18 It’s Farming. And It’s Better. Better Farming | January 2024 CROP FERTILITY PROGRAMS Looking at historical yield gains for both corn and soybeans across North America is exciting. Over the past 25 years, corn yields have increased by about 50 bushels per acre, and soybeans have increased by approximately 15 bushels. But are we feeding this crop adequately to maintain these high yields? Why are yields on the rise? A lot of this is attributed to genetic yield gain and the management practices growers are utilizing during specific stages of crop development to minimize stresses on plants. This allows for continuous water and nutrient uptake and the conversion to sugars, protein, and starch to make more yield. The question we should be asking ourselves is, “Are we feeding the crop enough nutrients to sustain this continual yield growth today and in the future?” To answer this, we need to look at what the corn and soybean crop needs to make a bushel of grain for each crop. For this article, I am going to focus on phosphorus and potassium. Similar principles would apply to other crop nutrients. Phosphorus is a primary nutrient. It aids in photosynthesis and cell division, which is critical for crop development. It is taken up for enhanced root development and can be instrumental in the initial stages of development of a crop. As well, phosphorous helps with crop maturity of plants. Potassium is instrumental for water regulation and controls the stomates in a plant. It also aids with stalk quality (formation of lignin and cellulose), and can help later in the season with improved lodging resistance. It assists with disease and insect resistance (think about soybean aphids that usually attack low-K soil test areas). Industry experts would refer to it as the “Power of Potash.” A 2015 survey conducted by the International Plant Nutrition Institute showed samples that tested below the critical levels for phosphorus and potassium ranged from 31 to 38 per cent for phosphorus and nine to 65 per cent for potassium for various states. Critical levels are defined as the level below which a profitable yield response would be expected in the year of application. Simply put, if you apply fertilizer, you will get a positive return on the investment that covers the initial cost and provides a return above that. This intrigued me, so I decided to investigate what soil test levels would be like for Ontario. All soil lab companies keep historical data sets. For Ontario, I recently talked with Chris Meier, Business Development and Key Account Manager for A&L Canada Laboratories based in London. Chris pulled a fiveyear history of data for Ontario, looking at soil test levels for phosphorous and potassium. On the phosphorus front, 70 per cent of samples were in the very low, too low, and medium categories, with the split almost equal among the three levels. Paul Hermans photo AN ADEQUATE, WELL-BALANCED FERTILITY PROGRAM WILL ENSURE YOUR CROPS ARE HEALTHY. DO YOUR CROPS GET THREE SQUARE MEALS? By PAUL HERMANS
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