Bunker and Bag Storage Cost Comparison

 

 John Roach, F&L Farm Business Consulting, LLC

 

INTRODUCTION

 

Which method of horizontal forage storage is the most economical?  The question has been addressed many times.  This is my attempt using real life numbers to answer the question.  As with any economic analysis, the results are dependent upon the assumptions used.  It is impossible to develop a set of assumptions that will fit every producer’s situation.  Therefore, as you review this analysis please keep in mind that you will have to adjust the end result based upon the practices used by your business. 

 

As the numbers reveal, this is an important decision that every dairy business must address.  It would be irresponsible of any manager to come to a meeting and make a decision based upon an analysis that was done on an example production unit.  You must go through this type of an analysis for your business to get the correct answer for your situation.  Use this analysis only for the purpose of insuring that you have addressed all of the variables when making your own calculations.

 

 

METHODS OF STORAGE

 

            Method 1 Bunker Silo

ุ      Bunker silo with (2) 35 foot haylage and (1) 80 foot corn silage bays 

ุ      Four-12 foot high poured-in-place walls

ุ      Walls 160 feet in length

ุ      Both ends open with 50 foot concrete aprons on each end

ุ      Concrete floor

ุ      Silage piled 4 feet over walls at the highest point

ุ      Thirty feet of the apron on both ends used to pile feed

ุ      Forage stored on 30 feet of both aprons, forage 6:1 ramp to 16 feet high.

ุ      Storage and handling loss 20%

ุ      Covered with plastic and truck tire sidewalls 1 tire/yd2

 

Method 2 Silo Bags

ุ      Bag size 12’ x 250’ with 230’ of usable storage length

ุ      Bags stored on a 275’pad (250’asphalt for bag 25’of gravel apron)

ุ      Asphalt pad constructed with 2 -  2” layers of asphalt

ุ      Gravel base compacted 8” of 3” breaker rock and 4” of พ” gravel.

ุ      Each bag will use 15’ of pad width

ุ      Storage and handling loss 5%

 

 

 

COMMON ASSUMPTIONS

 

Cattle

ุ      400 milking, 365 days/year

Diet

ุ      51 pounds of dry matter intake/cow/day

ุ      50% of the dry matter intake is from forage (25.5 pounds/cow/day)

ุ      Forage is 50/50 corn silage, haylage

Feed Out Method

ุ      Must be able to feed fully fermented forage 365 days/year

Labor

ุ      Time to remove forage from storage is equal in both methods

ุ      Labor to install tires and plastic charged at $12.00 per hour

ุ      Feeding technician labor charged at $15.00 per hour

Equipment Repair

ุ      Cost to maintain loading equipment is considered equal

 

 

BUNKER CAPITAL COSTS

     150’ x 160’ with 4 walls and 50’ apron on both ends

ุ      Walls 640’ with 7’ footings @ $100/ft                          $ 64,000

ุ      Concrete floor 24,000 ft2 @ $1.50/ft                                        $ 36,000

ุ      Concrete apron 15,000 ft2 @ $1.50/ft                                       $ 22,500

ุ      Excavating

- Strip 8” topsoil 968 yd3 @ $2.00/yd3                 $1,935

- Site prep other 2,000 yd3 @ $2.25/yd3           $4,500

- Finish grading                                     $   800

- 4” พ" gravel @ $9.00/yd3 in place                  $4,230

- 10% contingency on excavating                      $1,147             $  12,612

 

ุ      Tires 3,800 @ $1.5 each delivered                                           $    5,700

Total                                                                                       $140,812

 

ุ      20 year useful life based upon ft2

- Corn silage  53% of total              $3,732

- Haylage 47% of total                                $3,309             $  7,041

 

ุ      Industrial Loader 8 year useful life @ $50,000 85% time                                  

      - Corn silage  50% of total              $2,656

- Haylage 50% of total                                $2,656             $  5,313

 

 

 

 

 

 

 

BAG CAPITAL COSTS

Pad 180’ x  275’ with a 25’ gravel apron

ุ      Asphalt 180’ x 250’ (2) 2” layers 45,000 ft2 @ $0.72/ ft2                     $32,400

ุ      Excavating                                                                                           

- Strip 8” topsoil 1,322yd3 @ $2.00/yd3       $ 2,457

- Site prep other 2,540 yd3 @ $2.25/yd3     $ 5,715

- Finish grading                                           $ 1,016

- 8” of 3” 1,228 yd3 @ $9.00/yd3 in place   $11,055

- 4” of พ” 623 yd3 @ $9.00/yd3 in place     $ 5,610

- 10% contingency on excavating                $ 2,822                        $28,675

Total                                                                                             $61,075

 

ุ      20 year useful life                                                                           

- Corn silage  50% of total              $1,527

- Haylage 50% of total                                $1,527                         $3,054

 

ุ      Skidsteer 3 year useful life @ $22,000 25% time                           

- Corn silage  50% of total              $1,833

- Haylage 50% of total                                $1,833                         $3,666

 

BUNKER ANNUAL COSTS

            Corn Silage Filling  1,127 tons DM harvested

ุ      Packing time  45 hours @ $60/hr                                                    $2,700

ุ      Finish packing 3 hours @ $60/hr                                                     $   180            

ุ      Plastic 5 rolls 60’ x 100’ @ $248 ea.                                              $1,240

ุ      Labor tires/plastic on .75 minute/tire 2,000 tires @ $12/hr   $   300 

ุ      Labor tires off .94 minute/tire 2,000 tires @ $15/hr             $   470 

ุ      Labor to remove spoiled feed .25 hrs/day @ $15/hr                        $1,369

Total                                                                                              $6,259

 

ุ      Cost of 1 harvested acre of corn silage                                            $   276

 

Haylage filling 1,110 tons DM harvested

ุ      Packing time  60 hours @ $60/hr                                                    $3,600

ุ      Finish packing 6 hours @ $60/hr                                                     $   360

ุ      Plastic 2 roll 60’ x 100’ @ $248 ea.                                               $   496

ุ      Plastic 2 roll 60’ x 150’ @ $371ea                                                 $   742

ุ      Labor tires/plastic on .75 minute/tire 1800 tires $12/hr                     $   270 

ุ      Labor tires off .94 minute/tire 1,800 tires $15/hr                              $   423

ุ      Labor to remove spoiled feed .5 hrs/day @ $15/hr              $2,738

Total                                                                                              $8,629

 

ุ      Cost of 1 harvested acre of haylage                                                 $   234

 

 

BAG ANNUAL COSTS          

Corn Silage filling 980 tons DM harvested, 163 ton DM stored in each bag

ุ      Bagging 6 bags @ $2,550/bag                                                        $15,300

ุ      Labor plastic off 1 hour/bag @ $15/hr                                            $      90 

Total                                                                                              $15,420

Haylage filling 980 tons DM harvested, 163 ton DM stored in each bag

ุ      Bagging 6 bags @ $2,550/bag                                                        $15,300

ุ      Labor plastic off 1 hour/bag @ $15/hr                                            $      90 

Total                                                                                              $15,420

 

OTHER CONSIDERATIONS

 

There are other issues that need to be identified and discussed as we look at the issue of bunker or bags.  In the case of an expanding dairy, owner equity is often a limiting factor in making the decision of bunker or bag.  If equity allows only the construction of the milking center and cattle housing, bags may be the only option for expanded feed storage.  

 

While cow numbers are increasing in an expanding dairy, the number of cow may not be sufficient to support the forage removal rate required by a bunker sized for steady state.  Bunkers are more suited to a larger size dairy mainly due to forage removal rates.  

 

There is a learning curve associated with managing a bunker. In an expansion, the manager is already juggling several other learning curves and may elect not to add one more. While learning to manage a bunker, forage quality often suffers in the first few years due to inadequate packing or poor covering among other factors.  Providing high quality forage is key to profitability in any dairy. It is absolutely critical in an expanding dairy.  Therefore, the decision to invest in a bunker system may be delayed until the newly expanded dairy has overcome its initial growing pains.  Bags may be a good fit during this interim period.

 

SUMMARY CONSIDERATION

 

As the analysis shows, minimizing storage losses is the key.  Given the assumptions used in this analysis, it appears that at a 20% storage loss rate for bunkers, storing corn silage in a bag or a bunker is a breakeven.  With haylage stored in a bunker at a 20% storage loss bagging appears to have the edge.

 

Both bunkers and bagging are proven, effective methods of storing forage.  Each has a known set of management points that need to be addressed if quality forage is to be provided to the end user, the cow.  Each method has costs that are associated with the system.  Each manager has to evaluate the management and cost issues and use the method that fits with their business. 

 

F&L would like to thank the following businesses for information used in completing this analysis:

 

O&S Harvesting, Bonduel, WI

KSI, Inc., Sheboygan Falls, WI

Murphy Concrete and Construction Company, Black Creek, WI

Schaumann's Structure, Inc., Seymour, WI

 

Forage Storage Costs

 

 

 

 

 

 

Haylage

Corn Silage

 

Bag

Bunker

Bag

Bunker

Tons Stored (dry matter)

               980

          1,110

               980

         1,127

Annual Costs

 

 

 

 

Bunkers

 

 

 

 

Packing

 

          3,960

 

         2,880

Plastic

 

          1,238

 

         1,240

Labor tires/plastic on

 

             270

 

             300

Labor tires/plastic off

 

             423

 

             470

Labor remove spoil feed

 

          2,738

 

         1,369

 

 

 

 

 

Bags

 

 

 

 

Bag

         15,330

 

         15,330

 

Labor plastic off bags

                 90

 

                 90

 

Total cost

 $      15,420

 $      8,629

 $      15,420

 $      6,259

Annual cost/ton

 $        15.73

 $         7.77

 $        15.73

 $        5.55

 

 

 

 

 

 

 

 

 

 

Capital Costs 20yr

 

 

 

 

Bunkers

 

 

 

 

Bunker walls

 

          1,504

 

         1,696

Flat work floors

 

             846

 

             954

Flat work aprons

 

             529

 

             596

Excavation

 

             296

 

             334

Tires

 

             135

 

             150

Loader

 

          2,656

 

         2,656

 

 

 

 

 

Bags

 

 

 

 

Asphalt

               810

 

               810

 

Excavation

               717

 

               717

 

Skidsteer

            1,833

 

            1,833

 

Total cost

 $        3,360

 $      5,966

 $        3,360

 $      6,386

Capital Cost/Ton

 $           3.43

 $         6.09

 $           3.43

 $        6.52

Total All Costs

         18,780

       14,595

         18,780

       12,645

Total Cost / ton

 $        19.16

 $      13.15

 $        19.16

 $      11.22

 

 

 

 

 

Cost of 21 A Corn silage

 

 

 

         5,791

Cost of 29 A Haylage

 

          6,775

 

 

Total All Costs

 

       21,370

                  -  

       18,436

Total Cost / ton

 

 $      19.25

 

 $      16.36