The full proceedings paper is at: www.extension.org/72744 Since 2000 the cost of fertilizer has more than doubled. According to information provided by the USDA Economic Research Service (2013), the national average price per pound of N has increased between 2000 and 2012 by a factor of 2.6. Over the same time period, phosphate price increased by a factor of 2.8, and potassium price increased by a factor of 4.0. As a result, fertilizer costs now contribute 30% to 40% of the annual variable costs to grow many cereal grains. Table 1. Fertilizer priceDuring the same time period environmental regulations have greatly decreased the construction of swine finishing facilities that use liquid manure handling systems that require the use of a lagoon or storage pond. In response to these economic and regulatory realities, some swine production companies are considering the use of deep pit slurry systems instead of an outdoor lagoon or storage. Benefits of the deep pit slurry system include the exclusion of rainfall, reduction in storage visibility, and conservation of valuable major plant nutrients (N, P, K) for the purpose of reducing production costs for feed grains. The objective of this presentation is to compare the fertilizer value of the manure produced from swine finishing barns that use a liquid manure handling with a treatment lagoon, and swine finishing barns that store manure below slotted floors in pits.

1. Fertilizer Value of Swine Manure:
A Comparison of Lagoons and
Deep Pit Slurry Systems
John P. Chastain, Ph.D.
Professor and Extension Agricultural Engineer
Waste to Worth Conference, Seattle, Washington
The Westin Seattle Hotel • March 30 – April 3, 2015

2. Introduction
 Most modern swine facilities in
NC, SC, and other Southern
states use under-slat flush or
re-charge pits to remove
manure from buildings.
 Such systems required large
volumes of water to operate.
 Recycled liquids are used due
to large volumes needed.

3. Recycling liquids requires adequate
treatment.
 Treatment needed to reduce solids,
ammonium content, and to provide adequate
storage time for pathogen reduction.
 Treatment lagoons are typically used to
provide treated water to recycle through the
buildings (≈ 0.5% TS or 99.5% water).
 So in the South treatment lagoons and recycle
systems typically go together.

4. Several changes have occurred since
2000.
 New and expanded regulations that make
expanding or siting new swine farms much
more difficult.
 Increase in construction cost of clay or
synthetically lined lagoons.
 Increase in grain prices.
 Increase in grain transpiration costs.
 Increase in fertilizer costs.

5. Prices of Nitrogen (USDA-ERS, 2013)

6. P2O5 & K2O Prices (USDA-ERS, 2013)

7. Between 2002 and 2012…
 Nitrogen prices have increased by a factor of
2.6
 Phosphate prices up by a factor of 2.8
 Potassium prices up by a factor of 4.0
 Price instability
 Common for fertilizer costs to contribute 30%
to 40% of the cost to produce grain

8. Result…Companies are considering
deep pit barns
 Easier to locate under regulatory requirements
 Reduce risk during high rainfall i.e. hurricanes!
 Conserve plant nutrients in swine manure
 Use manure nutrients to produce more grain to
feed swine
 Reduce transportation costs of grain from
Midwest
 Promote integration of swine and grain
production

9. Objective
 To compare the fertilizer value of the manure
produced from swine finishing barns that use
a liquid manure handling with a treatment
lagoon, and swine finishing barns that store
manure below slotted floors in pits.
 Compare the realized economic value of
manure if manure is spread based on
agronomic rates for N versus P2O5.

10. Assumptions for the Comparison
 Corn yield of 160 bu/ac
 Agronomic rates (CAMM Program Manual chapter 5 &
and EC-476, available at clemson.edu):
 1.2 lb N / Bu × 160 Bu/ac = 192 lb N/ac
 0.52 lb P2O5 / Bu = 83 lb P2O5 / ac
 1.2 lb K2O / Bu = 192 lb K2O /ac
 Part of the P2O5 and K2O will come from what
already exists in the soil.
 Variation in soil-test values not included.

11. Prices Used in Calculations
 Ammonium Nitrate - $0.71 per lb of N
 P2O5 - $0.69 /lb
 K2O - $0.50 / lb

12. Definitions
 Inventory value – the total value of N, P2O5,
and K2O in the manure without regard for
plant utilization.
 Realized economic value – the total value of
N, P2O5, and K2O in land applied manure that
does not exceed the agronomic need of the
crop. That is, over applied nutrients are not
given any value for the current crop.

13. Case 1. Four 880 swine finishing houses
that use a single treatment lagoon.
Number of Hog Spaces = 3520

14. Lagoon water nutrients and volume
3520 finishing hog-spaces
 Ammonium-N: 3.1 lb/1,000 gal (ATAN = 0.80)
 Organic-N: 0.9 lb/1,000 gal (mf = 0.60)
 Plant Available N = PAN: 3.0 lb/1,000 gal
 P2O5: 2.0 lb/1,000 gal
 K2O: 4.9 lb/1,000 gal
 Moisture: 99.63%
 Volume = 2,432,320 gal / year, or
 691 gal/hog-space/year or 89.6 ac-in / year.

15. Annual Nutrient Production from Lagoon Water
 3.0 lb PAN/1,000 gal x 2,432,320 gal/yr
= 7,297 lb PAN/yr
 2.0 lb P2O5 /1,000 gal x 2,432,320 gal/yr
= 4,865 lb P2O5 /yr
 4.9 lb K2O /1,000 gal x 2,432,320 gal/yr
= 11,918 lb K2O /yr

16. Fertilizer Inventory Value – Lagoon Water
 7,297 lb PAN/yr x $0.71/lb N = $5,181/yr
 4,865 lb P2O5 /yr x $0.69 / lb P2O5 = $3,357/yr
 11,918 lb K2O/yr x $0.50 lb K2O = $5,959/yr
(Higher than normal K2O content maybe solubilized
from sludge .)
 Total Inventory Value = $14,497 per year or
$4.12 / hog-space / year.

17. Area of corn that can be fertilized based on
agronomic rate for nitrogen using lagoon water.
 PAN to Spread ÷ N Demand = Acres Needed
 For our 4-house swine lagoon example:
7,297 lb PAN/yr ÷ 192 lb N/ac = 38 ac / year.
 Liquid application rate = 64,008 gal/ac
or 2.36 ac-in
Not much if you are a grain producer!

18. How much P2O5 is applied if we apply
lagoon water based on N?
 We will spread 4,865 lb P2O5 /yr along with
the N.
 Spreadable acres = 38
 P2O5 rate = 4,865 lb P2O5 /yr ÷ 38 ac
= 128 lb P2O5 /ac
 The 160 bu/ac corn only needs 83 lb P2O5 /ac
 Excess of 45 lb P2O5 /ac or 54% over
application.

19. How much K2O is applied if we apply
lagoon water based on N?
 We will spread 11,918 lb K2O/yr along with
the N
 Spreadable acres = 38
 K2O rate = 11,918 lb K2O/yr ÷ 38 ac
= 314 lb K2O /ac
 The 160 bu/ac corn needs 192 lb K2O/ac
 Excess is 122 lb K2O /ac or an excess of 64%

20. Realized economic value of the lagoon water for
application based on N
 Nitrogen: 192 lb N/ac × $0.71/lb N = $136.32/ac
 P2O5 : 83 lb N/ac × $0.69 / lb P2O5 = $57.27/ac
 K2O: 192 lb K2O/ac × $0.50 / lb K2O = $96.00/ac
 Total value from lagoon water = $289.59/ac
 Value of wasted P2O5 = 45 lb P2O5 /ac × $0.69 / lb P2O5
= $31.05/ac
 Value of wasted K2O = 122 lb K2O /ac × $0.50 / lb
P2O5 = $61.00/ac
 What percentage of lagoon water value was
realized? ($289.59 / $381.64) × 100 = 76%

21. Area of corn that can be fertilized based on
agronomic rate for P2O5 using lagoon water.
 P2O5 to Spread ÷ P2O5 Demand = Acres
Needed
 For our 4-house swine farm example:
4,865 lb P2O5 /yr ÷ 83 lb P2O5/ac = 59 ac / yr
17 ac/hog-space
Need 1.55 times more corn land if lagoon water
is spread based on P2O5 rate (59 ac vs. 38 ac).
 Liquid application rate = 41,226 gal/ac
or 1.52 ac-in

22. How much N is applied if we apply lagoon
water based on P2O5?
 We will spread 7,297 lb PAN/yr along with
the P2O5
 Spreadable acres = 59
 N rate = 7,297 lb PAN/yr ÷ 59 ac
= 124 lb N /ac

23. Calculation of additional N Needs
 Fert. N = (N-rate needed) – (N manure credit)
 Fert. N = 192 lb N/ac - 124 lb PAN/ac
= 68 lb N/acre.
 Lagoon water saved 65% on N cost.
 Allows more efficient use of N to grow the
crop by including a second application of N to
provide optimal yield.

