T he costs of treatment include the cost of the mechanical treatment (cutting or pulling) and the cost of chemical treatment (herbicide to control the sprouts). This comparison did not include the cost of dozer piling and burning.

Estimated Mechanical Treatment Cost Per Acre

Table 3 shows that pulling tamarisk cost 46.9 percent more than cutting it.

Assumptions of the cost comparison:

• Even though the T300 compact tracked loader was used to cut tamarisk for 10 of the 76.25 cutting hours, we assumed that the S160 rubber-tired skid steer loader would have taken the same time to complete the task.
• Even though the Cimarron National Forest owned the S160 rubber-tired skid steer loader, we based the costs of using the S160 rubber-tired skid steer loader and the T300 compact tracked loader on authorized Bobcat dealer rental rates.
• Diesel fuel cost $3 per gallon.
• Total rental time was based on combined operation and maintenance times. Time to transport equipment from the rental shop and back was not included.
• The Star Hill JAWZ attachment and Bobcat brush saw are owned by the unit doing the project. The cost of the attachments was not included in the analysis.

The cost of replacing parts broken during the study (hydraulic hoses, fittings, and so forth) is not included in the cost estimate. The cost of using a dozer to pile the tamarisk for burning is not considered. Table 4 shows the daily, weekly, and monthly costs of renting the two Bobcats.

The weekly rates are based on five 8-hour days (40 hours) in a 7-day period. Monthly rates are based on 160 hours in a 4-week period. The Bobcat S160 used 92 gallons of diesel that cost $276. The Bobcat T300 used 148 gallons of diesel that cost $448.

The best rental arrangement for the 91.5 hours the Bobcat S160 was used would be to rent it for 2 weeks at the weekly rate and 2 days at the daily rate for a total rental cost of $1,700. The best rental arrangement for the 109 hours the Bobcat T300 was used would be to rent it for 1 month at the monthly rate of $2,850.

Estimated Chemical Treatment Cost Per Acre

The labor for treating tamarisk sprouts with herbicide cost $597.62. Even though the study plot where tamarisk was cut had 85 percent more sprouts, the cost of labor for chemical treatment was split evenly between the two plots. The time needed to drive to areas that might need treatment within each plot was similar regardless of the number of sprouts that might need to be treated there. Table 5 shows the costs of labor and of herbicides used to chemically treat tamarisk sprouts.

Only 56.6 percent as much chemical (including the diesel carrier) was used to treat sprouts in the plot where tamarisk was pulled (30 gallons) as was used in the plot where tamarisk was cut (53 gallons).

Table 6 shows the estimated total cost for mechanical and chemical treatments. The cost of piling and burning tamarisk that had been cut or pulled is not included in the total treatment cost.

Pulling tamarisk cost an estimated 13.4 percent more per acre than cutting it.