The Inside Scoop on Shovels
The shovel is perhaps the best multiuse tool in our garden sheds. Dig a trench, turn over some sod for a new garden patch, make cement, move a pile of manure, compost, gravel or sand--nothing is so essential in these basic tasks as a well-worn shovel. It's so familiar that hardly anyone thinks about how it works. But let's take a closer look.
To American gardeners, a shovel means a round-point, cupped, steel blade attached to a four-foot handle. The tool evolved into its present form for railroad construction in the mid-19th century.
European gardeners hardly recognize such a tool--their traditional digging implement is a short-handled spade with a nearly flat blade.
Both tools have solid garden roles, but each is designed for different tasks. The straight edge of a spade is for cutting. It can't be beat for lines that are true and smooth-sided trenches. (The word is related to the Greek word for sword.) With its short handle, a spade is well suited for work in confined spaces--down near the ground or among plants. A shovel is shaped to lift and toss earth or gravel. (It's a linguistic cousin of "scoop.") The long handle lets you work standing erect and increases the reach of your throw. Many Americans, however, use the word "shovel" indiscriminately to mean either a shovel or a spade.
How a Shovel Works
The shovel consists of three tools in one: a handle (lever) and a cutting blade (inclined plane) formed on the leading edge of a scoop. The blade cuts into the soil by concentrating muscle power or weight onto the sharp point. The handle provides leverage for lifting or prying the soil. The fulcrum for the lever action is the surface of the soil when the blade is inserted for digging. When you dig, you first cut and then pry. The longer the handle, the greater the leverage.
The earliest digging tools were fashioned completely from wood. Probably the oldest known is a digging stick from 60,000 years ago unearthed in Zimbabwe. Shovels with separate blades begin to shup in the archaeological record about 5,000 years ago. Dr. Lucy Lewis Johnson of the anthropology department at Vassar College says shovels made from the shoulder blades of animals were used in northern European flint mines around 3,000 B.C. Too soft for digging, shovels of bone were probably used to remove material loosened by a pick or mattock.
Thanks to iron metallurgy, devices very similar to both our spade and shovel were going strong by Roman times. When Cato the Censor (234-149 B.C.) compiled the world's oldest surviving tool catalog, he specified that a commercial olive grove of about 150 acres required eight heavy spades, four smaller spades and an unspecified number of shovels (along with assorted axes, scythes, wedges, manure baskets and an olive-crushing mill).
At the hardware store you'll find shovels and spades in several grades, ranging from flimsy "economy" tools to industrial-grade, husky versions; the middle ground is best for most home gardeners. Most homeowner-grade shovels and spades employ hollow-back construction. "Construction-grade" tools are usually solid shank. These terms refer to how the manufacturer forms the socket to join the blade and handle.
Solid-shank tools have both blade and socket forged from a single bar of metal. Hollow-back shovels are usually stamped from a metal sheet that's rolled over to create a depression called a frog. Some shovels have a plate welded over the frog to increase strength and keep the wooden handle drier and less prone to decay.
The solid-shank construction is stronger at precisely the point where the greatest forces are exerted on the tool--the fulcrum. If you're working very heavy soil or prying lots of roots and stones, solid shank is the way to go. Hollow-back construction, however, produces a lighter, less fatiguing and less expensive tool.
Handles come in two flavors--long and short. Short handles are usually topped with a long handles are sometimes shaped to provide easy gripping surfaces. The traditional handle material is northern hardwood--usually ash, sometimes hickory. Both combine great strength with a reasonable flexibility. Some manufacturers have also introduced handles of fiberglass and epoxy, sometimes reinforced with carbon fibers. They're a little lighter than wood, less likely to break under extreme loads and resistant to water and decay.
The angle at which blade and handle meet is the lift. Spades typically have very little lift, thus maximizing the force you exert on the back of the blade with your foot. The standard lift in the North American garden shovel is about 37 degrees--a concession to the tossing (as opposed to digging) function of the tool.
