Judul: Compost Characteristic Made of Calliandra, Rice Straw, and Vegetable Leftovers
Abstrak: Compost is organic fertilizer which is important for improving physical, chemical and biological characteristics of soil. The function of compost is however depends on the quality of compost. Until now, the quality of compost was valued by C/N ratio and the nutrient content only, without determine humic and fulvic acid content. Organic acid content in compost was hold very important function in improving soil characteristic. In this research, three compost materials, i.e. calliandra, rice straw and vegetable leftovers, with 1 m3 volume each, were composted for six weeks. Based on physical compost characteristic, ripe compost can be taken after six weeks. Changes in temperatures, colour, and smell were observed during the composting. Compost product at each steps of composting was analyzed for nutrients and organic acids content. The result of this research showed that calliandra material produced higher compost’s volume than compost from mixed material, rice straw, and vegetable leftovers. Nutrient content of vegetable leftovers compost was higher than calliandra, mixed material and rice straw compost based on oven-dry (60oC) compost. Qualitative determination of humic acid and fulvic acid can be used as an indicator of compost quality. The highest organic acid content, particularly humic acid was found in rice straw compost and followed by vegetable leftovers, mixed material and calliandra compost that has the lowest humic acid content. Whereas, the highest fulvic acid content was found in calliandra compost and followed by mixed material, rice straw and vegetable leftovers compost. Functional group analysis result in FTIR curve showed changes model and functional group connection that almost similar for each material during composting process, but has different absorbance in composting age., Kompos merupakan pupuk organik yang mempunyai fungsi dan peranan yang penting untuk memperbaiki sifat-sifat fisika, kimia, dan biologi tanah. Fungsi dan peranan kompos pada tanah sangat ditentukan oleh kualitas kompos. Sampai saat ini, penilaian kualitas kompos sering hanya dilihat dari nisbah C/N dan kandungan unsur-unsur hara tanpa memperhitungkan kandungan asam-asam organik khususnya asam humat dan asam fulvat. Jumlah asam-asam organik tersebut memegang peranan sangat besar dalam memperbaiki sifat-sifat tanah. Pada penelitian ini, tiga bahan kompos dari tanaman kaliandra, jerami padi dan sampah sayuran dengan volume masing-masing 1 m3 dikomposkan sampai matang. Berdasarkan sifat-sifat fisik kompos, maka kompos sudah matang setelah dikomposkan selama 6 minggu. Selama proses pengomposan parameter yang diamati adalah perubahan suhu, volume, warna, dan bau kompos. Kompos yang dihasilkan pada setiap tahap pengomposan dianalisis kandungan unsur-unsur hara dan asam-asam organiknya. Hasil penelitian menunjukkan bahwa bahan tanaman kaliandra menghasilkan volume kompos paling tinggi bila dibandingkan kompos dari bahan campuran, jerami padi dan sampah sayuran. Kompos sampah sayuran mengandung unsur hara paling tinggi dibandingkan kompos kaliandra, campuran dan jerami padi berdasarkan bobot kering kompos 60ºC. Penentuan secara kualitatif dari asam humat dan asam fulvat dapat dijadikan sebagai indikator dari kualitas kompos. Kandungan asam-asam organik khususnya asam humat paling tinggi terdapat pada kompos dari bahan jerami padi diikuti oleh kompos sampah sayuran, campuran dan terendah pada bahan tanaman kaliandra. Sedangkan kandungan asam fulvat paling tinggi terdapat pada kompos kaliandra diikuti oleh kompos campuran, jerami padi dan sampah sayuran. Hasil analisis gugus fungsional
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Judul: The Effect of Sheep Manure and B8 Decomposer on Compost Quality
Abstrak: Bahan organik mempengaruhi sifat fisik, kimia, dan biologi tanah, sehingga dapat menjaga fungsi tanah sebagai media pertumbuhan tanaman. Jerami padi, brangkasan jagung dan batang pisang merupakan limbah pertanian yang potensial untuk dijadikan bahan utama pembuatan kompos. Kualitas bahan kompos menentukan laju dekomposisi bahan kompos. Dalam proses pengomposan sering ditambahkan dekomposer, sebagai agen untuk mempercepat proses dekomposisi. Tujuan percobaan pengomposan ini adalah untuk mempelajari pengaruh kotoran domba dan pengurai B8 terhadap kualitas kompos dari jerami padi, brangkasan jagung, dan batang pisang. Percobaan dilakukan di Kebun Percobaan Cikabayan IPB, Dramaga Bogor. Proses pengomposan dilakukan secara aerob. Seberat 15 kg bahan campuran jerami padi, brangkasan jagung dan batang pisang dengan perbandingan 2:2:1 digunakan untuk bahan utama pengomposan untuk setiap satuan percobaan. Perlakuan percobaan pengomposan meliputi kontrol (tanpa kotoran domba dan B8), standar (ditambah 3 kg kotoran domba, tanpa B8), D1 (tanpa kotoran domba, ditambah B8 25 ml), D2 (tanpa kotoran domba, ditambah B8 50 ml), DoD1 (ditambah 3 kg kotoran domba dan B8 25 ml), dan DoD2 (ditambah 3 kg kotoran domba dan B8 50 ml). Semua perlakuan ditambahkan 300 g urea, dibasahi, dibalik dan diaduk setiap 3 minggu. Tumpukan kompos dipertahankan lembabannya selama proses pengomposan. Pengamatan suhu kompos dilakukan setiap minggu mulai minggu ke-1 hingga minggu ke-12 dengan menancapkan termometer kompos ke dalam tumpukan kompos. Pengambilan contoh kompos dilakukan pada 0, 4, 8, dan 12 minggu pengomposan. Uji kualitas kompos didasarkan pada sifat kimiawi kompos yang meliputi kadar C-organik, N, dan S. Hasil percobaan menunjukkan bahwa perlakuan kotoran domba dan dekomposer B8 berpengaruh nyata terhadap kadar N, kadar S, nisbah C/N dan C/S, tetapi tidak berpengaruh nyata terhadap kadar C organik. Kualitas kompos terbaik ditemukan pada perlakuan DoD2 dengan nilai C-organik 29,9%, kadar N 1,9%, kadar S 1,2%, nisbah C/N 16,1, dan nisbah C/S 24,7, meskipun secara statistik perlakuan DoD2 dan DoD1 tidak berbeda nyata. Kata kunci : Nisbah C/N, dekomposisi, unsur hara, kompos, Organic matter affects the physical, chemical, and biological properties of the soil, therefore it can maintain soil function as a medium for plant growth. Rice straw, corn stover and banana stalks are potential agricultural waste to be used as the main material for composting. The quality of the compost material determines the rate of decomposition of the compost material. In the composting process, a decomposer is often added, as an agent to speed up the decomposition process. The purpose of this composting trial was to study the effect of sheep dung and decomposer B8 on the quality of compost from rice straw, corn stover, and banana stalks. The trial was carried out at the Cikabayan Experimental Station IPB, Dramaga Bogor. The composting process is carried out aerobically. A mixture of 15 kg of rice straw, corn stalk and banana stalks with a ratio of 2: 2: 1 is used for the main composting material for each trial unit. The trial treatments were Control (without sheep dung and B8), Standard (added 3kg sheep dung, without B8), D1 (without sheep dung but added B8 25 ml), D2 (without sheep dung but added B8 50 ml) , DoD1 (added 3 kg sheep dung
Keyword: C/N ratio, decomposition, nutrients, compost

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model