The Value of a Soil Test

Sep 16, 2022

Many times, when we discuss the cost of grid soil sampling farmers get hung up on the cost per acre instead of the value of the test itself. The words “cost” and “value” get mixed and the $12.50 per acre cost becomes a hurdle which is not overcome. The value is never realized because the cost is the only item of focus.

To show the value I must describe the why of grid soil sampling through a story. Consider a teacher, after several weeks of teaching a whole host of subject matter wants to evaluate how her students are learning. She could give a single student a test on math, with another student getting tested on science, while a third gets a test on social studies. The teacher will get results, but only from specific students, what if the test each student gets is their weakest subject, or their strongest, and it represents the knowledge of the entire class?

Now let’s consider the method of testing we’ve all grown up with in school. Each student receives a test which includes all subject matter the teacher wants to evaluate. This enables the teacher to determine whether, or not, each student has successfully learned the subject matter, or, if certain students need additional attention for specific areas of study.

Tying this back to soil sampling we can test one of two ways. First, we can sample a field with a composite test, with each sample representing 25 acres. Each sample will consist of 6-8 soil cores across the sample area, with one portion being tested for pH, another portion being tested for phosphorus, and another tested for potassium, etc. just as a teacher testing a few students in the class to represent the whole class. Or, secondly, we can break the field up into 2 ½ acre grids, just as students in classroom desks. Each grid is tested for all nutrients of interest, P, K, Ca, Mg, along with CEC, OM, and pH. The 2 ½ acre grid procedure allows us to determine nutrient variability to prescriptively manage our field’s fertility with the goal of improving such things as herbicide performance, nutrient availability, and ultimately yield.

Watching football used to be 3 yards and a cloud of dust with the offensive line and running or half backs as the only option for gaining yards and scoring. Enter in the forward pass, now we have new and exciting option. The spread offense creates new opportunities to gain yards and score touchdowns which are exciting to play and watch as fans. No longer are the backs and offensive line the only options. Instead opportunities with quarterbacks and receivers enable offenses to thrive while keeping defenses guessing what to do next. Composite soil sampling is the 3 yards and a cloud of dust mentality while grid sampling is the forward pass of nutrient management. We now have options to variable rate applications of N, P, K, and lime to improve areas needing improvement and managing adequate levels where we already have adequate levels.

The economic impact of grid soil sampling is easier measured in application rates for product over the acres tested. Sunrise Cooperative applies MAP, Potash, and Lime VRT more than other nutrients, therefore we will measure these with rate per acre applied, meaning rate on acres needing the nutrient, and rate on total acres, meaning average product calculated over all acres. As we grid sample we will find many areas of a field which do not need nutrient, since it is adequate to excessive in soil test value, therefore the amount applied on total acres will always be less than the product amount on applied acres in any given field.

Looking at 5 growers across our trade area which have a history of grid soil sampling. Their average MAP application on applied acres is 111 lbs. per acre per year while the average rate across total acres is 88 lbs./acre per year. Potash is similar with 139 lbs. per applied acre per year and 121 lbs. per total acres per year. The goal with soil sampling is to only apply maintenance nutrient to a field, what the crop takes off through grain production. Lime has a similar story, 4564 lbs. per applied acre while total acres is 2674 lbs. per acre.

Right Rate, Right Place, Right Source which are 3 of the 4 R’s Sunrise has been promoting for several years. How do these rates compare to your operation. Are they higher or lower? Measurement leads to management and improved return on investment through improved yields, long term. The longer someone has been grid soil sampling the closer these rates get to maintenance instead of buildup, reducing cost per acre while improving nutrient availability and yield.

Other value propositions of Sunrise Precision Solution (SPS) team’s level of experience, interpretation of results, and prescriptive management. Our team keeps track of fields to be sampled and work hard to complete soil tests as soon as field is ready. Timely collection leads to timely results. We have close relationship with our lab, SureTech, which enables us to have results imported into our software for fast turnaround of information, helping our farmer/ owners make sound decisions with actual data. Also, our SPS has the experience to develop prescriptive management of nutrients to maximize return on investment for fertilizer inputs, which will improve yield through balanced nutrition.

The process of collecting grid soil samples also creates value. We increase the number of observation points by pulling one sample for every 2 ½ acres in a field. By increasing the sample size, versus a whole field composite sample, we are able to measure variability across a field and therefore gaining insights to better manage nutrient applications. Just like a teacher measuring the progress of her students.

Sunrise Cooperative has been at this for a long time. The value will be demonstrated by our experience, understanding, and delivery of results allowing the cost to be better understood.

Craig Houin, Data Innovation Lead - Sunrise Cooperative

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