Throughout the growing season, farmers have to decide if and when they should apply fertilizers like nitrogen. If you’ve ever toured a farm or stopped in to the local coffee shop you might have heard farmers talking about ‘side-dressing’ their crop. What in the world are they talking about? Hint: it isn’t the latest fashion trend from Lady Gaga or that delicious ranch dressing on a Cobb salad.
Nitrogen is an essential nutrient for the growth of almost all plants. It is the major nutrient needed to carry on many of the metabolic systems of the plant including photosynthesis. Most fertilizers are labeled NPK (nitrogen, phosphorus, and potassium), with N, or nitrogen, being the first ingredient and in the highest concentration. Corn is notoriously a nitrogen intensive crop meaning that it needs a lot of nitrogen to grow and be healthy.
Farmers might apply fertilizer (manure, synthetic, or another source) in the spring of the year before planting so that the seed and the growing plant have nutrients available throughout the growing season. This method of broadcasting fertilizer across the entire field – called top dressing – makes it available as the plants begin to grow. But nitrogen is water soluble which means it can be absorbed by water (rain) and move through the soil and potentially into our waterways. We don’t want that. And farmers don’t want to see those valuable nutrients being washed away either. Plus, the fertilizer is also available for all plants (not just the corn) and weeds might start to grow rapidly causing other problems.
So, many farmers opt to apply fertilizers at specific times throughout the growing season, right when plants need them. Plants absorb most nutrients through their roots, so it is important to get the fertilizer onto the soil. Broadcasting fertilizer by spraying onto a growing crop isn’t ideal because some of that fertilizer might hit the leaves – not the ground.
To help solve this problem, the farmer puts on his engineering hat and tries to figure out how to apply fertilizer during the growing season, directly onto the ground where the plants need it. The solution is side dressing with drop tubes. Sprayer implements are tall tractors designed to drive over the tops of plants (up to eight feet tall) without damaging those plants. Their wide booms allow for the spray to be spread over a large area. Then from each of those nozzles, a tube can be attached all the way to the ground delivering that liquid directly onto the soil. The fertilizer is applied just to the side of each plant, hence the term side-dressing. The plant needs a lot of nutrients as it tassels and produces an ear of corn, and applying extra fertilizer right before that happens could really help the plant succeed.
Nitrogen is expensive and farmers want to figure out how to apply it in the best way. By applying it when the crop needs it, there is less chance that it will be lost and therefore less can be applied. By applying nitrogen where it is needed strategically, less is needed to be spread out across the entire field and therefore less is wasted. Hoses from the boom do this and minimize or eliminate any damage to the growing plants. Using this technique, farmers can see an increase of 5 bushels per acre up to 17 bushels per acre. Y-drops on the end of each hose further directs the flow of the liquid closer to the root zone of each plant instead of just in between each row. By using Y-drops, farmers can see an additional increase of one to 8 bushels per acre.
Because the tall sprayers allow farmers to spray while the crop is growing, and the tubes allow them to apply the fertilizer to the soil near the root zone, another added benefit is that this method of fertilizer application expands the time in which the fertilizer can be applied. Growing plants are hard to manage and a rainy summer or too dry summer can impact plant growth. This side-dressing method might expand a two week window of fertilizer application to four weeks. Farmers can better manage their fertilizer applications instead of making quick decisions to stay ahead of the weather or to balance other obligations.
This video does a great job of showing how the drop tube system works for side-dressing fertilizer. The whole process can be relatively quick and efficient for both the farmer and the corn!