Organic fertilizers are fertilizers that have a natural origin and that, therefore, are opposed to chemical fertilizers, which are artificially produced. An important functional difference between organic fertilizers and chemical fertilizers is that, while the former contain a fair variety of nutrients for plants, the latter often contain only a small group (sometimes only one). Precisely for this reason chemical fertilizers are also called "targeted fertilizers". Naturals are often preferred to chemical ones, on the one hand, due to their low cost, and on the other, due to their soil improvering (they improve the soil structure). The low cost is mainly due to the fact that the number of farm animals, from which it is possible to obtain organic fertilizers, is soaring.
Organic fertilizers can be classified into two broad categories: nitrogen fertilizers and NP fertilizers. The first must contain (as established by current regulations) a conspicuous amount of organic nitrogen that must necessarily come from a biological source. Their phosphorus and potassium content, on the other hand, is relatively low. In addition to nitrogen, they can also contain microelements in variable quantities, or nutrients that are only absorbed in traces by vegetables but which, for this reason, are not considered important. NP fertilizers, on the other hand, have a fair amount of organic nitrogen and phosphorus strictly of biological origin. Like nitrogen, NP fertilizers also do not have much potassium and may contain varying amounts of trace elements.
Organic fertilizers can originate from parts of the body of animals or from their droppings or, again, have plant origin. Let us now see two examples of natural fertilizers: the flagpole and guano. The flagpole consists of feathers and feathers from farm animals that are not used for other purposes and therefore, being considered waste, are used to fertilize the soil. The flagpole is a nitrogenous fertilizer and contains a percentage of organic nitrogen between 13% and 14%. Guano is, instead, a NP fertilizer as it contains organic nitrogen in a percentage that varies between 3% and 9% plus an amount of phosphorus between 3% and 20%. Essentially the term "guano" means the set of all those products that originate from the excrement of birds (especially seabirds).
Organic fertilizers: fertilizing techniques
Organic fertilizers can be used to fertilize the soil in three different ways: by direct surface spreading, by strip administration and by targeted fertilization. Direct surface spreading should be done before sowing. In fact, once spread, the fertilizer begins a process of decomposition which, if carried out near the sprouts, can damage them. Once this process is completed, you can proceed with sowing. Strip administration is practiced above all in crops where seed germination is hindered by the particular composition of the soil; while targeted fertilization is carried out only on restricted portions of the earth and has the purpose of providing the plants with a particular element that they need.