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Economic Considerations for Dairy Waste Management Systems

Myron Bennett and Donald Osburn
Department of Agricultural Economics
Charles D. Fulhage and Donald L. Pfost
Department of Agricultural Engineering

The dairy waste management systems commonly used in Missouri are the solid, liquid tank (slurry) or lagoon. Solid systems have been the traditional way to handle waste, but in the future they are expected to be used only in smaller operations (less than 100 cows).

Liquid tank systems are commonly combined with scraping and allow the maximum use of waste nutrients for crop production. These systems are often used when a lagoon is not economical due to soil types and/or geological considerations. Operations may switch from the solid system to the liquid tank system to reduce labor, to improve water quality and to fix other problems. To be viable, these systems must minimize the amount of excess water being transported to the field by tank wagons.

Lagoon systems are favored by large operations because labor and investment costs are minimized and a flushing system can be used to collect and transport waste to the lagoon. These systems normally use an irrigation system with pump, pipe and traveling gun to transport and spread the waste.

Economic data

Statewide liquid tank and lagoon systems were studied because they are the most likely alternatives to upgrade dairy operations. Data collected was used to project waste management system costs associated with operations ranging in size from 100 to 1,000 cows. Because the solid system is best suited to herds of less than 100 cows, it was not analyzed.

An economic analysis based on the data collected was published in MU publication MP666,Waste Management Systems for Dairy Herds. The data in this guide was taken from that publication. Refer to it for more complete details.

Assumptions

Lagoon-gutter flush system

Lagoon size is based on a 365-day storage capacity with 100 percent of the waste going into the lagoon, including dry cow waste but excluding calf and replacement heifer waste. Land required for spreading the effluent is based on 100 pounds of nitrogen per acre used annually by plant production.

The lagoon system is assumed to hire a custom irrigation system at $60 per hour. Other components are assumed to be owned. Other equipment includes the water storage tanks for flushing gutters and the electric pump and pipe needed to recycle water from the lagoon to the flush tanks. The estimated costs include a clay lagoon seal compacted by a sheepsfoot roller.

The irrigation system includes a traveling gun irrigator that will distribute 1 acre-inch (27,154 gallons) of effluent per hour. The custom operator provides everything except "equipment check labor." The dairy operator is responsible for properly operating equipment. A cost comparison per hour for owned and custom traveling gun irrigation systems is shown in Figure 1.

Cost per hour for owned and custom traveling gun irrigation systems Figure 1
Cost per hour for owned and custom traveling gun irrigation systems.
 

Liquid storage tank system

The liquid tank system is assumed to include a cast-in-place, reinforced, in-ground, concrete storage tank with 120-day capacity, to be loaded by gravity. Above-ground tanks would need a mechanized pump for daily loading into the tank. A concrete stave silo with adequate reinforcement can be purchased for 70 percent of the cost stated in this analysis. Other storage facilities will normally cost more than the in-ground concrete tank.

The equipment cost includes an open-impeller, centrifugal chopper pump used to agitate the slurry in the tank while pumping from storage to tank wagon(s). Other equipment includes a manure scraper operated by a 40-horsepower tractor and a 3,000-gallon tank wagon pulled by a 100-horsepower tractor. The number of tank wagons varies by herd size (e.g., one wagon for 100- and 200-cow herds, but two tank wagons for 300-cow herds) to permit waste distribution within a 10-day period during the 120-day storage period.

Labor required for loading, hauling and spreading the waste assumes one person at the storage tank to operate the tractor and agitator pump to fill the tank wagons and a tractor operator for each tank wagon used to distribute waste to the fields.

Fertilizer nutrient equivalent value

Dairy waste applied to the land has an equivalent fertilizer nutrient value for the replaced commercial fertilizer and/or for the increased production of plant growth used by animals or harvested. The assumed value of the fertilizer nutrients is as follows: nitrogen, 23 cents per pound; phosphate, 22 cents per pound; potash, 14 cents per pound.

Fertilizer nutrient availability is shown in Tables 7 and 14 for the two systems, based on data in Tables 8 and 9. Less nitrogen is available from the lagoon system due to oxidation, denitrification and dilution. Figure 2 illustrates how ammonia-nitrogen loss varies with time until incorporation (Table 8). In the case of irrigated lagoon effluent, incorporation occurs if the soil is dry enough for the liquid to soak in and the application rate does not exceed the soil infiltration rate. Figure 3 shows the organic nitrogen availability versus years after application (Table 9).

