Fertilizer: What You need to Know By William Cousins
hether you’re a first-time food plotter or an old hand, you probably know that the planting instructions aren’t the same for all Whitetail Institute products, but they all contain at least one step calling for the addition of fertilizer to the seedbed. Have you ever stopped to consider why? More specifically, what exactly does fertilizer do? The quick, general answer is that it adds nutrients to the seedbed. Just like humans, plants need access to nutrients to survive, grow and be healthy. Humans get most of the nutrients they need from food. Plants get them from the air, water and soil. Fertilizers don’t address the nutrients plants get from the air and water because they’re readily available. As for nutrients plants get from the soil, most soils hold some of the essential nutrients plants need, but more often than not, the level of one or more essential soil nutrients is lower than optimum. Fertilizer is used to add nutrients to the soil to bring any existing nutrient levels that are low into optimum range. Most of us know the basic roles nutrients play in our bodies. For example, we know protein is needed for muscle growth, and Vitamin C can help ward off the common cold. Surprisingly few, though, know the specific roles nutrients play in the plant world. Obvi-
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ously, there isn’t enough room here to provide a fully detailed explanation. Thankfully, only a few soil nutrients are of real concern to most food-plotters, and there’s plenty of room to hit the high points of those. In this article, we’ll limit this discussion to the major roles of nutrients in fertilizer.
Preliminary Matters Soil pH and Lime. Even though soil pH and lime are neither nutrients nor fertilizers, no discussion of what fertilizers do would be complete without at least mentioning them. That’s because fertilizer does nothing unless the plants can access it, and unless soil pH is within the neutral range (about 6.5 to 7.5), soil nutrients are bound up in a way that
keeps most forage plants from fully accessing them. For example, if you fertilize and plant in soil with a soil pH of 5.0 without raising soil pH by adding lime to the seedbed first, the forage you just planted will almost always be able to access only about half of the fertilizer you put out. In other words, if you spend $100 on fertilizer and plant in 5.0 pH soil, you’ll be flushing about $50 down the toilet. That’s why soil pH is the most important factor you can control to assure food plot success, and why the existing soil pH of your soil is the first reading you should look at when you receive your soil-test report back from the lab. Test Your Soil With a Laboratory SoilTest Kit. Only a soil test performed by a qualified soil-testing laboratory can provide the precision to make sure you know exactly what the pH of your soil is, what the existing levels of soil nutrients are, and how much lime and what fertilizer you should add to the seedbed to correct deficiencies. The benefits offered by precision laboratory soil testing are real. It can mean the difference that makes your forage stand really flourish, and save you money at the same time. Often, you can save hundreds of dollars by eliminating wasted lime and fertilizer expenses. High-quality laboratory soil-test kits are available from the Whitetail Institute, agricultural universities, county agents and many farm supply stores. In this article, we’ll be referring to the report generated by the Whitetail Institute’s soil-testing laboratory because it is specifically designed for foodplotters instead of farmers. It cuts right to the chase, providing only the information most food-plotters really need in an easy-to-read format. Soil Test “Readings” and “Recommendations.” The Whitetail Institute soil-test report provides readings of existing soil pH levels and soil nutrients, and includes recommendations of what to add to the soil to bring any low levels into optimum range. This distinction is important for understanding the report. One reason is that a reading for nitrogen isn’t provided, but a recommendation for nitrogen fertilizer is. That’s because nitrogen in the air, while plentiful, is not a form of nitrogen that plants can use directly, so in most cases, you’ll need to add a standard amount of nitrogen based on the needs of the forage you’ll be planting or maintaining. Another reason is that terminology can difwww.whitetailinstitute.com