Etude de l'impact de la fertilisation minérale sur la composition chimique et la teneur en tanins condensés de fourrages issus de prairies à haute valeur biologique

Abstract

The biodiversity of agro-ecosystems in Europe is declining with the intensification of agriculture and the abandonment of land. Agro-environmental and climate measures (MAEC) are nowadays an important tool for environmental protection, conservation of animal and plant species, and maintenance of landscapes in agricultural areas. The objective of this study was to investigate a compromise between farmers and ecologists through the comparison of two MAEC measures ("P3B", which authorises the application of 50 kg N/ha, and "P4B", which prohibits the use of all fertilising materials) for the preservation of biodiversity in high biological value grasslands in the Grand Duchy of Luxembourg. The problem of the study is therefore the following: what is the impact of a 50 kg N/ha input on the conservation status of biodiversity in high biological value grasslands? To answer this question, an experiment was carried out on 21 plots belonging to habitat 6510 in the Grand Duchy of Luxembourg. The samples taken from the high biological value grasslands were freeze-dried and then ground. They were then analysed by the near infrared spectrometry (NIRS) method to determine their chemical composition, and by the butanol-HCl method to determine their condensed tannin content. The results show that the dose of 50 kg N/ha does not allow a significant variation in the floristic composition between the fertilized and non-fertilized quadrats. However, the application of this dose of fertiliser and the type of soil allowed a significant variation in biomass yield between the fertilised and non-fertilised quadrats. In conclusion, the P3B measure, which results in an input of 50 kg N/ha, can be recommended to farmers to increase their biomass yield without impacting the conservation status of the biodiversity of their grassland.