Plants require nutrients in order to grow, develop and complete their life cycle. The supply of nutrients to the plants should be balanced in order to maximise the efficiency of the individual nutrients so that these meet the needs of the particular crop and soil type. Plant nutrients are available from four different sources: the soil itself, livestock, municipal and industrial wastes, biological nitrogen fixation, and mineral fertilizers. Mineral fertilizers allow farmers to supplement the nutrients which are already present in the soil or provided by organic manures and legumes, and thus match the supply of nutrients with the needs of the crops.
All fertilizers contain at least one major plant nutrient. The term 'straight fertilizers' is used in connection with fertilizers that have a declarable content of only one of the major plant nutrients, namely nitrogen, phosphorus or potassium. Based on the 3 fertilizer ingredients of nitrogen, phosphorus and potassium, fertilizers can be categorized into 4 types as follows:

• --Nitrogen fertilizers The only major nutrient these fertilizers contain is nitrogen.
• --Calcium ammonium nitrate (CAN), which is a mixture of ammonium nitrate and calcium/magnesium carbonate, contains nitrogen which is immediately available to plants.
• --Ammonium nitrate (AN) is a more concentrated source of nitrogen (33.5% to 34.5% N).
• --Urea is the most concentrated solid nitrogen fertilizer available (46% N), and has become the world’s major source of nitrogen.
• --Urea ammonium nitrate solutions (UAN), which contain 28% to 32% N, are used where distribution and application techniques suit liquid fertilizer use, for example on large arable farms in France,Germany and the UK.
• --Ammonium sulphate (AS) has a relatively low nitrogen content (21% N). In addition to N, it contains sulphur (24% S), and is therefore not, strictly speaking, a straight fertilizer.

EVVEN C.A.will create an organic fertilizer from several readily available ingredients its shrimp aqua-culture production cycle offers, to build a vertically integrated industry on Margarita Island, Venezuela. The unique plant design makes the speed of manual harvesting comparable to that of machine harvesting. It enables EVVEN C.A, through novel and innovative design, to collect all the emulsion the shrimp produce.