Merits of Organic and Chemical Fertilizers

Traditional organic fertilizers are derived from once-living tissue. Examples are processed sewage such as Milorganite, bone meal which is mainly phosphorus, tankage, fish craps, cottonseed meal, corn gluten, soybean residues, etc. Several such ingredients maybe mixed, and may be "souped up" with chemical concentrates. In general they are weak, of low analysis. The analysis may be something like 5-3-2 rather than 10-6-4 or better. As a result, organics are usually more expensive than inorganic fertilizers per unit of nutrient. But of course they have the advantage of organic rnaterials - the ability to improve soil structure and release balanced nutrients slowly

Inorganic or chemical fertilizers, in contrast, are a better bargain. But they are more hazardous in the sense that careless application may bum foliage. Granular, non-dusty formulations are less likely to cause this difficulty, because the pellets roll easily off vegetation and onto the soil. Chemical fertilizers are quickly soluble, so their effect is immediate; grass may green within a day or two after fertilization. But by the same token, effects are not so long-lasting.
Much depends upon the kind of soil. Soluble fertilizers leach through sandy soils almost immediately and are spent quickly. On heavier soils the nutrients may be held by the clay, constituting a kind of "savings bank" upon which the plant roots can draw over a prolonged period. This is especially true when soil temperatures are cool - in the lower 50's.

Of recent years, man has somewhat bridged the gap between organic and inorganic fertilizers by synthesizing organic types, chemically speaking, from ingredients with inorganic qualities. For example, urea is combined with formaldehyde to make "urea-forms." These synthetic organics, often advertised as "slow release" or "non-burn" are mostly for special applications, or as one constituent in a blend. As with natural organics, the cost of such nutrients is high because of the extra processing. Likewise the nutrients are released by soil processes slowly and over a fairly prolonged period.