Menu
Search

2.5.2.b Correctly calculating doses

It is important to respect the correct doses during treatments and to apply them at the appropriate time in order to avoid further treatments. The calculation of doses is based on three parameters:

  • Sprayer progression speed
  • Width being treated.
  • The equipment's output rate

Each of these parameters must be within a recommended range of values depending on the type of sprayer. The formula to calculate the volume of spray applied per hectare is applicable to all sprayers:

Volume/ha (L/ha) = output rate (L/min) x 600 / (spray width (m) x speed (km/h)).

As a general rule, volumes of spray mixture per hectare are:

  • 250 to 500 L/ha for hydraulic spraying
  • 120 to 300 L/ha for the air-blast spraying
  • 100 to 180 L/ha for pneumatic spraying

Sprayer speed

Measurement of the sprayer's speed makes it possible to check the reliability of the speedometer and is necessary because the drive train and the tractor's wheel dimensions may be different from those shown in the technical data. This measurement must be carried out under actual application conditions, i.e. in the vineyard with the air assistance engaged. The timing must be carried out over a distance of at least 50 metres with the equipment running. The engine speed should ensure that the power take-off rotates at 540 rpm or that the fan is driven at its nominal speed in the case of a direct hydraulic connection. To ensure good quality application, the maximum speed should not exceed 5.5 km/h, this being reduced to 3.5 km/h in the case of oscillating cannons.

Treatment width

The width treated depends on the machine used. In all cases, the treated width corresponds to the number of rows per pass multiplied by the spacing between rows. For example, for a face-by-face treatment every three rows for vines spaced 2.20 metres apart, the treated width is 6.60 m.

Output rate

The output rate should be verified at the beginning of the season and each time the nozzles or flow regulator orifice plates are changed. There are two methods for measuring the output rate (in l/min):

  • Measuring the output rate of each nozzle or diffuser. This procedure is recommended because it detects possible output rate homogeneity defects. The sprayer is started at a chosen pressure and the quantities of water flowing out of each nozzle are measured for a given time (min) with a graduated cylinder or a direct-reading flow meter.

  • Measurement of the overall output rate with initial tank and full circuit when the previous method is not possible (non-disengageable fan, old pneumatic sprayer)

Output rate (l /min) = Measured volume (l) / measuring time (min)

The flow rate depends on the cross-section (flow regulator orifice plate size) and the spray pressure. In general, the spray pressure varies from 12 to 18 bars, for hydraulic spaying with swirl nozzles; from 8 to 15 bars, for air-blast spraying and from 1.5 to 5 bars for pneumatic spraying.

This chapter is an extract from the information sheets provided by Vigne Vin Occitanie._

Contribute Print Share

Contribute

Personal information contained in this form is automatically saved in a database and this absolutely necessary for us to connect with users. We will only process or use your data to contact you, ensure that your request has been dealt with, create and manage your personal information and make sure that we properly execute our services.