A researcher with Niverville, Manitoba based Agra-Gold Consulting reports farmers appear interested in using variable rate techniques to apply livestock manure but current manure application technology is not yet advanced enough to be fully effective.
A growing number of farmers are using variable rate application with commercial fertilizer to tailor fertilizer application to the nutrient requirements on different parts of a field.
Agra-Gold Consulting & Farmer’s Edge Precision Consulting have completed a study to determine whether these techniques can be adapted to manure application.
Project leader Scott Dick says typically a GPS mapping system is linked to an ammonia fertilizer applicator equipped with a valve that varies the amount of fertilizer applied.
With manure one of the challenges we face is that the manure composition throughout the pump-out of that storage varies and so you may start out with 20 pounds of nitrogen per thousand gallons which may then decrease throughout the pump-out down to 15 pounds.
The other difficulty that we do face is that we do have a fixed nitrogen to phosphorus ratio.
What I mean by that is that in commercial variable rate fertilizer you can put your nitrogen and phosphorus into different boxes in the equipment.
With manure it’s coming as one package and so, as the concentration may be 20 pounds of nitrogen per thousand gallons the phosphorus concentration might be six pounds and you can not independently vary the rates of those two nutrients with manure.
In our study we just basically looked primarily at nitrogen and varying the rate of nitrogen and then the phosphorus rate that went on was uncontrollable in that particular situation.
Dick says adapting variable rate techniques to manure application would appear to have good potential but we still need to see some refinement in the applicator technology.
Source: Farmscape