24. How much K2O is applied if we apply
lagoon water based on P2O5?
 We will spread 11,918 lb K2O/yr along with
the P2O5
 Spreadable acres = 59
 K2O rate = 11,918 lb K2O/yr ÷ 59 ac
= 202 lb K2O /ac
 The corn needs 192 lb K2O/ac
 Over by only 10 lb K2O /ac.

25. Realized economic value of the lagoon
water for application based on P2O5.
 Spread to provide 83 lb P2O5/ac ($0.69/lb)
 Nitrogen applied = 124 lb PAN/ac ($0.71/lb), and
 K2O applied = 192 lb P2O5/ac ($0.50/lb).
 Total value from lagoon water = $241.31/ac
 Value of wasted K2O = 10 lb/ac × $0.50/lb = $5.00/ac
 Only 2% nutrients wasted – 98% utilization.
 Need to add 68 lb N/ac at optimal time.

26. Summary: Value of Lagoon Water
for 160 bu/ac corn – 4 houses
 Spread based on N: 76% realized economic
value: lagoon water was worth $11,004/year
or $3.13/hog-space/year.
 Spread based on P2O5: 98% realized economic
value: lagoon water was worth $14,237/year
or $4.04/hog-space/year.

27. Now we need to consider the
sludge. We will look at the value
on an annual basis.

28. Lagoon sludge nutrients and volume for a 4
house finishing farm - 3520 hog-spaces
 Ammonium-N: 6.1 lb/1,000 gal
 Organic-N: 15.5 lb/1,000 gal (mf = 0.36)
 PAN – incorp.: 10.5 lb/1,000 gal (ATAN = 0.80)
 PAN – injected: 11.7 lb/1,000 gal (ATAN = 1.0)
 P2O5: 47.3 lb/1,000 gal
 K2O: 6.3 lb/1,000 gal
 Moisture: 90.0%
 Volume = 58 gal/hog-space/year (new ASABE Standard)
 Annual Volume = 204,160 gal of sludge/year (10% TS)

29. Direct Injection Minimizes N Losses and
Odor Emissions
Towed Hose
Tank Type

30. Annual Sludge Nutrient Production & Value
using direct injection – 3520 hog-spaces
 11.7 lb PAN/1,000 gal × 204,160 gal sludge/year
= 2,389 lb PAN/yr × $0.71/lb = $1,696/yr
 47.3 lb P2O5 /1,000 gal × 204,160 gal sludge/year
= 9,657 lb P2O5 /yr × $0.69/lb = $6,663/yr
 6.3 lb K2O /1,000 gal × 204,160 gal sludge/year
= 1,286 lb K2O /yr × $0.50/lb = $643/yr
 Sludge is best used as a P fertilizer and is worth
$9,002/year or $2.56/hog-space/year.

31. Results of spreading lagoon sludge to 160
bu/ac corn based on P2O5
 Spread to provide 83 lb P2O5/ac ($0.69/lb) will
fertilize 116 acres or 33 ac/hog-space
 The volume spread / acre = 1760 gal/acre.
 Nitrogen applied = 21 lb PAN/ac ($0.71/lb), and
 K2O applied = 11 lb K2O/ac ($0.50/lb).
 Total value from sludge = $77.68/ac
 Provided 27% of fertilizer requirement value.
 Realized economic value = 100% or $2.56/hog-space

32. Summary: Realized Value of Lagoon Water +
Sludge for 160 bu/ac corn – 3520 hog-spaces
 Spread water based on N and sludge based on
P2O5
Value of manure = $3.13/hog-space for water
+ $2.56 for sludge = $5.69 / hog-space.
 Spread water and sludge based on P2O5:
Value of manure = $4.08 + $2.56 for sludge =
$6.64 / hog-space

33. Case 2. Four 880 swine finishing houses
that use deep slurry pits that provide 1
year of storage
Number of Hog Spaces = 3520

