Soil Compaction in the Landscape

Soil Compaction in the Landscape

One big goal of establishing a home lawn and landscape is to enjoy an attractive setting for family and friends, while also helping manage healthy soils and plants.  Soil compaction at these sites can cause multiple problems for quality plants establishment and growth.  Soil is an incredibly important resource creating the foundation for plants and water absorption.

Photo courtesy: Stephen Greer, UF IFAS

Soils are composed of many different things, including minerals.  In Florida, these minerals often include sand of differing sizes and clay in the northern area of the counties in the panhandle of Florida. Soil is also composed of organic matter, nutrients, microorganisms and others.  When soil compacts, the air spaces between the sand or clay are compressed, reducing the space between the mineral particles.  This can occur anytime during the landscape and lawn construction phase or during long term maintenance of the area with equipment that could include tractors, mowers, and trucks.

What can be done to reduce soil compaction?  There are steps that can be taken to help reduce this serious situation.  Make a plan on how to best approach a given land area with the equipment needed to accomplish the landscape of your dreams.  Where should heavy equipment travel and how much impact they will have to the soils, trees, and other plants already existing and others to be planted?  At times heavy plywood may be needed to distribute the tire weight load over a larger area, reducing soil compaction by a tire directly on the soil.  Once the big equipment use is complete, look at ways to reduce the areas that were compacted.  Incorporating organic matter such as compost, pine bark, mulch, and others by tilling the soil and mixing it with the existing soil can help.  Anytime the soil provides improved air space, root will better grow and penetrate larger areas of the soil and plants will be healthier.

Even light foot traffic over the same area over and over will slowly compact soils.  Take a look at golf course at the end of cart paths or during a tournament with people walking over the same areas.  The grass is damaged from the leaves at the surface to the roots below.  Plugging these areas or possibly tilling and reestablishing these sites to reduce the compacted soils may be necessary.

Photo courtesy: Stephen Greer, UF IFAS

Water absorption is another area to plan for, as heavy rains do occur in Florida.  Having landscapes and lawns that are properly managed allow increased water infiltration into the soil is critically important.  Water runoff from the site is reduced or at least slowed to allow the nutrient from fertilizers used for the plant to have more time to be absorbed into the soil and taken up by the plants.  This reduces the opportunity for nitrogen, phosphorus, and other nutrients to enter water areas such as ponds, creeks, lagoons, rivers and bays.  Even if you are miles from an open water source, movement of water runoff can enter ditches and work their way to these open water areas, ultimately impacting drinking water, wildlife, and unwanted aquatic plant growth.

Plan ahead and talk with experts that can help with developing a plan.  Contact your local Extension office for assistance!

 

Thinking about Planting a Tree?

Thinking about Planting a Tree?

Need tips on planting and caring for trees?  The primary focus in care of your newly planted tree is root development. It takes several months for roots to establish and newly planted trees and shrubs do not have a very strong root system. Start by digging the hole in a popcorn bowl shape. Once planted, backfill around the root system, but be careful not to compact the soil as this will hinder root growth. Be sure to keep the topmost area of the root ball exposed, about one to two inches. A layer of mulch will be applied here.

Frequent watering is much needed, especially if you are planting in the summer. Water thoroughly, so that water percolates below the root system. Shallow watering promotes surface root growth, which will make the plant more susceptible to stress during a drought. Concentrate some of the water in a diameter pattern a few feet from the trunk. This will cause the root system to grow towards the water, and thus better establish the root system and anchor the tree.

Figure: A Traditional Staking Option. Credit: Edward F. Gilman, UF/IFAS Extension.

Mulch is important in the conservation of soil moisture. Pine needles, bark, wood chips, and other organic materials make a great mulch. A three inch layer of mulch will usually suffice. It’s important to keep the mulch a few inches from the trunk as mulching too close to the tree trunk can cause rot.

You should always prune the bare roots of trees during planting. These exposed roots in containers can be damaged in shipping and removing some of the roots will help trigger growth. Pruning some of the top foliage can also reduce the amount of water needed for the plant to establish, as well. Trees and shrubs grown and shipped in burlap or containers usually need very little pruning.

Newly planted trees often have a difficult time establishing if the root system cannot be held in place. Strong winds and rain can cause the plant to tip over. Avoid this by staking the plant for temporary support. A good rule of thumb to determine staking need is if the trunk diameter measures three inches or less, it probably needs some support! Tie the stake to the plant every six inches from the top. However, only tie the trunk at one spot. Don’t tie too tightly so that the tree has no flexibility. This will stunt the growth of the tree.

