Producers are always looking for the best way to maximize their return on investment and the big brains of the agricultural industry are doing everything they can to make that proposition easier and easier. To that end, a growing trend in agriculture is concerned with pinpointing and targeting smaller areas of a field to more efficiently manage a farm.
Wes Anderson, global fertility specialist with CropPro Consulting based out of Beaumont, Alta., spoke earlier this summer during the Ag in Motion Discovery Plus virtual farm show. Anderson works with farm clients to enhance the fertility of their farms using SWAT map variable-rate technology.
Why it matters: SWAT imaging is among the technologies that layer data for a fuller picture of what’s happening in the field.
Anderson explained “agronomy at a higher resolution,” means taking the traditional management zone (an entire field) and dividing that into multiple areas with similar response characteristics to various inputs. “Basically we’re talking about managing areas of the field that are much smaller than the traditional boundary,” said Anderson. “We all recognize that there’s plenty of variability in the field for multitudes of reasons. There’s opportunity to manage things differently in different parts of the field. Whether that’s herbicide rates, fertilizer rates, or even seeding rates.”
There are two key components that must be in place in order to see that return on investment. The first is correctly identifying the management zones. “They have to represent the response characteristics for whatever it is you’re applying,” said Anderson.
The second is getting the agronomy right. “You can be the best agronomist in the world and make a good recommendation based on the information you have on hand, but if your map or management zones are wrong or based on the wrong characteristics to begin with, it really doesn’t matter how good the agronomy is,” Anderson warned.
Enter the SWAT (Soil, Water, and Topography) Map. “We physically go out with a device called a ‘SWAT box’ that maps the electroconductivity and elevation in the field,” Anderson said.
From that data, topography and water modelling can be extracted that show where water is collecting, flowing and shedding.
There are multiple layers of data that can be combined to create a SWAT map, Anderson noted. “Really it all comes down to the dominant characteristics of that field,” he said. “In a field with a lot of salinity or a lot of textural change, the electroconductivity layer is going to be very important because it delineates those areas of the field really well.”
In other cases, for instance when a field has little or no salinity but is very hilly, topography is the crucial element because it determines where water is shedding and where it is collecting.
However, when it comes to Anderson’s area of expertise — fertilizer applications — the most important factors are soil, water and topography.
With soil, the factors explored could be salinity, texture, or topsoil depth. “We need to think in 3D,” said Anderson. “Not just what we see on the surface, but what is zero to six inches, versus what is six to 12 inches deep.”
Water is arguably the biggest factor in crop variability, he noted. Yield is lost by too little or too much water, sometimes at the same time, in the same field in the same year. “You might lose yield to too much water in a depression and yet, at the same time, a few metres away, at the top of a hill, it’s too dry,” he said.
Topography, meanwhile, affects everything. “It affects erosion over time, which affects topsoil depth,” Anderson noted.
The goal when looking at fertilizer applications is to delineate different parts of the field based on their yield potential and fertilizer response, and to base treatment applications on that data. “We might have some areas of the field that are saline,” Anderson said. “They have low yield potential and will always have low yield potential as long as they’re saline. And as a result, they will have low fertilizer response because often there are huge amounts of nutrients in those areas from years and years of over-application.”
Anderson pointed to another example, where an eroded knoll that has low yield potential might still respond to phosphorus because all the phosphorus has been washed away with the topsoil.
With this information, a farmer can specifically target an area of a field to maximize its potential. The same high-resolution agronomy concepts would be applied to anything from weed control to disease management, he noted.