Organic and mineral soil improvers intended for the cultivation of butterhead lettuce

The aim of the research was to select soil improver which will enhance the soil fertility and to assess the effect on the growth and yielding of lettuce. Algal biomass from the species Scenedesmus acutus, Chlorella vulgaris and soil supplement – zeolite was used in the laboratory experiment. Four fertilizing combinations were used for each plant three times. Doses of fertilizers were established according to the content of nitrogen. Physicochemical analysis of the soil, tested substrates and plant growth parameters were examined. Algal biomass had the greatest impact on the improvement of soil fertility and plant productivity. Fertilization with Scenedesmus acutus caused the increase of almost all soil parameters, e.g. an increase in total organic carbon by 3694 mg kg-1, Kjeldahl’s nitrogen by 1287 mg kg-1. It was found that algal can be used in organic farming, in which the use of soluble mineral fertilizers is impermissible