Judul: Analysis of soil Chemical and Biological Characteristics of Soil in Several Types Land Use in Sulawesi Tengah
Abstrak: Penggunaan lahan yang beragam serta pengelolaan yang intensif mengakibatkan penurunan tingkat kesuburan tanah di suatu lahan. Penggunaan lahan di Sulawesi Tengah banyak difungsikan sebagai perkebunan dan pertambangan sehingga populasi mikrob di setiap penggunaan lahannya berbeda-beda. Penelitian ini bertujuan mengetahui karakteristik sifat kimia dan sifat biologi tanah pada berbagai penggunaan lahan di Sulawesi Tengah. Pengambilan sampel tanah dilakukan dengan menggunakan metode purposive random sampling di Sulawesi Tengah. Lokasi penelitian yaitu Kecamatan Lore Utara dan Mantikulore (pertambangan emas), Kecamatan Nokilalaki (Kakao), dan Kecamatan Banawa Selatan (Kelapa Sawit). Hasil analisis menunjukkan populasi mikrob dan fungi tertinggi terdapat pada penggunaan Lahan Sawit yang memiliki kadar C-organik yang rendah dan kadar N-total yang sedang. Sedangkan populasi mikrob dan fungi terendah terdapat pada lahan Tambang Konvensional dengan kadar C-organik dan N-total yang rendah. Berdasarkan hasil analisis kimia tanah, Lahan Kakao memiliki kadar C-organik dan N-total lebih tinggi di antara penggunaan lahan lain, sedangkan kadar P dan K total t e r t i n g g i dimiliki oleh lahan Tambang Konvensional. Kadar C-organik dan nisbah C/N tanah berpengaruh terhadap tinggi rendahnya nilai respirasi yang dihasilka, Land use diversity and land management intensively have decreased soil fertility. One of the dominant land uses in Central Sulawesi are plantations and mining, which has an impact on the microorganism’s population. This study was aimed to determine the characteristics of chemical and biological properties of soil in various land uses in Central Sulawesi. Soil sampling was carried out using the purposive random sampling method in Central Sulawesi. The research location are North Lore District and Mantikulore District (Mining), Nokilalaki District (Cocoa), and South Banawa District (Oil Palm). The results showed that the highest concentrations of bacteria and fungi population was Oil Palm plantations which has low C-organic levels and moderate total N levels, the lowest bacterial and fungal populations was Conventional Mining with low levels of organic C and total N. Based on soil chemical properties, Cacao land has the highest content of C-organic and the total N, otherwise Conventional mining has the highest Phosphate and Potassium content. Meanwhile, C-organic and C/N ratio of soil have an effect to the high and low value of the soil respiration.
Keyword: Cocoa, C/N ratio, Gold mining, Oil Palm, Plantation

Judul: The Chemical Properties of Soil in Taliwang Distric, West Sumbawa Regency on Land Use of Teakwood Plantation, Dryland, and Paddy Soils.
Abstrak: Sifat kimia tanah berperan besar dalam menentukan kesuburan tanah. Kesuburan tanah secara kimia dinilai dari kandungan nitrogen, fosfor, basa dapat ditukar (K, Ca, Mg, dan Na), pH tanah, karbon organik, dan kapasitas tukar kation. Penelitian ini bertujuan mengkaji sifat kimia tanah di Kecamatan Taliwang, Kabupaten Sumbawa Barat pada tiga penggunaan lahan berbeda yaitu Kebun Jati (L1), Ladang (L2), dan Sawah (L3). Penelitian ini dilaksanakan pada September 2020 hingga Maret 2021. Contoh tanah diambil pada L1 dan L2 masing-masing empat lapisan, sedangkan pada L3 tiga lapisan. Analisis kimia tanah dilakukan di Laboratorium Kimia dan Kesuburan Tanah, IPB University. Hasil penelitian menunjukkan bahwa pH tanah umumnya berkisar agak masam hingga netral (6,4- 7,3), nilai pH tanah sawah cenderung nertral sedangkan nilai pH tanah kebun jati dan ladang tergolong agak masam. Kandungan C-organik tergolong rendah hingga tinggi (0,93% - 4,09%), kandungan N-total tergolong sangat rendah hingga sedang (0,07%-0,21%). Nilai P-tersedia tergolong sangat rendah pada semua contoh tanah (0,09 ppm-1,31 ppm). Rendahnya nilai P-tersedia pada lokasi penelitian diduga karena P diikat menjadi bentuk tidak larut oleh basa-basa seperti Ca dan Mg yang kandungannya tinggi di dalam tanah yang diamati. Di samping itu karena tanah yang diamati merupakan tanah yang berkembang dari bahan induk yang miskin akan unsur P. Nilai KTK tanah berkisar dari 13,9 cmol(+)/kg sampai 30,4 cmol(+)/kg. Nilai KB tanah yang diamati tergolong sangat tinggi yaitu lebih dari 100% dan tergolong tinggi sampai sangat tinggi. Kebun jati memiliki kandungan karbon organik, N-total, P-tersedia, basa dapat ditukar dan KTK lebih tinggi dibandingkan dengan ladang dan sawah. Kandungan karbon organik, N-total, dan P-tersedia yang termasuk kategori rendah pada penggunaan lahan kebun jati, ladang, dan sawah harus menjadi perhatian utama dalam pengelolaan tanah di Kecamatan Taliwang, Kabupaten Sumbawa Barat. Kata kunci: Basa dapat ditukar, Karbon organik, Kapasitas tukar kation, N-total, pH tanah, P tersedia., The soil chemical properties play a major role in determining soil fertility. Soil fertility is characterized chemically by the nitrogen and phosphorus content, exchangeable bases (K, Ca, Mg, and Na), soil pH, organic carbon, and cation exchange capacity (CEC). This research was aimed to examine the chemical properties of soil in Taliwang District, West Sumbawa Regency on three different land uses, namely teakwood plantation (L1), dryland (L2), and paddy soil (L3). The study was conducted from September 2020 to March 2021. Soil samples were taken at L1 and L2 each from four layers (horizons), while in L3 soil samples were taken from three layers. Soil chemical properties analysis was conducted at the Laboratory of Soil Chemistry and Fertility, IPB University. The results showed that the pH of the soil were generally ranged from slightly acidic to neutral (6.4-7.3), the pH value of paddy soil is neutral while the pH value of teakwood plantation soil and dryland soil is relatively slightly acidic. Organic carbon of soil samples of three landuse observed is relatively low to high (0.93%-4.09%), the total nitrogen content is classified as very low to moderate (0.07%-0.21%). The available-P value is very low in all soil samples (0.09 ppm-1.31 ppm). The low value of available-P at the research site due to the high
Keyword: Available-P, Carbon organic, Cation exchange capacity, Exchangeable bases, Soil pH, Total-N

Judul: Penyelesaian Masalah Rotasi Aliran Fluida Kental Von Karman Menggunakan Metode Homotopi
Abstrak: Von Karman equation is an equation that describes fluid viscous flow induced by infinite disk rotation. By assuming steady flow and laminar, viscous incompressible fluid flow is represented in Von Karman equation by an angular velocity and the vertical direction velocity as the independent variables. Von Karman equation is a nonlinear problem that is solved using the homotopy method. The use of homotopy method is done by defining an homotopy function that requires auxiliary parameters to control the convergent region of the solution. The solution is a recursive formula with given initial conditions. Using software based-functional shows that velocity components converge to a value.
Keyword: