Mineral fertilizers / Inorganic
Fertilizers are broadly divided into organic fertilizers (composed of enriched organic matter—plant or animal), or inorganic fertilizers (composed of synthetic chemicals and/or minerals).
Inorganic fertilizer is often synthesized using the Haber-Bosch process, which produces ammonia as the end product. This ammonia is used as a feedstock for other nitrogen fertilizers, such as anhydrous ammonium nitrate and urea. These concentrated products may be diluted with water to form a concentrated liquid fertilizer (e.g. UAN). Ammonia can be combined with rock phosphate and potassium fertilizer in the Odda Process to produce compound fertilizer.
The use of synthetic nitrogen fertilizers has increased steadily in the last 50 years, rising almost 20-fold to the current rate of 100 million tonnes of nitrogen per year. The use of phosphate fertilizers has also increased from 9 million tonnes per year in 1960 to 40 million tonnes per year in 2000. A maize crop yielding 6-9 tonnes of grain per hectare requires 30–50 kg of phosphate fertilizer to be applied, soybean requires 20–25 kg per hectare. Yara International is the world's largest producer of nitrogen based fertilizers. This growth is the result of the ever increasing need for food of the population.[1]
Most of the fertilizers used in agriculture come as separate compounds for each macronutrient or in combination. They are applied at different stages of the growth of the plant and they influence positively the volume of the crop. However, the combination of inorganic fertilizers and the cultivation of highly yielding cultivars has put the toll on the quality and the taste of the product and the plant themselves. Plants proved to be less resistant against diseases and the taste faded. There is always the risk of over-fertilization burn and vast areas of agricultural land have been compromised  due to the building up the level of salts in the soil, compensated by the lack of organic material addition.  The use of inorganic fertilizer may increase yielding for a few years, but because of the intensive cultivation contributes to the erosion of the soil. Once the soil has become eroded, exhausted and the salts have been already built in,  there is not easy remedy and only the pass of time and the influence of nature can restore the initial balance. The complimentary use of pesticides, insecticides and herbicides make the matters even more serious.
At this point, most of the do-it-yourself stores and garden centres have on their shelves different formulas of inorganic fertilizers. Most of them are called complete fertilizers because they contain nitrogen, phosphorus and potassium.   However this nomination does not really covers the needs of a plant. Plants also need calcium, magnesium and other micronutrients, which, although they are consumed in very little quantities are equally important. Therefore it is always wise to read the labels. The use of inorganic fertilizer at home has to be done with caution, because it absolutely does not mean that if you add more of the prescribed quantity the plants will grow faster. On the labels it is always written the necessary dilution. If you apply a more concentrated dilution you risk burning your plants, due to over fertilization. Over-fertilization results stunting, the pH of the soil may be altered by the salts in your dilution and in certain cases the roots may be affected and the leaves can show sign of fertilizer burn. Furthermore, the soil will get also saturated in salts and become unproductive. Many horticulturists prefer to apply half-concentrated dilutions than the ones written on the product labels, twice as often.
In the last years foliar feeding has become available for home use. It prevents the salt building in the substrate, but increases the risk of leaf burn. For these reasons it applied only during overcast days. If applied in full sun, the water parts of the fertilizer will evaporate quicker than being absorbed and the salt parts will burn the leaves of your plants. If applied when it rains, the fertilizer dilution will be simply washed away. Commonly, foliar feeds can be used also as root feeding and the other way around. Root feeding has to be diluted in two times more volume of water in order to obtain a foliar fertilizer. For example, if you have a normal (root) fertilizer and you have to use 10 ml for every litre of water, in order to use it as foliar feed you have to dilute only 5 ml or less to every litre of water. This is just a random example.
To conclude, inorganic fertilizers have a quick action, they improve yielding and flowering, but there is always the risk of altering the proprieties of the soil and burning your plants. It is cheaper than organic fertilizers, it is easy to use and it is cheaper to transport, deliver and to store. Nevertheless, it is not an ecological product because it produced in polluting factories, and it is not at all organic. We will discuss about organic fertilizers very soon and we will give you some great formulas to make yourself the organic fertilizers or to use organic material for better crops.



[1] http://en.wikipedia.org/wiki/Fertilizer