Agron 182 Homework 13

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#

How many pounds of pure calcium carbonate are required per acre furrow slice to replace 1 milliequivalent of hydrogen per 100 g?

1000

A pure MgCO3 lime is 87% available based on particle size. What is its ECCE?

103%

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%

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 per 1000 square feet to do the job?

110#

The molecular weight of magnesium carbonate is 84 and that of calcium carbonate is 100. What is the CCE of pure finely ground MgCO3?

119%

To raise the pH of a soil to pH 6.9 requires a change in the base saturation of 36%. The CEC is 38 meq/100g of soil. How many meq's of bases per 100 gms of soil will be required?

13.7

A soil sample sent to the testing lab should be a mixture of _______ subsamples taken from the sample area.

15-20

A soil sample sent to the lab for analysis, representing a ten acre wheat field should contain:

15-20 cores

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

A soil with 6 meq of Ca per 100 grams of soil would have ______lbs/acre of Ca.

2400

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 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

The ECCE of a liming material is 80%. How much of this material would be required to satisfy a need of 300#/A of limestone?

375#

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

You want to raise the pH of a soil from 5.4 to 6.9. The pH 5.4 is 77% base saturated and the CEC is 29.0 meq/100g. At pH 6.9 the % base saturation is 95%. How many meq's of lime must be added to raise the pH of 100 gms of this soil?

5.2

A soil has a cation exchange capacity of 28 meq/100g and is 80% base saturated. How much lime must be added to achieve 100% base saturation?

5.6 meq/100g

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 with a pH of 6.0 requires 6 meq/100g CaCO3 to improve the soil pH. One should therefore apply ____ #/A of CaCO3.

6000

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

How much liming material should be added to a soil with a lime requirement of 4800 lbs/acre? The liming material is 89% pure, has a particle size effectiveness of 81%, and the active ingredient has a neutralizing value of 110%.

6075 lbs/acre

A pure lime sample was found to have a neutralizing value of 64% and is 96% effective based on size. What is the ECCE of this sample?

61%

The effectiveness of a liming material is 65%. This means that in 3 years _______.

65% will have reacted

A lime requirement calls for 7000 lbs. of CaCO3 per acre. Assume an ECCE of 100%. How many milliequivalents of H+ will this neutralize per 100 grams of soil?

7.0 meq

If your lime requirement is 2000#/A and the product you select has a calcium carbonate equivalent of 90% and it is 80% effective by size. The ECCE of this material is:

72%

A lime sample has a calcium carbonate equivalent of 85% and is 92% available based on fineness. What is the ECCE of the lime sample?

78.2

The calcium carbonate equivalent of a lime sample is 102% and the % available based on fineness is 82.0%. What is the ECCE of this sample?

83.6

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/100 g, how much limestone is required to do the job?

9 meq/100 g

A soil with a pH of 6.3 requires 4 meq/100g of CaCO3 to improve the soil pH. One should therefore apply ___ #/1000 square feet of CaCO3.

92

A soil contains 4 meq of Mg per 100 grams of soil. This equals _____ lbs/acre.

960

By taking the late spring nitrogen test in late May the test will measure: A.) the degree to which the early spring weather promoted mineralization B.) the degree to which autotrophs fixed nitrogen C.) the degree to which early plant growth removed nitrogen from the soil D.) A and C

D.) A and C

Deficiency symptoms can be used to identify fertilizer needs. Which of the following is not a problem when using this method? A.) knowing how much fertilizer to add B.) being able to correct the problem during this growing season C.) knowing what factors caused the deficiency symptom D.) All of the above are problems

D.) all of the above are problems

In preparing a soil sample for soil testing, one should attempt to mix cores from: A.) both surface and subsoil B.) each different soil series in the field C.) both A and B D.) neither A or B are correct statements

D.) neither A nor B are correct statements

In preparing a soil sample, one should not take cores from: A.) a sandy spot in the field B.) edge of the field C.) subsoil D.) one should avoid all three conditions

D.) one should avoid all three conditions

A soil sample should represent an area of uniform: A.) texture B.) drainage C.) slope and erosion D.) past management E.) all of the above

E.) all of the above

A soil contains 8 meq of H per 100 grams of soil. This equals _____ lbs/acre A.) 4 B.) 8 C.) 12 D.) 16 E.) none of the above are within 1.5 lbs of the of the correct answer

E.) none of the above are within 1.5 lbs of the of the correct answer

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.

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

The soil test values from the Iowa State Soil Testing Lab represent:

an index of nutrient availability over the growing season.

Soil test results are now reported in parts per million. This value represents:

an index of nutrient availability.

A tissue test has proven most successful as the only means for determining the fertilizer needs of:

apples

A sample for the corn stalk nitrogen test is best taken __________.

at physiological maturity

Ideally, the available nitrogen level in the soil for non-legume crops should:

be low at the end of each growing season.

The pH - % base saturation curve method for determining lime requirement works best:

between pH 5.5 and 8.0

A corn plant in July shows symptoms that are suspected to be nitrogen deficiency. The best way to confirm this is to:

do a tissue test for nitrate.

A coarse liming material is _______ effective than (as) a fine liming material.

less

A corn field has a need of 180 # N/ac. If the field received an application of manure, the amount of commercial nitrogen fertilizer applied to this corn should be:

less than 180 # N/ac.

If the soil test is ________ for P or K the most economical fertilizer recommendation usually applies enough fertilizer to meet this year's crop needs plus a rate that somewhat exceeds the need of the next crop.

low

A tissue test is most useful as the only means for determining fertilizer needs for ______ crop needs.

perennial

The most accurate fertilizer recommendations are based on:

soil testing backed by field research.

The biggest problem with using a sap test to determine a fertilizer need is that it:

varies with small changes in the environment (temperature, cloud cover, etc.).

Traditionally, nitrogen recommendations for corn have been based upon:

yield expectations.