The efficiency of organic fertilizers may be limited in drought years. Potatoes were grown organically under reduced tillage in dry (2020) and wet (2021) conditions. Plant nutrition was compared by using either hair meal pellets (HMP) or transferred mulch from green manures (Mulch). In the 2020 drought, less nitrogen was mineralized in Mulch during the summer and resulted in increased nitrogen leaching risk before winter. Yields did not differ significantly. It is recommended to adjust crop rotation dynamically to drought events to avoid leaching losses.

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