Kajian Efektivitas Penggunaan Kasgot dalam Penyerapan Tembaga (Cu) dan Seng (Zn) pada Tanah Perkebunan Kopi

Abstract

Heavy metal contamination of coffee plantation soil is an environmental problem resulting from the long-term use of pesticides and inorganic fertilizers. Initial soil test results showed copper (Cu) levels of 0.256 mg/kg and zinc (Zn) levels of 0.650 mg/kg, exceeding quality standards and necessitating remediation efforts. The research method was conducted experimentally using three variations of kasgot doses (25%, 50%, 75%) with observation times of days 15, 30, 45, and 60. Analysis of Cu and Zn levels was carried out using Atomic Absorption Spectroscopy (AAS). In addition, sterilized and non-sterilized kasgot tests were conducted to determine the role of microbes. The results showed that Cu metal degradation was most effective in the initial phase. On the 15th day, a 50% dose reduced Cu levels by 58.5%, while a 75% dose provided the best reduction on the 30th day by 31.2%. However, effectiveness decreased after the 45th day due to metal desorption and changes in soil pH to a more acidic one. For Zn metal, a significant decrease occurred in the final phase. On the 60th day, effectiveness reached 75% (25% dose), 74% (50% dose), and 78% (75% dose). Therefore, it can be concluded that the effectiveness of kasgot is influenced by the dose and incubation time. Cu is more optimally remediated after 15–30 days, while Zn is effective after 60 days. Microbial activity and the functional groups –COOH, –OH, and –NH₂ in the kasgot play an important role in the bioremediation process.