Composting Balance Calculations

Alken-Murray recommends a C/N ratio of 20 to 30 for composting of manure and various high carbon wastes To balance the C/N ratio to the desired level of 30, use the following algebraic equations, courtesy of the Water Quality & Waste Management website belonging to the North Carolina Cooperative Extension Service: Alken-Murray's compost-augmenting microbial cultures in Alken Clear-Flo 7014 can be used to initiate a wide assortment of composting applications.

6/18/2008

  Let:                         A     =    weight of poultry  litter
                               1 - A     =    weight of wheat straw
                          A + (1 - A)    =    1

   Formula =  A x [manure C/N ratio]  +  (1 - A) x [wheat straw C/N ratio  = 1 x 30
     7.5A  +  130  -  130 A    =   1 x 30 (desired compost ratio)

7.5 A  -  130 A    =    30  -  130
                             -122.5 A    =   -110      which is the same as,
                              122.5 A    =    110
                                                           Parts by weight
                                                        ______________________
      litter:       A   =  110 / 122.5   =    0.90      0.90 / 0.90   =   1.00
      straw:    1 - A   =   1  -  0.90   =    0.10      0.10 / 0.90   =   0.11
                                             _____                       _____
                                              1.00                        1.11

Therefore, in this example, for every 90 lbs. of manure, 10 lbs. of straw would be required to bring the C/N ratio to 20. Keep in mind that for this to work, extra fungi and/or bacteria with strong cellulase enzyme are needed to break this difficult carbon source into a useable offset for the excess nitrogen and phosphorus in the swine (or chicken) manure, using Alken Clear-Flo 7014, 7014C or 7016.

 To balance the moisture content, use these algebraic computations:

Average moisture content of litter/straw mixture = 0.90 x 50% + 0.10 x 10% = 46 %

Let:                         B     =    weight of litter/straw mixture
                               1 - B     =    weight of water needed
                          B + (1 - B)    =    1

   Formula =  B  x 46  +  (1 - B) x 100 = 1 x 50
     46B  +  100  -  100B    =   50 - 100

                             -54B   =   -50   which is the same as,
                              54B    =   50
                                                           Parts by weight
                                                        ______________________
      litter/straw:       B   =  50/54   =    0.92      0.92 / 0.92   =   1.00
      water:    1 - B   =   1  -  0.92   =    0.08      0.08 / 0.92   =   0.08
                                             _____                       _____
                                              1.00           

Litter Compost Recipe:

weight compost mix
litter: 1.00 x 1.00 = 1.00
straw: 0.11 x 1.00 = 0.11
__________________ ...........
water: 1.11 x 0.08 = 0.09

Part by Pounds per 100 lbs. compost mix

manure: 0.9 x 0.92 x 100 = 83 lbs.
straw 0.1 x 0.92 x 100 = 9 lbs.
__________________
water 1.00 x 0.09 x 100 = 8 lbs.