In France, over 40 million m³ of slurry is produced annually from pigs, cattle and poultry, together with 17 million m³ from pig farms. With over 1,700 models in operation by the tip of 2023, methanization continues to develop and, consequently, the quantity of digestate produced will increase. Natural fertilization of soils is the final step within the recycling of slurry and digestate.
Because the composition is extremely variable, using common reference values is just not appropriate for precision fertilization. Though laboratory evaluation is the gold customary, it’s nonetheless costly and takes a number of days and even weeks to acquire the outcomes.
Fast evaluation methodologies built-in in slurry tanks supply an fascinating different that must be to explored. They use sensors primarily based on sure bodily properties of the slurry parts. There are three predominant strategies:
- sensors primarily based on close to infrared spectrometry (mild alerts);
- sensors primarily based on electrical conductivity; and
- extra not too long ago, sensors primarily based on nuclear magnetic resonance spectrometry.
A research carried out by IFIP has made it potential to match these three strategies: how they work, their benefits and their limitations..
IR-devices in a slurry tanker. Supply: IFIP.
IR Methodology
The IR technique is offered as probably the most correct method to foretell the content material of the primary slurry parts. Nevertheless, the standard of the outcomes obtained requires common calibration of the spectral measurements. These calibrations require technically advanced upkeep, which needs to be carried out ideally by a specialised operator. The set up is kind of advanced and upkeep makes the system comparatively costly. A slurry tanker with intensive use within the framework of an agricultural work firm (ETA) or a Cooperative for the Use of Agricultural Equipment (CUMA) will amortize its value extra effectively.
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Electrical conductivity
The measurement {of electrical} conductivity is properly fitted to soluble components, particularly ammonia nitrogen and, to a lesser extent, potassium. Due to the correlations between components, the end result could also be of curiosity for complete nitrogen, however it’s nonetheless not correct for phosphorus. The gear, its set up and upkeep are easy, which means a really cheap value of use.
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Magnetic resonance
Nuclear magnetic resonance (NMR) predictions have benefits: correct estimates, absence of delicate parts in touch with effluents and no calibration operations required. Nevertheless, regardless of these advantages and possibly as a result of its decrease stage of growth, it has not been carried out at area stage.
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Conclusions
Of the three potential strategies for built-in sensors to estimate slurry and digestate composition, solely close to infrared (NIR) and electrical conductivity are getting used within the area at the moment.
The selection between these two strategies will most likely rely upon the consumer’s profile: the extent of demand concerning the standard and nature of the predictions, the kind of gear already bought, the extent of use of the slurry tank, the extra companies desired (mapping instruments, automation of utility information) and the flexibility of the sensor, and so forth.
The usage of these sensors stays restricted, with most likely lower than 200 slurry tankers fitted with them thus far, in comparison with a possible market of a number of thousand models. Nevertheless, their growth continues on account of rising financial and regulatory strain for precision natural fertilization.
Pascal Levasseur, IFIP environmental engineer, as a part of the Val’Or undertaking: ‘Higher recycling of natural fertilisers on farms, with spreading on the coronary heart of many points‘, (‘Mieux valoriser les engrais organiques sur les exploitations agricoles, l’épandage au coeur de multiples enjeux’) executed in collaboration with FRCuma Ouest, FDCuma 53, FDCuma 44 and Aile, with the assist of CASDAR of the Ministry of Agriculture.
