Excessive Delay in Nutrient Release by Controlled-Release Fertilizers Can Reduce Chestnut Yield

Farmers are increasing the use of fertilizers in chestnut, only cash crop produced mountainous areas northeastern Portugal. This calls for more studies to guide them towards a ecological intensification. The effects three controlled-release fertilizers, two that release nutrients over months (BoskGrow 20:05:20_3m, Exactyon 18:05:13_3m) and one six (Exactyon 18:05:12_6m), an organic amendment authorized farming (Humix 12:03:05) were compared with untreated control during three-year field trial (2019–2021). BoskGrow 18:05:13_3m Humix 12:03:05 gave significantly higher nut yields (90.6 97.0 kg tree?1, average 2019 + 2021) than 18:05:12_6m (66.3 tree?1) (69.5 tree?1). Leaf concentrations nitrogen potassium tended be 20:05:20_3m treatments, they stated as most important causes establishment productive groups. 12:03:05, although less concentrated nutrients, led chestnut yield at level possibly due multiple positive matter on soil plants. Under conditions this experiment, where rainfall is low summer, whose nutrient takes long time, such 18:05:12_6m, seem not good fertilization option reduced uptake increased levels inorganic end growing season. emerged possible solution producers.