Judul: Development of fertilization recommendation for Nitrogen, Phosphorus, and Pottasium on pineapple (Ananas comosus (L) Merr.) smooth cayenne be based on soil nutrient status
Abstrak: Nitrogen (N), phosphorus (P), and pottasium (K) are needed in a large amounts foe plant growth and production of pineapple, however, exceed application may decrease the growth and production of pineapple. Therefore, the fertilization application must be based on soil nutrient status and plant requirements. Minus one test was conducted to prove the potential of N, P, and K nutrients as limiting factor for pineapple plant growth in Inceptisol-Darmaga, Inceptisol-Ciawi, Ultisol-Jasinga, and Andisol-Ciapus on pineapple.
Keyword: Minus one test, Nutrient status, Extraction method, Optimum dosage, Critical level, Kalibrasi uji tanah, Korelasi uji tanah, Tanah inceptisol, Tanah ultisol, Tanah andisol

Judul: Development of soil test of phosphorus and potassium for fertilizer recommendation of tomato
Abstrak: The best management practices for fertilizer application on vegetable crop in Indonesia are not available at present. Environmentally friendliness in fertilizer recommendation based on soil analysis has been adopted by many developed countries for crop production. Soil testing using single-nutrient soil analysis in Indonesia has been developed since 1970. However, due to limited research fund, soil testing has not been programmed continuously and recommendation for fertilization of specific location based on soil family has not been established yet. Therefore, this research developed the basic model of P and K fertilizer efficiency and recommendation based on soil analysis for tomato in Inceptisols. This model will be adopted for other vegetable crops and different soil type in the future. Tomato is a vegetable growing well on Inceptisols soil type, which generally has low pH and high P-fixation. Research was done in greenhouse and open field of Cikabayan, UF, IPB, from March 2010 to December 2011. The objective of this research was to develop the best management practice for P fertilizer and K fertilizer recommendation based on soil analysis on Inceptisols for tomato. The study was designed in two years. The first year was to build recommendation for P and the second year for K fertilizer. Each study consisted of three experiments. First experiment was correlation study that aimed at finding out the best extraction method. The second experiment was calibration study that aimed at developing soil response category. The third experiment was recommendation study that aimed at building P and K fertilizer recommendation for each soil category on Inceptisols for tomato. Treatments were phosphorus and potassium rates i.e. 0X, ¼ X ½ X ¾ X and 1X, where X was 368.6 P2O5 kg ha-1 and was 608.6 K2O kg ha-1. Correlation of soil P and K test with tomato growth was conducted in the greenhouse through media obtained from soil incubation processes. Soil P test used five extraction methods i.e. Bray I, Bray II, Mehlich I, Morgan Wolf and Truog. Soil K test also used five extraction methods i.e. Mehlich I, Morgan Vanema, Truog, HCl 25% and NH4OAc 1 M pH 7. Calibration test was arranged in a completely randomized design with two factors. The treatment consisted of several soil P status (levels) ranging from very low to very high. Fertilizer dosage i.e. X, ¾ X, ½ X, ¼ X, and 0X was the second factor, where X was 368.6 P2O5 kg ha-1 for P and was 608.6 kg ha-1 K2O for K. Results showed that there were significant differences among P and K fertilizer treatments on plant height, stem diameter, leaf number, fresh biomass and dry biomass for both correlation test and calibration test. The correlation test showed that the best extraction reagent was Mehlich I for P and Truog for K. Fertilizer recommendation criteria for “very low-nutrient status” was 183.3 P2O5 kg ha-1 and 281.3 K2O kg ha-1. Fertilizer recommendation for “low-nutrient” status was 71.4 P2O5 kg ha-1 and 178.6 K2O kg ha-1.
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Judul: Pemodelan Harga Saham Menggunakan Model Lévy dan Model Black-Scholes
Abstrak: Stock may produce high profits. However, it has a high risk as well, because the stock prices fluctuate over time. Therefore, a model is required to estimate the future stock prices accurately. In this paper, Lévy model is compared to Black-Scholes model in estimating the stock price at Bank of America Corporation. As a result, it is concluded that the Black-Scholes model is more accurate than Lévy model.
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