Ashburn, GA, (very close to Heaven!) | Macy - 8/7/2006 18:15
Carl Hobbs will likely jump in, but they install systems that use GPS to know position (rotation) of the rig and do variable water application based upon that position and a prescription map.
The system that we market (http://www.betterpivots.com/) uses GPS to triangulate the degree angle of where the pivot is in the field at a given point in time. It was developed by the University of Georgia and Farmscan. The GPS position relative to the programmed coordinates of the pivot poiont tells the controller where in the field it is, and it sets rates accordingly.
We set the pivot up on a desktop computer using special software that sets up the pivot rates from a desktop computer, then transferred via flash card to the VRI controller. The VRI controller varies the rate of irrigation as a percentage of the base rate by 1. Controlling which nozzles are on and which are off; 2. Turning the end gun on and off; 3. Controlling the pivot speed.
We use soil types, field toporgraphy, overlap, off target areas, and sometimes crops and crop ages to use as the basis for adjusting rates. The average system, according to our base data, is saving between 12 and 16 per cent water, and, better yet, the water we are using is better distributed according to crop need in that area of the field. Energy savings are being realized, too.
The precision ag industry is making strides in the area of adjusting rates of fertilizer, lime, insecticide, seed, plant growth regulators, and more addressing variablility in the field. Water is yet another variable that can be managed now.
Georgia now has 27 VRI systems commercially installed by our company, South Carolina 5, with one in Arkansas and another in Florida. We sent a kit to North Dakota, but with some of their weather problems with the late spring and now the hot summer, I am not sure that it has been installed yet.
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center pivot irrigation using GPS
