, fine) to increase his soil to 100% base saturation. You should tell him to apply _____ #/A.
7000
A loam soil 4-feet deep is at field capacity. This soil probably contains about ________ inches of available water.
8
A loamy soil should hold approximately ____ inches of available water in a four foot profile?
8
You need 100 grams of soil at 25% moisture for an experiment. You have oven dry soil and water. How much of this soil would you use?
80
A soil had the following meq of exchangeable cations per 100 g of soil: Ca 12, Mg 3, H 4, K and all other bases 1. The percent base saturation is
80%
What is the percent base saturation, if the following are held at the cation exchange sites: 5 meq of H+16 meq of Ca++2 meq of Mg++1 meq of K+1 meq of Na+
80%
A soil has a bulk density of 1.30 g/cm3. How much does a cubic foot of this soil weigh?
81.1#
What is the percent base saturation, if a soil contains: 1 meq NH4+13 meq Ca++3 meq H+6 meq Mg++ 1 meq Al+++
83%
The density of a soil is 1.43 gm/cm3. The density of this soil in the English system is about _____________.
89#/FT3
To change the soil pH from 5.5 to 6.5 requires increasing the base saturation from 60% to 90%. If the CEC of the soil is 30 meq/100g, how much limestone is required per acre to do the job?
9000#/A
What is the percent base saturation, if the following are held at the cation exchange sites: 3 meq NH4+18 meq Ca++2 meq H+
91.3%
A limestone contains 70% CaCO3, 15% MgCO3, 5% CaO, and 10% non-reactive materials. All are finely ground. The ECCE of this material is
97%
In the determination of base saturation, Al (aluminum) is not considered a base. This is because:
Al ions react to increase soil acidity
Plants usually grow best in soils that have mostly _______ ions on their cation exchange sites.
Ca++
Of the two, it takes more pounds of pure _____ to neutralize a soil than pounds of the other
CaCO3
Tissue testing to determine the nutrient needs for__________ in a field of broccoli is probably the best method.
Cu
When a plant removes a cation from the soil, it generally replaces it with
H
Dolomite is used to add ________ to the soil.
Mg
From an understanding of the lyotrophic series, we know that cations are bonded to the clay minerals with different bond strengths. Of the following which cation is held most tightly?
Mg++
Basic Cations include:
NA, K, Mg, Ca
In preparing a soil sample for soil testing, one should attempt to mix cores from:
NOT both surface and subsoil NOT each different soil series in the field
You would expect ______ to be leached most readily from soil.
Na
The soil test for phosphorus reflects the level of
P available to plants the next growing season
If a soil is wetted to the point that any additional water added would be removed by gravity, the soil is at
SMT= 0
The biggest problem with using a sap test to determine a fertilizer need is that:
a low test does not confirm a soil deficiency of that nutrient
pH determinations measure the:
active H+
Which layer of water on a soil particle is held more tightly?
adhesive layer
The % base saturation method for measuring lime requirement is not accurate on strongly acidic soils because it does not measure the acidity that comes from_______.
aluminum
Liming an acid soil will likely result in _____ in the microbial activity in the soil.
an increase
A soil with a SMT=15 atmospheres is:
at pwp
A base saturation of 75% means that 75% of the exchange sites are occupied by:
bases
The theorized ice-like structure of hygroscopic water is due to:
both
The capacity of a soil to resist a pH change when either an acid or a base is added is called:
buffering capacity
The most common basic cation on the soil exchange complex is:
calcium
Capillary water:
can move upward, downward, and horizontally in a soil.
The soil with the greatest percent total pore space is:
can't tell from that stupid graph
Soil A has 15% moisture and soil B has 20% moisture. The soil with the highest SMT is
cannot tell from information given
At the wilting point a portion of the ________ water has been lost but part of it still remains in the soil.
capillary
Water held between 1/3 and 30 atmospheres soil moisture tension is known as _______ water.
capillary
Calcium carbonate works as a liming material because:
carbonate reacts to ultimately form CO2 and H2O.
A soil with a high ______ has a high buffering capacity.
cation exchange capacity
The number of negative charges in the soil is measured by the
cation exchange capacity
The order of ions in the lyotropic series is usually determined by:
charge and hydrated size of ions
Cations in the soil move readily back and forth between the soil solution and:
charged sites on clay surfaces
A corporation owns a large area of unique soils and is using it to raise specialty crops. The owners decide to set up their own soil testing program. After consulting with established laboratories, they will still need to do a lot of work on:
correlation studies
Soil texture ______influence the rate of lime that should be applied.
does
Saturated flow is:
downward movement of water in soils due to gravity
Soluble salts are more commonly found in the soil in:
dry regions
As measured in soils, pH gives an accurate measure of the H+ ions on the exchange sites.
false
Available water in a soil is the same thing as capillary water.
false
The total nutrient content of the soil is a reliable measure of its availability to plants.
false
Capillary water movement in the soil is ______ at 1/10 atmosphere tension than at 5 atmospheres.
faster
Several plastic pots are filled with soil and used for growing early tomatoes in a greenhouse.The tomatoes will probably obtain more plant nutrients from the soil if the water content is maintained near _____ than from the other pots.
field capacity
Available capillary water is water held between:
field capacity and wilting point
When one goes from 1/3 atmospheres to 15 atmospheres tension in the soil, one goes from
field capacity to the permanent wilting point
A good soil test recommendation considers:
field research your soil type climate
The B horizon of a soil has a SMT of 1/2 atmosphere. Based on this fact, which of the following statements could not be true?
gravitational water exists in this horizon
when a soil has a base saturation of 50% this means that
half of the exchange sites are occupied by basic cations
A highly buffered soil
has a high cation exchange capacity
Hygroscopic water is not considered available to plants because
held at high tensions
Which of the following soils would presently be less desirable, but has a good potential for improvement with good management?
high CEC saturation and low base saturation
The potassium analysis of a fertilizer is reported in %K. A bag of the identical fertilizer is labeled %K2O. The number on the second bag is
higher than the first
Most of the water that moves through the soil by saturated flow moves
in macropores
Limestone is ground to
increase its surface area
Long term soil fertility storage is primarily in the:
insoluble compounds
A soil test for phosphorus in Iowa
is an index of the P available to plants over the season
soil pH:
is related to the base saturation of a soil.
Deficiency symptoms can be used to identify fertilizer needs. Which of the following is not a problem when using this method?
knowing how much fertilizer to add. being able to correct the problem during this growing season. knowing what factors caused the deficiency symptom.
In Iowa, the best time to both estimate soil nitrogen levels and be able to add nitrogen if needed is _________.
late may to early june
Which soil texture would be expected to hold the least amount of available soil water?
loamy sand
The strength of bonding by different ions in the soil is expressed by the:
lyotropic series
The number of reserve cations held by the soil colloids is usually _________ the number of active cations in the soil solution.
many thousands of times as large as
A liming material with a low _______ will have a high _______.
molecular weight; neutralizing weight
The gravitational potential of a soil at point A in a mellow, uniform soil is 96 cm, and the matric potential is -47 cm. At point B the gravitational potential is 96 cm, and the matric potential is -36 cm. Water will
move from B to A
Soil A has a soil moisture tension of 12 atmosphere and Soil B has a soil moisture tension of 18 atmosphere. Which soil has the highest percent moisture?
need more information
Calcium carbonate equivalent (CCE) considers both the ______ of the active ingredient and the purity of the liming material.
neutralizing value
An Iowa loess soil contains 3% organic matter and 20% clay. It has a pH of 5.5 and a base saturation of 60%. How many meq of CaCO3 is required to raise the soil pH to 6.8 and an 85% base saturation?
none of the above are within 2 meq of the correct answer
A 100 g sample of soil contains 9 meq of calcium, 2 meq of magnesium, 1 meq of potassium, 1 meq of sodium and ammonium combined, 2 meq of hydrogen and 1 meq of aluminum. The percent base saturation of this soil is:
none of the above are within 4% of the correct answer (it's 81.2%)
K2O is
none of these
P2O5 is
not a common ingredient of fert not an inorganic acid not used by plants
A tissue test is more likely to be used as the only means of determining fertilizer recommendations for:
pears
A tissue test is most useful as the only means for determining fertilizer needs for ______ crop needs.
perennial
The main reason lime is added to the soil is to:
raise the pH
Point A has a SMT = 0.1 atmospheres. Point B is four inches away at the same depth in a uniform soil. If the SMT at point B is 12 atmospheres you should expect
rapid movement from A to B
Hydrogen ions in the soil
reduce soil pH replace cations used by plants
A soil with a 15% base saturation is probably
relatively fertile
Ideally, a soil sample taken for a soil test should:
represent 10 acres or less
Short term fertility storage is found primarily in the:
reserve ions
Three soils, a clay loam, a sandy loam and a silt loam, have a soil moisture tension of 2.5 atmospheres. Which soil probably has the most available water remaining? (Assume allhave good structure)
silt loam
The soil at point A is just drier than the permanent wilting point. The soil at point B is just drier than field capacity. They have the same gravitational potential. How will water move in this soil?
slowly from B to A
Five Ohio soils all have a pH of 5.5. The pH vs percent base saturation curves for these five soils are identical. Which will require the most lime to raise the soil pH topH 6.5? soil % clay % organic matter ____ ______ ________________ 1 10 6 2 24 4 3 26 3 4 28 2 5 30 1
soil 2
Consider two identical poorly drained fields. One was tiled at 24 inches and the other at 42 inches. Which will be better aerated at the surface when the soils are saturated below the tile.
soil deeper (42 in not 24)
As hydrogen ion concentration in the soil increases:
soil pH decreases
If one were to choose one method to determine fertilizer needs on an agricultural field, the best method over a 10 year period would be periodic:
soil tests
The soil moisture content of a soil is high, this implies:
the SMT is low
Tissue testing is not more widely used in determining fertilizer needs because:
the nutrient level of tissue is too variable
A silt loam soil and a sandy loam soil each have a soil moisture tension of 1/3 atmospheres. Which soil probably has the higher Pw?
the silt loam
A uniform soil 5 feet deep holds 2" of capillary water and 2" of gravitational water per foot. One-and-a-half inches of water are added to this air dry soil. After 3 days
the top 9 inches is at field capacity, the rest is air dry.
One of the challenges of using nutrient deficiency symptoms as a means of determining nutrient needs is that:
they may show up long after damage is done to the crop.
Today, one of the biggest sources of error in soil testing is failure
to get a representative soil sample
A soil with a high buffering capacity would be slower to show pH change than a soil with a low buffering capacity.
true
Soils with excess calcium carbonate have pH values ranging from 7 to 8.3.
true
The number of ions on reserve always exceeds the number of ions in the active zone.
true
When an acid soil is limed with Ca(OH)2, the exchanged hydrogen would end up in (as)
water
Active ions are found in (on) the:
water film around clay particles
Capillary water moves toward areas:
where the soil is drier
Na2SO4 _____ be an acceptable liming material.
would not
Traditionally, nitrogen recommendations for corn have been based upon:
yield expectations
