Impact of Paper Waste and Earthworm on Nutrient and Heavy Metal Content of Rice Straw Compost in the Absence of Manure

Plant residues after harvest are serious problem. In the recycling process of these residues, composting and vermicomposting is an economic, ecologic, and biologic alternative. Recycling of rice straw waste is also difficult due to its degradation resistant structure. Although it is prohibited in many countries, it is still open burned which destroy soil and environment. Paper waste also has a large share in municipal solid waste and is a suitable recycling material. Rice straw wastes are composted and vermicomposted with or without paper waste in the absence of manure. There are significant differences (p<0.01) between the treatments for all nutrients and heavy metals. NPK contents are highest in the treatment of Rice Straw Vermicompost (RSV). Mg, Zn and B are also the highest in RSV treatment while Ca, Fe and Cu contents are greater in the treatments Rice Straw Paper Compost (RSPC) and Rice Straw Paper Vermicompost (RSPV). Heavy metal contents are the lowest in Rice Straw Compost (RSC) treatment and increase in the presence of earthworm while all the heavy metal contents are below the limit values. This study also shows it is possible for rice straw to be converted into N rich compost without involving any manure.