Judul: Evaluasi kualitas sifat fisik tanah pada berbagai penggunaan lahan di lahan kering. Studi kasus: DAS Mikro Cikardipa, Sub DAS Cisukabirus, DAS Ciliwung Hulu, Desa Sukagalih, Kecamatan Megamendung, Kabupaten Bogor.
Abstrak: Lahan kering merupakan salah satu agroekosistem yang berpotensi besar untuk usaha pertanian. Desa Sukagalih yang merupakan wilayah DAS Mikro Cikardipa, Sub DAS Cisukabirus, DAS Ciliwung Hulu mempunyai lahan kering yang diusahakan secara intensif untuk pengembangan pertanian. Lahannya berlereng dengan curah hujan yang relatif tinggi sehingga sangat rentan terhadap erosi dan penurunan kualitas fisik tanah yang dapat menyebabkan kerusakan tanah. Penelitian ini bertujuan untuk mengidentifikasi pengaruh penggunaan lahan dengan berbagai kemiringan lereng terhadap sifat fisik tanah dan mengevaluasi kualitas sifat fisik tanah untuk pertanian konservasi. Pengamatan tanah serta pengambilan contoh tanah ditentukan berdasarkan peta satuan lahan yang didapat dari overlay peta tanah, peta lereng, peta penggunaan lahan DAS Mikro Cikardipa, Sub DAS Cisukabirus, DAS Ciliwung Hulu. Pengambilan contoh tanah utuh dengan menggunakan ring sampler digunakan untuk penetapan bobot isi dan permeabilitas tanah. Pengambilan contoh tanah terganggu untuk analisis tekstur, kadar bahan organik dan bobot jenis partikel. Pengamatan kedalaman solum tanah dilakukan langsung di lapang. Analisis data dilakukan secara statistic menggunakan metode Duncan Multiple Range Test (DMRT). Hasil penelitian menunjukkan bahwa penggunaan lahan maupun kemiringan lereng pada tiap penggunaan lahan berpengaruh nyata terhadap tekstur tanah, kadar bahan organik tanah, permeabilitas tanah, dan kedalaman solum tanah. Secara umum, tanah di lokasi penelitian belum mengalami penurunan kualitas fisiknya. Hal ini diduga banyaknya petani yang menerapkan teknik konservasi baik secara vegetatif, mekanik, dan kimia sebagai upaya meningkatkan kualitas tanah dan perbaikan pengelolaan lahan.
Keyword: Dry land, Land use, Physical of soil, Soil quality, Agroecosystem, Vegetative methode, Agriculture, Watershed, Soil conservation

Judul: Karakteristik sifat fisik dan hidrologi tanah pada berbagai penggunaan lahan: studi kasus di desa cimulang, kecamatan rancabungur, kabupaten Bogor, provinsi Jawa Barat
Abstrak: The increasing population has caused increasing pressure over land utilization that has lead to more conversion of forest land into agriculture land (dry farm and plantation). This land conversion degrades land quality as indicated by decreasing quality of soil physical properties, decreasing of water infiltration, and increasing of runoff. A research to study soil physical and hydrology characteristics on mixed farm, oil palm plantations, and dry farm was carried out in Cimulang village, Rancabungur District, Bogor Regency. The study was conducted on different slope, i.e. 0-5%, 5-8% and 8-15% in the same soil type. Parameters observed in this study were infiltration capacity, hydraulic conductivity, bulk density, porosity, pore drainage, and soil ability to hold water (fiels capacity, available water, and fiels water content). Measurements of bulk density, porosity, pore drainage, and the ability of soil to hold water are done in the laboratory using undisturbed soil samples. Meanwhile, the measurements of infiltration and hydraulic conductivity were done in the field. The result shows that dry farm has the lowest quality of soil physical and hydrology as indicated by the highest bulk density and low porosity, macro pores, infiltration, and hydraulic conductivity. Land of oil palm has lower quality of soil physical than mixed farms. The quality of soil physical in mixed farms is better due to greater amount of plant residue and unintensive soil management that makes the land remains protected with minimum soil damage. The above result proved that the main factor affecting the soil physical properties and hydrology are the intensity of soil management, the quantity and quality of plant residue and organic material.
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Judul: Estimating Parameter and the Convergence of Parameter Estimator of Poisson Hidden Markov Model
Abstrak: Model hidden Markov terdiri dari sepasang proses stokastik yaitu proses observasi dan proses yang memengaruhi observasi. Proses stokastik yang memengaruhi observasi ini diasumsikan membentuk rantai Markov dan tidak diamati. Model Poisson hidden Markov (MPHM) adalah salah satu model hidden Markov diskret dan proses observasinya jika diketahui proses yang memengaruhinya diasumsikan menyebar Poisson., A hidden Markov model (HMM) consists of a pair of stochastic processes, that is the observation process and process that affected observation. The stochastic process which causes this observation is assumed to form a Markov chain and is not observed. Poisson hidden Markov models (PHMM) is one of the discrete HMM and the observation process given the cause is assumed having a Poisson distribution.
Keyword: Poisson hidden Markov model, Forward-Backward algorithm, Expectation Maximization algorithm