30
Figure 21
shows a case in which the computer is programmed to apply the first rate memory (It will apply 30 Kg
of Fert. L, 40 Kg of Fert. A and 5.0 seeds/m). To select another rate group, press “Rate” key till the desired rate
is highlighted.
11.3. Automatic Rate Mode
11.3.1. Variable Rate Prescriptions
In this mode, rate prescriptions are loaded indicating the fertilizer rate (in Kg/ha) and the number of seeds (S/m)
for each area of the plot. The computer receives positioning information from the GPS and determines the area
of the plot in which the implement is. In this way, it commands the CVT to apply the corresponding amount of
fertilizer or seeds in that particular area. The computer will send a sonorous message every time that a product
rate changes automatically due to the implement has enter into a zone with another characteristics.
The rate prescription is composed of a shape file (shape file of polygons) that determines the
zones or areas with similar attributes. A data base file (dbf) contains the prescript rate values
associates to each area. Thus, the first attribute corresponds to linear Fertilizer in Kg/Ha, the
second corresponds to Alongside Fertilizer in Kg/Ha and the third one corresponds to seeds
every 10 meters.
The following prescription example is called PRESCRI1, and therefore it is composed of two standard files for
the GIS treatment in precision agriculture:
•
PRESCRI1.SHP
defines the shape and the exact position of the zone of the plot. (Standard Shape
format)
•
PRESCRI1.DBF
defines the applied products rates. (Standard
Database III
format)
(a) prescri1.shp
(b) prescri1.dbf
Figure 22. Example of a variable rate prescription. (a) The
prescri1.shp
file stores the position and shape of the zones
of the plot. (b) The
prescri1.dbf
file stores the rate of each product to be applied on each zone.
Fertil. L
Fertil. A
Seed
225.000
50.000
70.00
130.000
30.000
56.00
115.000
95.000
56.00
215.000
50.000
70.00
50.000
0.000
56.00
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
Zone 1
Zone 2
Zone 3
Zone 4
Zone 5