Following these tips will help ensure your tree becomes well established in your landscape. For more information please contact your local county extension office.

Information for this article can be found in the UF/IFAS EDIS publication: “Planting and Establishing Trees” by Edward F. Gilman and Laura Sadowiski: https://edis.ifas.ufl.edu/pdf%5CEP%5CEP31400.pdf

Supporting information also provided by UF/IFAS Extension Forestry Specialist Dr. Patrick Minogue, of the North Florida Research Education Center in Quincy, Florida.

Soil has Many Names, Just Not the “D-word”

Soil has Many Names, Just Not the “D-word”

For all my years in the classroom, I never let students say the “d-word” when discussing soil science.  In some instances, we had a “d-word” swear collection jar of a quarter when you used the term and even today, I hesitate from spelling the word out in text due to feedback from all those I have corrected.  In case you still need a clue on the “d-word”, it ends in irt.

As a horticulturist for 46 years, I have read, heard, and been told many secrets to growing good plants.  I still hold firm that without proper knowledge of how soil works, most of what we do is by chance.  Soil is a living entity comprised of parent material (sand, silt, and clay), air, water, organic matter (OM), and microorganisms.  It is this last item which makes our soils come to life.  If you have pets, then you know they need shelter, warmth, air, water, and food.  From this point forward think of soil microorganisms as the pets in your soil.  If you take care of them, they will take care of your plants.

Sandy Soil

Sandy soil without any organic matter at the Wakulla County Extension office.

There is a huge difference in habitat from a sandy soil to a healthy soil with a good percentage of OM (5% – 10%).  In one gram of healthy soil (the weight of one standard paper clip), you can have bacteria (100,000,000 to 1,000,000,000), actinomycetes (10,000,000 to 100,000,000), fungi (100,000 to 1,000,000), protozoa (10,000 to 100,000), algae (10,000 to 100,000), and nematodes (10 to 100) (1).  A teaspoon of healthy soil can contain over four billion organisms (2).  These microorganisms are part of the soil food web and they form a relationship between soil and your plants.  They help convert nutrients to useable forms and assist with other plant functions.

The question becomes how to take care of your soil pets.  For years we have performed practices that compromise these populations.  Growing up we put all of our grass clippings in the weekly trash.  We know now how valuable those clippings are and to leave them be.  Two practices still common today though are tilling and raking leaves.

OM Soil

Master Gardener Volunteer vegetable bed with organic matter added.

Tilling has a limited purpose.  If I place a layer of organic matter on top of the ground, then tilling incorporates the OM which feeds my pets.  Excess tilling of soil introduces large amounts of oxygen which accelerates the breakdown of OM thus reducing our pet populations over time.  Another adverse result from tilling is disturbing the soil structure (how the parent materials are arranged) which can reduce pore spaces thus limiting water percolation and root growth.  There is a reason agriculture has adapted no-till practices.

Raking leaves (supposedly the sign of a well-kept yard) is removing large amounts of OM.  Do you ever wonder why trees in a forest thrive?  All of their leaves fall to the ground and are recycled by the microorganisms.  Each of those leaves contains macronutrients (carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, sulfur, and magnesium) and micronutrients (boron, copper, chlorine, iron, manganese, molybdenum, nickel, and zinc) which are necessary for plant growth.  You would be hard pressed to find all those nutrients in one fertilizer bag.  So recycle (compost) your leaves versus having them removed from the property.

We are in our off season and tasks such as improving soil health should be considered now for soils to be ready in spring.  Remember a little organic matter at a time and never work wet soils.  As your OM levels build over the years, remember to change your watering and fertilizing schedules as the soil will be better adapted at holding water and nutrients.  Soil tests are still recommended before fertilizing.

If you would like more tips on improving your soil, contact me or your local county horticulture extension agents.  For a more in depth look at caring for your soils, read The Importance of Soil Health in Residential Landscapes by Sally Scalera MS, Dr. A.J. Reisinger and Dr. Mark Lusk (https://edis.ifas.ufl.edu/ss664).

  1. Chapter 2: Soils, Water, and Plant Nutrients.  Texas Master Gardener Training Manual.
  2. The Importance of Soil Health in Residential Landscapes. 2019.
Romaine: Lettuce of an Empire

Romaine: Lettuce of an Empire

Who doesn’t enjoy a fresh, crisp bowl of salad? Lettuce happens to be a vegetable that is easily grown in Florida for fall & winter gardens. In Florida, four types of lettuce are commonly grown: crisphead, butterhead, leaf, & today’s topic, romaine.

Photo courtesy of Tyler Jones, UF/IFAS.

