## 1 Introduction  
Hops (_Humulus lupulus_ L.) are the most expensive ingredient for breweries, used for their aromatic, preservative and bittering properties. Hop cultivation requires a large amount of nutrient input. In particular, as this species exhibits rapid growth in spring (it can grow up to 25 cm per day), the utilisation of high amounts of nutrients, especially nitrogen, is needed [1]. The use of different types of nutrients can influence both the yield and quality of plants [2, 3, 4] and, therefore, the quality of the processed product. In grape cultivation, fertilisation is part of the _terroir_ effect, since it can affect wine quality not only by modifying grape microflora but also by affecting secondary metabolism [3, 5]. [PERSON] et al. [5] observed an effect of nitrogen (N) fertilisation on grape production, which highlighted significant differences in the monoterpene composition of wines and their sensorial features. Similar findings have also been reported for the tea tree (_Camelia sinensis_ L.): several studies have shown that foliar fertilisation affects the aromatic compounds of leaves and teas. The research by [PERSON] et al. [6], in particular, found a correlation between N application and the increment in (E)-2-hexneal and (Z)-3-hexanol, both of which are responsible for the typical greenish odour of green tea. Terpene, monoterenoid and sesquiterpenoid biosynthesis also increased in _Ctrysanthemum Boreale_ (Makino) flowers following NPK (nitrogen, phosphorus and potassium) and lime fertilisation treatments [7]. In this context, the hop secondary metabolism is known to be influenced by different factors, such as the terror [8; 9; 10], biotic and abiotic stress [11; 12], and plant nutrition [13; 14; 10]. Traditionally, the most commonly used N fertilisers include ureas, coated ureas, ammonium nitrate, ammonium sulfate (highly acidifying), calcium nitrate and potassium nitrate [15]. Other synthesis fertilisers rich in N, P and K are commonly used for hop nutrition during the growing season [16]. Over recent decades, the agricultural world, including the brewery sector, has shown particular interest in organic production and manuring, as a result of an increased human awareness of environmental issues, which has led, in turn, to new research into organic raw materials [17; 18]. This can be found in hop cultivation, where there is an increase in organic farming methods. For example, differences in hop cone quality have been found in an experiment comparing hops cultivated organically (probiotic microorganisms and plant extracts, horse manure and probiotic microorganisms) with those undergoing conventional manuring [19]. Organic hops exhibited a higher content not only of xanthohumol, proanthocyanidine and flavan-3-ol but also of alpha acids when compared with cones cultivated using conventional manuring. The impact of agronomic practices on hop quality is also evidenced in a study on different hop cultivars by [PERSON] et al. [10], where hops cultivated using copper sulphate exhibited a quantitative decrease in the aromatic profile of 4-mercapto-4-methylpentan-2-one, characterized by a blackcurrant-like note. In beer production, the aromatic fraction contained in the essential oil of hops gives the beer a unique character. Therefore, the use of different hop fertilisation methods, acting directly or indirectly in secondary metabolism and terpene biosynthesis, could affect beer quality and sensory characteristics [20]. Similar sensory differences have previously been observed in a study on consumer preferences [21], where beers obtained using different fertilised hops were given to consumers, who effectively perceived differences in beer quality. This result highlights the importance of hop fertilisation [21]. Moreover, considering the increased interest in sustainability, the identification of a fertilisation method that could meet the needs of hop producers, brewers and the environment becomes more urgent.