Beginning gardeners can oftentimes be confused about how to best fortify their soil when so many varieties of fertilizers are available. Some are specifically formulated to accomodate the needs of particular plants, and this can simplify matters. Azalea fertilizer, for example, is intended for plants like azaleas, rhododendrons and camellias that thrive in acidic soil. If pH balance is not a concern in one’s garden, however – and if it hasn’t already been conditioned in the past – then the choice of fertilizer can boil down to personal taste as well as what is conveniently available.
Conventional fertilizers are fast acting: they can condition the soil and make it ready for planting almost instantly. They are also less costly than organic or slow-release types. However, conventional fertilizers can easily burn the roots of budding plants because they have such concentrated amounts of potassium, phosphorus and nitrogen. They should be applied, and well watered-in to the soil, before any planting is done. Their nitrogen can easily leach into the ground, too, because it is freely exposed to contact.
Because different plants assimilate various nutrients at differing rates, some gardeners opt for slow-release fertilizers. There are a few ways in which these are formulated to release their nutrients over time. Some are composed of materials that dissolve slowly. Others only release their nitrogen after microorganisms in the soil decompose them. Still others are granular materials coated with resin or sulphur to control the rate in which nutrients filter out into the garden. Slow-release fertilizers don’t need to be applied as often as conventional ones (because little nitrogen is wasted), and they pose less of a danger to plants’ roots. They may be more difficult for one to find, however, and they are more expensive, per unit, as a rule.
When fertilizers are labelled “organic”, this simply means that they have been derived from the remains or by-products of living organisms. Organic fertilizers include cottonseed meal, blood meal, bone meal, hoof and/or horn meal, and manure. Most are complete in themselves (meaning that they supply the three nutrients that are of primary importance to gardeners: nitrogen, phosphorus, and potassium), but they usually have a lower nutrient concentration than conventional fertilizers. This is especially true of manure, which offers less nutrients for the price than most other kinds and may also contain excess salt, weed seeds and possible even heavy metals (if it comes from a large, industrial city). Manure is also bulky and a bit unweildy; and, of course, odorous. Many gardeners still swear by it, however, because it is so rich in organic materials and in many ways resembles composted soil more than fertilizer. This holds true whether it is derived from horses, cows, pigs, chickens, or sheep.
Fertilizers come not only in a plethora of varieties but also forms. We can buy liquids (intended to be distilled with water), tablets, granular solids, water-soluble powders, and pellets. Some of these are intended only for slow-release, with all the advantages and disadvantages that come with that. For the rest, it is usually only a matter of personal taste – i.e., what will be most convenient for you to apply to your garden.