Friday 3 March 2017

EM surveying - Knowledge is Power... (and Potential profit!)

An Electromagnetic Survey is one of the key layers required on the precision farming journey. Precise location and understanding of soil types is a key piece of information in driving decisions around water use and nutrient placement. Not only can an EM survey be used to reduce water inputs it can form the basis of other decisions related to plant health, production and nutrient uptake. Turning the pretty maps into useful data requires some powerful software. That is where VA Gateway comes in. Gateway allows for in depth analysis of multiple layers, including Yield and EM. All Agri Optics customers have access to VA Gateway and AgCloud the online version.

With the software we create reports on the various layers of data collected. Clients get information on two EM soil profiles, one measuring the conductivity in the top 0-50 cm of soil and the other looking at changes in the top 0-125cm of your soil profile. Our report explains our findings on each layer with an explanation of what you are seeing. Depending on the variability arising from the survey, we then create different management zones based on the range in EM units. These zoned maps can then be imported into your variable rate irrigation (VRI) software if they are used for irrigation or into your VR seed drilling control box if you are using it for variable rate seeding based on your soils.

Figure 1. Top left is a shallow EM map and to the right of it a zoned map of that layer. Below is the same but for the deeper EM (0-125cm).
We also report on topography features. As we log the EM data at 2cm accuracy we are also mapping these features. This data set in its own right is very useful and gives you the surface characteristics of the area surveyed in the form of six additional maps, slope, elevation, landscape change, aspect, any depressions and witness index (which way water will move in a rain or irrigation event). This data can be a powerful management tool. The water movement models can help highlight potential areas of issue, so they can be addressed, be it nutrient movement or run off.

Figure 2. Gateway software generates water movement models based on the topography data.
The elevation data can also be used to create contour maps that can be used in the design stage of your centre pivot system, e.g. when calculating tower spacing's or to help with budgeting for any required earth works.

Figure 3. Gateway software can be used to create 3D contour maps.
We can also create moisture probe placement maps based on your EM and elevation data to find your optimum site within each management zone. These sites can also be used as ground-truthing sites with HydroServices neutron probe to put actual specific values to the different zones water holding capacities and then convert the EM map into a water holding capacity map.

A further report can be created to gauge the likely payback time from the installation of VRI based on your soil variability, the crop you are growing, its value per unit and the cost of your VRI system. This is proving very helpful for those who are unsure as to whether they have enough variability in the surveyed area to warrant VRI.

All our data is collected using strict protocols, with the highest standards in continuity and quality every time. This ensures our clients have powerful, solution-focused information. For more details check out our website

Post credit to Chris Smith.