The Role of NIR Spectroscopy in Precision Fertilisation with Manure

To close the nutrient cycle, the nutrients in animal manure should be valorised in plant production. However, due to its heterogeneity, the fertiliser value of animal manure can vary significantly between farms and even between different loads obtained from the same farm. This makes that the use of animal manure often increases the variability in soil fertility within a field rather than reducing it.

In the context of precision fertilisation, one could try to compensate for this variation based on crop measurements. However, it would be far better if the nutrient content of the manure could be known at the time of application. This would allow farmers to adjust the dose applied to this composition and the needs of the local crop. Near-infrared (NIR) spectroscopy has the potential to bridge this gap through online measurement of the manure composition. In this paper, our experiences with the calibration of NIRS systems for online measurement of manure composition on slurry tankers will be presented. Some interesting observations on the variation in manure composition between different loads from the same storage facility and even within a load will be discussed together with scenarios on how this information could be used efficiently in practice.

Wouter Saeys, Rodrigo Watté and Annelies Postelmans, KU Leuven Department of Biosystems, MeBioS, Kasteelpark Arenberg Leuven, Belgium

22 pages, 4 figures, 2 tables, 43 references