以水萃取液與腐植物質中有機碳之測定建立堆肥腐熟化程度評估指數

Abstract

Twenty-three compost samples consisting of plant residues, poultry manure, swine manure, and cattle manure were collected from Taiwan local compost plants. Total organic carbon (TOC) and oxidable carbon (OXC) in water extract and humic substances of compost were determined by elemental analysis and Walkley-BIack method. Highly significant correlations were found between two methods for each individual group and total samples. Thus, the oxidable carbon could be accurately converted into total organic carbon by general equations TOC = 1.11 OXC, TOC = 1.05 OXC + 11.5, and TOC = 1.09 OXC in water extract, alkaline extract, and fulvic fractions, respectively. The results could be of great help in laboratories in which the element analysis is not available or in simple routine analytical determination. The information of evaluation indices including ratio of organic carbon to organic nitrogen in water extract (Cw/Nw-org), ratio of organic carbon in water extract to total organic nitrogen (Cw/Norg), ratio of organic carbon in humic acid lo fulvic fraction (CHA/CFF)，and humification index (HI) based on total organic were obtained. The Cw/Norg and CHA/CFF could effective cooperatively evaluate the degree of maturity, but the Cw/Nw-org and HI could not be suitable for evaluating the degree of maturity of various compost. Most Cw/Norg and CHA/CFF obtained by conversion of oxidable carbon could ably evaluate the degree of maturity of compost, excluding some poultry manure compost samples derived from CHA/CFF that could be mistaken to immature compost. 採集台灣地區23家堆肥場之堆肥，包括植物殘渣堆肥、雞糞堆肥、豬糞堆肥與牛糞堆肥，分別以元素分析儀及Walkley- BIack法測定堆肥水萃取液與腐植物質中全有機態碳含量（TOC）與氧化態碳含量（OXC）。兩測定方法間有極顯著的相關，可將全部堆肥樣品分別使用TOC= 1.11 OXC、TOC = 1.05 OXC + 11.5 及 TOC = 1.09 OXC等方程式，將堆肥水萃取液、鹼萃取液與黃酸型態的氧化態碳含量，轉換而得到全有機碳含量。這樣的結果對於沒有元素分析儀設備或常作例行性分析的實驗室而言，是十分有幫助的。根據堆肥樣品水萃取液與腐植物質全有機態碳含量等資料，可得到水萃取液有機碳含量與有機氮含量比値(Cw/Nw-org)、水萃取液有機碳含量與固態型式全有機氮含量比値(Cw/Norg)、腐植酸有機碳含量與黃酸型態有機碳含量比値(CHA/CFF)及腐質化指數(humification index, HI)等腐熟化程度評估指數。其中Cw/Norg與CHA/CFF兩評估指數可有效地共同評估堆肥腐熟化程度，而Cw/Nw-org與HI則較不適合用於評估不同來源堆肥之腐熟化程度。此外，根據氧化態碳含量轉換得到的Cw/Norg與CHA/CFF 兩評估指數，除了部分雞糞堆肥樣品在CHA/CFF評估指數上，易造成將堆肥樣品評估成爲未腐熟堆肥外，大部份均能符合對堆肥腐熟化程度的區分。