Contrasting Nitrate and Ammonium Stocks in Soils of Sweet Cherry and Apple Orchards

Efficient nitrogen (N) management in perennial fruit orchards is constrained by species-specific differences in N demand and fruit N removal, which can result in distinct soil N uptake patterns even under similar fertilization regimes. This study assessed whether apple (Malus domestica Borkh.) and sweet cherry (Prunus avium L.) orchards differ in soil mineral nitrogen (Nmin) composition by analyzing nitrate (NO3−) and ammonium (NH4+) stocks in topsoil (0–20 cm). Soil samples were collected in spring from a long-term orchard experiment over two consecutive years and from a commercial orchard on two sampling dates in Germany. In apple orchards, Nmin was dominated by NO3− (83%), whereas cherry orchards showed a more balanced composition (42% NO3− and 58% NH4+). These patterns were consistent across years, sites, fertilization types (mineral or organic), and key soil properties, including total organic carbon and total nitrogen, but were not explained by these factors. The elevated NH4+ proportion in cherry soils suggests a species-associated pattern in soil N dynamics. Overall, the results highlight species-associated differences in soil Nmin composition between apple and sweet cherry orchards. Accounting for tree species differences may therefore improve N management and enhance N use efficiency in apple and sweet cherry production.