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The Weekly News Source for Wyoming's Ranchers, Farmers and AgriBusiness Community

Don’t Guess, Test Your Soil

by Wyoming Livestock Roundup

This year, fertilizer prices have increased by as much as 230 percent compared to last year. Therefore, whether planting forages, crops or a garden, the best way to know what nutrients the soil needs is through a soil test.  

Testing soil is inexpensive and essential to determine soil properties and fertility levels to make good management decisions about fertilizer, manure and lime application rates. Knowing what soil is lacking can ensure appropriate nutrient and amendment applications are being applied. 

Applying the correct amount can reduce input cost and environmental impact, while increasing crop yield. Studies performed by Terry L. Kastens and Kevin Dhuyvetter concluded a farmer could save four to five U.S. dollars per acre on fertilizer by relying on accurate soil testing reports. 

Furthermore, if producers are wanting to improve a lawn and/or garden, applying the correct amount of fertilizer is important. The only thing worse than starving a plant of nutrients is accidentally overfertilizing it.  

Plants use only the nutrients they need. Absorbing more than necessary can result in abnormal growth or adverse effects.  

When applying fertilizer without knowing the soil needs, it can be easy to over or under apply certain nutrients and not meet soil needs. Therefore, knowing the nutrient status variability within a field(s), lawn or garden means fertilizer application can be adjusted to more closely meet the supplemental nutrient needs of a crop or grass for specific areas.  

Additionally, knowing the nutrient status of soil can help producers decide if it is necessary to fertilize this year based on management goals and resources.

For help sampling soil, contact the nearest University of Wyoming Extension office. Extension offices across Wyoming have soil probes for producers to borrow and use. 

Local Extension educators can help obtain soil samples. When collecting soil cores using a soil probe, it is important to obtain random samples throughout the sample area such as a field, lawn or garden. 

It is also important to avoid non-representative areas – eroded areas, riparian areas, etc. However, these areas and other areas producers may suspect to be different should be sampled separately.

It is recommended to collect 10 to 15 core samples composited into one soil sample for an area up to 40 acres. The core samples should be taken from zero to eight inches to analyze surface soil samples.

Subsoil samples should be taken from eight to 36 inches or eight to 24 inches and 24 to 36 inches to test for residual nitrate. If producers do not have a probe, a soil sample can be taken using a spade with furrow slices at the same depths as the core samples.   

There are different soil analysis packages ranging from $15 to $30. One of the most common and recommended soil analysis packages for crops and gardens is the S-4 routine analysis, and it costs $20 per sample. 

This test measures pH, buffer pH, sum of cations, base saturation (percent), soluble salts, organic matter, nitrate-nitrogen, phosphorus, potassium, calcium, magnesium, sodium, sulfur, zinc, iron, manganese and copper. However, it is important to choose the best analysis package based on management goals.  

Ward Labs can provide recommendations based on soil analysis, but a local University of Wyoming Extension educator can also help make recommendations based on soil analysis. For best results, it is important to apply fertilizer at the right time, which will depend on what you are growing and their growing season.

More information on proper soil sampling can be found at Soil samples should be mailed to Ward Labs at 4007 Cherry Ave., Kearney, NE 68847. 

Alex Orozco is a University of Wyoming Agriculture and Natural Resources Extension educator. He can be reached at 

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