The paper provides a brief outline of the history of land reclamation in Poland and discusses its impact on the natural environment and plant crops, using the results of author’s studies and those conducted by other researchers. The process of land reclamation in Poland was practically stopped after 1990. Over the period 2000–2004 less than 4.0 thousand hectares of agricultural land was reclaimed yearly compared to 118 thousand ha in 1990 and 200–280 thousand ha during 1961–1976. As shown by the relevant studies, crops are higher on drained fields than on undrained grounds, also hay yields from reclaimed permanent grassland are better. Drainage enhances the water retention of mineral soils, 2–3 times reduces the surface flow of water, thus alleviating erosion and the washout of fertilisers, and reduces the flood wave. The average concentration of N-NO₃ in drainage water is higher than in rivers which receive the water from drains. The concentrations of other chemical components in drainage water and in rivers are similar or higher in rivers. Drainage of peat soils results in the mineralisation of organic components. As a consequence, peat bogs settle; in the Polish climatic conditions the rate of the process averages 3 cm per year for arable fields and 1 cm for grassland.

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