Fertilizers composed of natural materials offer an alternative to the premixed formulas available for purchase. Organic materials applied as fertilizer are only effective for your tomato plants when soil is adequately moist and warm enough to promote soil organism activity. Microorganisms in the soil have to break down the nutrients as part of the decay process before tomato plants can absorb the nutrients in the organic material. Due to rapid growth and high fruit production, tomato plants have relatively high fertilizer needs.
Either composted or raw manure may be used to fertilize tomatoes, though its NPK content is only around 2-1-1, according to the University of Minnesota Extension, and therefore should not be depended upon as the sole fertilizer. Composted manure, which may be mixed with yard waste during composting, has a reduced risk of containing pathogens. Raw manure may also be applied to the garden, provided it has or will have the opportunity to age before you plant tomatoes. Apply a layer of 1 to 2 inches of raw manure in the fall and then work it into the top six inches of soil. Never apply raw manure near growing tomatoes.
Rather than purchasing bone meal, which is a costly albeit rich source of phosphorous, gardeners can make their own bone ashes. Collecting any type of animal bones, burn them and save the ashes. Apply the bone ash at a rate of 3 to 5 pounds per 100 square feet and till in before planting tomatoes. Bone ash supplies 22 to 27 percent phosphorous, which is good for tomatoes because they have high phosphorous needs.
Though a smelly process, gardeners can make their own fish emulsion to add nitrogen to the soil. A typical fish emulsion contains one part fish waste (intestines and other discarded parts) and two parts water, mixed and allowed to begin rotting. For tomatoes, apply fish emulsion at a rate of 2 gallons per 100 square feet prior to planting. Tomatoes grow best if they do not have too much nitrogen early in the growing season, which encourages heavy foliage growth but poor fruit set. Diluted fish emulsion may be applied as side dressing when the earliest fruit is about one third grown and then again after picking the first ripe fruit.
The ashes from burning wood contain potash, a form of potassium, as well as boron, phosphate and other elements. Wood ashes will raise the soil pH level, just as limestone does, although twice as much is needed for the same effect. Spread ashes in the desired area in late fall or winter and then till it into the soil in the spring. Do not allow unincorporated ashes to come in contact with tomato seedlings or plant roots. Apply no more than 20 pound of ashes per 1000 square feet, advises the University of North Carolina, because large amounts of ashes in your garden could be toxic.