Starting with the Soil: Nutrition in the Garden
The days are getting longer, the weather fairer, and the spring songbirds are becoming restless. While it may be hard not to fantasize about the tender, fresh shoots that arrive just before summer, there is much work to be done below the surface before gardeners can reap the fruits of their labor. Every type of garden – raised, in-ground, window box – comes with its own challenges for soil maintenance and nutrition. Soil, which is a rich and complex system, requires maintenance before planting can begin. A little bit of hard work, some knowledge, and a whole lot of love will prepare a garden to be productive and rewarding.
The first step for determining a new garden location is to decide on the construction of the beds. Raised beds, or mounds of earth that are raised about 6 to 8 inches above ground level, are beneficial where soil quality is lacking, as they provide an opportunity to amend existing soils with augmented nutrition. They also function as a solution to lowlying areas that are prone to flooding, lifting the plants out of the water’s path and allowing for proper drainage. A raised bed built with a frame system to stand at waist height can be an accessible option for gardeners with physical impairments or who’d prefer not to crouch and bend. Once these raised beds are established, materials must be added periodically to maintain the desired height and quality nutrition within the soil.
One problem encountered by many first-time Ozarkansas gardeners who choose to plant directly into the ground is overly compact soil. Rain and gravity, along with foot or mechanical traffic, will compact soil over time, impeding root growth and nutrient absorption. When establishing garden beds, gardeners must make a decision between till and no-till methods of preparing the soil for planting. Tilling can be an efficient mechanical method of breaking up soil, incorporating nutrient-rich surface soil into the root zones. By disrupting the growth of existing plants, tilling also may reduce or eliminate competitive vegetation.
However, many farmers are skeptical that tilling is necessary, or even beneficial, to soil health. Patrice Gros at Foundation Farm, a small-scale, organic farm in Carroll County that offers fresh food, inspiration, and education to its surrounding communities, is an advocate of no-till methods. Patrice aims to recreate nature’s processes on his farm by forgoing interventions such as composting and tilling.
“Tilling destroys the natural components of the soil, such as the structure and microbiology,” he says. Patrice advises against tilling in order to “protect and preserve the soil biology.”
Another reason to avoid tilling is that compaction zones can form just beneath the reach of the tillers blades, leading to sections of impenetrable soil that hinder root growth and causing water pooling beneath the surface and above the layer of dense soil matter. Mixing in organic matter adds valuable nutrients and breaks up dense areas of soil. Compost is a valuable source for nutrient-rich soil.
Conventional wisdom maintains that home composting, especially of kitchen scraps or yard and garden wastes, is a useful way of improving soil structure by allowing it to maintain moisture and increasing its ability to easily crumble.
Gathering of food scraps for a compost pile begins indoors. Consider storing scraps in a specific compost container, such as a stainless steel bucket with a lid, to prevent unwanted pests and odors. Every few days, the indoor scraps should be transferred to an outdoor pile.
For the optimal outdoor compost pile, find a place with several hours of sunlight, as heat helps decomposition. An ideal compost bin doesn’t need to be elaborate, it simply needs to hold ingredients so that the soil can heat up and activate the bacteria for decomposition. Self-contained bins should retain heat and moisture and be turned periodically.
Some compost bins come with a handle that allows for easy rotation, though a simple compost pile and gardening fork work fine. Turning compost adds oxygen, which speeds up breakdown of organic matter. It moves surface material to the interior, where the bacteria is more active, aiding in decomposition.
When building a healthy compost mixture, diversity is essential. Each component activates different naturally occurring microbes that work together to promote decomposition. The key ingredients for making compost in the garden are the “greens,” the “browns,” and bulk matter. “Greens” are fresh green matter, which can include fruit and vegetable scraps, coffee grounds, grass, or leaves. The “browns” are dried leaves or dried plant material, wood chips or sawdust, straw, and scrap and shredded paper. Bulk matter such as sticks should be cut down to aid in decomposition.
A good ratio is 70 to 80 percent browns, 20 to 30 percent greens, and just a bit of bulk. This will establish an ideal equilibrium between nitrous and carboniferous components. If a mixture is odorous, it has too much green material. A pile that is dry or not decomposing sometimes needs more green material and less brown.
Composting isn’t praised by everyone. Similar to his stance on tilling, Patrice says he believes that composting isn’t necessary to increase the productivity of the soil and that “nature does the work for the plants.” Instead of composting, Patrice plants cover crops, such as oats, that seasonally add to the biomass of his garden and contribute their own valuable nutrients. He allows natural elements, such as leaves, to provide the organic matter for his plot.
Heavily mulching a garden space also benefits the soil. Mulch helps retain moisture in the bed, assists in weed control, and as the mulch breaks down, those nutrients benefit the soil.
