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Garden Help Desk: How soil tests can help ensure your garden has adequate nutrients

By USU Extension - Special to the Daily Herald | Jan 6, 2024
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Sending a soil sample for testing is not complicated. Follow the directions on the submission form. Collect your sample and put it in a plastic bag. Fill out the form and send the sample, the form and your payment to an analytical lab.
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A soil test report will include basic information about your soil plus recommendations for managing or correcting any problems with your soil.
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Bright clusters of paperwhite blooms can add variety to indoor winter plant displays, but once they are done blooming, it's best to discard the spent bulbs and start fresh with new bulbs the following fall.

I got my soil test results back from the lab but there wasn’t any information about the nitrogen or the organic matter. Why wasn’t that on the report?

Nitrogen is a high-demand nutrient. It leaches easily from the soil. It generally needs to be added in some form each year for good performance of any crop. Phosphorus and potassium do not leach easily, and their test values can be stable from season to season, depending on the kind of crops you’ve grown in the past.

An average soil in the United States has an organic matter content of 2% to 4%, but a Utah soil may have only 0.5% to 1% organic matter. Organic matter improves the structure of soil and helps it stay loose, fluffy and workable.

Because nitrogen and organic matter usually need to be added every year, the routine test from the Utah State University Analytical Laboratory (USUAL) doesn’t test for these unless specifically requested. You don’t see nitrogen or organic matter information on your soil test report because you’ll add organic matter based on how your soil looks and feels and add nitrogen based on what you’re growing and how the plants are doing.

Gardeners in our state typically need to add organic matter to their soils every season to maintain good soil structure. Adding shredded leaves, compost, garden waste or some other organic material every year can meet that need for most Utah gardens.

Compost, manures or other animal-based sources, some plant-based sources and synthetic fertilizers are all options for adding needed soil nutrients like nitrogen, phosphorus (P), or potassium (K). If your soil test shows high to very high levels of P or K, follow the recommendations on your soil test report and use a fertilizer without P or K when indicated. The amount depends on the recommendations in your soil test report, the kind of crop you’re growing (lawn, fruit trees, vegetable garden, flower beds or trees/shrubs) and how well those plants are doing. Remember, enough is good, but more isn’t better!

Shade trees and shrubs need little, if any, fertilizer. Fruit trees may need nitrogen once in the spring, depending on how their growth looked the year before. Vegetable gardens are the most likely to benefit from additional nitrogen each year. A soil test may not measure the nitrogen level in the soil, but it can rule out other nutrient issues if your plants aren’t performing well. If all the other soil nutrients in a soil test are adequate and you’ve been giving your plants good care, you may need to make some careful and well-timed applications of nitrogen to your plants.

A soil test is just one tool in a successful gardening toolbox, but it is an important tool! Take advantage of all the guidance your test includes.

You’ll find more information about how to use your soil test results at http://tinyurl.com/3mwkddv4.

You can find fertilizer information at http://tinyurl.com/3svaxnbn and http://tinyurl.com/mbbvmmx6 if your soil test shows adequate levels of other nutrients.

Find information about getting a soil test for your own yard or garden at http://tinyurl.com/43fx4rcm.

I got a little bulb planter with tiny white daffodils as a gift this year. They were very fragrant, and I’d like to plant them near my patio to enjoy next fall. How should I take care of them until I can plant them in the spring?

From your description, I’m guessing you received a planter of paperwhites, members of the Narcissus family, which also includes daffodils and jonquils. You’re right — their fragrance is wonderful! That’s one reason they are popular holiday flowers.

Unfortunately, these pretty plants are only hardy in zones 8 and warmer, so they’re not hardy in our zone. They can’t be forced to bloom indoors again, either. The bulbs are energy (food) storage structures, and that stored energy is depleted as the bulbs grow and bloom. Without a season of full sun (outdoors), the leaves that are left after flowering won’t be able to recharge the bulbs.

It’s best to discard the spent bulbs. Hang on to that little bulb planter they were growing in, though, because you can purchase new paperwhite bulbs next fall to plant in the planter and enjoy the bright blooms and fragrance again next holiday season.

Check back next fall for information on how to force paperwhites for mid-winter blooms.


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