Answer Key
to Nutrient Management Exercises (1-7)

 

Exercise 1a. Determine Total Manure Produced.
Livestock type A
Animal numbers
B
Manure produced*
(tons/head/year)
C
Number of months
in confinement
/ 12
D = A x B x C
Total manure produced for land application
(tons/year)
Cow – calf 300 2.4 6 / 12 360
      / 12  
      / 12  
      / 12  
* Refer to Data Sheet #1 and #2   Total 360

 

Exercise 1b. Calculating the Nutrient Content of Manure.
Livestock A*
Total manure
produced for land application (tons)
B**
Manure
Crop N content (lbs/ton)
C
=A x B

Total Crop N available
(lbs)
D**
Manure Crop P2O5 content (lbs/ton)
E
=A x D

Total P2O5
available (lbs)
F**
Manure Crop K2O content (lbs/ton)
G
= A x F

Total K2O
available (lbs)
Beef 360 5.1 1836 11 3960 16 5760
Dairy              
Hogs              
Poultry              
Other
             
* Column D from Ex.1a
** Refer to Data Sheet 3
Total 1836 lbs Total 3960 lbs Total 5760 lbs

 

Exercise 1c. Nutrient Value of Manure.
Nutrient value of manure
What is the economic value of manure? Manure may appear to be a cost to the producers in terms of removal, storage and disposal. But manure has a nutrient value and this can be expressed as a commercial fertilizer equivalent.
Nutrient Weight of
nutrient in manure
(lbs)

****Commercial fertilizer
cost ($/lb)

Total value of
manure nutrient ($)
Beef
N* 1836lbs x $ 0.27 = $495.72
P2O5** 3960lbs x $ 0.33 = $1306.80
K2O*** 5760lbs x $ 0.16 = $921.60

 

Exercise 3a. Interpreting Soil Test Results
  1. Convert ppm to lbs/acre for the 0-6 inch sample depth, then determine the amount present in the 0-2 inch depth. Provide the 0-2" lbs/acre equivalent for both Nitrogen (6.327) and Phosphorus (24).
    N 8ppm+11ppm=19ppm, 19/2=9.5ppm avg., 9.5x2=19lbs/acre in 0-6",19(1/3) = 6.327lbs/acre in 0-2"
    P 53ppm+19ppm=72ppm, 72/2=36ppm avg., 36x2=72lbs/acre in 0-6", 72(1/3) = 24lbs/acre in 0-2"
  2. If there is 8 ppm of nitrate-N in the 0-6" sample depth and 6 ppm of nitrate-N in the 6-12" sample depth, how many ppm of nitrate-N are there in the 12-24" depth to approximate 38 lbs/acre of available nitrate-N?
    0-6" = 8ppm = 16 lbs/acr Therefore, 10 lbs/acre are in the 12-24" depth
    6-12"=   6ppm = 12 lbs/acre (lbs/acre) / 2 = ppm
    28 lbs/acre = 5 ppm in the 12-24" sample
  3. For an 80 bushel malt barley crop, how many lbs/acre of nitrogen would you need? How many lbs/acre of P2O5 is required?
    N – 56 lbs/acre P2O5– 27 lbs/acre
  4. What is the conversion factor for P to P2O5?
    2.3
  5. What is the conversion factor for K to K2O?
    1.2
  6. What is the pH of the combined soil sample and is it a problem? What is a normal acceptable range of surface soil pH?
    0-6" – 6.5
    6-12" – 6.85
    Not a problem. An acceptable pH range is 6.2 – 7.2
  7. What is the Electrical Conductivity (E.C.) of the soil? Are the E.C. levels of these soil samples acceptable? What related problem can occur with frequent manure application?
    E.C. is a measure of salt content in the soil.
    0-6" = 0.46
    6-12" = 0.52
    These are acceptable values
    Inhibited plant growth can result at E.C. levels as low as 2.
  8. What other analyses would you recommend for monitoring manure application onto soil? Why? (Try to provide at least 3 possible analyses)
    Organic matter content – possibly prioritize fields based on lowest organic matter content
    Sodium absorption ratio (SAR) and Na – to avoid soil crusting and/or poor structure problems
    Cl – chloride is a common element in manure and can build to toxic levels in soil
    K – Excess potassium levels inhibit Ca and Mg uptake by plants which can induce grass tetany
    P – Excess phosphorus is prone to runoff in surface waters and causes eutrophication of water bodies
    E.C. – inhibited plant growth can result at E.C. levels as low as 2

 

