Grainswest - Winter 2019

Winter 2019 grainswest.com 49 BYLEE HART has shown test results can show variability, and this has been his own experience. In one study he recalled, a soil sample from a single field was sent to two labs. One recommending a 125-pound nitrogen application, the other just 55. “The two rates were applied and there was no difference in yield,” he said. “So, going with the higher recommendation would be a waste of money.” He concluded that proper, representative field sampling is important, and farmers need to do their homework in selecting a soil test lab that produces recommendations that best relate to their region and farming conditions. The variability of results among testing labs prompted agrono- mist Jack Payne to recommend farmers find a lab they trust and stick with it. “Soil analysis can vary from one to another, which doesn’t mean there is anything wrong with the lab procedures, it just means don’t bounce from one lab to another,” said Payne, operations coordinator for Farmers Edge consulting services in Olds. “With most soil analysis and recommendations, the actual rate is going to be plus or minus the recommendation based on your cropping history, your farming system and growing condi- tions. So, it is important to be consistent with the lab providing the analysis. Stick with one lab, have confidence in their analysis and adjust rates based on your farming situation.” Payne recalled two instances that underscore the value of soil testing. He had been tasked with completing soil testing and fertilizer recommendations for a Peace River region farm that had experienced two successive dry growing seasons. It was a good-news, bad-news situation. Though yields had been down, soil testing indicated high nutrient carryover. “This farmer would normally apply 90 to 100-plus pounds of nitrogen, but the soil test was showing he could get away with about half that,” said Payne. Based on his recommendation, the farmer applied about 40 pounds of nitrogen, and the season pro- gressed with nearly ideal growing conditions. “I was concerned the recommendation had been too low,” admits Payne. But the farmer reported that by the third week of July neighbours were asking how he managed such an excellent crop. The neighbours had applied a flat rate of 100 pounds of nitrogen. With good growing conditions and the nutrient carryover in the soil, their crops had lodged. Another client had experienced successive years of higher yields and a soil test analysis showed low soil nutrient levels. “We developed a nutrient recommendation that bumped up fertility and his barley achieved malt quality,” said Payne. “These aha mo- ments demonstrate the value of doing a soil test, knowing what nutrients are available and developing a recommendation that produces target yields and quality.” Steve Larocque of Beyond Agronomy consulting services in Three Hills also encourages farmers to annually test their soil. “It is something we always do on our farm,” he said. “But the next best scenario is to do it at least every three years.” He notes some nutrient levels fluctuate more than others. “Nutrients such as nitrogen and sulphur can be quite variable from year to year, whereas phosphorus, potassium, organic matter and many micro- nutrients don’t change that fast.” If farmers are unable to test soil in a given year, Larocque suggests they make use of online nutrient uptake and removal calculators tailored for western Canadian growing conditions. These include Alberta Agriculture and Forestry’s Alberta Farm Fertilizer Information and Recommendation Manager. Farm- ers can input crop variety, soil type, moisture and historical yield data to determine the nutrient uptake of newly harvest- ed crops. This can be used to guide fertilization rates for the following season. Like his agronomist colleagues, Larocque recommends regular soil testing with a reputable lab. “If you just do it once every so many years, it’s possible to get outlier results that don’t tell you anything. But if you consistently soil test your fields using the same benchmarks, you’ll find you get more consistent results, which gives you confidence in the numbers over time. From there you’ll have a better idea of where your nutrient levels are at and what you need to apply.” Photos: CourtesyofFarmersEdge Soil samples are processed in the Farmers Edge US Soil Laboratory in Grimes, Iowa.