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: Effect of Soil P and K Content on the Growth and Yield of Tomato (Lycopersicon esculentum) in Garut Andisols.
Abstrak: Tomat merupakan komoditas hortikultura yang banyak dibudidayakan dan dimanfaatkan di Indonesia. Produktivitas tomat dapat ditingkatkan dengan pendekatan teknologi budidaya seperti menggunakan teknologi irigasi dan pemupukan yang presisi. Penelitian ini menggunakan rancangan kelompok lengkap teracak (RKLT) dengan satu faktor berupa taraf status hara P dan K (rendah, sedang, dan tinggi) menggunakan perangkat uji tanah kering (PUTK). Analisis taraf hara P dan K pada tanah Andisol menggunakan PUTK terhadap tanaman tomat dapat digunakan. Hasil pada penentuan taraf hara P berbeda nyata pada hasil bobot kering tajuk, bobot kering total, jumlah buah total, dan bobot buah total. Taraf hara P tinggi menunjukkan rataan hasil produktivitas yang paling tinggi yaitu 307,59 gram/tanaman. Hasil pada penentuan taraf hara K menunjukkan perbedaan sangat nyata pada jumlah buah total dan berbeda nyata pada bobot kering tajuk, bobot kering total, dan bobot buah total. Taraf hara K tinggi menunjukkan rataan hasil produktivitas yang paling tinggi dari semua perlakuan yaitu 320,17 gram/tanaman., Tomato is a horticultural commodity that is widely cultivated and used in Indonesia. Tomato productivity can be increased by using cultivation technology approaches such as using irrigation technology and precise fertilization. This study used a completely randomized block design (RKLT) with one factor of P and K nutrient status levels (low, medium, and high) from the results of Garut Andisol soil testing using a perangkat uji tanah kering (PUTK). Analysis of P and K nutrient levels in Andisol soil using PUTK for tomato plants can be used. The results for determining the levels of P nutrients were significantly different in the results of shoot dry weight, total dry weight, total fruit number, and total fruit weight. The high level of P nutrient indicates the highest average yield of productivity, that is 307.59 gram/plant. The results for determining the K nutrient levels showed highly significant differences in the total fruit number and significantly different in shoot dry weight, total dry weight, and total fruit weight. The high K nutrient level showed the highest average yield of all treatments, that is 320.17 grams/plant.
Keyword: PUTK, Taraf Hara, Generatif, Vegetatif

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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