Manure ammonia-nitrogen loss versus days until incorporation Figure 2
Manure ammonia-nitrogen loss versus days until incorporation.

Manure organic nitrogen available versus years after application Figure 3
Manure organic nitrogen available versus years after application.

With the liquid tank system, the waste volume and concentration per cow is constant with herd size; the calculated nutrient value of the waste is a constant $63 per cow per year. With the lagoon system, the assumed annual pumpdown per cow per year decreases with herd size, therefore, the calculated nutrient value per cow per year decreases from $23 per cow per year for the 100-cow herd to $10.50 per cow per year for the 1,000-cow herd. Figure 4 compares the annual value of waste per cow for the two systems.

Annual value of waste per cow for tank and lagoon systems Figure 4
Annual value of waste per cow for tank and lagoon systems.

Cost comparison of systems

Important cost comparisons of the two systems, using data from the tables, are presented graphically in Figures 5 to 8. From Figures 5 and 6 (or Table 3, lines 6 and 7 and Table 10, lines 6 and 7), the total investment and the investment per cow, respectively, for a lagoon system ranges from about 60 percent less than a liquid tank system for a 100-cow operation to 43 percent less for the 1,000-cow operation. Economy of scale for the liquid tank system is reached with a herd size of 500 cows.

Total investment for tank and lagoon systems Figure 5
Total investment for tank and lagoon systems.
 

Investment per cow for tank and lagoon waste systems Figure 6
Investment per cow for tank and lagoon waste systems.
 

Depending somewhat on herd size, the lagoon system's annual cost per cow (fixed cost plus operating cost) ranges from 55 to 60 percent less for the lagoon system than for the liquid tank system (Figures 7 and 8, or Tables 1 and 2, line 5).

Annual costs per cow for lagoon dairy waste systems Figure 7
Annual costs per cow for lagoon dairy waste systems.
 

Annual costs per cow for liquid tank dairy waste systems Figure 8
Annual costs per cow for liquid tank dairy waste systems.
 

For details on annual fixed costs and annual operating costs, see Tables 4, 5 and 6 for the lagoon system and Tables 11, 12 and 13 for the liquid manure tank system.

From Figures 9 and 10 (or Table 1 and 2, line 8), the net annual cost per cow for a lagoon system ranges from about 59 percent less than a liquid tank system for a 100-cow operation to 35 percent less for a 500-cow operation. The net annual cost per cow accounts for the fertilizer equivalent value of the plant nutrients in the waste, if spread on the land and used by crops.

Net annual cost per cow for lagoon dairy waste systems Figure 9
Net annual cost per cow for lagoon dairy waste systems.
 

Net annual cost per cow for liquid tank dairy waste systems Figure 10
Net annual cost per cow for liquid tank dairy waste systems.
 

Dairies with herds exceeding 150 cows are required to have a letter of approval from DNR in order to operate. This may cause some operations to install a new waste management system. Cost-sharing assistance may be available from the Agricultural Stabilization and Conservation Administration (ASCS) up to $17,500 per operation, limited to 75 percent of the average cost. (Some husband-wife operations may qualify for $35,000 cost-share.) Cost-sharing may reduce waste management costs by 20 to 30 percent for herds of 300 cows or less.

Conclusions

The net cost of the lagoon system ranges from $0.24 per hundredweight of milk produced by the 1,000-cow herd to $0.43 per hundredweight for the 100-cow herd. The net cost of the liquid tank system ranges from $0.39 per hundredweight of milk produced by the 1,000-cow herd to $1.04 per hundredweight for the 100-cow herd.

Even though waste from liquid tank systems are more concentrated and valuable than the waste from lagoon systems, the liquid system's net cost is from 1.5 to 2.4 times greater than the lagoon system's net cost, depending on herd size.

The liquid tank system requires 4 to 5 hours of labor per cow per year (mostly for tractor operators) compared to virtually no labor for the lagoon system (with custom irrigation).

The liquid tank system requires 5 to 10 times larger plant filter area than the lagoon system. This can be a major consideration for operations with limited acreage.

Large dairies, more than 300 cows, may benefit from purchasing a traveling gun irrigator rather than relying on a custom operator charging $60 per hour.

Data to support such a decision is presented in Tables 15, 16 and 17. Lack of available labor and management may make hiring a custom irrigation system a better choice, even for the largest of operations.