Early studies of shovel design efficiency in coal mining concluded that shovels should have short handles and that shovelers could work at about 21 scoops per minute, moving loads of 11 to 24 pounds. Of course, these studies also suggested that the best position for shoveling was to kneel--appropriate perhaps in a mine hole but rarely for gardeners.
About 10 years ago, when industrial engineer Andris Freivalds, a professor at Pennsylvania State University, studied design efficiencies of shovels, he provided scientific support for common practice. He tested square versus rounded blades, short versus long handles, weight of shovels and varying degrees of lift. He measured energy expenditure by analyzing gas composition of the subjects' respiration, looked at compression forces in the lower back and gathered the diggers' subjective ratings of perceived exertion.
We'll skip the detailed data and complex mathematical analysis and get straight to Freivalds's useful recommendations for "the design of the common, all-purpose shovel." They're also good guidelines for buying a shovel. He suggests a lift angle of "approximately 32 degrees," which compares favorably with the standard 37 degrees. Lift of 48 degrees reduced back strain considerably because the subjects could stand up straight, but the material kept falling off the shovels when they went to move it. Freivalds also found a long handle far superior to a short one for scooping and moving earth from one spot to another because it promoted upright posture.
He recommended a "large square-point blade for shoveling" and a "round-point blade for digging." The square blade carries a larger load, whereas the rounded blade presents a more efficient cutting surface. The traditional square blade of a spade may derive from its historical use as a tool to cut peat, sod or soft garden soil, none of which provide much resistance to the blade.
Based on his studies, Freivalds also recommended minimizing weight without sacrificing too much strength or durability. In his sand-shoveling task, the hollow-back construction allowed subjects to work longer with less fatigue.
When you apply Freivalds's recommendations to the classic American shovel, it passes the test as an excellent all-purpose tool--the best choice if you're going to get by with just one. But certain tasks go easier with specialized tools, which is why manufacturers produce dozens of designs in varying grades.
Two variations on the shovel and spade are especially handy. Sometimes called floral or border spades, they're simply scaled-down versions of the garden spade. My border spade, for example, has a 5- by 9-inch blade, compared with a standard 7- by 12-inch model. It's especially useful for tasks in cramped quarters, like digging perennials among overgrown shrubs. The border spade is also a good fit for gardeners who tire quickly using larger versions. Another useful variation is the ditch or irrigation spade. It has a long, slender blade and a short handle--perfect for digging narrow trenches.
Safe and Comfortable Use
Most gardeners recognize that shoveling can be a real pain in the back. But Jerome F. McAndrews, vice president for professional affairs of the American Chiropractic Association, points out that most shovel-related injuries don't occur while digging. It's moving the dirt that's the problem. He advises using a long-handled shovel so you don't have to bend down so much, and varying your position when shoveling for a long time. "The key," McAndrews says, "is to work muscles on both sides of the body." He notes that muscle spasms when shoveling often occur in cool weather. "It may be spring," he says, "but remember that cool air will constrict the blood vessels exactly as you're calling on those muscles for extra exertion."
Choosing and Buying a Shovel
Whether you're buying a shovel or a spade, make sure it's a good fit. If your garden consists of nice, loose loam, consider the lighter, hollow-back construction. Heft several examples to gauge comfort. One hand should grasp the handle at the thick point above the shaft; the other should fit in the thinned handhold toward the top of the shaft.
Look for a warranty of around 10 to 15 years, good handle materials and heavier-gauge metal. Expect to spend at least $25 to $30 for each tool. Solid-shank versions are usually part of the professional line and can be hard to find in some hardware stores and garden centers. They usually carry a lifetime warranty and will cost another $20 to $25.
The strategy I favor is to look for American shovels and British spades. For shovels, established makers are Ames, True Temper or Union. They all offer shovels in at least three grades. All three companies also make fine spades. The British market, however, favors spades in the garden, so British makers have far more practice making spades. Both Spear and Jackson and Bulldog are available in the U.S., primarily via mail-order companies.
David Lyons gardens in Cambridge, Massachusetts, with a solid-shank garden spade, a hollow-back shovel, and a garden fork.
Photography by Sabin Gratz & National Gardening Association