When prepping a garden and establishing compost, it is important to consider what nutrients plants will need and where they will get them. Healthy soil yields healthy produce, and Calvin Bey, of Harmony Gardens, a venture based in Washington County that was created to provide useful information on gardening, health, and sustainability issues, has led many workshops that focus on soil health and the nutritional value of produce. In addition to being healthier for consumers, nutrient-dense food is shown to have a longer shelf life.
One way of measuring the nutritional value of produce is through a Brix measurement. Brix is a term that refers to the sugar and mineral content in the juice of plant leaves and fruit. It is measured with a refractometer, and the measurement process is simple. First, collect the juice, and place it in the refractometer. When light passes through the liquid, the device measures the relative amount of sugar and minerals. It gives a reading that varies with the amount of soluble solids.
“The higher the reading, the higher the sugar/ mineral content will be,” Calvin says. He also says he is optimistic about the future of these metrics. “Regarding commercial use, we are just beginning to see farmers and marketers using the Brix as an indicator of fruit value. We will see more of this as the public demands knowing the quality of fruit that they are purchasing.”
But before growing healthy, nutrientdense produce, one must first have healthy soil. Macronutrients, such as carbon and nitrogen, are nutrients that plants require in large amounts. Micronutrients are those that plants need in only small or trace amounts, but are nonetheless important to soil nutrition and health. Calvin stresses that knowing and understanding what nutrients are important, and what a specific garden’s soil might require, are keys to creating a healthy and productive garden.
Nitrogen is an important component in soil health. It is easily added to compost through materials such as the “black gold” of highly nitrous coffee grounds, tea leaves, and other common table scraps. The element promotes cell growth and the utilization of chlorophyll during photosynthesis. It is responsible for the growth of new leaves and shoots, though too much nitrogen can cause stunted growth and delayed maturity. To combat an excess of nitrogen in compost, add carboniferous components such as dry leaves, straw, or wood ash.
Phosphorus and potassium are also important macronutrients. Potassium keeps cells and cell fluid in motion and helps plants retain moisture. It works to regulate and activate plant enzymes, and plants lacking potassium will be weak and misshapen, causing them to drop fruit prematurely. Similarly, plants that lack phosphorus will be stunted and will fruit late. Nutrients such as calcium, magnesium, and sulfur are equally important and often must be introduced by way of organic fertilizers.
Calcium facilitates cell division, and without it plants will yellow and their leaves can curl. Soil that lacks calcium produces plants that can have blackened shoots and stunted growth. Because calcium is crucial in helping plants absorb other nutrients, it is a keystone in a healthy soil system. Magnesium plays an important role in photosynthesis. Sulfur has been found to increase the protein content of vegetables.
Micronutrients such as zinc, boron, copper, manganese, and chloride are also important to soil health. The majority of these nutrients can be found in good home compost, and those that are lacking can be easily added through organic fertilizers.
“Not all soils are the same, but soils need organic matter,” says Mary Savin, a soil science professor in the Dale Bumpers College of Agricultural, Food and Life Sciences at the University of Arkansas. “It potentially will take time and care to cultivate a healthy soil. Keep the soil in place; prevent erosion.”
It can be difficult to visually diagnose excess or insufficient minerals in soil, and many problems with soil have symptoms similar to diseases. Knowing what specific nutrients soils require is important in maintaining a healthy garden.
“History is important, and what one owner may have to do to manage his or her soil might be different than another will have to do because of previous land use and/or existing conditions,” Mary says. “Soil tests are important. Know your soil conditions, and then work to improve them. Soils are dynamic. They change over time.”
The University of Arkansas System Division of Agriculture Cooperative Extension Service offers free soil testing that can determine what macro and micronutrients are lacking or in excess and can offer recommendations for improving soil health. Knowing the soil’s contents is helpful in determining what nutrients the soil might be lacking and what to add to help the plants grow best. To test soil, gather approximately one pint of dry soil from each garden bed and take it to the local Extension Service office.
“Remember that soil is living,” Mary says. “The soil is so important for providing so many of the functions that we depend on. Soil cleans our water and air, controls climate, regulates gases, stores water, and provides a habitat.”
She encourages gardeners to think holistically when approaching something as intricate as soil. “Nutrients are recycled, and contaminants are broken down in soil,” she says. “Food and fiber are grown in soil. It is so important to take care of the system.”
While healthy, nutrient-dense soil also yields nutritious and satisfying produce, and establishing the proper beds and understanding and balancing a soil’s nutrition profile are crucial in establishing a healthy home garden, it is important to remember that there are multiple strategies for achieving this goal.
“As you will find in agriculture, especially sustainable and organic, there is no ‘one way,’” says Curt Rom, a professor of horticulture at the University of Arkansas. “There are many options and many compromises to be made.”
As home gardeners consider different methods of preparation, it is important that they evaluate each option to find the best choice for them. Underneath each luscious tomato and tender lettuce leaf is healthy soil. The involved yet rewarding work of gardening begins with preparing below ground for successful planting and a bountiful growing season.