Performing a soil test is one of the most underutilized range management tools. Knowing your soil’s fertility and what nutrients are provided is crucial. Often, producers just put out the same fertilizer they always have and hope for the best.
Soil fertility and health is essential for forage production. When forage production is increased, that means there is less need for providing supplements. When you have to provide fewer supplements, that means less cost for you, the producer. Do you see the importance of taking care of the soil?
In order to improve pasture health, productivity, and longevity, a producer must take a practical first step. This first step is where doing a soil test comes in. However, this often gets put on the back burner as producers deal with the everyday tasks of caring for their land and livestock. Here are five tips to get the most return from your soil test.
Tip #1: Establish your soil test parameters
The first step in doing any test is to set what it is that you are looking for. Once you have decided that, you can choose what lab you will be using. You will want to identify a certified soil testing laboratory that does the kind of test that you are looking for. There should be at least 1 in every state, and it is often on the campus of your local land grant college. Here in Texas, that would be the Soil Testing Lab with the Texas A&M AgriLife Extension Service.
There are many different types of tests that you can go with depending on what you are looking for and the price. Suppose the primary goal is to use this test to make fertilizer decisions. In that case, soil pH, organic matter, phosphorus, and potassium will be critical. If you have some carbon or microbial activity goals, there are other tests to go with.
Finally, you will want to establish the depth from which you will take the core samples. Doing this will ensure a more uniform sampling. Let the lab that you are going with know what this is as well. Your core depths, whether 6 inches or 2-3 inches, should be selected based on measure decisions.
Here are some of the tests that you can choose from:
- Routine: This is the basic test that you can choose from. It will determine the available soil pH, salinity, nitrates, and levels of the primary nutrients (Phosphorus, Potassium, Calcium, Magnesium, Sodium, and Sulphur). It will also provide the Basic N-P-K fertilizer recommendations. This test is acceptable for most applications.
- Micronutrient: This test estimates the levels of Zinc, Iron, Manganese, and Copper that are available. You should use this test for specialty crops in high-pH soils where corn or sorghum is being grown. You can also use this test to troubleshoot any deficiencies.
- Boron: This soil test determines the level of water-extractable boron in the soil. You will want to use this test where clover, alfalfa, or other legumes are grown on sandy soils.
- Detailed salinity: This test measures the pH, electrical conductivity, and water-soluble levels of the major cations in the ground. You can conduct this test if water quality is of concern.
- Lime requirement: This one determines the amount of lime that will be needed to raise the soil’s pH to the desired level. This test is required on very acidic soils where alfalfa or other legumes are grown.
- Texture and organic matter: This is a specialty test for specific applications. It will determine the amount of sand, silt, and clay in the soil. This particular test is usually requested for environmental or research purposes.
Tip#2: Make an action plan
The investment of doing a soil test will only do you good if you follow through. Considering how you will utilize the test results to make your management decisions would be best. Ensure the timing is correct when you improve the soil performance.
Depending on the topography, you may only need to collect samples from part of the pasture. Consider taking samples based on similar management zones or paddocks. If the area is inaccessible to fertilize, do not take a sample from there.
Another area to avoid is within 150 feet of limestone roads. The road dust may influence the soil. Also, avoid areas of cattle concentration like feeding areas, near water troughs, or loafing areas. The higher levels of manure and urine can affect the test results.
Tip# 3: Do the soil test right
How you take the samples can be just as important as what you take. Performing the steps correctly can reduce the negative influence on your test. Following the same steps for every sampling will mean a more uniform result.
It would help if you started with clean sampling materials. You want previous samplings to be independent of your results. Discard and re-sample a core if it looks or feels significantly different from the other cores in that area. Walking in a random zigzag pattern takes 10-15 cores to get an excellent overall sampling of your pasture.
After removing the grass tuft from the top, put all the cores in a plastic bucket. Thoroughly mix them together and then use the mixed cores to fill the soil sample bag. After each sampling, you will need to clean the bucket out to prevent cross-contamination. If you are interested in learning more about how to take a good soil test, then check out my previous post, “Don’t hold back your soil test”.
Tip#4: Move the limiting nutrients to the front of the line
With the current high input prices, it may not be economical to address all of the nutrient shortfalls in one year. Assess the limiting nutrients and prioritize which nutrient applications will give you the most return. Once you take care of the most important, then you can move down the list as needed.
The first thing that you will need to address is soil pH. For grass-based pastures, the pH range you need is 6.0-7.0. A legume-mixed field will require a minimum pH of 6.5. Legumes respond best to improved pH, so lime applications are necessary to increase their production.
The results will also tell you how much Nitrogen, Phosphorus, and Potassium to apply. Nitrogen is often the first nutrient that is applied because of the apparent yield response. However, Inadequate levels of Phosphorus and Potassium can limit yield boosts. Correcting P and K from low to optimum levels can improve pasture yield by 65-80%. Getting the potassium level right is also a good idea if you plan to plant any new forages to help with root development.
Tip#5: Keep at it
Like many other management practices used to improve a pasture, doing a soil test is not a “one and done”. Things like rainfall, grazing, and other environmental conditions can affect soil nutrient levels. Ideally, it would help if you sampled each pasture every 3-5 years to monitor any changes in soil fertility.