Table 1
Summary of lagoon system costs

  Herd size
100 200 300 500 750 1000
1. Average investment per cow $363 $297 $268 $242 $224 $217
2. Annual operating costs (Table 6, line 10) $3,663 $5,367 $6,821 $10,053 $13,363 $16,765
3. Annual fixed costs (Table 5, line 7) $5,051 $8,271 $11,219 $16,810 $23,247 $29,914
4. Total annual costs (line 2 + line 3) $8,714 $13,638 $18,040 $26,863 $36,610 $46,679
5. Annual costs per cow $87 $68 $60 $54 $49 $47
6. Value of waste (Table 7, line 12) $2,304 $3,435 $4,292 $6,265 $8,245 $10,509
7. Net annual cost (line 4 minus line 6) $6,410 $10,203 $13,748 $20,598 $28,365 $36,170
8. Net annual cost per cow $64 $51 $46 $41 $38 $36

Table 2
Summary of liquid manure tank system costs

  Herd size
100 200 300 500 750 1000
1. Average investment per cow $910 $599 $546 $443 $412 $381
2. Annual operating costs (Table 6, line 10) $8,025 $12,502 $18,814 $31,457 $47,265 $68,674
3. Annual fixed costs (Table 5, line 7) $13,887 $17,435 $24,416 $31,565 $43,863 $52,715
4. Total annual costs (line 2 + line 3) $21,912 $29,937 $43,230 $63,022 $91,128 $121,389
5. Annual costs per cow $219 $150 $144 $126 $122 $121
6. Value of waste (Table 7, line 12) $6,291 $12,580 $18,872 $31,454 $47,180 $62,908
7. Net annual cost (line 4 minus line 6) $15,621 $17,357 $24,358 $31,568 $43,948 $58,481
8. Net annual cost per cow $156 $87 $81 $63 $59 $58

Table 3
Lagoon system: investment

  Herd size
100 200 300 500 750 1000
1. Lagoon $25,416 $44,253 $61,196 $97,121 $138,922 $182,455
2. Fencing (0.727 per feet) $872 $1,091 $1,163 $1,454 $1,599 $1,745
3. Storage tanks (gutter flush) $3,000 $6,000 $9,000 $12,000 $15,000 $18,000
4. Recycling pump and pipe $3,500 $4,000 $4,500 $5,500 $6,500 $7,500
5. Consultation $3,500 $4,000 $4,500 $5,000 $6,250 $7,500
6. Total investment $36,288 $59,344 $80,359 $121,075 $168,271 $217,200
7. Average investment per cow $363 $297 $268 $242 $224 $217

Table 4
Lagoon system: annual fixed costs as a percent of new cost

  Lagoon and fence Equipment Consultation
Years useful life 20 10 to 20  
Fixed costs as percent
Depreciation 5.0 9.01 5.0
Interest 6.02 6.02 6.0
Repairs and maintenance 1.5 1.5  
Taxes 0.83 1.03  
Insurance   0.5  
Total percent 13.3 18.0 11.0
1Allows for 10 percent salvage.
2Annual interest charge is 6 percent of original investment (equivalent to investment x 50 percent x 12 percent APR.)
3Tax assessment varies based on value added to the property. A lagoon established on a suitable site in an area where unfavorable geological conditions predominate will add more value to the property than one established in an area with many favorable sites.

Table 5
Lagoon system: total annual fixed costs

  Herd Size
100 200 300 500 750 1000
1. Lagoon and fence1 $26,288 $45,344 $62,359 $98,575 $140,521 $184,200
2. Equipment, initial investment1 $6,500 $10,000 $13,500 $17,500 $21,500 $25,500
3. Consultation1 $3,500 $4,000 $4,500 $5,000 $6,250 $7,500
4. Lagoon and fence (line 1 x 13.3 percent2) $3,496 $6,031 $8,294 $13,110 $18,689 $24,499
5. Equipment, annual costs (line 2 x 18 percent) $1,170 $1,800 $2,430 $3,150 $3,870 $4,590
6. Consultation (line 3 x 11 percent2) $385 $440 $495 $550 $688 $825
7. Total annual fixed costs (line 4 + line 5 + line 6) $5,051 $8,271 $11,219 $16,810 $23,247 $29,914
8. Annual cost per cow $50 $41 $37 $34 $31 $30
1Transferred from Table 3.
2Transferred from Table 4.

