Commercial fertilizer is the most expensive input in warm-season forage production. Since this is a costly resource, we need to use it efficiently. This action will ensure that a producer can optimize the return on the investment for the most profits.
I will tell you that when it comes to efficiency, that does not mean being the “cheapest.” Going with the lowest cost in the long run can actually end up costing the most. Here are four ways to optimize what fertilizer you put out while reducing forage production costs.
Get your soil tested.
Adequate soil fertility is the key to successful forage and hay production. It is literally the foundation on which all the others are built. Unless all the required nutrients are supplied in adequate amounts, your forage production will not reach its full potential.
Soil testing is the best tool for a forage production manager to monitor soil fertility levels. Routinely performing soil tests can help identify nutrient deficiencies and inadequate soil pH. On the other hand, it can also indicate which nutrients are present at high enough levels for fertilizer to be skipped.
Tests conducted within the last three years will provide you with information that is current enough for you to make your decisions. They will also let you know how well your pasture improvement plan is working. This is, of course, if you have been following the fertilizer recommendations provided in your results. If you did not, then it may be a good idea for you to collect another soil test so you can have the most accurate measurements that you need.
After the test
Once you have the results, look at the current levels of the nutrients you want. If they are in the optimum range, you can consider skipping the application this year. Phosphorus (P) levels in forages should be between 100 and 150 ppm. Potassium (K) is in the 100 to 200 ppm area. Any decisions you make regarding fertilizer should be made in relation to whether the field is below, within, or above the optimum range.
When you decide to apply, your fertilizer is just as important as what type you use. The general rule here is that you only want to apply fertilizer to your warm-season grasses once you have five consecutive nights where the lows do not get below 60 degrees. If you apply before that time, you will be feeding the weeds more than anything, and that will just be a waste of money.
In a previous article, “Don’t hold back your soil test,” I discussed the importance of soil testing and the steps to conduct one.
Choose the most adequate fertilizer source.
Where you choose to get your fertilizer from can have just as much of an impact on the efficiency of your application as anything. There are several commercially available sources to supply Nitrogen, Phosphorus, Potassium, and other micronutrients to forages. Again, I emphasize that this is not an area where you want to go with the “lowest sticker price.” Instead, do a little math to find out which will work best for you.
The three primary sources of nitrogen fertilizers used in pastures around the country are ammonium nitrate, ammonium sulfate, and urea. Biosolids and animal manures are also excellent sources of Nitrogen if you prefer to go the organic route. No matter what you go with, it is essential to consider things like price, fertilizer effectiveness, method, and rate of application.
Example
It would be best if you calculated fertilizer costs based on dollars per pound of the nutrient you need. Breaking it down into this will give you a more “apples-to-apples” comparison. Here is an example that you can follow to arrive at your answer (disclaimer: this is just an example, and you should contact your local supplier to get a price).
- Ammonium nitrate (35% N) costs $550/Ton. 2000 lbs of ammonium nitrate contains 700 lbs of Nitrogen (2000 X 0.35 = 700), so the price per lb of Nitrogen is $0.79.
Along with the costs, it is vital to consider the acidity potential of each N fertilizer source you may use. Regardless of which you go with, N fertilization typically reduces the pH in the soil. Some, however, can cause this reaction more rapidly than others. So, it is also a good idea to consider the additional costs of adding a lime application.
Manage your grazing properly.
It is vital that you have a handle on the weeds that are in your pasture. Weeds compete with forages for light, water, nutrients, and space while providing no value. The way that your animals graze can play a significant role in the need for fertilizer.
Your type of grazing management can significantly impact your soil fertility status. Animal feces and urine can recycle a large amount of Nitrogen, Phosphorus, Calcium, and other nutrients back into the soil. However, grazing animals tend to spend more of their time near water, shade, and feeding areas, and a spread-out distribution of this can be a significant challenge.
Stocking rates and grazing methods, such as rotational or continuous, are essential factors that may affect nutrient distribution. Generally, rotational grazing leads to a more evenly distributed distribution. The stocking rate can impact things like soil compaction. The more animals you have, the more they will be walking over your soil.
Use legumes to your advantage.
Another way to reduce input costs without sacrificing yield is to incorporate legumes in your forages. The roots of legumes pull Nitrogen from the air as a nutrient source for the plant to grow. The roots also release Nitrogen into the soil as an available nutrient for other plants. The plant dies and releases even more Nitrogen into the soil as its components decompose.
It would be best if you did some research before choosing a legume since not all legumes are the same. This will help you find which would work best for your operation. Fixed Nitrogen can replace 25 to 75 pounds of fertilizer per acre in a typical year. According to the University of Wisconsin-Madison, a 30% stand of legumes in the pasture can supply 30 to 50 lbs of Nitrogen per year.