On Thu, 17 May 2012 13:12:13 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

" fired this volley in news:8c560f45-
:

I would think this is a common problem for farmers and Jan might be
interested in developing a system for accurate slow speeds for farmers
needs.

GPS is useful for maintaining a good pattern, but not really very good
for manually-controlled tractors. The GPS has to drive to make it
accurate.

For the most accurate path control with a manual tractor, one uses a foam
dripper to mark the lines. Dyed foam will be visible for days, unless it
rains hard.

As I said before, the problem of matching application rate to coverage
was long ago solved by using PTO-driven pumps, the volume of which
exactly matches the speed of the tractor (assuming the same gear and not
below the critical "self sealing" pumping speed, of course).

One can calculate gallons-per-acre almost to the quart with a pto pump in
good condition. Within fairly wide variations, speed doesn't matter a
whit.

Of course it takes calibrated nozzles, a known boom width, and all that
other flow-related crap. But once you have the equipment in place, you
make one run over a field with water, figure your consumption, and
develop your concentrations (again, within acceptable ranges) on that.

If the concentration is too low because the volume is too high, you
reduce the number of nozzles or their size. And vice-versa.

This problem was NAILED decades ago.

Lloyd


LLoyd

I would disagree with you here. I use 3/8 to 1/2 of lable rate on most
every product. That leaves no cushion for error (saves me over $2K a
year) if you're trying to keep application rate variation well under
+/- 5 percent you got to keep everything constant and be very
observant for any sign of wear or plugging. Another huge item is to
exactly finish the tank twenty feet after the last row.

50 RPM will raise the pressure 2 PSI while hardy changing speed. or
you're already 5% higher on field rate. A primary screen plugging
will drop you 1 or 2 psi if you're positive its not RPM, you can spot
it right away. I'm also logging pump and nozzle wear from day to day
and making minor gal/acre adjustments. Again if you keep everything
constant, ths is easy to spot

most folks don't believe me when i tell them farming is more techical
than they know.

karl