Extension Master GardenerSM Volunteers of Buncombe County

fertilizer

Soil Tests: What They Tell You and What They Don’t!

“Have you done a soil test?” is one of the first questions Extension Master Gardeners ask if you’re starting a new gardening project. Do you know what a soil test can tell you—and what it can’t?

Soil Test Box and Sample Information Sheet

Useful information from soil tests:

  • Nutrients your plants need to grow
    • Primary macronutrients: Nitrogen (N), Phosphorus (P), and Potassium (K)
    • Secondary macronutrients: Calcium (Ca), Magnesium (Mg), and Sulfur (S)
    • Minor nutrients: boron, chlorine, copper, iron, manganese, molybdenum, nickel, and zinc
  • Soil acidity level (pH)

Your soil test will tell you the amount and type of fertilizer to use to provide the nutrients your plants need and how to adjust the soil pH to the appropriate level. It can also tell you if you have too much of certain nutrients! Overfertilizing can be as detrimental to your plants’ growth as too little fertilizer.

 Your soil test won’t tell you if you have:

  • Poorly structured soils
    • Plants may have difficulty getting established on sites where topsoil was stripped away, or soil layers were disturbed and/or compacted during construction.
    • Heavy clay soils, in particular, are difficult for roots to penetrate.
  • Too much or too little soil moisture
    • Poorly drained soils may prevent plant roots from getting enough oxygen.
    • Drought or fast-draining soils may lead to root damage/death from too little soil moisture.
    • Watering too frequently or not deeply enough can create moisture problems for plants in good soils.
  • Plant competition
    • Shallow tree roots or the roots of plants spaced too closely may compete for soil nutrients.
    • Allelopathic plants—such as walnut trees—may act as herbicides and keep nearby plants from thriving.
    • Shade from other plants may inhibit growth of sun-lovers.

So, knowing the proper nutrients and soil pH is a start, but having your plants thrive means making sure your soil has appropriate soil structure and moisture, and providing them with appropriate space and plant companions.

Article by Debbie Green Buncombe County Extension Master GardenerSM Volunteer

For more information:

 Soil testing in North Carolina:

https://content.ces.ncsu.edu/extension-gardener-handbook/1-soils-and-plant-nutrients#section_heading_7241

 “What a Soil Test Does Not Tell You” (scroll down to last article in this newsletter):

https://hnr.k-state.edu/extension/info-center/newsletters/2018/Feb20_2018_7.pdf

Allelopathy in walnut trees:

https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-021/430-021_pdf.pdf

 

 

 

A Recipe for Gardening Success: Start with Good Soil

In South Carolina Low Country kitchens, there is an inviolate rule when it comes to making shrimp and grits: Start with good shrimp. What does this have to do with gardening in Western North Carolina? Everything. To make a healthy, productive garden, start with good soil. 

Contents of good soil

What is good soil?
Think of soil as a mixture of solid material (minerals and organic matter), air, and water. The ideal soil contains 50 percent solid materials, 25 percent air, and 25 percent water.

Plant nutrients
Healthy plant growth depends on 18 nutrients in this mix. The primary nutrients include carbon, hydrogen, and oxygen, as well as nitrogen, phosphorus, and potassium. Secondary nutrients are calcium, magnesium, and sulfur. Micronutrients are iron, chlorine, manganese, boron, zinc, copper, molybdenum, nickel, and cobalt. 

Fertilizers
Think of fertilizers as supplements. There is no substitute for starting with well-balanced soil, but fertilizers can provide elements that may be lacking in the soil and can stimulate plant growth. All fertilizers, synthetic or natural, slow or fast release, are labeled with three numbers:

  • N for nitrogen, responsible for foliage growth and color;
  • P for phosphorus, which promotes early root growth and the production of flowers, fruits and seeds; and
  • K for potassium, which helps with hardiness and disease resistance.

Use a soil test to determine what nutrients your soil may need. For more information about soil testing, see https://www.buncombemastergardener.org/testing-soil-advantage-free-testing-december-1-soil-sample-form-gardeners/.

Regardless of what kind of fertilizer you use, be sure to read the directions, use the proper proportions, and follow the manufacturers’ safety guidelines when applying.

Amendments
Compacted soil has too little air. Poorly drained soil holds too much water. Adding organic matter can help remedy both. North Carolina Extension soil specialists recommend adding about 2 inches of organic matter—compost, manures and pine bark (less than ½ inch in diameter)—to make up about 25 percent of the top 8 inches of your garden soil. For clay soils, they say composted leaves (leaf mold) and pine bark are best—they do NOT recommend hardwood bark, peat moss, pine straw, sand, or wood chips.

Putting it all together
When soil texture and nutrients are in the right balance, plants, beneficial insects, and bacteria thrive. Think back to that bowl of shrimp and grits. We’ve got fresh and flavorful shrimp, but what about the grits? The best grits are smooth and have a consistent texture. The same holds true for soil.

This means removing clods of clay and breaking up large clumps of dirt. The amendments and fertilizers are evenly distributed. Like a cake batter, your ingredients are well-mixed. Finally, rocks and debris are raked out and removed. The product is a luscious soil that is easy to turn, well-drained and rich in the elements that create a welcoming environment for your garden and all the organisms that support it.

