Fall Best for Soil Test?

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Manhattan, Kansas (November 4, 2010)--Fall can be better than spring for soil testing.

The weather in spring is more likely to leave soils waterlogged and difficult to sample. Plus, spring has evolved into the traditional time to test both farm and garden soils. Typically, soil testing labs are at their busiest and the turnaround time for results is the slowest of the year.

As a bonus, if test results suggest soil needs more organic material, fall provides a bounty of free options. Including somewhat fresh materials is possible, too, because landscape plants are no longer young and/or spring-tender. Incorporating such materials into the soil subjects them to winter’s freeze-thaw cycles – one of the best ways to turn crushed or mowed organics into compost in a matter of months.

Every land-grant university’s statewide system of local Extension offices can help farmers and homeowners learn how to sample soil effectively. Kansas State University Research and Extension offices often have soil samplers available for checkout, too, and they can forward samples for testing in K-State’s lab for a small fee.

Each sample should contain soil from the surface to about 6 to 8 inches deep. One way to collect that soil is to use a shovel, dig straight down, and then shave a small layer off the back of the hole.

To limit testing costs, soil gathered from several locations in field, garden or yard should go into the same clean plastic container for mixing. A cup to 1.5 cups of that mix, placed in a resealable plastic bag, will be the representative sample to submit.

Soil tests typically determine pH and fertility. Those factors, in turn, reflect the kinds of inputs soil does or does not need. K-State’s lab often finds, for example, that homeowners will need to make soil more acidic to grow rhododendrons. They will need to fertilize their lawn with nitrogen, but may already have more than enough potassium and phosphorus.