VALORIZATION OF AMMONIACAL NITROGEN FOR AGRICULTURE
SPREADING: TRADITIONAL METHODS
Slurry, like manure, is a fertilizer rich in macro-nutrients (N-P-K) and various other nutrients, including trace elements. Although it is often criticized for its odours, it is an important source of natural fertilizer for agriculture.
A wide range of specific vehicles are used to spread liquid manure. The spreading vehicle is equipped with a slurry tank and mechanical systems that vary according to the spreading method chosen. The slurry tanker comes in the form of a galvanized steel tank attached to a single or multi-axle trailer.
To overcome the problems caused by surface spreading, which include greenhouse gas emissions, ammonia volatilization and increased phosphorus concentration at the soil surface, incorporation processes are used.
The main incorporation methods (there are many variations depending on the effectors used on the slurry tons) consist of mixing the slurry with the surface layer of the soil during application.
Direct injection of liquid material into the soil is also a form of incorporation. Flexible downspouts, called pendulums, supported by an arm, can spread the liquid under the foliage directly to the soil surface. The boom is positioned low above ground level and equipped with hoses to distribute the slurry to be spread. Each slinger can also be attached to a metal skid that slides over the soil surface, removing residue and creating a vacuum for the liquid. This method limits ammonia loss and minimizes odours with little exposure of the liquid to air.
These practices limit odours reduce the risk of runoff and thus keep nutrients in the soil and reduce the volatilization of ammonia nitrogen. Indeed, the method of application and the presence or absence of incorporation have an impact on the amount of nitrogen that will be accessible and assimilated by the crops.
The case of boom aero precision
Low aero precision is a technique that consists of sprinkling slurry at a low height from the ground. It allows the slurry to be spread evenly. However, slurry and manure containing less than 7% dry matter must be applied by boom to prevent drizzle. Mist consisting of droplets tends to disperse with the wind, promote the volatilization of ammonia and spread bad odours.
VOLATILIZATION OF AMMONIA NITROGEN
Nitrogen is a crucial element for plants. Nitrogen in manure exists in two forms: ammoniacal nitrogen and organic nitrogen. Ammonium nitrogen is immediately available to crops if it is not lost through volatilization or leaching after nitrification.
Extremely volatile, ammonia (NH3), during and immediately after application, represents a significant loss of nitrogen source for crops. Under certain atmospheric conditions (temperature, wind, …) the volatilization of ammonia nitrogen can represent a loss of 80% of this compound during and immediately after application. It should be noted that the volatilization of the ammoniacal compound is linked to other malodorous substances. Reducing volatilization also means reducing, to some extent, odours.
Liquid manure is an important source of ammonia nitrogen for crops. Volatilization occurs quickly after application and depending on its exposure to the atmosphere. In certain cases, when this volatilization is important, the farmer is led to compensate for this loss by adding mineral fertilizers. Liquid manure is one of the residual fertilizer materials that contains the most ammoniacal nitrogen.
To mimic losses, incorporation methods should be used to avoid leaving slurry on the surface after application. If this is the case, the loss will be significant and this quickly, with 50% of the volatilization occurring within four hours of application.
SOLUGEN: VALORIZATION OF AMMONIACAL NITROGEN
Solugen’s slurry treatment technology allows the separation of the slurry components.
If we take the example of a maternity slurry we will have after treatment:
– 84% of the treated volume in the form of reusable pure water. (*)
– 10% of the treated volume in solid form (about 30% dry matter) rich in phosphorus (85% of the phosphorus contained in the treated manure)
– 4.5% of the volume treated in the form of a liquid potassium concentrate
– 1.5% of the volume treated in the form of liquid ammoniacal nitrogen.
(*) the percentages can be subject to some variations.
This results in the following advantages:
– Drastically reduced transport costs for the solid fraction and the potassium concentrate
– Easier fertilization process, especially regarding phosphorus management, and easier compliance with agro-fertilization plans.
– An important reduction of greenhouse gases normally generated during storage (especially when mixing manure) and spreading.
– And finally, we produce ammonia nitrogen in a liquid form. In its original state in the manure, most of it would have been lost during spreading. This form, which is more stable than ammonia in terms of volatilization, makes it a first choice nitrogen fertilizer, especially for injection or fertigation, and is easy to use and to dose according to the concentration level of the solution.