TITLE:
Physico-Chemical and Microbial Quality of Locally Composted and Imported Green Waste Composts in Oman
AUTHORS:
Saifeldin A. F. El-Nagerabi, Abdulkadir E. Elshafie, Saif N. Al-Bahry, Hasina S. AlRawahi, Huda AlBurashdi
KEYWORDS:
Aspergillus Niger, Coliform Bacteria, Physico-Chemical Properties, Green Waste Compost, Heavy Metals, Oman
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.2 No.5,
November
25,
2011
ABSTRACT: In this work the physical, chemical and microbial properties of four locally composted green waste composts (GWCs) namely Almukhasib, Growers, Plantex, and Super along with four imported GWC (Florabella, Mikskaar, Potgrond, and Shamrock) were studied to evaluate the quality of these composts with the acceptable standards. All composts showed normal physical properties, except the bad smell from sulfur reducing bacteria in Almukhasib, light brown color Plantex and one viable weed seed in Shamrock compost. The germination indexes of the composts comparable to the standard (90%) were 100% for Mikskaar, followed by Shamrock (92%), Florabella (97), Potgrond (95%), Plantex (98%), Growers (77%), and 5% for both Super and Almukhasib. The physical and chemical properties vary considerably as follows: pH 3 - 10.5, 5.1 - 6.5 (standard 5 - 8), electrical conductivity (EC) 0.4 - 10.2 mS·cm-1, 0.8 - 1.8 mS·cm-1(standard 0.0 - 4.0 mS·cm-1), moisture content (MC%) 29% - 43.7%, 64% - 74% (standard 35% - 60%) and water holding capacity (WHC%) 92% - 200% and 400% - 800% for the locally produced and imported composts, respectively. Wide ranges in the chemical properties were expressed as ammonia concentration 512.4 - 1640.1 mg·kg-1, 459.4 - 656.5 mg·kg-1(standard -1), organic matter 17% - 67.6%, and 53.3% - 66.2% (standard 35%) for the locally composted and imported composts, respectively. The concentrations of the heavy metals (Zn, Ni, Pb, Hg, As, Cd, and Cr) were lower than the recommended levels. The average of the bacterial colony forming unit per gram of locally produced and imported composts ranged between 260 - 1740 CFU/g and 330 - 2870 CFU/g, whereas the fungal CFU were 10 - 2800 CFU/g and 27 - 1800 CFU/g, respectively. The most probable number (MPN) for coliform bacteria was 43 - 1100 CFU/g for locally produced composts, and 23 - 480 CFU/g for the imported composts. Therefore, these composts can not be used directly without effective treatment as substrate for plant growth, soil amendment and as biofertilizer.