Soil Testing is about Getting the Right Sample

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Soil Testing is only a cost, if you don’t use the results

Farmers have long understood the importance of soil testing, and technology is allowing us to gain a deeper understanding of our soils and better manage fertility across a field. Fertilizer manufacturers have responded with innovative new products and retailers have invested in new fertilizer blending technology that allows them to easily prepare prescription dry blends of fertilizer impregnated with small amounts of needed micronutrients on every granule.

In the field the one area that has lagged behind is our soil sampling strategy and method. Too often sampling is an after thought without regard to timing or a soil sampling plan. There are sites in fields that will test high and these can easily skew results and underestimate fertilizer needs What soil sampling strategy is used, is a very individual grower preference says Steve Redmond, Precision Ag Specialist with Hensall District Co-op. Bulk sampling with a sample representing 25 to 50 acres is still the norm. However, “while bulk soil sampling is quite common, and grid sampling is in practice, the future lies in zone sampling that takes into account various pieces of data like topography, soil texture, crop yields, field history and farmer experience” says Redmond. Steve also recognizes that this can be a big challenge when deciding how to take a sample that represents these zones. According to Steve, this is the value of knowing the field and talking to the grower about sampling appropriate areas of the field. Clare Kinlin, MacEWEN Agricentre agrees with Steve’s comments and adds the need to have several years of data to create the right zones. “Yield’s in Eastern Ontario this year will be much more driven by drainage than to soil fertility or anything else, because of the excessively wet growing season in our area” Tillage system can impact when and how sampling should be done. Strip tillage is increasing in popularity and this requires a different sampling strategy.

Most growers rely on their retailer or agronomist to sample their fields and provide recommendations. This has tremendous benefit, because the agronomist gets to know your fields, builds a historical data base and understands your yield goals and cropping system to custom design the best fertility program. As a grower it is important that you talk too your agronomist about sampling appropriate areas of the field.

Using the Right Tool at the Right Time

‘It all boils down to collecting good data by using the right tool for the job’ says Felix Weber, Ag Business & Crop. Felix uses the example of a shovel or an auger type sampler that is not as accurate as a straight probe because they collect more soil near the surface which can skew test results.

Both Redmond and Kinlin both rely on an automated soil sampler that has GPS capability. The accuracy of sampling depth, consistency and speed of collecting sufficient sample numbers are key benefits they see with their sampler. For crop consultants, there is a huge advantage in time savings without the worker fatigue or problem with getting the probe in the ground. Using an automated sampler, workers are more likely to gather enough subsamples to adequately represent that part of the field.

Steve also adds that with the number of Nutrient Management Plans they prepare and the future of 4R Nutrient and Precision Ag requirements, a sampler is an in-valuable tool.

Automation of soil sampling also gets back to the foundation of precision agriculture of data collection with gathering accurate, repeatable sampling. Geo-referencing sampling points improve on tracking trends in soil test changes and evaluate whether your current fertilizer program needs adjustment. Knowledge is key to a more profitable fertility program by identifying the high and low yielding areas and how those relate to your fertility program. The soil sampling season is short, and cereal harvest presents an opportune time to sample. “We need to stop sampling plowed ground where sampling depth is impossible to measure” concludes Weber.

Accuracy, consistency, speed, time and labour saving are key benefits agronomist identify with automated soil sampler


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