Exercise 3b. Interpreting Manure Test Results

1. Determine the amount (lbs/ton) of total nitrogen as-is in the manure.

2.83% x {(100-71.7) / 100} = 0.8% as-is
0.8
100
= x
2000

x = 16 lbs / ton total N in the manure

2. Determine the amount (lbs/ton) of P2O5 as-is in the manure.

4.95% x (28.3 / 100) = 1.4% as-is
1.4
100
= x
2000

x = 28 lbs/ton total P2O5 in the manure

3. Determine the amount (lbs/ton) of K20 as-is in the manure.

2.8% x (28.3 / 100) = 0.79% as-is
0.79
100
= x
2000

x = 15.85 lbs/ton total K2O in the manure in the manure

Exercise 4a. Application Rate Calculation

A*
Total beef
manure
produced
(tons)
Next crop B(1)
Recommended N
fertilizer
rate
(lbs/acre)
from soil tests
C(1)
Total N
from manure
test
(lbs/ton)
D(1)
= B(1) / C(1)
Manure
application rate
(tons/acre)
E(1)
= A / D(1)
Land required
to balance N
requirements
360 barley (80 bu) 56 lbs/acre 16 x 0.35 = 5.6 lbs/ton
available 1st year
10 tons/acre 36 acres
A*
Total beef
manure
produced
(tons)
Next crop B(2)
Recommended P2O5 fertilizer rate
(lbs/acre)
from soil tests
C(2)
Total P2O5
from manure
test
(lbs/ton)
D(2)
= B(1) / C(2)
Manure application
rate (tons/acre)
E(2)
= A / D(2)
Land required
to balance phosphorus
requirements
360 barley (80 bu) 27 lbs/acre 28 x 0 .50 = 14.0
lbs/ton
available 1st year
1.9 tons/acre 189.5 acres
* Column D in Exercise 1a.

** This factor is the frequency of manure application in years.In this example, manure is applied every other year, so a value of 2 is used. If manure was applied every 5th year, a value of 5 would be used.

*** This value will be used in Exercise 4b

F
= D(1) – D(2)
Excess manure
applied when
balancing for N (tons)
G
= F x C(2)
Excess P2O5
applied (lbs/acre)
8.1 tons 113.4 lbs/acre
H
= D(1) – {D(2) x 2**}
Excess manure
(tons) applied
based on
application every
other year
I***
= H x C(2)
Excess P2O5
(lbs/acre) applied
based on
application
every other
year
6.2 tons 86.8 lbs/acre

Exercise 4b. Application Rate Calculation

1. From (I) in Exercise 4a, enter the amount by which applied P2O5 exceeds crop requirements when manure application is every other year.
86.8 lbs P2O5/acre/year (A).

2. Determine the P buildup factor. This is the inverse of the pounds of P2O5 necessary to raise the soil test level 1 ppm.

As an average, 20 lbs P2O5 is needed to raise the soil test P 1 ppm. The inverse of 20 is 0.05 (B).
3. Multiply amount in line (A) by the soil test buildup factor (B)
86.8 lbs P2O5/acre/year x 0.05 = 4.34 (C)
4. The suggested threshold for sensitive soils and landscapes in Alberta (sandy and organic soils; runoff-prone lands) is 200 lbs/acre for elemental P.
Elemental P x 2.3 = P2O5.
Therefore, the soil test P threshold value for P2O5 is
460 lbs/acre or 230 ppm (D) based on a 0-6" sample.
5. Using the current soil test P level, calculate the available ppm of P storage before reaching the sensitive soil threshold level.
Threshold level (D) = 230 ppm.
Current soil test P level based on two field management areas
of 53 + 19 ppm, (74 / 2), = 37 ppm. Amount of available soil test P that
can be applied before the threshold P level is reached is (D) 230 - 37 = 193 ppm (E).
6. Manure application based on a Nitrogen rate, and every other year, will build up the soil test P level to the sensitive threshold level in how many years?
E / C = 44.5 years (F)

Exercise 5. Priortizing Fields for Manure Application

Category Points Category points
Field 1 Field 2 Field 3
Planned crop (points based on crop nitrogen requirements)
potatoes 10


canola 8 8

corn 8


first-year corn following forage legume 1


non-forage legumes (peas, beans, lentils) 2


cereal grains (removed as grain) 4


cereal grains (removed as silage) 5
5
prior to direct seeding forage legume 8


topdress good legume stand 1

1
topdress fair legume stand 2


topdress poor legume stand 3


grass pasture or other non-legumes 7


Soil test results (select one from each category)
Phosphorus  
> 200 ppm 1
1
100-200 ppm 3

3
20-100 ppm 5 5

< 20 ppm 10


Potassium  
> 3000 ppm 6
6
250-3000 ppm 8 8
8
< 250 ppm 10


Site/soil limitations (select one from each category)
Surface and groundwater proximity        
Applied and incorporated within 10-year
floodplain or within 200 feet of surface water or groundwater access
1

1




Application outside the above restrictions 5 5
5
Slope        
> 9% 1


6-9% 3
3
2-6% 5 5

<2% 10

10
Soil texture        
Sands, loamy sands 1
1
Sandy loams, loams; Or loamy sands spring applied 3

3
Other soils; Or sandy loams, loams spring applied 5 5

Depth to bedrock        
O - 10 inches (0 - 25 cm) 0
1
10 - 20 inches (25 - 50 cm) 1


