Růžek L., Růžková M., Koudela M., Bečková L., Bečka D., Kruliš Z., Šárka E., Voříšek K., Ledvina Š., Šalounová B., Venyercsanová J. The study is focused on the microbial and chemical parameters of green compost in which composites based on acetylated wheat B-starch and maltodextrin (patented procedure) were biodegraded and also on the parameters of lettuce grown on this compost before and after the biodegradation. With a load of up to 1 g of composites per 1 l of compost, and with a storage period of 0, 7-14, 15-20 and 21-147 days, mixture of compost wiped off the surface both of wellpreserved composites and of the immediate surroundings of their residues was evaluated. Microbial biomass, basal respiration (BR), metabolic quotient, dehydrogenase and arylsulfatase activity (ARS) and the parameters of the lettuce growth on this compost did not show any negative changes. On the contrary acetylated wheat B-starch and maltodextrin stimulated both ARS and BR. ARS showed the most rapid onset among all tests. The height of the aboveground parts of the lettuce (Lactuca sativa L. var. capitata) grown on green compost was significantly better, compared to commercial peat-based substrates.