Table 6
Lagoon system: annual operating costs

  Herd size
100 200 300 500 750 1000
Operating recycle pump
1. Size electric pump (hp) 1.5 1.5 3.0 5.0 7.5 7.5
2. Annual pumping time (5 hours daily x 365 days) 1,825 1,825 1,825 1,825 1,825 1,825
3. Cost per hour (1kw x hp x .07 per kw) $0.11 $0.11 $0.21 $0.35 $0.53 $0.53
4. Anuual pumping costs (line 2 x line 3) $201 $201 $383 $639 $967 $967
Irrigation lagoon annual pumping cost
5. Estimated acre-inches to pump annually 57 85 106 155 204 260
6. Custom pumping charge per hour1 $60 $60 $60 $60 $60 $60
7. Annual lagoon pumping costs (line 5 x line 6) $3,420 $5,100 $6,360 $9,300 $12,240 $15,600
8. Check labor hours per year2 7 11 13 19 26 33
9. Annual labor costs (line 8 x $6 per hour) $42 $66 $78 $114 $156 $198
10. Total operating costs (line 4 + line 7 + line 9) $3,663 $5,367 $6,821 $10,053 $13,363 $16,765
1Assume a traveling gun pumps 500 gallons per minute, which allows pumping one acre-inch per hour.
2Check labor required to inspect the irrigation system periodically to determine if the traveling gun and equipment are operating adequately. Assume one hour per 8 hours operation.

Table 7
Lagoon system: value of waste to plant production

  Herd size
100 200 300 500 750 1000
Nutrients produced (pounds per year)1
1. Ammonia nitrogen 2,623 3,912 4,876 7,130 9,384 11,960
2. Organic nitrogen 1,312 1,956 2,438 3,565 4,692 5,980
3. Phosphorus 1,994 2,973 3,710 5,425 7,140 9,100
4. Potassium 6,838 10,198 12,770 18,600 24,480 31,200
Pounds of fertilizer nutrient equivalent available
5. Ammonia nitrogen (line 1 x 50 percent2) 1,312 1,956 2,438 3,565 4,692 5,980
6. Organic nitrogen (line 2 x 70 percent2) 918 1,369 1,707 2,496 3,284 4,186
7. Phosphate (line 3 x 2.32) 3,440 5,128 6,400 9,358 12,317 15,698
8. Potassium (line 4 x 1.22) 7,385 11,014 13,792 20,088 26,438 33,696
Value of fertilizer equivalents
9. Nitrogen (line 5 + line 6 x $0.23 per pound) $513 $765 $953 $1,394 $1,834 $2,338
10. Phosphate (line 7 x $.22 per pound) $757 $1,128 $1,408 $2,059 $2,710 $3,454
11. Potash (line 8 x $0.14 per pound) $1,034 $1,542 $1,931 $2,812 $3,701 $4,717
12. Total value of fertilizer equivalent $2,304 $3,435 $4,292 $6,265 $8,245 $10,509
13. Minimum number acres to irrigate5 22 33 41 61 80 102
14. Value of fertilizer equivalent per acre (line 12 divided by line 13) $105 $104 $105 $103 $103 $103
1Average analysis of lagoon waste.
2Average percent available to plant.
3Conversion of phosphorus to phosphate.
4Conversion of potassium to potash.
5Application of 100 pounds of available nitrogen per acre.

Table 8
Manure ammonia-nitrogen loss by days until worked into the soil

Days until incorporation Percent ammonia-N available for crops
0 to 2 80
2 to 4 60
4 to 7 40
more than 7 20

Table 9
Manure organic nitrogen available by year

Manure applied Percent organic N available during current year
current year 40 to 60
1 year ago 10
2 years ago 5
3 years ago 5

Table 10
Liquid manure tank system: investment

  Herd size
100 200 300 500 750 1000
1. Manure tank1 $62,727 $91,207 $119,681 $176,624 $247,791 $318,952
2. Agitating and loading pump $10,000 $10,000 $10,000 $10,000 $10,000 $10,000
3. Scraper $750 $750 $750 $1,000 $1,000 $1,000
4. Tank wagon, 3,000 gallon, capacity2 $15,000 $15,000 $30,000 $30,000 $45,000 $45,000
5. Consultation $2,500 $2,900 $3,300 $4,100 $5,100 $6,000
6. Total new investment $90,977 $119,857 $163,731 $221,724 $308,891 $380,952
7. Average investment per cow $910 $599 $546 $443 $412 $381
1Cost based on concrete construction.
2Number of tank wagons: 100 to 200 cows — 1; 300 to 500 cows — 2; 750 to 1,000 cows — 3.

