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 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.
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).
Chapter 2: Soils, Water, and Plant Nutrients. Texas Master Gardener Training Manual.
The Importance of Soil Health in Residential Landscapes. 2019.
Daniel Leonard, Horticulture Agent at UF/IFAS Extension Calhoun County, answers commonly asked questions about raised bed gardening. In the video he discusses construction materials, the type of soil to use, fertilization, crop rotation, cover crops, and smaller container 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!
A common question for gardeners at the end of the season is if one should till the soil or use no till practices. Opinions vary regarding this question, even among Extension Agents. However old crops harbor insects, both good and bad. This phenomenon was noticed on some recently cut back tomato plants. The intention was to cut the leftover spring garden tomatoes back to encourage fall production. Instead, a host plant for mealybugs was provided.
Mealybugs on a tomato plant. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments. They are about 1/8 inch in length and usually pinkish or yellowish in color. Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental and vegetable plants. Mealybug damage produces discolored, wilted, and deformed leaves.
One very common example of an insect pest likely to claim residence in your garden’s crop residue, are squash bugs. They like to overwinter on squash, cucumber, and other cucurbit crop residue. If you choose to not till your garden and leave a portion of last seasons crop in your garden, then you should consider applying an insecticide to your spent crop at the end of the season. A product containing a pyrethrin or pyrethroid as an active ingredient would be a good broad spectrum insecticide to control any pest that may reside on plant residue. More information on pyrethrins and pyrehtroids can be found at the EPA webpage: Pyrethrins and Pyrethroids. If you choose to apply an insecticide, it is important that you follow the information on the label regarding pollinator protection. Another option is to plant a trap crop on the edge of your garden to help attract pest insects away from your desired crops. More information on trap crops can be found in the EDIS Publication: Intercropping, Pest Management and Crop Diversity.
An adult squash bug on a zucchini leaf. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
So the answer to the till or no till question is…it depends. It is really up to the gardener. Yes, the residue from crops will add nutrients and organic matter to your soil, but it could also increase pest pressure in your garden. If you don’t plan to remove crop residue and don’t plan to till, then keep an eye out for what could be hiding in your garden.
The insect ground pearls can damage many types of turfgrass in North Florida. Learn to identify ground pearl damage and find the insects in your soil with Larry Williams, Horticulture Agent with UF IFAS Extension Okaloosa County.
The first sign that something is going wrong in a plant is often a loss of the color green. When a sago is forming all new yellow leaves it is a matter of concern. Typically, this a common nutritional deficiency – manganese. Sandy soils of the Panhandle have a hard time retaining nutrients. Manganese and other micronutrient availability is highly influenced by soil pH. Being an essential plant nutrient, manganese is critical to growth. More specifically, it is the base of the metalloenzyme cluster of the oxygen evolving complex (OEC) in photosystem II (PSII). I hope that means more to you than it does me. Basically, manganese is part of the photosynthetic activity and since it isn’t very mobile in the plant, the new growth of sagos turns yellow.
If the nutrient deficiency isn’t corrected, the newly-formed leaves will become deformed and turn brown. In a sago this is referred to as “frizzle-top”. Many people believe the plant has a disease when they see the symptoms and may apply fungicides to no avail. Keep in mind the discoloration of the affected leaves cannot be reversed. However, manganese replacement in the soil will enable the sago to form normal leaves with the next growth phase. Damaged fronds can be removed later to improve the appearance of the sago over time.
Begin this process by determining the soil pH through a soil test. Your local Extension office can help you obtain lab submission forms and explain the collection procedure. Manganese is most available for uptake by sagos when the soil pH is between 5.5 and 6.5. If the pH is above 6.5, larger amounts of manganese will have to be present before the plant can utilize it. When the soil pH is below 5.5 the nutrient is quickly leached out of the soil during rain events.
To correct a manganese deficiency the sago plant will need to receive manganese sulfate. The product is readily available at local nurseries, garden centers and building supply stores. The amount needed for each plant will vary with the size of the sago and the existing soil pH. Sagos growing in sandy, acidic soil will require less manganese sulfate than those in high pH soils. Refer to the package label for application rates.
