Judul: Uji karakteristik water absorbent pati singkong serta pengaruhnya terhadap tanaman cabai pada tanah bertekstur pasir
Abstrak: Tin mine tailing in Bangka Belitung island covers significantly large area. Unfortunately, this tailing contain very high sand (>90%) but very low clay (<5%) and very low organic matter (<1%), that is has very low water retention ability. Common effort to overcome low water retention problem is by using intensive irigation. However, intensive use of irigation tends to be inefficient. To reduce the intensity of irigation, the use of water absorbent is presently began widely introduced, one of them is SWA (Super Water Absorbent) Cassava Starch. A study to examine the characteristics of SWA Cassava Starch and observe its effect to chilli plants in sand-textured soils was conducted in a greenhouse. The study consisted of two series of experiments. First, evaluation of SWA Cassava Starch (in swelling condition) degradability based on the decrease in the weight of SWA (swelling) toward the time. Second, evaluation of the effect of water absorbent on chili plant growth using Completely Randomized Design with three treatment factors namely (1) Water absorbent consisting of 8 standard; (2) sand soil consisting of 2 standard, and (3) Watering consisting of 2 standard. SWA Cassava Starch in applied in wet method before which SWA is soaked in water until it reaches equilibrium. Result of the experiments showed that SWA Cassava Starch (in swelling condition) degradability tend to be the same on the Regosol soil or sand tailings simulation soil. Second experiment indicated that in general water absorbent had no significant effect on chili plants growth, eventhough SWA Cassava Starch treatment with a dose of 0.1 g/kg in combination with chitosan tends to give a better effect. Chili plants growth at “a without watering treatment” with SWA treatment have a shorter life cycle compared to “once a week watering treatment”.
Keyword: Bogor Agricultural University (IPB), sand soil, chili plants, SWA cassava starch

Judul: Pengaruh Aplikasi Basah Water Absorbent Pati Singkong Terhadap Sifat Retensi Air pada Tanah Bertekstur Pasir
Abstrak: Water retention is one of soil physical properties that indicate water availability tobe used by a plant. The low water retention ability is generally owned by sand textured soils such as former mine tailings and other sand texture of soils. Plant on soil with low water retention ability will quickly sustain of water stress that extreme condition will lead to permanent wilting. Common effort to overcome this problem is generally by high frequency irrigation. This effort is however inefficient. Other alterative is needed to solve this problem. Presently BATAN (Badan Tenaga Nuklir Nasional) introduce a Super Water Absorbent (SWA) of Cassava Starch that capable to retain water ± 300 than of it weight. Nevertheless, how the SWA work and influence soil water retention characteristic is still questionable. The study aimed to assess the effect of SWA on soil retention characterstic was carried in a green house of IPB. Results of the study showed that SWA application had no significantly effect on the amount of water retained by soil with very high sand. Organic matter and content of sand are influencing the soil capability in water holding and storing.
Keyword: Bogor Agricultural University (IPB), water retention, super water absorbent, sand textured soils

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