Judul: Pengaruh Pupuk Anorganik Dan Pupuk Organik Terhadap Produksi Dan Kualitas Ubi Jalar (Ipomoea batatas (L.) Lam) Dan Sifat Kimia Podsolik Jasinga
Abstrak: Podsolic is the soil that has a very wide spread in Indonesia, which reached 47,526 million ha of total land area of Indonesia. Podsolic is soil with organic matter content less than 2 %, base saturation is generally low (<35 %), acid (pH 3.5-5.5), low to high cation exchange capacity depending on the texture and clay mineral, low content of nutrients, especially N, P, K, and Ca, and generally have relatively low fertility rate. Sweet potato is a plant that has little risk of crop failure and has a wide adaptability to the environment, so that it can be cultivated on various types of land, altitude, and different levels of soil fertility. This research is a field experiment of planting sweet potatoes in demonstration plot of BPN RI, Setu village, Jasinga, Bogor District with total area of 1800 m2. The design of treatment randomized complete block design factorial two factors. The first factor is the dose of inorganic fertilizer (15-15-15 and Rock Phosphate), while the second factor is the organic fertilizer (with and without humic). Soil analysis was performed at the Center for Soil Research, Bogor and analysis of the quality of sweet potato conducted at the Laboratory of Technopark, Bogor Agricultural University. This study aims to determine the effect of inorganic fertilizer (15-15-15 and Rock Phosphate), and organic fertilizer (humic) on growth, production and quality of sweet potato (Ipomoea batatas (L.) Lam.) and soil chemical properties Podsolic Jasinga. The results showed that the inorganic fertilizer15-15-15 (Phonska) increased stem length and starch content, while inorganic fertilizer Rock Phosphate tends to produce biomass weight than inorganic compound fertilizer 15-15-15. Interaction between inorganic fertilizer and organic fertilizer significantly increased the number of leaves and weight of tuber. In the treatment without humic, inorganic compound fertilizer 15-15-15 tended to increase Pavailable, whereas giving Rock Phosphate increased pH, P-available, and K-dd. The treatment with humic, giving P1 15-15-15 compound fertilizer and Rock Phosphate dose of R2 increased available-P and soil cation exchange capacity, while lower dose of P2 and R1 increased available-P and soil cation exchange capacity. Organic fertilizer and inorganic fertilizer did not decrease the Al-dd but tended to increase the Al-dd.
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Judul: The Growth and Prodution of Sweet Potatoes (Ipomoea batatas L.) Ase Kapas Clones With Different Doses of Phosphorous Fertilizer.
Abstrak: Ubi jalar merupakan sumber karbohidrat non beras yang mampu meningkatkan ketersediaan pangan dan diversifikasi pangan. Pemupukan salah satu faktor penting dalam budidaya tanaman ubi jalar. Penelitian ini bertujuan untuk menguji beberapa dosis fosfor optimal terhadap pertumbuhan dan produksi ubi jalar varietas ase Kapas. Percobaan penelitian ini dilakukan di Kebun Perobaan Cikabayan IPB dan Laboratorium Pasca Panen dari bulan Januari 2020 hingga Juli 2020. Percobaan penelitian disusun dalam Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan lima taraf percobaan yaitu 0 kg ha-1 SP36, 50 kg ha-1 SP36, 100 kg ha-1 SP36, 150 kg ha-1 SP36, 200 kg ha-1 SP36 dari dosis pupuk rekomendasi (100 kg ha-1 SP36). Terdapat tiga ulangan dengan lima perlakuan sehingga ada 15 percobaan. Ubi jalar Ase Kapas menunjukkan respon kuadratik terhadap peningkatan dosis pupuk P untuk peubah pertumbuhan tajuk, jumlah daun aktif dan jumlah cabang dengan nilai maksimum pada rata-rata dosis pupuk 143,6 kg SP36 ha-1. Produksi umbi tidak menunjukkan respon yang nyata terhadap peningkatan dosis pupuk SP36. Pada kondisi tanah kebun percobaan dengan status P tersedia yang rendah (8,3 ppm atau setara 16,6 kg ha-1 pada kedalaman 20 cm) maka secara praktis pupuk SP36 dapat diberikan dengan dosis 150 kg SP36 ha-1 atau 150% dosis pupuk rekomendasi., Sweet potato is a source of non-rice carbohydrates that can increase food security and diversity food. Fertilization an important factor in the cultivation of the sweet potato plant. The research aimed to determine the optimum fertilizer doses of the fertilizer for the growth and production of seet potato Ase Kapas clone. The experiment was performed at the field experiment Cikabayan IPB and post-harvest laboratory from January 2020 to July 2020. The experiment was arranged in a Randomized Complete Design Group (RCBD) single with single factor of phosphor fertilier dose is 0, 50, 100, 150, 200 kg ha-1 SP36 (100 kg ha-1 SP36 is a reference dose). There were three repliations with five treatments that led to 15 trials. Ase Kapas sweet potato showed a quadratic response to an increase in the dose of phosphorus fertilizer for crown growth variables, the number of active leaves and the number of branches with maximum values in the range average 143,6 kg SP36 ha-1. Tuber production did not show a significant response to increasing the dose of SP36 fertilizer. In the soil conditions with low available phosphorus status (8,3 ppm or equivalent to 16,7 kg ha-1 at a deep of 20 cm), SP36 fertilizer can be given at a dose of 150 kg SP36 ha-1 or 150% of the reference dose.
Keyword: Phosphorus fertilizer, regression analysis, sweet potato

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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