Table 11
Liquid manure tank system: annual fixed costs as a percent of new cost

  Tank Equipment Consultation
Years useful life 20 20  
Fixed costs as percent
Depreciation 5.0 12.91 5.0
Interest 6.02 6.02 6.0
Repairs and maintenance 0.5 2.5  
Taxes 0.83 1.03  
Insurance   0.5  
Total percent 12.3 22.9 11.0
1Allows for 10 percent salvage.
2Annual interest charge is 6 percent of original investment (equivalent to investment x 50 percent x 12 percent APR).
3Tax assessment varies based on value added to the property. A lagoon established on a suitable site in an area where unfavorable geological conditions predominate will add more value to the property than one established in an area with many favorable sites.

Table 12
Liquid manure tank system: total annual fixed costs

  Herd size
100 200 300 500 750 1000
1. Tank $62,727 $91,207 $119,681 $176,624 $247,791 $318,952
2. Equipment, initial investment1 $25,750 $25,750 $40,750 $41,000 $56,000 $56,000
3. Consultation2 $2,500 $2,900 $3,300 $4,100 $5,100 $6,000
4. Tank (line 1 x 12.3 percent) $7,715 $11,219 $14,721 $21,725 $30,478 $39,231
5. Equipment, annual costs (line 2 x 22.9 percent3) $5,897 $5,897 $9,332 $9,389 $12,824 $12,824
6. Consultation (line 3 x 11 percent) $275 $319 $363 $451 $561 $660
7. Total annual fixed costs (line 4 + line 5 + line 6) $13,887 $17,435 $24,416 $31,565 $43,863 $52,715
8. Total annual costs per cow $139 $87 $81 $63 $58 $53
1From Table 10, line 2 + line 3 + line 4.
2Transferred form Table 10.
3Transferred form Table 11.

Table 13
Liquid manure tank system: annual operating costs

  Herd size
100 200 300 500 750 1000
Power supply, hours use annually
1. Scraper tractor, 40 hp 183 304 426 669 852 1,278
2. Agitation pump tractor, 100 hp1 7.2 10.8 14.5 21.9 31.0 40.2
3. Tank wagon tractor(s), 100 hp2 172 260 406 699 1,118 1,610
Power costs
4. Scraper tractor (line 1 x $7.62 per hour3) $1,394 $2,316 $3,246 $5,098 $6,492 $9,738
5. Agitation and wagon tractor (line 2 + line 3 x $19.36 per hour.3) $3,469 $5,242 $8,140 $13,957 $22,245 $31,948
Labor costs
6. Tractor operators (line 1 ÷ (24 x line 3) x $6 per hour.) $3,162 $4,944 $7,428 $12,402 $18,528 $26,988
7. Total operating costs (line 4 ÷ line 5 ÷ line 6) $8,025 $12,502 $18,814 $31,457 $47,265 $68,674
8. Total operating costs per cow $80 $63 $63 $63 $63 $69
1Based on one hour per 16,000 cubic feet waste.
2Hauling time per load by herd size (minutes): 100 cows — 36 minutes; 200 — 36; 300 — 42; 500 — 48; 750 — 54; 1,000 — 60.
3Based on "Doane's Machinery Operating Costs, 1991."
4Time on line 3 is doubled because one person is at agitation pump site plus hauling time.

