Judul: Pergerakan Kalium (K+) dan Pospor (PO42-) dalam Kolom Tanah Andosol dan Regosol.
Abstrak: Pertanian intensif merupakan sistem pertanian yang menggunakan berbagai teknologi dalam rangka meningkatkan produksi. Salah satu cirinya adalah penggunaan pupuk anorganik secara terus menerus. Penggunaan pupuk anorganik khususnya pupuk kalium dan pospor sangat bermanfaaat bagi pertumbuhan tanaman. Namun, jika digunakan secara terus-menerus dapat berdampak negatif terhadap tanah dan tanaman. Oleh karena itu, perlu memaksimalkan efektifitas penggunaan pupuk P dan K serta meminimalkan pergerakannya ke air bawah tanah dengan pengetahuan tentang pergerakan solute atau bahan kimia seperti pupuk P dan K. Penelitian ini bertujuan mengkaji pergerakan solute khususnya Kalium dan Pospor di dalam kolom tanah Andosol dan Regosol. Contoh tanah Andosol Gunung Bunder dan Regosol Dramaga diambil dengan menggunakan pipa PVC dengan panjang 40 cm dan diameter 10 cm yang diambil dalam keadaan tidak terganggu sedalam 30 cm yang mewakili top soil (0-30 cm). Pengukuran pergerakan P dan K dilakukan dengan alat constant head berdasarkan penurunan tinggi air di permeameter. Larutan pupuk KCl dan TSP dialirkan ke kolom tanah yang digunakan dalam keadaan jenuh, dengan menggunakan konsentrasi tertentu secara periodik dan rentang waktu tertentu. Ekstrak yang keluar dari kolom tanah di tampung dengan labu ukur, kemudian konsentrasi larutan diukur dengan menggunakan spektofotometer dan flamefotometer hingga diperoleh konsentrasi yang sama dengan konsentrasi larutan yang dimasukkan kedalam kolom tanah. Pergerakan solute khususnya kalium dan pospor didalam tanah dapat terjadi melalui proses difusi dan aliran massa, atau dispersi hidrodinamik. Kemampuan tanah menjerap solute (kalium dan pospor) sangat mempengaruhi pergerakan solute. Hasil yang diperoleh pada pergerakan kalium ditanah Regosol relatif lebih cepat dibandingkan dengan tanah Andosol. Titik kesetimbangan (C/Co)=1 pergerakan kalium pada masing-masing tanah berbeda yaitu pada tanah Regosol adalah sebesar (V/Vo)=6,5, sedangkan Andosol sebesar (V/Vo)= 8,5. Sama dengan kalium, pergerakan pospor di tanah Regosol juga berlangsung lebih cepat daripada di tanah Andosol. Titik kesetimbangan (C/Co)=1 di tanah Andosol adalah sebesar (V/Vo)=6,8, sedangkan di tanah Regosol sebesar (V/Vo)= 5,6. Pergerakan kalium dalam tanah lebih lama dari pada pergerakan pospor baik di tanah Andosol maupun di tanah Regosol.
Keyword: constant head, difusi, solute, aliran massa

Judul: Potassium (K+) Movements in Andosol Lembang, Grumusol Cianjur and Latosol Dramaga Soil Columns
Abstrak: Modern agriculture using excessive and continuous use of inorganic fertilizers needs to be reviewed because apart from being inefficient in terms of cost, it also has a negative impact on the environment. One example is the use of K fertilizer. Therefore, it is necessary to maximize the effectiveness of using K fertilizer and minimize its movement to underground water with knowledge of the movement of solutes or chemicals such as K fertilizer. This study aims to examine the movement of solutes, especially potassium (K) in the soil. Soil column of Lembang Andosol Soil, Latosol Dramaga and Grumusol Cianjur. The measurement of the movement of K is carried out using a constant head device based on the decrease in water level in the permeameter. KCl fertilizer solution is flowed into the soil column which is used in a saturated state, using a certain concentration periodically and a certain time span. The extract that came out of the soil column was accommodated with a measuring flask periodically, then the concentration of the solution was measured using a flamephotometer to obtain a concentration equal to the concentration of the solution that was inserted into the soil column. The movement of solutes, especially potassium in the soil, can occur through the process of diffusion and mass flow, or hydrodynamic dispersion. The ability of the soil to absorb solute (potassium) greatly affects the movement of solutes. Equilibrium point (C/Co)=1 movement of potassium in each different soil, namely in Andosol soil is equal to (V/Vo)=7.5, Latosol is (V/Vo)=4.8 and Grumusol (V/Vo) )=4,1. From the three types of soil, it shows that the movement of K nutrients is dominated by mass flow, which can be concluded from if the velocity of water and fertilizer is almost the same, then the process of nutrient movement is dominated by mass flow.
Keyword: mass flow, solutes, physical and chemical properties of soil

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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