The following is an excerpt from the West Plains IPM Update and was written by Kerry Siders, Texas A&M AgriLife, EA-IPM, Hockley & Cochran County.
Ground Application vs. Aerial Application at Harvest Time:
Received a call from Larry Smith yesterday about something we have contemplated before, but never really put a pencil to. That is if the damage caused by a ground rig to good irrigated cotton, which is lapping the middles when applying a harvest aid, exceeds the cost of putting a plane in the field. So this can be a perennial question for many. Let us try to break it down and put a pencil to it.
In this example we will use a ground rig which covers twenty-four rows per through. The wheels will make contact with four rows, which is 1/6 or 0.167 of the area. For sake of a conservative calculation we will say that the ground rig will damage (remove from plant or render non-harvestable) 0.5 bolls per plant the rig comes into contact with. For calculation purpose we will use a plant population of 42,000 plants per acre. So if we damage 0.5 bolls per 42,000 plants that is 21,000 bolls per acre, and we only effect 16.7% of the area (21,000 X 0.167) which is 3507 bolls damaged per acre. Does not seem that bad so far. This is pretty good irrigated cotton so it will take 300 or less bolls to make a pound of lint. So 3507 bolls divided by 300 = 11.69 pounds of cotton lint. At $0.70 per pound lint, 11.69 lbs cotton has a value of $8.18 per acre. So the ground rig could possibly cost $8.18 in lost/damaged cotton, not to mention the cost of the operating the rig.
Last I checked the cost per acre on a plane was less than that. So thank you Larry for prompting me to put a pencil to this. Each of you may need to consider the damage you may be causing with a ground rig to cotton ready for harvest aid. Each field situation is different, but this may give you a method of considering if it would be advantageous to put a plane on the field vs. a ground rig. Call if questions.
Please call or come by if you have any questions,