2.5.3.c The importance of the type of tractor adjustment for sprayer operation

Does the vineyard present any constraints which require a more adaptable system?

When a plot's terrain is uneven or sloped, the speed of agricultural machinery can vary. Treatment doses (quantities prepared by volume) depend in part on the sprayer's speed and flow rate. If the speed is modified but the flow rate is unchanged, then it is unlikely that the entire area to be treated will be covered evenly. A portion of this area will receive more product than desired, while the last area treated may require a new mixture, with a different volume/hectare than the previous one. There are three types of spray regulators:

• Constant Pressure: The spray pressure is regulated by a pressure regulator and remains constant. The product output from the nozzle is therefore constant. The volume sprayed per hectare is therefore only constant if the speed of the sprayer is constant. When the terrain is uneven, the winegrower may slow down the speed but the product has the same output flow rate, which can cause product overdosing or underdosing, which is not optimal. This first type of controller is best suited to flat, easily accessible plots.

• Flow Rate Proportional to Engine Speed: The system does not modify the volume/hectare for small speed variations, but there is a risk of overdosing in the event of tractor slippage since the system takes into account the engine speed. This type of regulator may not be suitable for plots with clay soil where skidding/slippage may occur frequently.

• Proportional to the speed of travel and electronic flow: The nozzle's rate of flow is adjusted according to the tractor's speed of travel. This is the optimal system, the volume sprayed per hectare does not vary whatever the speed of travel. When the vineyard requires many speed changes, this is the most suitable model. Sensors transmit the information and allow modulation of the pressure or flow. This last type of regulator is suitable for all types of plots and topography.

Power required by the sprayer

Air-blast or pneumatic sprayers require fans that provide the energy necessary for the treatment droplets to reach the target. This fan system requires a certain amount of power from the tractor, which should not be too low or too high, as this could reduce the quality of the spraying. The power must not only be suited to the type and number of outlets (nozzles) and the fan, but also to the stage of the vegetation and the treatment type.