A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science Inter-University Program on Environmental Toxicology, Technology and Management, School of Environment, Resources and Development

Thesis (M.Sc.) - Asian Institute of Technology, 2006

The present study aimed to evaluate the nutrients and metal contents in organic fertilizers. The analyzed samples were finished product organic fertilizers purchased from the markets, pig and cow manures from big and small farms and raw materials of animal feed. The result showed that most of organic fertilizers samples contained macronutrients (N, P, and K) lower than the product specific requirements value of DOA, Thailand (N not less than 1%, P not less than 0.5%, and K not less than 0.5%). Some organic fertilizers contained high toxic elements contents such as Cd (11.4 mg/kg DW.), As (24.4 mg/kg DW.) and Pb (126 mg/kg DW.). Moreover the concentrations of non-essential element like Al in organic fertilizers samples were ranged from 3574 to 76573 mg/kg DW. This high aluminum content was likely to be the result of its addition in feed to prevent milk fever. Pig manure samples contained the macronutrients and some essential elements which seemed to be higher than cattle manure samples. However, the concentrations of toxic elements in pig manures were quite high. Pig manure samples contained As (30 mg/kg DW.) and Cd (37.8 mg/kg DW). In the present study, cattle manure samples contained Al concentrations higher than pig manure samples. The possible sources may be come from animal feeds and supplements. The present study showed in some feeds sample contained As (P1; 14 mg/kg DW.) and in Cd (P4; 1.8 mg/kg DW and P6; 1.2 mg/kg DW.) were higher than standard value of EU (10 mg/kg DW. ). Moreover, the present study found the concentration of other element such as Pb (7.6 mg/kg DW.). However this concentration was not higher than standard value of EU (10 mg/kg DW.). In addition in this study found Al (535.4 mg/kg DW.), Ni (11 mg/kg DW.), Mn (319 mg/kg DW.) Cr (37.7 mg/kg DW.), Zn (1978.7 mg/kg DW.) in feeds sample. The toxic elements and trace element contents of animal feeds still remain poorly documented. Based on this research (macronutrients. micronutrients, and toxic moats information), researcher found pig manure was appropriately used as raw material for organic fertilizer and was better than cattle manure in term of nutrients content. However. in pig manure contained higher amounts of toxic elements than cattle manure. Therefore, before applying organic fertilizer, the users should know their soil background and information. Therefore, direction for usage and labeling (ingredient and nutrient content) need to be involved. Some metal standard fertilizer and feed need to be added more. Moreover the setting of metals standard in organic fertilizers should be done