The mineralization speed of an organic fertilizer in the soil depends on the chemical (e.g., chemical composition, chemical reaction, etc.) and – especially – physical characteristics (specific surface area, hydration capacity, etc.) that are able to influence, directly or indirectly, the activity of the soil microbial biomass.
It is well known that it is possible to produce fertilizers with very different physical properties despite starting from the same matrix.
The various formulations differ mainly for the shape and size of particles and can be described by a property: the specific surface area. The specific surface area is the ratio between the surface and the weight of the pellet. The specific surface area is, of course, the surface that is exposed to the activity of the microbial biomass: the more it grows, the larger becomes the substrate available (at equal weight) to the enzymes that degrade the organic matter.
However, it is not the only important property; in fact, the substrate should also provide a favorable environment for the growth and development of the microbial biomass; in this sense, one of the most important properties is the ability of hydrating, that is to absorb water from the surroundings and hold it.
Given the importance of these factors, water retention tests were performed with ILSA and at the University Alma Mater Studiorum Bologna (Department of Agro-environmental Sciences and Technologies) with specific studies on the kinetics of water retention of the AGROGEL® -based products.
Kinetics of water retention of the pelleted product
In this case, the curve is presented with data processing according to an equation of first order. It is interesting to see how, after 8-10 hours, the water retention value is very close to that of saturation. It is also noted how at the zero point of the x-axis scale, the product
is already showing an interesting water retention value: this is an indicator of the wettability of the product.
Kinetics of water retention of the granular product
Again, the curve is presented with data processing according to an equation of first order. It is interesting to see how, in order to arrive at a value close to saturation, a longer time than the pelleted product is needed. It is also noted how, at the zero point of the x-axis scale, the product is already showing an interesting water retention value: this is an indicator of the wettability of the product.
Studies have shown that the AGROGEL®-based products have very good ability to hydrate and, in both cases, a specific surface area that makes for the microbial system to have intense activity.
For this reason, especially when taking into account their hydration rate, just a light rain, irrigation or even abundant dew – in the case of surface administration – is enough for hydration to get the mineralization processes started.
Therefore, depending on soil, temperature and weather conditions one can choose the product, in pellet or granular form, which allows the implementation of targeted strategies, so as to obtain maximum nutritional efficiency.