Judul: Evaluasi Gas Rumah Kaca (CH4, CO2 dan N2O) dari Feses Sapi FH Laktasi yang Diberi Pakan Rumput Gajah dan Jerami Padi
Abstrak: Livestock sector is one of potential sector to produces greenhouses gases from feces. FH (Frisien Holstein) is one of the dairy cows mostly raised in Indonesia. Feces production of FH approximately 18.45-36.9 kg per day. Dairy cows feces produces the main greenhouse gases such as CH4, CO2 and N2O. Dairy cows feces either solid or liquid has the potential to emit CH4, CO2 and N2O. The aim of this experiment was evaluate the production of greenhouse gases from lactating dairy cow feces that fed with elephant grass (EG) and rice straw (RS). This experiment was conducted from September to December 2014 in KUNAK, Animal Waste Processing and PAU Laboratory of Bogor Agriculture University, and Greenhouse Gases Laboratory of BALINGTAN. BALINGTAN method in measuring greenhouse gases was used in this research. Feces were collected as much as 1 kg in 24 hours and incubated for 8 weeks to measure greenhouse gases. CRD (complete random design) repeated measurements was used with 3 treatments : RS (100% rice straw), EG (100% elephant grass) and RSEG (50% rice straw+50% elephant grass). Measured variables were greenhouse gases (CH4, CO2, N2O), proximate feed analysis, feces proximate analysis, total of feces organic matter, C organic feces, N feces, ammonia (NH3) concentration, feces weight in 24 hours, dairy cows body weights, and feed consumption. The result showed that CH4 gas production from lactating dairy cow feces had no significant effect in each treatment (P>0.05). There was no differences on the CO2 production (P>0.05) between RS, EG, and RSEG but N2O production was higher in RS (P<0.05) than EG and RSEG. Different feeding significantly affected CH4 gas production in the first week (P<0.05), while for the second week until the last week of the study was not significant effect (P>0.05). The first week of CH4 measurement, generated the highest production on dairy cows in RS treatment and followed by RSEG, while EG treatment produces CH4 lower than RS and RSEG. Furthermore, CO2 production in the first week to the third week showed an increase volume in all treatments. In the third week until the sixth week showed a decline in CO2 gas production and increased back on the last week of incubation. Peak production of CO2 gas in all treatments occurred in the third week, it demonstrated the high content of digestible organic matter such as energy and protein and the declined of CO2 production caused by decreasing of digestible substrate. Production of greenhouse gases associated with the substrate that used by the bacteria which is the fiber has longer degradation process so CO2 gas produced slower. Furthermore, the highest production of N2O gas was produced from RS treatment (P<0.05). Fluctuation of N2O gas production was influenced by the concentration of NH3, N content of feces and the role of microbes during the feces incubation process. Generally, the production of CH4 and CO2 produced from dairy cows lactating feces was higher than N2O. The greenhouse gases produced from feces was associated with organic matter content, easily digestible substrate, and length of fermentation. Lactating dairy cow feces with elephant grass and rice
Keyword: elephant grass, greenhouse gases, lactating dairy cows feces, rice straw

Judul: Methane Gas Flux Analysis from Biogas Sheep Manure and Combination of Sheep and Beef Cattle Manure
Abstrak: Sektor Peternakan berkontribusi sebagai penyumbang emisi gas rumah kaca (GRK) seperti metana (CH4), karbon dioksida (CO2), dan dinitrogen oksida (N2O). Tujuan penelitian adalah menganalisis fluk gas CH4 dari biogas kotoran domba dan kombinasi kotoran domba serta sapi potong. Perlakuan meliputi 100% kotoran domba (T1) dan kombinasi 15% kotoran domba serta 85% kotoran sapi potong (T2) dengan dua ulangan untuk setiap perlakuan. Analisis TS, VS, C, N, dan C/N rasio setiap perlakuan diperoleh dari kotoran ternak dan substrat biogas pada awal pengamatan setiap perlakuan. Pengukuran fluk CH4 dan CO2 dilakukan setelah sepuluh hari memasukkan substrat ke dalam digester dengan interval tiga hari sekali selama empat kali pengukuran. Hasil penelitian menunjukkan bahwa nilai TS pada perlakuan T1 dan T2 berbeda secara signifikan (p<0,05). Nilai pH rata-rata pada perlakuan T1 adalah 6,7 dan pada perlakuan T2 adalah 6,6. Nilai rata-rata fluk gas CH4 T1 adalah 40 mgCH4/m2/day dan 107,13 mgCH4/m2/day pada T2 dan kedua perlakuan menunjukkan perbedaan secara signifikan (p<0,05). Komposisi substrat sangat menentukan kandungan TS dan nilai pH dalam fermentasi anaerob produksi biogas., The livestock sector contributes to greenhouse gas (GHG) emissions such as methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). The study aimed to analyze CH4 flux from the biogas of sheep manure and the combination of sheep and beef cattle manure. The treatments included 100% sheep manure (T1) and a combination of 15% sheep manure and 85% beef cattle manure (T2) with two replications for each treatment. Analysis of TS, VS, C, N, and C/N ratio was obtained from livestock manure and biogas substrate at the beginning of the observation. Measurements of flux CH4 and CO2 were made after ten days of feeding the substrate into the digester at intervals of once every three days for four observations results showed that the T1 and T2 treatment TS values were significantly different (p<0.05). The average pH value in the T1 treatment was 6,7 and the T2 treatment was 6.6. The mean value of CH4 T1 flux was 40 mgCH4/m2/day and 107.13 mgCH4/m2/day in T2 and both treatments differed significant (p<0.05). The composition of the substrate largely determines the TS content and pH value in the anaerobic fermentation of biogas production.
Keyword: biogas, gas rumah kaca, kotoran domba, kotoran sapi potong, beef cattle manure, biogas, greenhouse gases, sheep manure

Judul: Mencari Aproksimasi Akar-Akar Polinomial Kompleks Dengan Algoritma Weyl
Abstrak: Mencari akarMakar polinomial dengan menggunakan algoritma Weyt. Algoritma WeyJ merupakan algoritma rekursif yang proses kerjanya dapat diana10gkan dengan algoritma Bisection. Karena algoritma Weyl bergerak dalam bidang kompleks maka memerlukan nilai awal hempa bujur sangkar. Dalam proses penyempitan bujur sangkar tersebut algoritma Weyl memerlukan algorittna Turan untuk menentukan jarak antara suatu titik dengan akar polinomial yang terdekat dengan titik tersebut. Karena apabiJa jarak tersebut temyata lebih hesar dari Yl panjang diagonal bujur sangkar yang diamati maka bujur sangkar tersebut tidak memuat satu pun akar polinomial. Untuk seJanjutnya bujur sangkar tersebut diabaikan. Sebaliknya apabila jarak yang diperoleh lebih keeil dari \6 panjang diagonal bujur sangkar yang diamati, maka bujur sangkar tersebut yang akan diperkeciL
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