Spreadsheet: 4e25da01-cf40-4cd3-a36a-e972b0565989
Sheet: Compost Calculation 

Business name:
Decision maker:
Address:
TMK:
Determine estimated compost mix and composting time
Given:
Step1a:
Bulking Agent:
Pen Size: |  | 'W           x |  | 'L                           = |  | ft2
amount: |  | in thick x (1ft÷12in) x |  | ft2 x (1yd3÷27ft3) = |  | yd3
 |  | yd3 x (27ft3÷1yd3) x | 0 | lb/ft3                      = |  | lbs/pen per day
 |  | yd3          x | 0 | lb/yd3                     = |  | lbs/pen per day
Note: 12 inches in 1 foot, 27 ft3 in 1 yd3, and __lb/ft3 or _lb/yd3 for bulking agent
See Ref. Tables for bulking agent information
Mwa% = moisture content: |  |  | %
% N = |  | % | C:N Ratio = |  | :1
See Ref. Tables for bulking agent information
Manure:
Animal Units (AU) = |  |  | AU
Mm% = percent moisture: |  |  | %
manure production: |  |  | lbs/day/AU
nitrogen production: |  |  | lbs/day/AU
 | fixed solids: |  | lbs/day/AU
volatile solids: |  |  | lbs/day/AU
confined in building per day: |  |  | day
 | pens per building: |  | pens/building
 | hrs/day confined: |  | hrs/day
See NRCS Nutrient_Acctg_Wksht_all_livestock.xls AW as Excreted wksht
Step 1b: [NAME] Agent
See bulking agent data above
Step 2a: Determine the moisture content of the waste
Wwa = wet weight of bulking agent in barn:
amount: |  | in thick = |  | cu.yds = |  | lbs/pen per day
 |  | x pen per bld. |  | pens per bld. |  | lbs/building per day
Wm = wet weight of manure in building:
Total AU *manure production*confined in building = |  |  |  |  | lbs per day
Wmwa = wet weight of manure plus bulking agent
Wmwa = Wwa + Wm = |  |  | lbs per day
determine moisture content of manure plus bulking agent:
See Equation [10-11] p.10-49
[NAME] = (((Wm*Mm%)+(Wwa*Mwa%))÷100))÷(Wmwa) = |  |  |  |  | %
where:
[NAME] = % moisture of manure plus bulking agent
Wm = wet weight of manure
Mm% = % moisture content of manure
Wwa = wet weight of bulking agent
Mwa% = % moisture content of bulking agent
Wmwa = weight of manure plus bulking agent
Step 2b: Determine amount of additional bulking agent to added, if any, to the compost mix
that will result in desired final moisture content that is between 40% to 60%
See Equation [10-12] p.10-50
Waa= ((Wmwa)*(Mmwa-Md))÷(Md-Maa) = |  |  |  | lbs
where:
Waa= Wet weight of additional bulking agent to be added
Wmwa=wet weight of manure plus bulking agent
Mmwa= % moisture content of manure plus bulking agent
[NAME] desired % moisture of compost mixture (between 40% to 60%)
Maa = %moisture content of additional bulking agent
Wmwa= |  | lbs per day
Mmwa= |  | %
Maa= |  | %                         Md= |  | %
Wwa = Wwa + Waa = |  | lbs
For Wmwa & Mmwa input data from calculated data
For Maa & Md adjust as needed
until desired moisture content (between 40% to 60%) is reached
Since compost mix is within the desired moisture content
no amendment is needed.
Step 3: Calculate the C:N Ratio of compost mix
Determine the carbon and nitrogen content of the bulking agent:
Wwa = total weight of bulking agent: |  |  |  | lbs per day
 | Wdrywa = Wwa*((100-Mw%)÷100) = |  |  | lbs per day
where:
Wwa= wet weight of bulking agent
Mwa% = % moisture content of bulking agent
Wdrywa = dry weight of bulking agent
Note: See Equation [10-18] p.10-50
weight of nitrogen in bulking agent:
Wnwa = ((%N*Wdrywa)÷100) = |  |  |  | lbs per day
Note: See Equation [10-16a] p.10-50
Wcwa = weight of carbon in bulking agent:
Wcwa = Wnwa * C:N = |  |  | lbs per day
Note: See Equation [10-17b] p.10-50
Determine the carbon and nitrogen content in manure:
volume of volatile solids in piggery building:
VS = total AU*volatile solids /day*confined in barn = |  |  |  |  | lbs per day
weight of carbon in manure:
Wcm = VS÷1.8 = |  |  | lbs per day
Note: See Equation [10-13b] p.10-50
weight of nitrogen in manure:
Wnm = AU * nitrogen production * time swine in piggery building per day
Wnm = |  | lbs per day
C:N Ratio of manure: |  | Wcm/Wnm =
Determine C:N ratio of manure and bulking agent mixture:
C:N = (Wcm+Wcwa)÷(Wnm+Wnwa) =
Note: See Equation [10-15] p.10-50
Manure and bulking agent mixture C:N Ratio
is at the desired C:N Ratio 25:1 to 40:1
so no amendment needed to achieve C:N Ratio
Step 3b - Determine the amount of commercial nitrogen
to add to bring the C:N ratio to 25:1 to 40:1
weight of nitrogen in current compost mix:
Wcompost = Wnm+Wnwa = |  |  | lbs per day
Wdrym = Wm*((100-Mm%)÷100) = |  |  |  | lbs per day
where:
Wm = wet weight of manure
Mm% = % moisture content of manure
Wdrym = dry weight of manure
Note: See Equation [10-18] p.10-50
% N in manure = (Wnm÷Wdrym)*100 = |  |  |  | %
Pounds of commercial nitrogen to add to bring compost mix to 25:1 to 40:1:
Wnd = ((Wcm+Wcwa)÷Rd)-(Wnm+Wnwa) = |  |  |  | lbs per day
where:
Wnd = dry weight of commercial nitrogen to add to mix
Wcm = weight of carbon in manure
Wcwa = weight of carbon in bulking agent
Wnm = weight of nitrogen in manure
Wnwa = weight of nitrogen in bulking agent
Rd = desired C:N ratio of 25 to 40
Note: See Equation [10-21] p.10-51
The final compost mix consists of the following:
Manure and bulking agent moved out of piggery by animals
and gravity in dry litter waste management system: |  |  |  |  | lbs per day
Nitrogen added to lower C:N Ratio: |  |  |  |  | lbs per day
windrow or static pile method ~ 14 day to a month time needed to compost
in vessel method ~ 7 days time needed to compost
(optional) curing compost ~ 30 to 90 days
For Equations, See Reference
Agricultural Waste Management Field Handbook
p.10-49 to 10-58 March 2012
 | Input Data
 | Calculated Data
 | Answer