Table 14
Liquid manure tank system: value of waste to plant production

  Herd size
100 200 300 500 750 1000
Nutrients produced (pounds per year)
1. Ammonia nitrogen 7,027 14,054 21,081 35,135 52,703 70,270
2. Organic nitrogen 11,225 22,450 33,675 56,125 84,188 112,250
3. Phosphorus 4,212 8,424 12,636 21,060 31,590 42,120
4. Potassium 15,444 30,880 46,332 77,220 115,830 154,440
Fertilizer nutrient equivalent (pounds per year)
5. Ammonia nitrogen (line 1 x 50 percent1) 3,514 7,027 10,541 17,568 26,352 35,135
6. Organic nitrogen (line 2 x 60 percent2) 6,735 13,470 20,205 33,675 50,513 67,350
7. Phosphate (line 3 x 2.35) 7,266 14,531 21,797 36,329 54,493 72,657
8. Potassium (line 4 x 1.25) 16,680 33,350 50,039 83,398 125,096 166,795
Value of fertilizer equivalents
9. Nitrogen (line 5+line 6 x $0.23 per pound) $2,357 $4,714 $7,072 $11,786 $17,679 $23,572
10. Phosphate (line 7 x $0.22 per pound) $1,599 $3,197 $4,795 $7,992 $11,988 $15,985
11. Potash (line 8 x $0.14 per pound) $2,335 $4,669 $7,005 $11,676 $17,513 $23,351
12. Total value of fertilizer equivalent $6,291 $12,580 $18,872 $31,454 $47,180 $62,908
13. Minimum number acres to irrigate6 103 205 307 512 769 1,024
14. Value of fertilizer equivalent per acre (line 12 ÷ line 13) $61 $61 $61 $61 $61 $61
1Assumes 50 percent incorporated with 80 percent loss and 50 percent incorporated within two days with 20 percent loss. Value will increase if 100 percent incorporated within two days.
2Assumes not spread on same fields each year (50 percent year 1 plus 10 percent year 2).
3Conversion of phosphorus to phosphate.
4Conversion of potassium to potash.
5Average percent available to plant.
6100 pounds of nitrogen per acre.

Table 15
Annual fixed costs expressed as percent of initial cost of irrigation system

  Acre-inches lagoon waste pumped annually
50 to 175 175 to 300
Years useful life 15 10
Depreciation 6.0 percent 9.0 percent
Interest 6.0 6.0
Repairs and maintenance 7.0 10.0
Taxes 1.5 1.5
Total fixed costs 20.5 percent 26.5 percent
1Based on used equipment with above average maintenance and care.

Table 16
Traveling gun system: annual fixed costs

  Acre-inches lagoon waste pumped annually
50 to 175 175 to 300
  Initial cost percent Annual fixed costs percent Annual fixed costs
1. Traveling gun $10,0001 20.5 $2,050 26.5 $2,650
2. PTO pump, 500 gpm $3,0001 20.5 $615 26.5 $795
3. Agitation pump $3,5002 20.5 $718 26.5 $928
4. Aluminum pipe $4,2001 20.5 $861    
$8,4001     26.5 $2,226
5. Total annual fixed cost     $4,244   $6,599
1Workable used equipment.
2Not needed if you have a solids separator.

Table 17
Annual operating costs of traveling gun irrigation system

  Herd size
100 200 300 500 750 1000
Annual operating costs
1. Acre-inches of waste1 57 85 106 155 204 260
2. Agitation pump time (hours)2 4 8 12 20 30 40
3. Minimum acres spread over3 22 33 41 61 80 102
4. Number of times system set up4 2 3 4 6 8 10
5. Set up time (hours) 16 24 32 48 64 80
Power costs
6. Irrigation pump (line 1 x $14.14 per hour 80 hp)7 $806 $1,202 $1,499 $2,192 $2,885 $3,676
7. Agitation pump (line 2 x $19.36 per hour 100 hp)7 $77 $155 $232 $387 $581 $774
8. Laying pipe (line 5 x 25 percent7 $77 $116 $155 $232 $310 $387
Labor costs
9. Check labor hours8 (line 1 x 12.5 percent) 7 11 13 19 26 33
10. Total labor hours (line 5 + line 9) 23 35 45 67 90 113
11. Total labor costs (line 10 x $6 per hour) $138 $210 $270 $402 $540 $678
12. Total annual operating costs (add lines 6, 7, 8 and 11) $1,098 $1,683 $2,156 $3,213 $4,316 $5,515
13. Total annual fixed costs (Table 12, line 5) $4,244 $4,244 $4,244 $4,244 $6,599 $6,599
14. Total annual costs (line 12 + line 13) $5,342 $5,927 $6,400 $7,457 $10,915 $12,114
15. Cost per acre-inch (line 14 ÷ line 1) or per hour operation $93.72 $69.73 $60.38 $48.11 $53.50 $46.59
1Transferred from Table 6, line 5; also irrigation operating hours.
2Four hours per 100 cows.
3Transferred from Table 7, line 13.
4One set-up per 10 acres.
5Eight hours labor per set up.
6Assume tractor operates 25 percent of time required to lay pipe.
7Tractor power cost taken from "Doane's Machinery Operating Costs, 1991."
8Check labor is used to check the irrigation system periodically to determine if the system is operating adequately. Assume one hour per eight hours operation.

WQ302, reviewed May 1994


WQ302 Economic Considerations for Dairy Waste Management Systems | University of Missouri Extension