10/08/2026
Hi, All! We wanted to share our soil sample from our garden plot we started in the Rolla Community Garden, and discuss what information we took from it and how it determined the amendments we added to the garden this fall in anticipation of next year’s gardening season.
We took the soil sample over to the Rolla MFA Bulk Fertilizer Plant (12671 CR 5110, Rolla MO 65401), where they sent it off to MidWest Labs for analysis. There are many other places to send off soil samples…this is just one that I’ve used in the past. Make sure to tell them what you are planting so they know what recommendations to give to you – in this case, we wanted a recommendation for a GARDEN.
The main info we were looking for on page 1 is the pH and organic matter (OM).
pH is vitally important as it takes a while to change (which is why Fall is such a great time to prepare your garden for Spring!) and is fundamental to ensuring our plants are able to access the nutrients available in the soil. Check out this article that discusses nutrient availability vs. pH (https://hydroponic-research.com/ideal-ph-ranges-how-they-affect-nutrient-uptake/). For our vegetable garden, we actually would like somewhere between 6.0-7.0 (with 6.5 being the sweet spot!). The pH was surprisingly high for our area at a 7.4 (the garden I started at home in my lawn was a 5.3 and required 50 lbs of lime for 1000 sq ft to bring up to the 6-7 pH range). While the recommendation on page 3 didn’t suggest elemental sulfur to lower pH, we made the decision to add about 7 lbs (for a 600 sq ft garden) to bring the pH down a bit to our desired range. (Note: Sulfur lowers pH, Lime raises pH).
We want our OM to be around 5-10% for our vegetable garden (https://extension.umd.edu/resource/organic-matter-and-soil-amendments/). At 5.5%, we were doing excellent for traditional soils here in MO (mine was 2.8 when I started), which leads me to suspect that either this plot had been gardened in the past or the Community Garden had some topsoil brought in for the whole area when it was established. Regardless…Yay for us! We still added a bit of compost because it’s just good for the garden and helps with the transition from a grass lawn to our desired garden. We also added a LOT of wood mulch. This will add to the organic matter in the future, but the main reason was to help smother the grass and provide a medium that will help retain moisture and protect the soil in our transition.
After that, we moved to page 3 to get our main fertilizer recommendation – N (nitrogen), P (phosphorus), and K (potassium). As you can see on this recommendation…not a lot was needed (which, again, leads me to believe the area was amended previously). This report recommended .18 lbs of N and .17 lbs of K per 100 sq ft of garden. We have a 600 sq ft garden plot…so we rounded it up to about 1 lb each. Each garden is going to be different (mine initially required 3 lbs N, 7 lbs P, and 2 lbs K for a 1000 sq ft garden), which is why it is so important to start off with a soil test to understand where your deficiencies are at the beginning.
Now that we’ve made our adjustments… we will let Mother Nature work over the winter to incorporate them. We will see how our garden does next year and likely won’t take another soil sample for a few years unless we see some major issues. We will discuss more in our garden series, but for now… We’d love to see any other soil samples you may have taken and let us know if you have any questions!
Learn about common soil amendments and sources of organic matter to improve your garden soil.
