Changes of carbon, nitrogen, phosphorous, and potassium content during storage of vermicomposts prepared from different substrates D. Das & Michael Powell & P. Bhattacharyya & P. Banik Received: 20 May 2014 /Accepted: 3 September 2014 /Published online: 11 September 2014 # Springer International Publishing Switzerland 2014 Abstract The study was conducted to determine the optimum storage time for vermicompost without signif- icant loss of nutrients; nitrogen (N), phosphorous (P), and potassium (K). Cattle manure, paddy straw, munic- ipal solid wastes, and fly ash were used for vermicompost preparations. The dynamics of N, P, and K in the vermicomposts were studied during 180 days of incubation at 28–32 °C. In general, N concentration increased in the first 90–105 days of incubation and then gradually decreased until the 180th day while P and K concentrations steadily decreased over the length of the study, with the rate of loss leveling off after 150 days. The rate of nutrient loss was directly related to the initial level, decreasing the fastest for the nutrients with the highest initial concentrations. Optimum storage times were substrate and N dependent. Keywords Vermicompost . Storage time . Nutrients . Temporal variation . Wastes Introduction Production of organic waste possesses the major envi- ronmental as well as disposal problems due to potential soil and ground water contamination. In many countries, these wastes are largely disposed of in landfills in low- lying areas or are directly applied to agricultural land, which may result in contamination of soil, crops, and water (Bhattacharya et al. 2012). Considering these potential dangers, bioconversion of these wastes pro- duces soil amendments with reduced environmental hazard potential. In recent years, vermicomposting has emerged as a highly efficient recycling technology that could be adopted to stabilize varied kinds of solid wastes (Garg et al. 2006; Suthar et al. 2012; Goswami et al. 2013). Vermiconversion is the conversion of biodegrad- able or sluggishly biodegradable solid wastes to valu- able fertilizer through the combined action of earth- worms and microorganisms. Eisenia fetida is considered the most eurythermal species of epigeic earthworms and has produced faster decomposition and better minerali- zation of organic matter as compared to other species (Triphathi and Bhardwaj 2004; Gupta et al. 2008) be- cause of the beneficial microorganisms, enzymes, and hormones contained in their intestines (Verma 2011; Goswami et al. 2014). Adoption of vermicomposting technology enhances the solubility of major nutrients and is dependent on the original substrate. The types of microorganisms within earthworm intestines can also increase the solubility of nutrients (Kumar et al. 2010). Yadav and Garg ( 2011 ) showed that during vermicomposting of different organic materials like Environ Monit Assess (2014) 186:8827–8832 DOI 10.1007/s10661-014-4046-5 D. Das : P. Banik (*) Agricultural and Ecological Research Unit, Indian Statistical Institute, Kolkata, India e-mail: banikpabitra@gmail.com M. Powell Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada P. Bhattacharyya Indian Statistical Institute, North-East Centre, Tezpur, Assam, India