Although there are limited studies conducted on the differences in nutrients between tomatoes grown by traditional farming methods and those grown organically, a study conducted by Hallmann E. and Rembialkowska E. (2007) involving five tomato cultivars revealed that those grown organically contained higher levels of sugar, Vitamin C, flavones and beta carotene, but less lycopene. Whether this holds true for all organically grown tomatoes is unknown, but suggests that organic soil produces tomatoes with enhanced flavor and high in vital nutrients.
Organic soil is enriched by a number of practices such as crop rotation and the use of green manure, cover crops, composted manure and lime or rock phosphates to amend the soil. These practices provide nutrients in usable form, reduce the risk of insect and disease, retain moisture and improve the texture and quality of the soil.
Well-rotted manure worked into the existing soil in fall (or early spring before planting) allows time for the release of vital nutrients into the soil where it becomes accessible to the tomato plant. A rate of 10 to 15 tons per acre is applied in commercial production. For home gardens, a quart or two of manure mixed into the existing soil before planting provides the nutrients a tomato plant requires.
Legumes as Cover Crops
Legumes grown as a cover crop and tilled into the soil in the fall or early spring provide supplemental nitrogen. Legumes "fix" nitrogen in the soil, as they are able to use nitrogen directly from the air and deposit excess nitrogen into the soil. In the home garden, growing tomatoes in an area where legumes were grown the prior year is recommended.
Compost adds organic matter to soil, improving texture and promoting good drainage. For the home gardener, a compost bin provides ample amounts of organic matter for tomatoes. Kitchen scraps, grass clippings, leaves and dried plant material break down quickly in a compost bin, providing rich loose soil for planting.
Tomatoes prefer a pH level of 6.0 to 6.8. If pH levels decrease, the soil becomes acid and prevents the uptake of vital nutrients. Calcitic or dolomitic lime (both made from finely ground limestone) raise pH, but dolomitic limestone contains high levels of calcium. Unless there is a deficiency of magnesium in the soil, calcitic limestone is recommended. Mix lime in well with the existing soil.