Soil testing, often overlooked, is a powerful tool in range management. Understanding your soil’s fertility and nutrient composition is critical to informed decision-making. Instead of relying on guesswork, soil testing empowers producers to make targeted fertilizer applications, maximizing their resources and improving forage production.
Soil fertility and health are the bedrock of forage production. By increasing forage production, the need for costly supplements is reduced. This cost-saving potential, coupled with improved soil health, underscores the importance of soil testing for producers, providing a sense of financial security.
Improving pasture health, productivity, and longevity doesn’t have to be daunting. The practical first step is soil testing, a straightforward process that can often be overlooked in the midst of daily tasks. Here are five practical tips to help producers get the most out of their soil tests and make the process more manageable.
Tip #1: Establish your soil test parameters
The first step in any test is determining what 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 available levels of zinc, iron, manganese, and copper. 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. It is recommended that you use it 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. If water quality is of concern, you can conduct it.
- Lime requirement: This test determines the amount of lime needed to raise the soil’s pH to the desired level. It 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. For example, if the test results indicate a need for lime application, plan to do this during a period when the pasture is not being grazed to allow the lime to react with the soil.
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, such as 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 must 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, which are the most deficient and, therefore, limit plant growth, and prioritize which nutrient applications will give you the most return. Once you take care of the most important, 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 used 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
Soil testing is not something you do just once and forget about. Over time, factors like rainfall, grazing by livestock, and changing environmental conditions can impact the nutrient levels in your soil. This change means that the nutrients available to your pasture today might not be the same a few years from now. Regular testing helps you stay on top of these changes.
To keep your pasture healthy and productive, it’s recommended that you test the soil every 3 to 5 years. This range gives you a better idea of how the soil’s fertility changes over time. It helps you adjust your management practices accordingly. By testing regularly, you can prevent nutrient imbalances and ensure your pasture continues to thrive.
Doing a soil test every few years helps you avoid problems before they start. Without knowing what nutrients are in your soil, you could end up over or under-fertilizing, which could hurt your pasture’s growth. A simple soil test can provide valuable information to help you make the best decisions for your land and livestock.
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