An interesting, little known fact about romaine lettuce is that it was cultivated extensively by the Roman Empire. By the fourteenth century, the Catholic Hierarchy had moved from Rome to Avignon, France bringing their prized lettuce along with them. During this period, the plant was known as “Avignon” lettuce. In England, romaine is called “cos” lettuce named after the Greek islands from which the lettuce was originally distributed. Of course, in the U.S., the name we give, Romaine, refers to the time when it was grown extensively in the Roman Empire.

Romaine is grown both commercially and in backyard gardens across the state. Like all lettuce, this is a cool season vegetable. September through March is a generally the extent of the growing season. Romaine can be grown from seeds or by transplants. If you are going the seeding route, just remember these seeds are very small and should be sown shallow and in a tight pattern, with 12”-18” row spacing and a light sprinkle of soil over the top. Newly planted seeds may require burlap or straw to help retain soil moisture for successful germination. Once plants reach a few inches in height, rows can be thinned to where plants are 8” apart.

Romaine needs adequate soil moisture throughout the season. Mulching around plants to retain moisture and adding a complete fertilizer such as 8-8-8 will help ensure a good yield. Lettuce is vulnerable to the usual suspects of garden pests. However, gardening in cooler months helps combat that threat.

Romaine lettuce is fun and rewarding to harvest, as well. You can pick a few leaves off a plant or harvest the entire head.

For more information, contact your local UF/IFAS County Extension office.

Supporting information for this article can be found in the UF/IFAS EDIS publication, “Romaine – Lactuca sativa L.” by James M. Stephens, Emeritus Extension Vegetable Crops Specialist, UF/IFAS: https://edis.ifas.ufl.edu/mv125

UF/IFAS Extension is an Equal Opportunity Institution.

Using a Buckwheat Cover Crop in Raised Bed Gardens

Using a Buckwheat Cover Crop in Raised Bed Gardens

2020 has not been the most pleasant year in many ways.  However, one positive experience I’ve had in my raised bed vegetable garden has been the use of a cover crop, Buckwheat (Fagopyrum esculentum)! Use of cover crops, a catch-all term for many species of plants used to “cover” field soil during fallow periods, became popular in agriculture over the last century as a method to protect and build soil in response to the massive wind erosion and cropland degradation event of the 1930s, the Dust Bowl.  While wind erosion isn’t a big issue in raised bed gardens, cover crops, like Buckwheat, offer many other services to gardeners:

Buckwheat in flower behind summer squash. Photo courtesy of Daniel Leonard.

  • Covers, like Buckwheat, provide valuable weed control by shading out the competition.  Even after termination (the cutting down or otherwise killing of the cover crop plants and letting them decompose back into the soil as a mulch), Buckwheat continues to keep weeds away, like pinestraw in your landscape.
  • Cover crops also build soil. This summer, I noticed that my raised beds didn’t “sink” as much as normal.  In fact, I actually gained a little nutrient-rich organic matter!  By having the Buckwheat shade the soil and then compost back into it, I mostly avoided the phenomena that causes soils high in organic matter, particularly ones exposed to the sun, to disappear over time due to breakdown by microorganisms.
  • Many cover crops are awesome attractors of pollinators and beneficial insects. At any given time while my Buckwheat cover was flowering, I could spot several wasp species, various bees, flies, moths, true bugs, and even a butterfly or two hovering around the tiny white flowers sipping nectar.
  • Covers are a lot prettier than bare soil and weeds! Where I would normally just have either exposed black compost or a healthy weed population to gaze upon, Buckwheat provided a quick bright green color blast that then became covered with non-stop white flowers. I’ll take that over bare soil any day.

Buckwheat cover before termination (left) and after (right) interplanted with Eggplant. Photo courtesy Daniel Leonard, UF/IFAS Calhoun County Extension.

Now that I’ve convinced you of Buckwheat’s raised bed cover crop merits, let’s talk technical and learn how and when to grow it.  Buckwheat seed is easily found and can be bought in nearly any quantity.  I bought a one-pound bag online from Johnny’s Selected Seeds for my raised beds, but you can also purchase larger sizes up to 50 lb bags if you have a large area to cover.  Buckwheat seed germinates quickly as soon as nights are warmer than 50 degrees F and can be cropped continuously until frost strikes in the fall.   A general seeding rate of 2 or 3 lbs/1000 square feet (enough to cover about thirty 4’x8’ raised beds, it goes a long way!) will generate a thick cover.  Simply extrapolate this out to 50-80 lbs/acre for larger garden sites.  I scattered seeds over the top of my beds at the above rate and covered lightly with garden soil and obtained good results.  Unlike other cover crops (I’m looking at you Crimson Clover) Buckwheat is very tolerant of imperfect planting depths.  If you plant a little deep, it will generally still come up.  A bonus, no additional fertilizer is required to grow a Buckwheat cover in the garden, the leftover nutrients from the previous vegetable crop will normally be sufficient!

