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Brazilton KS | I want to work through this exercise, but not tonight.
We did this exercise in Tillage and Planting some 18 years ago. Unfortunately i do not recall the results.
There are several ways to think it through. I am not saying your method is not valid, just that I have not gone through it yet.
Here is how I would approach it. Start out with a job, say for instance 3000 acres of corn to plant. State field size. Now calculate hours to do the job with both machines.
Contentions:
Transport time will be close to the same for both machines. The transport distance to complete the job will be the same regardless of which machine is used, as will speed. Net, obviously a slight decrease in overall eff for the larger planter because same lost time is divided over a smaller denominator.
Service time (greasing, fueling, fill seed, adjust depth, etc) is not linear. Stop and startup time is constant regardless of size. Frequency is greater on smaller machine. Larger machine is also going to use less total fuel, so less total time fueliing. I think this will be a wash, but need to analyze it more. I'm not sure where to get reasonable numbers for this one.
I want to think about the turn around thing. I'm going to consider the contention that the time to turn through 180 degrees is constant across machines, but I'm not sure I can defend that. If the turn time can be maintained constant, then it's going to wash. If both planters use the same number of end rows, it would appear to be able to be held constant. Note: a 24 row planter can turn in 24 rows, a 12 row also requires 24 rows. Larger implements will back the inside wheel when turned, allowing end rows to be equal to width.
Are you sure planter total seed capacity is really constant across size? I find this highly unlikely, however I am not sure. I know CIH built larger boxes for the 24 row back in the '90's because with 8 rows per box it would not plant as long (time) per fill as a 12 row would with 6 rows per box. For some reason, they left the small boxes on 16 rows, which seemed illogical to me. Actually, once the large box existed, why not put it on everything...which of course returns to the problem that caused the large box in the first place.
I don't contest the hypothesis that the smaller planter will be able to maintain a higher overall operating efficiency, however I do question the magnitude of the difference you stated.
Like I said, i want to play with this some more...maybe over the weekend. | |
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Planter width vs planter efficiency scenarios (long)
