Saturday, April 5, 2014

Sunny morning.  It’s refreshing to see the sunshine and blue skies, even if it’s a little chilly.

What is Swath Control?  Sometimes it’s also called “section control”.  It is a GPS-based control system for application machines or planters or even combines that reduces the effects of overlapping as operations occur in a field.

Not every field is a perfect square shape.  In fact, here in southern Indiana that is almost an impossibility.  Every field has “point rows”.

This is a yield map of the triangle field at the Waldo farm. In this particular case, almost every row is a ‘point row’. In the upper part of this picture, you notice that the rows get shorter and shorter along the left or SW edge of the field. On the other end of the rows, they meet the headland of the field in a more perpendicular fashion.

Since it’s almost planting time, we will use the planter to illustrate swath control.

The border or end rows of fields are planted upon entering the field.  Then, the main body of the field is planted.  During the planting of the main body of the field, as the tractor and planter approach the end of the field, (especially one with point rows like in the above field) one end of the planter begins to overlap the end rows.  As it moves forward, it must remain engaged in the lowered planting position until the full width of the planter meets up with the end rows.   In the past, all planting units across the width of the planter were either ‘on’ or ‘off’.   In order to avoid gaps or skipped areas in point-row planting, the planter would remain engaged in planting until the last area was filled in.  This would plant overlapping rows, making for too high population counts in those overlapping areas, and it was a waste of seed.

Double-planted areas like that are more prone to the problem of lodging, which is the technical term for the crop plants toppling over to lie flat on the ground.  Lodging makes harvest at best difficult, and often impossible to mechanically gather the grain.

Nowadays, with GPS guided and controlled planting machines, each row has a mechanism that allows each planting unit to shut off when it encounters an area already planted… like the end rows.  So, in the above situation, the row units across the planter shut off individually, and stop dropping seeds from one side to the other until the other end of the planter has entered the end row area.  Then, the whole planter is lifted, the turn-around is made, and the planter is lowered.  The opposite effect takes place as the GPS systems ‘turn on’ each row as it leaves the end rows and enters the main body of the field.

Our corn planter is a CaseIH model 1250.  It is controlled by the C-IH Pro 700 screen inside the MX 290 tractor.  During the planting season, we purchase a higher-accuracy XP GPS correction signal for the tractor roof-mounted receiver.   This system is set up and calibrated with precision, and performs the swath control task very accurately.  With 24 30-inch rows, the planter is 60 feet wide.  Some planters are even bigger.  So, without swath control, there could be a big area of overlapping planting on every pass across a field.

Here is a picture of a corn field planted with this new swath control technology. The border of end rows are on the right side of the picture, and you can see how each row of the planter stopped planting at just the right position to eliminate overlapping.

This same type of technology controls our sprayer.  Our JD 4730 sprayer has a 100-foot wide application boom, but it is controlled in 7 smaller sections.   Again, we apply around the border of the field when we begin application, and then spray the main body of the field.  The GPS systems control each of the 7 smaller sections of the sprayer boom and minimize any overlapping of applications.   This requires some specific set-up information in the machine.  But it works almost flawlessly, and benefits us in two ways.  Reduced costs and minimized overlapping.

Please click on this link to find an animated video that shows a sprayer equipped with swath control.  The video shows a sprayer with areas internal to the field that shut off sections, but the same principle governs the machine in a point-row situation at the field border.

We also have this type of system on our combines.  The gathering header for wheat and soybeans on the JD S680 combine is 40 feet wide.  In corn, it is 12, 30-inch rows or 30 feet.  As you are harvesting, we can encounter the point rows there, too.  This swath control system accounts for partial width harvesting as you are entering and exiting the main body of a field during harvest.  This adjusts the system of recording harvest information so that your yield information is more accurate.

Swath control is just one more valuable part of ‘precision agriculture’.