Water is a crucial natural resource, influencing plant productivity and sustaining ecosystems. Black locust, known for its drought resistance and adaptability to unfavorable conditions, is frequently used in the recovery of degraded regions. During juvenile phase, black locust requires sufficient soil moisture for proper growth. The objective of the research was to assess the water needs of black locust in the second stage of growth on reclamation plantations, specifically starting three years after planting. Water requirements were evaluated for five regions in Poland between 1 June and 31 August in 1981-2010. Water requirements, quantified as crop evapotranspiration, were determined by multiplying the plant coefficient by the reference evapotranspiration. The Blaney-Criddle equation, with the plant coefficient adapted using the Żakowicz method, was applied to estimate reference evapotranspiration. It was found that the average water requirements from June to August were 370 mm. Rainfall deficits were observed in all regions, with the highest shortfalls in central Poland. Additionally, all regions demonstrated an upward trend in water requirements for this species. The results provide valuable insights for planning and implementing irrigation strategies for black locust cultivated in reclamation plantations in Poland, supporting the sustainable management of water resources in the region. ...