Worth the work
When the days lengthen and temperatures moderate, our heads fill with spring dreams of fresh lettuce, rosy radishes, and sugar snap peas.  But before putting a seed in the ground, think of shrimp and grits. Work from the ground up: test the soil, then (like a good cook) add the necessary ingredients to make your soil the best it can be. It’s time well spent and your garden will show its appreciation all year long.

Article written by Janet Moore, Extension Master Gardener Volunteer.

Resources
Useful NCSU Extension publications include:
“Soils and Plant Nutrients”
https://content.ces.ncsu.edu/extension-gardener-handbook/1-soils-and-plant-nutrients
“Soil Facts: Modifying Soil for Plant Growth around Your Home”
https://content.ces.ncsu.edu/modifying-soil-for-plant-growth-around-your-home
“A Gardener’s Guide to Soil Testing”
http://content.ces.ncsu.edu/a-gardeners-guide-to-soil-testing
“Vermicomposting for Households”
https://www.ces.ncsu.edu/vermicomposting-north-carolina/vermicomposting-for-households/

Lawn Maintenance: How Much is the Right Amount?

How do you keep your lawn looking respectable year-round? You know you have to mow, but how much else do you need to do? Do you want a great lawn or a “good-enough” lawn? Here are tips on how to have the lawn you want.

Photo by Joey Williamson, Clemson Univ ExtensionMowing
Mowing is key to keeping your lawn presentable, no matter what! Your goal: keep your cool-season grasses three inches tall, mowing off no more than a third of the height at a time. Never let your lawn get above five inches. Grass may need mowing anytime of the year that temperatures get into the 70s.

Lawn growth varies wildly and individual lawns need individual evaluation. Overheard last week: “We’ve had so much rain that my husband is mowing the lawn every four days!” “Well, we’ve had so little rain that I haven’t mowed in three weeks!” Plan accordingly—fixed schedules won’t work!

Grasscycling
Many mowers will bag your cut grass, but you can save time and money—including on fertilizer—by leaving the clippings on the lawn. Mulching mowers keep the clippings small so they quickly dry out. Turf specialists estimate those clippings provide about 25 percent of the nutrients your lawn needs each year.

If your mower leaves clumps of cut grass, you may need to mow more often, or be sure the lawn is drier. Break up clumped clippings to avoid smothering the remaining lawn. If you bag or rake clippings, use them elsewhere in your garden or compost—hot composting will kill weed seeds!

Core Aerate LawnCore aeration
Aerating helps root growth in compacted soil and is worth doing, especially in years you overseed your lawn. Aerate this fall or when growth starts up again in the spring. Rent equipment that brings up small cores of lawn or hire someone to do the aeration. Just poking holes in the soil creates more compaction! Cores gradually break down—rake to break them up if they bother you. Mark irrigation system emitters and hoses so you do not damage them!

Watering
Lawns in active growth need consistent watering—an inch a week from rain or irrigation. Cool season grasses go dormant and brown up in the heat of summer. You may want to encourage dormancy to minimize maintenance. Dormant lawns may be able to go without rain for six weeks, but it is best to provide some watering every three weeks. Turf specialists advise that as little as ¼ inch may be enough.

Liming
Grass can’t effectively use nutrients if your soil is too acid. Many WNC lawns desperately need lime, but only a soil test will tell you how much. Lime takes awhile to work on soil pH—don’t expect immediate results. Test again in two or three years before liming again.

Fertilizer
Yearly nitrogen is a given, but some lawns need phosphorus, too—check your soil test! A lush lawn may require 2.5 to 3 pounds of nitrogen a year, but you can certainly use less, especially if you leave your grass clippings on the lawn. Plan to apply at least one pound of nitrogen every September and possibly another pound in October or November. If your lawn is still struggling, provide the remaining half-pound or pound in February. Fertilizing any later may lead to even lusher growth, but may make your lawn susceptible to fungal diseases come summer.

Dandelion weed in lawn
Dandelion weed in lawn

Weed management
With proper maintenance, you’ll find weeds aren’t as much of a problem. Identify your weeds. Pre-emergent herbicides can prevent crabgrass—an annual weed—from sprouting in bare spots. Decide if perennial weeds justify treatment. White clover may be a desirable addition to your lawn if you don’t need a uniform stand of grass. If you have a few dandelions, or other broadleaf weeds, try digging them out. Pervasive aggressive weeds may justify broadleaf herbicides.

Diseases and insects
There are many lawn ailments and pests, but with proper maintenance, damage is minimal, especially if you employ proper lawn maintenance practices. North Carolina State University provides many resources for identifying and treating lawn problems.

Article written by Debbie Green, Extension Master Gardener Volunteer.

Photo of woman mowing lawn courtesy of Joey Williamson, HGIC Horticulture Extension Agent, Clemson University,
http://www.clemson.edu/extension/hgic/plants/landscape/lawns/hgic1203.html

Free Lawn Care App:
http://www.lawncare.ncsu.edu/
Maintenance Calendar:
http://www.turffiles.ncsu.edu/turfgrasses/fine-fescue/lawn-maintenance
Organic Lawn Care:
http://www.turffiles.ncsu.edu/Files/Turfgrass/Articles/Bruneau_A/2008/Organic_Lawn_Care__A_Guide_to_Lawn_Maintenance_and_Pest_Management_for_North_Carolina.pdf
Weed ID:
http://turfid.ncsu.edu/

Contact Us

Buncombe County Extension Office
49 Mount Carmel Road
Asheville, NC 28806
Helpline 828-255-5522

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