CONTENT OF ZINC IN PLANTS FERTILIZED WITH MUNICIPAL SOLID WASTE AND URBAN GREEN WASTE COMPOSTS

In a vegetation experiment, the effect of composts made from unsorted municipal solid waste and urban green waste on the content of zinc in plants has been analyzed. The municipal waste composts matured in heaps for 1, 3 and 6 months. They were applied in three rates: 10, 20 and 30 g kg(-1) of soil. The compost made of urban green waste aged in a pile for 6 months and was added to soil in the amount of 10 g kg(-1) of soil. It has been determined that the content of zinc in plants was varied and depended on the type and rates of compost used as well as the species of crops. Application of higher rates of composts did not invariably result in an increased concentration of zinc in plant tissues; on the contrary, in some cases the level of zinc determined in fertilized plants was lower than in the control. Much more elevated concentrations of zinc were found after the application of fresh compost made of municipal waste (maturing for one month in a heap). Fertilization of maize and barley with urban green waste compost produced a more favourable result than the application of analogous rates of municpal solid waste compost, as the plants contained less zinc. With respect to the other test plants, such as sunflower, mustard and phacelia, the application of composted green matter caused a considerable increase in the content of zinc, as compared with the treatments fertilized with composted municipal waste, at the same fertilization rates.