> 20 inches (> 50 cm) 5 5
5
Total (highest value indicates field with highest priority)   41 18 35

 

Exercise 6. Determining manure application rates for your farm

Land needed to maintain a nitrogen balance

A
Manure (tons)
B
Manure application rate (tons/acre)
A / B
Land required (acres) to maintain a nitrogen balance
360 11.76 30.6

Land needed to maintain a phosphorus balance

A
Manure (tons)
B
Manure application rate (tons/acre)
A / B
Land required (acres) to maintain a phosphorous balance
360 2.73 131.9

 

Application based on Nitrogen A
Acres
B*
Recommended N fertilizer rate (lbs/acre)
C**
Manure Crop N
content (lbs/ton)
D= B / C
Manure Application
rate (tons/acre)
E= A X D
Total Manure Applied (tons)
Manure remaining starting from 360 tons***
Field Name and next crop
Jones’ field – canola 30.6 of 60 60 5.1 11.76 705 0
Application based on Phosphorus F
Acres
G*
Recommended P2O5 fertilizer rate (lbs/acre)
H**
Manure Crop P2O5 content (lbs/ton)
I= G / H
Manure application
rate (tons/acre)
J= F x I
Total Manure
Applied (tons)
Manure remaining starting from 360 tons***
Field name and next crop
Jones’ field – canola 60 30 11 2.73 163.8 196.2
Bill’s quarter – canola 71.9 of 100 30 11 2.73 273 0







* Based on soil test recommendations, or if not available, use Data Sheet 4
** From data sheet 3
*** From exercise 1a

Exercise 7. BMP Case Study Questions

  1. Joe has just applied manure to a stubble field. What is the Beneficial Management Practice for this situation?
    A) Incorporation within 12 hours
    B) Incorporation within 48 hours
    C) No incorporation
  2. Joe's field has an intermittent creek running through it. What is the Beneficial Management Practice for manure application?
    A) Joe should seed or maintain a vegetated buffer strip on both sides and ensure that there is no manure application within 30m of the buffer strip
    B) Joe should apply manure directly up to waters edge
    C) Joe should apply manure within 5m of the watercourse and not be concerned about maintaining any riparian vegetation along the creek
  3. You are thinking about cleaning your pens and applying the manure to a field with long inclined slopes with high runoff potential. What is the Beneficial Management Practice in terms of timing of application?
    A) In the fall just before freezing
    B) The spring just before thaw

    C) In the spring before crop seeding
  4. You have been hired to clean the manure out of a feedlot. What is the Beneficial Management Practice?
    A) Scraping and removing all of the organic material (manure)
    B) Scraping and removing all of the organic material (manure) plus the upper part of the earthen base
    C) Removing all the organic material (manure), the manure-soil combination and the upper portion of the earthen base
  5. Joe has just received his soil tests on a field that shows high Phosphorus levels. What is the Beneficial Management Practice for next years cropping decision?
    A) Use high P demanding crops (alfalfa, corn, or canola)
    B) Allow field to be in fallow for 2 out of the next 4 years
    C) Use low P demanding crops (Grass species and barley)
  6. You have just purchased a half-section of pasture land. There is a creek running through the property but no developed watering systems. What is the Beneficial Management Practice in regards to the following livestock watering systems?
    A) Unlimited access for cattle to creeks, rivers and streams
    B) Limited access to waterbodies with enhanced structural design

    C) Implement a pipeline watering system where water is pumped from a waterbody to an alternative site
  7. Bill has a 5000 head feedlot on a gently sloping (4%), south facing site. The feedlot is in a high rainfall area and generally gets a lot of snow. What is the Beneficial Management Practice for this situation?
    A) No structures in place at site
    B) Let run-on waters flush manure through pens and away from the site

    C) Diversion of run-on waters around or away from site
  8. You are thinking about building a new liquid manure storage system. In regards to odour and fly control, what would be the Beneficial Management Practice?
    A) Earthen lagoon with floating mat of straw; use of parasitic wasps
    B) Uncovered earthen lagoon
    C) Contained storage with overflow directed to a water body
  9. What is the most appropriate BMP for a catch basin?
    A) Unlined and located on sandy soils
    B) Unlined and located on clayey soils
    C) Located in a recharge wetland
  10. Joe has a small feedlot where he backgrounds 750 feeders. He owns a tractor, scraper and a loader and he has his own spreader. What is the most efficient method to reduce the volume and weight of the manure while also reducing the fly problem?
    A) One-time manure handling and application in the spring
    B) Frequent (biweekly) scraping and mounding into a temporary stockpile
    C) In-pen composting with manure piling every 30 days and removal for field application every 60 days