Today we started pulling soil samples to send off to a private laboratory that breaks down the samples and performs a nutrient analysis on the different rootzones. The main reason for doing this is that it tells us what we need to compensate for over the winter and then allows us to build a fertility program for the following season. To pull a sample on a green, for example, we use a 1" soil probe and walk the green in a zig-zag pattern, randomly pulling about 20 plugs at a 3" depth. The plugs are placed in a bucket like the one below where they are shaken to break the soil free from the turf and roots, then placed in a labeled, zip-lock bag. The goal is to get a representative sample of the entire green. It would be easy to simply send off a cup cutter plug but that only tells the story of what's happening in that specific area. We sample to a 3" depth because that's where all the action is happening. I'm not concerned about nutrient levels at a 10" depth because there are no roots that far down.
We will send soil samples from greens, tees and fairways. I select 4-5 different greens (and then tees and fairways) based on a variety of micro climates. Again, the goal is to get representation of the entire golf course. It's important to get a green in full sun, one in shade and another in partial sun. Turfgrass will metabolize nutrients at different rates depending on the growing environment and this can be a reflection of what the turf is pulling from the soil.
In addition to nutrient levels, soil pH is one of the most important tests done during the soil analysis. Turfgrass prefers soils that are neutral to slightly acidic; a range of 6.5 to 7.0. The pH of a soil will determine if nutrients are plant available or not. When the soil pH falls in the range above, most all plant nutrients are plant available in adequate quantities. In Highlands, our native soils tend to be on the acidic side. If the soil pH is well below the 6.5 target, a lime application is required to raise the pH. Dolomitic or Calcitic lime are common products used to raise soil pH. If the pH is too high, which isn't usually an issue, acidifying fertilizers that contain sulfur can help bring the pH down to the desired range. This chemical reaction in the soil takes time, and that's why lime is usually applied in late fall. This gives the lime all winter to work and correct the soil pH by the time the next growing season starts.
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