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: Optimasi Dosis Pemupukan Kalium pada Budi Daya Tomat (Lycopersicon esculentum) di Inceptisol Dramaga
Abstrak: This research objective was to find the optimum rate of potassium fertilizer for specific location of tomato cultivation in inceptisol Dramaga with high soil potassium content (231 ppm). The experiment was conducted at Cikabayan Teaching Farm IPB from July to October 2014. The experiment was arranged in Randomized Completely Block Design with four replications and single treatment factor which was potassium rate in five levels ie 0X (0), ¼X (152.2 kg ha-1), ½X (304.3 kg ha-1), ¾X (456.3 kg ha-1), and X (608.6 kg ha-1). The results showed that on high soil potassium content potassium fertilizer were not affect all of the measured variables, therefore K fertilization is unnecessary.
Keyword: Bogor Agricultural University (IPB), potassium., optimation, nutrient rate, inceptisol

Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh.
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.