Fluks CO2 dan Laju Dekomposisi Akar Mati Kelapa Sawit pada Kadar Air yang Berbeda

Abstract

Pengembangan lahan gambut menjadi lahan perkebunan kelapa sawit banyak dilaporkan berpotensi meningkatkan emisi Gas Rumah Kaca (GRK). Fluks CO2 yang selama ini diukur umumnya mencakup keseluruhan dari total respirasi heterotrof, sedangkan kajian terkait fluks CO2 dari bahan organik lain seperti akar mati kelapa sawit masih terbatas. Akar mati disimulasikan pada beberapa % kadar air berbeda dengan mengikuti kondisi kadar air di lahan gambut, sehingga dapat merepresentasikan pada kadar air gambut dalam mempengaruhi laju dekomposisi akar mati. Penelitian ini diharapkan dapat menunjukkan kisaran kontribusi akar mati kelapa sawit dalam menyumbang fluks CO2 dari respirasi heterotrof di lahan gambut, sehingga penetapan fluks CO2 dari respirasi heterotrof tidak overestimate. Pengukuran fluks CO2 menggunakan alat IRGA (Infra Red Gass Analyzer) Li COR 830 dengan metode sungkup tertutup (clossed chamber). Akar mati dikering udarakan dan dibersihkan dari sisa-sisa partikel gambut yang menempel di permukaan akar, lalu dilakukan pemotongan dengan ukuran 2 cm. Perlakuan pada penelitian ini terdiri dari perlakuan kontrol dan perlakuan kadar air 100%, 150%, 300%, dan 450% dengan lima ulangan untuk masing-masing perlakuan, sehingga terdapat 25 satuan percobaan. Masing-masing perlakuan dimasukan ke dalam chamber dengan ukuran diameter 11 cm dan tinggi 14 cm. Kadar air berpengaruh terhadap proses dekomposisi akar mati kelapa sawit dan pelepasan CO2. Perlakuan kontrol memiliki nilai fluks CO2 dan laju dekomposisi yang lebih rendah dibandingkan perlakuan kadar air. Nilai fluks CO2 terendah pada perlakuan kontrol dan tertinggi pada kadar air 100%. Dinamika laju dekomposisi pada nilai C/N tertinggi yaitu pada perlakuan kontrol dan terendah pada perlakuan kadar air 150% serta kehilangan bobot tertinggi pada perlakuan kadar air 100% dan terendah pada perlakuan kontrol. Meskipun nilai C/N masih tergolong pada kategori tinggi, penurunan tersebut mengindikasikan adanya laju dekomposisi yang terjadi selama masa inkubasi. Semakin lama masa inkubasi, semakin meningkatkan laju dekomposisi yang dilihat dari penurunan C/N dan kehilangan bobot yang meningkat akibat proses dekomposisi.

The development of peatlands into oil palm plantations is widely reported to increase greenhouse gas (GHG) emissions. CO2 flux that has been measured generally covers the entirety of total heterotrophic respiration. In contrast, studies related to CO2 flux from other organic materials such as dead roots of oil palm are still limited. Dead roots are simulated at several % of water content differently by following the water content conditions in peatlands to represent the content of peat water in influencing the decomposition rate of dead roots. This research is expected to show the range of contributions of dead roots of oil palm in contributing CO2 flux from heterotrophic respiration in peatlands so that the determination of CO2 flux from heterotrophic respiration is more reliable. CO2 flux was measured by IRGA (Infra Red Gass Analyzer) Li-COR 830 tool with a closed chamber method. Dead roots are air-dried and cleaned from the remains of peat particles attached to the surface of the roots, then cut with a size of 2 cm. The treatment in this study has consisted of control treatment and water content treatment of 100%, 150%, 300%, and 450% with five repeats for each treatment, so there were 25 experimental units. Each treatment is inserted into a chamber with a diameter of 11 cm and a height of 14 cm. The decomposition process of dead palm oil roots and CO2 release were affected by water content. The control treatment had a CO2 flux value and lower decomposition rate than the water content treatment. The lowest CO2 flux value is on control treatment and the highest at 100% water content. The dynamics of decomposition rate at the highest C/N values are at the control treatment and the lowest in the 150% water content treatment. Moreover, the highest weight loss is at 100% water content treatment and the lowest in the control treatment. Although the C/N value is still in the high category, the decomposition rate decreased during the incubation period. The longer the incubation period, the more the decomposition rate seen from the decrease in C/N and the increased weight loss due to the decomposition process.