We have been asked a lot lately about where to cut back on fertilizer or which farms to not apply fertilizer on this season due to the high fertilizer prices. Our response is initially: Groceries have gone up too...have you stopped eating? The answer is always “No”. When the grocery prices are high we find ways to be more efficient with food expenses, we can do the same with fertilizer (plant food) by following these tips to maximize fertilizer dollars. These tips are good practices every year, not only when fertilizer prices are high. You definitely don’t want to let your plants starve since 60% of crop yield depends on soil fertility.
1. Fertilizer Placement: Consider Rooting Pattern when making fertilizer placement decisions to promote optimum plant uptake. Corn and wheat are monocots and have fibrous rooting systems with mostly horizontal orientation vs. soybeans which are dicots and have a tap
root system with primarily vertical orientation. Corn and wheat explore soil near the surface for nutrients while soybeans have a greater ability to explore the depths. Soybeans therefore will be able to capture nutrients built up at lower depths over time. If you have to choose which crop to cut back on this season, soybeans will be able to fend for themselves better than corn or wheat.
Picture source: Quora
Fertilizer Placement: Starter Band What’s the most important meal of the day for us? Breakfast! Starter fertilizer is the plant’s breakfast. Just like us, it is important for plants to have adequate access to nutrients early in the growing season. Do as much fertilizer as you can banded to increase fertilizer use efficiency. Placing the fertilizer where the plant can easily access nutrients results in less opportunity for nutrient loss.
Fertilizer Placement: Variable Rate fertilizer placement can have 2 meanings: 1. changing the rate of a product throughout a field to apply only where you will get highest crop response. 2. Varying the application of nutrients throughout the season. Having multiple applications through the season will make sure the nutrients are there when the crop needs them, and save money by not applying any extra to compensate for loss, like is common to do when all fertilizer is applied at the start of the season.
2. pH in Optimum Range: Ensuring your soil pH is within optimum range, 6.2 to 7.3 (for most crops) is extremely important because pH regulates the natural nutrient availability in the soil. If your soil pH Is too low most nutrients needed for growth are not available to the plant. Think about soil as your nutrient bank account. If your pH is out of range you do not have access to the nutrients in your soil bank. Even if you add fertilizer (put a deposit into the soil bank) the plants can still not access the nutrients until pH is within optimum range.
If you spread fertilizer without first correcting pH you are wasting fertilizer. The chart above summarizes fertilizer wasted based on soil pH. As you can see from this chart, pH is the last thing we should let slip. Unfortunately it is usually the first. Your goal is to keep the soil in the sweet spot or optimum range all year and every year.
3. Nitrogen Management: Placement: 63% of nitrogen used by a corn crop is taken up from 7 inches around the stalk. Therefore band application at planting or in-season Y-Drop to place nitrogen directly into the main nutrient uptake zone is the most efficient placement of nitrogen.
Nitrogen Management: Nitrogen Holding Capacity varies with soil type. Roughly 10 x CEC is the soil nitrogen holding capacity at any one time. For example sandy soil has a lower CEC and therefore a lower nitrogen holding capacity than loam or clay. Be sure to calculate your farm’s nitrogen holding capacity to help determine when and how often to apply nitrogen to meet the crop needs. Split applications no matter what the soil type will result in less wasted nitrogen.
Nitrogen Management: Cover Crops Many cover crops are nitrogen fixing, and using these cover crop species can help you reduce your nitrogen fertilizer. Good nitrogen fixing cover crop species include: Austrian winter peas, faba beans, clover, alfalfa, and any type of beans.
Nitrogen Management: Corn Aim for 0.75 to 0.8 lbs of nitrogen per bushel of yield goal. This amount will meet the crop needs without having any waste.
4. Know Your Soil Nutrient Supply: Is Your Soil Fuel Gauge Full or on Empty? A good strategy is to keep your soil fuel gauge, which is your nutrient supply, near full or within optimum nutrient range, so you don’t run out of fuel on years like this when the fertilizer prices are high and you want to cut back a little on fertilizer. Soil test regularly to monitor your soil nutrient supply. If you have a base nutrient supply within optimum range you can save money on high fertilizer price years by only applying where you will get highest crop response. You don’t need to add to areas where there is already a sufficient amount of the nutrient.
Cost of Not Applying Fertilizer for One Year
Remember the plants still need to eat, so if you decide to skip applying fertilizer this season the plants will still scavenge the soil for all nutrients available and decrease your soil nutrient supply to grow the crop. Let’s look at the true cost of not applying fertilizer this season.
Background:
To build 1 ppm (part per million) Phosphorus requires 35 lbs actual Phosphorus which is approximately 67 lbs/ac MAP.
To build 1 ppm Potassium requires 20 lbs actual Potassium which is approximately 33 lbs/ac Potash.
These build values are required above crop removal rates next season to replace the nutrients mined from the soil on the no fertilizer year.
Example: no fertilizer applied in 2022, depletes soil 5 ppm of Phosphorus and 8 ppm of Potassium.
Assumptions: Fertilizer Cost in 2023
MAP $1150/mt
Potash $650/mt
The additional fertilizer expense above feeding the 2023 crop to rebuild the depleted soil from no fertilizer this year is: $252.54/ac.
"The best fertilizer for any soil is the footsteps of the farmer." Confucius
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