The soil provides food and water to plants. If these materials are not available or if the soil is in poor physical condition (hard and crusty when dry and sticky when wet) the plants will not grow and develop properly. To promote good growth and development of your plants, prepare the soil before planting by adding organic matter, applying fertilizers, correcting acidity, and plowing the seedbed properly. Take care of the soil during the growing season by applying starter fertilizer and by side dressing with fertilizer.
Improve soil tilth. A soil that is in good tilth, or physical condition, is loose and easy to work, and has proper water-holding capacity, drainage, and aeration. You can improve your soil tilth by adding organic matter, either by spreading manure, compost, or similar matter on the soil and working it in before planting or by turning under a green-manure crop.
Stable manure is a common form of organic matter used in gardens, although it is not readily available. It can also fulfill part of the fertilizer requirements of the soil. Because stable manure is low in phosphorus, add 1 to 1½ pounds of superphosphate to each bushel of manure. Use 500 to 1,000 pounds of horse or cattle manure per 1,000 square feet. Poultry, sheep, and goat manure should be used at half this rate.
Compost is an excellent source of organic matter and is easy to produce. It can be made from leaves, straw, grass clippings, manure, and any other disease-free waste vegetable matter. To make compost, pile these materials in layers as they accumulate during the season. Add 1 pound of a lime-fertilizer mixture to each 10 pounds of dry refuse; add ¼ pound to each 10 pounds of green material. The mixture can be made from 5 pounds of 10-10-10 fertilizer plus 2 pounds of fine limestone. This fertilizer treatment will hasten decay and improve the fertility of the compost. Spread soil over the material to hold it in place (Fig. 1). Water the pile to keep it damp and occasionally turn and mix the soil and decaying material. The pile will be ready to spread over garden soil in 6 to 12 months.
Green-manure crop. By growing a green-manure or cover crop, such as rye or oats, during the fall and spring and plowing it under, you can improve your soil tilth. The seed can be broadcast over worked-up unplanted areas and between rows of late vegetables. Stir the seed into the soil with a rake, hand cultivator, or harrow.
Fertilize the soil. Fertilizer applications should be made before planting. Later in the season additional applications may be necessary.
Have your soil tested, especially if it is your first year in your present location. A soil test will indicate the amount and availability of nutrients in your soil. Gather small amounts of soil from about eight well-scattered spots in your garden, mix them together, dry at room temperature, wrap in a sturdy ½-pint container, mark the container "For Vegetable Garden" with your name and address, and send to the nearest county soil testing laboratory or contact your county extension office. In a few weeks you will receive the results of the test along with fertilizer and lime recommendations for your garden.
If you do not have your soil tested, you can follow a general fertilizer recommendation of adding 1 pound of an all-purpose fertilizer such as 13-13-13 per 100 square feet.
The main elements applied through fertilizers are nitrogen, phosphorus, and potassium. When considered as fertilizer, they are usually referred to as nitrogen (N), phosphoric acid (P2O5), and potash (K2O), respectively. A fertilizer marked 3-12-12 contains 3 percent nitrogen, 12 percent phosphoric acid, and 12 percent potash.
Trace or minor elements are very rarely needed in Illinois soils.
Work fertilizer into the soil. Spread the fertilizer over the garden area and disk or rake it into the top 4 inches of soil before planting each crop. Or you can apply the fertilizer to the soil just before spading or plowing in the spring or fall.
Use starter fertilizer when transplanting to give your plants a faster start. Starter fertilizer is an all-soluble fertilizer high in phosphorus, for example 10-52-17 or 10-50-10. Mix the fertilizer with water (about 1 tablespoon per gallon of water). When you transplant, place about 1 cup of the solution around the roots of each plant. If a regular starter solution is not available, mix 1 cup of 0-45-0 or similar fertilizer in 12 quarts of water and use 1 cup of solution for each plant.
Side dress fertilizer later in the season. Often the soil needs more fertilizer, especially nitrogen, later in the season. Side dressing - applying fertilizer in a band along one side of the row about 4 inches from the crops - should be made for leafy crops, greens, and root crops when the plants are half-grown and for tomatoes, peppers, beans, sweet corn, cucumbers, etc., when they begin to set fruit. Use 2½ pounds of ammonium nitrate, 2 pounds of urea, or 5 pounds of nitrate of soda per 1,000 square feet. Avoid getting dry fertilizer on plant leaves as it will injure them. Hoe the fertilizer into the soil surface. In dry weather, water the soil to make the fertilizer more quickly available to plant roots.
Correct soil acidity. A slightly acid soil is best for growing most vegetables. If the soil test indicates that your soil is more acid than it should be, apply the recommended amount of lime. Add lime only if it is needed and avoid overliming.
Some soils are too alkaline. This can be corrected by adding sulfur to the soil. A soil test will indicate whether your soil is too alkaline. Work the lime or sulfur into the soil at the same time that you apply fertilizer.
Plow and prepare the seedbed properly. Plowing or spading can be done in either the spring or the fall. With fall plowing the soil can be worked and planted earlier in the spring, but not as much cover crop can be grown as with spring plowing.
Do not plow or spade the soil when it is too wet. A good test is to squeeze a handful of soil in your hand. It should crumble and not feel sticky.
You may apply fertilizer just before plowing or spading. Turn the ground over to a depth of about 8 inches. If fertilizer is added to the soil after plowing, rake or harrow the plowed area to work the fertilizer into the soil.
Just before planting prepare the seedbed for planting by working the soil with a rake or harrow. A freshly prepared seedbed will prevent weeds from coming up before the vegetables.
For small-seeded crops a smooth and finely pulverized surface insures easier planting, better germination, and a more even stand. Heavy soils low in organic matter should not be worked into too fine a consistency because they tend to get hard and crusty, preventing emergence of seedlings. Many Illinois soils should not be overworked.