It is clear that precision agriculture is quickly becoming conventional agriculture within grain production. You can find GPS in tractors, sprayers and spreaders across the country. Farmers can now precisely apply expensive and crucial inputs at varying rates across their fields.
The same yield gains, reduced inputs and increased profitability can be realized for alfalfa, hay and silage growers.
The question that both grain and forage growers need to consider as they venture into variable-rate applications is: What information and what map will I use to guide these applications?
As you make decisions about how to guide your variable-rate fertilizer, lime, irrigation and other products, keep in mind these four principles to make the most of this powerful new management tool available to growers.
Use the right map
The starting point for creating a variable rate prescription for your field is making a map that tells the planter or spreader to automatically change rates as you drive across differing soils.
There are many ways to make maps and it can be tempting to use the least expensive map or the map that is easiest to access, but like most things, if it’s a job worth doing – it’s worth doing right.
The starting point for many growers is the USDA soil survey because it is free and easy to use. The maps created by surveyors in the middle of the last century are quite impressive for the tools at their disposal and lack of GPS.
The maps can be helpful in assessing land suitability and gaining a general understanding of the range of soils in a field. However, the intention was never to guide the precise applications of varying rates of expensive and important crop inputs.
The USDA website provides this cautionary note when downloading the maps: “Warning: Soil map may not be valid at this scale.
You have zoomed in beyond the scale at which the soil map for this area is intended to be used … The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.”
(Source – http://www.progressiveforage.com/forage-production/management/precision-agriculture-s-role-in-improving-forage-production)