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Sweetwater County Soils - Testing & Management

Anyone who has done at least a little digging around in the Sweetwater county soil can tell you that we definitely don't have the best soil in the world. We love our little place in the desert but that's what it is, a desert. This is why it is so important to learn about your soil, especially for gardens in western Wyoming. With spring coming, it's a great time to start planning out what you are wanting to plant and where you want to plant it. Soil tests are a great way to improve plant growth and understand your soil better as you prepare for the upcoming season.


Soil Texture, pH, and Salinity

Soils are categorized by particle size. The smallest being clay, then silt, and then sand, the biggest. Soils native to south-western Wyoming are typically loam to sandy loam, with good drainage. This means that our soil has mostly equal parts sand, silt, and clay. We also have relatively high alkalinity, the average for the area is around 8, which is 10x higher than neutral (7). This is why it is hard to grow plants like blueberries or rhododendrons because they like soils that are more acidic. Salinity is also something that tends to be higher in our soils but is easily combated when soil is watered frequently because our soil has very good drainage.



Soil Fertility

There are 17 essential nutrients that are needed for plant growth, 14 of which come from the soil. The 3 most important macronutrients to manage are Nitrogen, Phosphorus, and Potassium. You may be thinking that these elements look familiar, that's because they are the elements that are on fertilizer labels! In general, Nitrogen needs to be added to the soil every year, but because most fertilizers are rich in Nitrogen, soils don't usually need to be tested if you are frequently fertilizing. Phosphorus and Potassium are recommended for regular testing because they tend to build up in our soils. Phosphorus in large amounts can contaminate water sources and Potassium can increase soil salinity. Other more trace elements can also be found with a routine soil test. Some common nutrient deficiencies are Chlorosis caused by lack of nitrogen or sulfur, Intervienal Chlorosis caused by iron deficiency, Purpling caused by phosphorus deficiency, and local Necrosis caused by lack of potassium.




Improving Garden Soils

Organic matter is definitely something that we lack here in Wyoming and adding it to your soil is essential, it is suggested to add 1-2 inches of organic matter into your soil annually. There are many types of organic matter but most have to go through a period of decomposition for various lengths depending on what it is.*** Organic matter is essential to a garden because it provides essential nutrients for the plant and for micro- and macro-organisms in the soil. These little creatures are so important for soil health as they improve aeration, nutrient cycling, and soil structure. Organic material can be incorporated in the spring or in the fall as long as the soil you are adding to is not wet.

Some other amendments that don't improve soil health but do help with aeration are inorganic mulches like perlite, pumice, vermiculite, and utelite. These materials help aerate soils that are heavy and allow your plant roots to breathe and have good drainage.

There are many sources that may suggest using amendments like Lime and Gypsum. Lime is not recommended because it is very alkaline and does nothing to improve our already very alkaline soil. Gypsum is sometimes promoted as an alkali treatment but if added will not greatly change the alkalinity of the soil or the structure. The best way to improve the health of your soil for where we live is by amending it with organic material or a soil pep.



How to Sample Your Yard

  1. Split your yard into zones so that every area of your yard that has been used differently in the past gets its own test. This could be an area that was used for a specific crop or reason, an underperforming area, or an area that you've noticed specific plant problems. Be sure to use your own intuition!

  2. Take multiple samples from each zone to be sure that you get an average soil test result. You do this by taking 4-6 samples from different areas within your zone. Put all of your samples into a clean bucket and mix them together. (Make sure that when you take your samples you are digging at least 6 inches deep into your soil)

  3. Collect your samples by placing 2 cups of soil from your bucket into your soil test bag. Make sure before you bag your soil that it is not extremely wet as it may create mold or accumulate bacteria before it gets tested. Its best to water your yard the day before you take your sample to losen the soil and then water after you take your samples.

  4. Send if your samples for analysis! The University of Wyoming no longer has a soil testing lab but our closest neighbor is Utah State University and they have a great soil testing lab with a variety of different tests. The University of Wyoming soil testing webpage now suggests the Colorado State University Soil Testing Lab but this and Utah State's lab are both great options. Getting your soil tested at an educational institution is the best option rather than by fertilizer/chemical company because they provide clear and unbiased results. It is also ideal to get your soil tested by a nearby soil testing lab because they understand our soil and its needs better than a company that is based out of a different region. Neaby soil testing labs can provide results that are more specific for this region. The University of Wyoming has an extension office for Sweetwater County and our Horticulture extension agent is Amanda Romero. She also has resources for soil tests and may be able to answer questions or contact specialists to help answer questions you may have.


When Should I Test My Soil?

Soil testing is a great way to plan for a future season. It can be done any time of the year but doing it in spring or fall can help you prepare and know what you need for the upcoming season. Doing a routine test every 1-2 years is great for annual crops and every 3 years for perennial areas. You can also rotate what zones you do each year to bring cost down.

It is important to note that if your soil is healthy and doing well, you may not need a soil test. But if you suspect that something may be off in your soil or you want to improve growth then soil tests are a great resource! If you are new to soil tests then a great place to start is with a Routine Soil Test for an established garden.



Soil and its nutrients are one of the biggest things that affect how our plants grow. Having healthy soil can not only change how beautiful your yard it but can help your fruits and veggies bloom more abundantly. If you need help interpreting your soil test results or want to know more about what you can do to improve your soil feel free to contact us, via phone, Facebook, or Instagram.


Soil Testing Links & Prices:

Utah State University: $30

Soil Testing Homepage

Soil Testing Form


Colorado State University: $35

Soil Testing Homepage

Soil Testing Form




***It's important to not put raw materials, such as manure or kitchen scraps in your soil because it can tamper with the health of your soil or burn your plants.

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