Judul: The Growth and Tuber Yield of Sweetpotato (Ipomoea batatas L.) Ase Kapas at Various Rates of Nitrogen Fertilizer
Abstrak: Ubijalar merupakan tanaman pangan penting di Indonesia. Produktivitas ubijalar dapat dipengaruhi oleh pemupukan. Tujuan penelitian ini yaitu menentukan dosis nitrogen bagi pertumbuhan dan produksi ubijalar Ase Kapas. Penelitian dilakukan pada bulan Januari sampai Juli 2020 di Kebun Percobaan Cikabayan IPB dengan rancangan kelompok lengkap teracak dengan 3 ulangan. Dosis N yang diaplikasikan yaitu 0; 22,5; 45; 67,5; dan 90 kg ha-1 . Bahan tanam yang digunakan yaitu bagian stek pucuk. Curah hujan selama penelitian cenderung tidak sesuai dengan kondisi optimal pertumbuhan ubijalar. Pada tanah dengan kandungan nitrogen berstatus sedang (0,29% setara dengan 174 kg ha-1 ), dosis N tidak berpengaruh signifikan terhadap perubahan panjang dan diameter sulur, jumlah daun dan cabang, panjang dan diameter umbi, serta bobot basah dan kering umbi dan brangkasan. Pada tanah dengan kandungan N total sedang, dosis 0 kg N ha-1 dapat diaplikasikan untuk mendukung pertumbuhan dan produksi yang baik bagi ubijalar klon Ase Kapas., Sweetpotato is an essential crop plant in Indonesia. The productivity of the sweetpotato could be affected by fertilization. The objective of this research is to assess optimal nitrogen rate for growth and root yield of sweetpotato Ase Kapas. The experiment was conducted at IPB University experimental field Cikabayan from January to July 2020 used randomized complete block design with 3 replications. The level of nitrogen fertilizer consists of 0; 22,5; 45; 67,5; and 90 kg ha-1 . The planting material is the vine cuttings. The rainfall during this experiment tends to be insufficient as climate requirements. In the soil with moderate N content (0.29% equal to 174 kg ha-1 ), nitrogen had no significant effect on the growth of length and diameter of main stem, the amount of leaves and secondary stems, length and diameter of storage roots, wet- and dry-weight biomass of storage roots and aboveground part. In the soil with a moderate N total, dose of 0 kg N ha-1 could be applied to support good growth and yield of sweetpotato clone Ase Kapas.
Keyword: produktivitas, suplai nitrogen, umbi, Urea, nitrogen supply, storage root, productivity

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.
Keyword: 

Judul: Analysis of M/G/1 Queue Model with Two Phases of Service and Bernoulli Feedback System
Abstrak: Model antrean M/G/1 dengan sistem feedback Bernoulli adalah model antrean dengan proses kedatangan mengikuti proses Poisson. Pada karya ilmiah ini dibahas sistem antrean M/G/1 dengan dua fase layanan. Setelah layanan pertama selesai, pelanggan dapat memilih untuk meninggalkan sistem dengan peluang ... dst, The M/G/1 queueing model with the Bernoulli feedback system is a queueing model with the arrival process following the Poisson process. In this manuscript M/G/1 queueing system with two phases of service is discussed. After the first service is completed, the customer can choose to leave the system with probability ... dst
Keyword: queue, Bernoulli, probability generating function, expected value