Organic and chemical fertilizers: two approaches
A fertilizer, whatever its origin, is a simple or complex substance whose purpose is to provide plants with the essential elements for their growth (germination, growth, root and foliar development and fruiting). There are two main families of fertilizers, each of which is subdivided into subclasses according to production or processing methods.
Industrial or chemical fertilizers
Fertilizers, known as industrial fertilizers, are chemical compounds obtained by the implementation of chemical reactions to isolate one or more elements. These fertilizers are mass-produced and available in infinite combinations and in various forms (granulated, powder, liquid..). Among others, we distinguish mineral fertilizers that come from sedimentary, eruptive or saline deposits, which are obtained by industrial transformation processes.
Their origin comes from animal waste (blood, feathers, bones, insect frass), animal excrements (guano, slurry, manure) or vegetable waste (slurry, legumes, compost). Depending on the method of production, some of these fertilizers may be considered organic and therefore must be certified organic to be used in organic agriculture. For example, liquid manure from a hog farm where the animals cannot move 360 degrees (in Canada), cannot be considered as an organic fertilizer, even though it is of organic origin.Raw organic fertilizers do not undergo any prior processing. This is the case, for example, with manure and slurry, which are applied directly to arable land.
Elaborate organic fertilizers come from the transformation of plant or animal waste, and bring in organic/mineral forms all the major elements (nitrogen, potassium, phosphorus) secondary (calcium, magnesium, sulfur) and trace elements (iron, manganese, copper, zinc, boron, molybdenum). Organic fertilizer is obtained by natural processes such as drying, grinding, extraction, or advanced distillation, as it is the case with the Solugen process.
The fundamental differences between the two main classes of fertilizers are summarized below:
Fertilizers are selected according to the types of plants, the desired action (sowing, post-emergence, for example) and the time of year. It is therefore important in practice that the fertilization is adapted to the specific needs of the plants at a given time, and to do so, the following parameters must be adequately identified.
- Plant needs
- Type of fertilizer
- Fertilizer formulation
- Nutrient availability
- Soil nutrient loading (organic and mineral reserves) (especially phosphorus).
- Fertilization period, etc.
If certain nutrients are immobilized (insolubilization for example), in insufficient quantity or in too high concentration (unsuitable fertilizer), or lost by volatilization (ammonia), then over-fertilization will be necessary, which in the case of multi-element fertilizers (N.P.K) can lead to harmful effects (over-fertilization of some elements) or even an environmental overload (phosphorus saturation).
Some organic fertilizers are available in the form of simple nitrogen fertilizers (only one macro element); however, their cost is generally high. Nitrogen, in its various forms, is one of the key elements in terms of fertilization. Under specific weather conditions it is also a source of various losses: runoff, leaching, denitrification, fixation and volatilization.
Under certain conditions 75 to 80% of ammoniacal nitrogen can volatilize into the atmosphere after application.
Liquid or water-soluble fertilizers for use in nutrient solution, or foliar nutrition
The roots absorb water and the mineral elements it contains to ensure the nutrition of the plant. The soluble or liquid fertilizer introduced into the watering circuit allows the plant easier access to nutrients.
There are three different scenarios:
Circulating nutritive solution: in off-ground culture (mineral wool for example), other organic support such as peat, or without substrate (hydroponics). The roots draw water and elements directly from the nutrient solution. This technique frequently uses a drip network and is found in the production of tomatoes, cucumbers, strawberries and flowers as well as in potted plants.
Fertigation: liquid or dissolved fertilizer (if soluble) is introduced into the irrigation water supply to the crops. In a future blog post we will come back to this fertigation process and the potential benefits of utilizing the organic liquid nitrogen solution extracted from pig manure with Solugen’s process. Fertigation offers many advantages, especially in regions where water management is an important aspect of agriculture.
Foliar nutrition: Foliar fertilization consists in spraying fertilizers directly on the foliage of plants. This practice allows the rapid absorption of small amounts of nutrients through the foliage.
Solugen: ammonia solution
One of the organic fertilizers is the ammonia nitrogen solution from Solugen’s pig manure treatment process. This fertilizer solution has the advantage of containing only one macro-nutrient (N) and its liquid form lends itself very well to various fertigation and foliar nutrition techniques.