34. Estimates for Four Deep Pit Swine Barns, 880
pigs /house – 3520 hog spaces
 Ammonium-N: 23 lb/1000 gal (ATAN = 1.0)
 Organic-N: 19 lb/ 1000 gal (mf = 0.60)
 PAN – Direct injection = 34 lb/1000 gal
 P2O5: 33 lb/1000 gal
 K2O: 28 lb/1000 gal
 Moisture: 92.5% or 7.5% TS
 Manure prod. = 418,326.5 gal/house/year
 For 4 houses = 1,673,306 gal/year
 475.4 gal/hog-space/yr

35. Annual Nutrient Production 4 Deep Pit
Houses - 3520 hog spaces, direct injection
 34 lb PAN/1,000 gal x 1,673,306 gal/year
= 56,892 lb PAN/yr
 33 lb P2O5 /1,000 gal x 1,673,306 gal/year
= 55,219 lb P2O5 /2yr
 28 lb K2O /1,000 gal x 1,673,306 gal/year
= 46,852 lb K2O /yr

36. Fertilizer inventory value for a 4 house deep
pit farm - 3520 hog spaces
 56,892 lb PAN/yr × $0.71/lb N = $40,393/yr
 55,219 lb P2O5 /yr × $0.69/lb P2O5 = $38,101/yr
 46,852 lb K2O/yr × $0.50 lb K2O = $23,426/yr
 If you can use all of it effectively the
total inventory value is $101,920 per
year.
 Equal to $28.95 per hog-space per year.

37. Estimation of spreadable acres based on N
requirement for corn fertilized with pit manure
 PAN to Spread ÷ N Demand = Acres Needed
 For our slurry example:
56,892 lb PAN/yr ÷ 192 lb N/ac = 296 ac / yr,
Or 84.1 acres/1000 hog-space/yr
Still not much for a grain producer!

38. Resultant application rates for P2O5 & K2O
using deep pit manure.
 P2O5 rate = 187 lb P2O5 /ac
 The corn only needs 83 lb P2O5 /ac without
counting soil test
 Excess of 104 lb P2O5 /ac
 K2O rate = 158 lb K2O /ac
 The corn needs 192 lb K2O/ac
 Short only 34 lb K2O /ac

39. Realized economic value deep pit manure
for application based on N
 Nitrogen: 192 lb N/ac × $0.71/lb N = $136.32/ac
 P2O5 : 83 lb /ac × $0.69 / lb P2O5 = $57.27/ac
 K2O: 158 lb K2O/ac × $0.50 / lb K2O = $79.00/ac
 Total value from manure = $272.59/ac
 Value of wasted P2O5 = 104 lb P2O5 /ac × $0.69
/ lb P2O5 = $71.76/ac
 Realized economic value = $80,687/year or
$22.92 / hog-space/yr. – 79%

40. Results of spreading deep pit manure to
160 bu/ac corn based on P2O5
 Spread to provide 83 lb P2O5/ac ($0.69/lb) will
fertilize 665 acres – 189 ac/hog-space.
 The volume spread / acre = 2516 gal/acre.
 Nitrogen applied = 86 lb PAN/ac ($0.71/lb), and
 K2O applied = 70 lb K2O/ac ($0.50/lb).
 Total value from sludge = $153.33/ac
 Realized economic value = $101,920/year or
$28.95/hog-space/year – 100%

41. Calculation of additional N Needs
Following Application of Slurry
 Fert. N = (N-rate) – (N manure credit)
 Fert. N = 192 lb N/ac - 86 lb PAN/ac
= 106 lb N/acre.
 Manure saved 45% on N cost – similar to lagoon
system we get more nutrients per year.
 Allows more efficient use of N by splitting the
application.

42. Some take home ideas…
 Lagoons are needed to provide treated water that
can be used to remove manure from flush or pit-
recharge swine buildings.
 Lagoon systems were designed to provide
treatment with little consideration for the N
losses or value of P and K.
 Application based on agronomic rates for P2O5
provided the best use of manure for both systems
–Realized economic value of 100%.

43. Some take home ideas…(2)
 Deep pit slurry systems allow a producer to increase
nutrient value per hog-space from $6.64 to
$28.95/hog-space – a factor of 4.3.
 Provided about 45% of the plant nutrients needed
for corn (160 Bu/ac)
 A deep pit swine production unit can support 3.7
times more corn land than a lagoon system –
189 ac/1000 hog-spaces vs. 50 ac/1000 hog- spaces.