Buckwheat “mulch” after termination. Photo courtesy of Daniel Leonard, UF/IFAS Calhoun County Extension.

Past the usual cover crop benefits, the thing that makes Buckwheat stand out among its peers as a garden cover is its extremely rapid growth and short life span.  From seed sowing to termination, a Buckwheat cover is only in the garden for 4-8 weeks, depending on what you want to use it for.  After four weeks, you’ll have a quick, thick cover and subsequent mulch once terminated.  After eight weeks or so, you’ll realize the plant’s full flowering and beneficial/pollinator insect attracting potential.  This lends great flexibility as to when it can be planted.  Have your winter greens quit on you but you’re not quite ready to set out tomatoes?  Plant a quick Buckwheat cover!  Yellow squash wilting in the heat of summer but it’s not quite time yet for the fall garden?  Plant a Buckwheat cover and tend it the rest of the summer!  Followed spacing guidelines and only planted three Eggplant transplants in a 4’x8’ raised bed and have lots of open space for weeds to grow until the Eggplant fills in?  Plant a Buckwheat cover and terminate before it begins to compete with the Eggplant!

If a soil building, weed suppressing, beneficial insect attracting, gorgeous cover crop for those fallow garden spots sounds like something you might like, plant a little Buckwheat!  For more information on Buckwheat, cover crops, or any other gardening topic, contact your local UF/IFAS County Extension Office.  Happy Gardening!

Now is Time to Use Solar Power Against Soil Pests

Now is Time to Use Solar Power Against Soil Pests

North Florida vegetable gardeners have made it to summer and now the plants and gardeners are starting to give in to the heat and humidity. The squash has likely succumbed to squash vine borers, many of the tomato varieties are having trouble setting fruit, stink bugs are all over, and gardeners easily wilt by noon. This is a good time to use our oppressive heat to your advantage in the vegetable garden by solarizing the soil.

Graph of annual temoerature

We have reached the peak of heat. Use it to your advantage in the garden. Source: National Weather Service.

Soil solarization is a method of pest control that creates a greenhouse to heat up the soil in an effort to drive away pests. Pests that can be reduced with soil solarization include weeds, various soil-borne fungal pathogens, and nematodes. Weed seeds can actually be killed by the increased temperatures, sometimes as high as 140 degrees Fahrenheit, while fungi and nematodes are merely driven deeper into the soil layer as they try to escape the heat. Although they are not killed, this can help vegetable gardeners as it may take these organisms 3-4 months to repopulate in high enough numbers to cause damage. Soil solarization can be considered another tool in your integrated pest management (IPM) toolbox, along with other cultural, physical, and chemical means of pest control.

Picture of raised bed garden covered in plastic.

A raised bed being solarized over the summer. Source: Evelyn Gonzalez, UF/IFAS Master Gardener Volunteer.

To properly execute soil solarization, the site should be in full sun and the existing vegetation removed, either by hand or with a tiller or other implement. Tilling can help loosen the soil surface and allow heat to penetrate deeper in the soil horizon. Before being covered with plastic, the area should receive rainfall or be irrigated, as the water will help conduct heat to greater depths. The next step is to cover the area with plastic. Note that this can also be done over raised beds! Clear plastic is best for maximum solar radiation penetration. Black plastic will heat up mostly on the surface and opaque plastic sheeting may not let enough light in to get temperatures high enough. The plastic should be slightly larger than the area covered, as the edges will need to be buried to create an air-tight seal. It’s recommended to leave the plastic in place for at least six to eight weeks, just in time to begin fall gardening preparations.

It’s important to monitor the site while it’s “cooking” to look for any holes that might appear. Small holes can be repaired with duct tape, while large holes or rips in the plastic may require starting over. Overlapping strips of plastic is not recommended since too much heat will be lost.

You may be wondering what happens to all of the good soil microbes. Well, unfortunately, they are also either killed or suppressed. Fortunately, researchers have found that they are able to repopulate quicker than the pest organisms, especially in soils with a good amount of organic matter.

Much more information on soil solarization can be found in these two documents:

Introduction to Soil Solarization – https://edis.ifas.ufl.edu/pdffiles/IN/IN85600.pdf

Solarization for Pest Management in Florida – http://edis.ifas.ufl.edu/pdffiles/IN/IN82400.pdf

Also, please contact your local county extension office for more gardening tips.