A lot is asked of soil in the vegetable garden. It must produce a variety of mostly fast-growing plants that produce massive crops of vegetables. The vegetables utilize nutrients from the soil in part to produce these massive crops, along with water and sunlight. Prepare and maintain the soil in your vegetable bed as though it were the most important component of your garden. It is.
Vegetables grow best in fertile, loose, well-drained soil that is rich in organic matter. If you have clay soil, it most likely takes a long time to warm up in spring, retains a lot of water and the surface may crust over during extended dry weather. Sandy soil has a loose structure with a lot of large particles that create air pockets. It warms up quickly in spring but dries out fast, due to its fast-draining structure. Loam soil--considered the perfect garden soil--is a balance of organic matter (compost and rotting plant materials), clay and sand. It has a loose structure with a lot of airspace for roots to grow into and for water to penetrate. Soil with predominantly clay or sandy structure can be amended with the addition of peat moss, compost, manure, wood chips, leaf mold and in the case of clay soil, coarse sand. The peat moss will add a bit of acidity to the soil's pH level, which will benefit the vegetables that prefer their soil to be slightly acidic.
It's possible to improve the fertility of your soil using organic compounds and forgo the use of chemical fertilizers altogether. Make compost using waste from your garden and fruit and vegetable scraps from your kitchen. In its simplest form, the raw ingredients for compost are piled up in an obscure corner of the yard and left to sit until the following season, when they are then added to the garden soil. You can accomplish much the same thing by growing a cover crop. Plant annual ryegrass or clover after you harvest your late summer crops. You can even plant cover crops between the rows of currently growing crops during August and September, according to Ohio State University Extension. The cover crop will also protect your garden from soil erosion during winter. Early the following spring, turn the cover crop under and allow it to decompose for two to three weeks before planting your vegetables. A cover crop can be planted any time of the year and turned under after a few weeks' growth.
Mulched soil in a vegetable garden is generally more productive than soil that is not mulched. Mulch regulates the temperature of the soil and prevents moisture from evaporating rapidly, thus keeping the plants' roots cool and moist. Wind and water can erode the soil and carry it away bit by bit. A mulch will help minimize soil erosion and maintain the depth of its fertile layer. If you use an organic mulch such as hay, straw, wood chips, cocoa hulls, shredded leaves or bark, it will add to the increased fertility of the soil as it decomposes. Mulch will also suppress the growth of weeds, which will benefit your vegetables.
Many pests and diseases that bother or devastate garden vegetable crops live in the soil. It is therefore necessary to rotate crops, never growing the same variety of vegetable in the same exact spot in the garden two years in a row, and preferably three. Tomatoes, potatoes and the cabbage family (broccoli, cauliflower, mustard greens, Brussels sprouts) are the most susceptible to attack by soil-borne pests and diseases, although it is important to rotate all vegetable varieties.
Maintain the soil in your vegetable garden regularly to keep it fertile with a loose, friable structure. Use a shovel or rototiller to turn the soil over at least once a year in spring (or fall if it suits you). Regularly add as much compost as you can make with your garden and kitchen scraps and plant a cover crop that can be turned under in spring or fall, or both. If your soil is heavy clay or very sandy, it may take several years of amending the soil before it begins to resemble the perfect garden loam. Continue adding peat moss, manure, compost, wood chips and leaf mold each year by placing at least 2 to 8 inches of a combination of these soil amendments on the surface of the soil. Incorporate them into the soil by turning over the top 10 to 12 inches with a spade or rototiller.