Judul: Pengaruh Pemberian Ekstrak Bahan Organik dari Kompos Kotoran Ayam, Kompos Kotoran Sapi dan Larutan Bahan Humat terhadap Fosfor Tersedia pada Inseptisol Dramaga dan Inseptisol Surade
Abstrak: Phosphorus (P) is an essential macro-nutrient for plant growth and development. Phosphorus problems in the soils are the small amount of P content and low availability because of high fixation. This research was aimed to find out the influence of applying organic matter extract from chicken manure compost, cow manure compost and solution of humate materials on the amount of available P in Dramaga Inceptisol and Surade Inceptisol. In this research, organic matter extract from chicken manure compost (1:10), cow manure compost (1:10), and solution of humate materials (1:4) were added to Dramaga Inceptisol and Surade Inceptisol. Analysis of available P was conducted using Bray I methods. The results analysis showed that available P were increased by adding chicken manure compost extract and cow manure compost extract. Addition of extract from chicken manure compost and cow manure compost which contained P of 1.43 ppm and 1.02 ppm each has increased available P in Dramaga Inceptisol from 5.3 ppm on control sample to 163 ppm and 216 ppm. The same treatment also increased available P in Surade Inceptisol from 4.8 ppm on control sample to 142 ppm and 179 ppm. Addition solution of humate materials A and B that containing P in Dramaga Inceptisol successfully increased available P from 5.3 ppm on control sample to 44 ppm and 35 ppm, and available P in Surade Inceptisol increased from 4.8 ppm on control sample to 26 ppm and 30 ppm.
Keyword: humate materials, cow manure compost, chicken manure compost, organic matter extract, Inceptisol, available P

Judul: Pengaruh Bahan Organik terhadap Ketersediaan Fosfor pada Tanah-Tanah Kaya Al dan Fe
Abstrak: Phosphorus (P) is one of the essential nutrients for plants. However, the availability of P that can be absorbed by plants in the soil is generally very low, because P in the soil are manily in adsorbed form. Addition of organic matter can improve the availability of P in the soil, because organic acids that are resulted by decomposition of organic matter have an ability to make chelation of Al and Fe so P may become available. The aim of this research was to study effect of organic matter in releasing and preventing adsorption of P and to study wether the effect of organic matter is better if it is applied before or after P fertilization. This research consisted of five treatments: (1) Soil (Andosol, Latosol, Podsolic) was added with straw compost and 2 weeks later P fertilizer was added, (2) Soil (Andosol, Latosol, Podsolic) was added with P fertilizer and after 2 weeks straw compost was added, (3) Soil (Andosol, Latosol, Podsolic) was added with cow manure compost and after 2 weeks P fertilizer was added, (4) Soil (Andosol, Latosol, Podsolic) was added with P fertilizer and after 2 weeks cow manure compost was added, and (5 ) Soil (Andosol, Latosol, Podsolic) was added with P fertilizer only. Each treatment on the three soils was incubated for 1 and 2 months. The results showed that treatment of organic matter and P fertilizer addition is more effective in increasing pH and P-availability, as well as lowering the Al-dd and Fe-availability on the three soils than the treatment of only addition of P fertilizer. Cow manure compost gives a higher effect than straw compost. The addition of organic matter to improve releasing adsorbtion of P and preventing adsorption of P on Latosol and Podsolic, meanwhile for Andosol effect of organic matter is less visible. Latosol and Podsolic, the addition of organic matter is better if it is done after P fertilization, meanwhile for Andosol the addition of organic matter is better if it is done before P fertilization. The highest available-P of Andosol is in the treatment is soil was added with cow manure compost and after 2 weeks P fertilizer was added is 10.67 ppm, meanwhile available-P for Latosol is soil was added with P fertilizer and after 2 weeks cow manure compost was added is 90.95 ppm, and Podsolic is Soil was added with P fertilizer and after 2 weeks cow manure compost was added is 40.73 ppm.
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Judul: Desain Sistem Transfer Energi Nirkabel Berbasiskan Tesla Coil
Abstrak: Tesla coil merupakan alat yang ditemukan oleh Nikola Tesla yang dapat mentransmisikan daya tanpa kabel dengan memanfaatkan prinsip induksi elektromagnetik. Pada penelitian ini dibuat sebuah prototype Tesla Coil dengan menggunakan transistor C1970 dan receiver menggunakan rangkaian LC. Identifikasi alat meliputi pengaruh daya input transmitter terhadap receiver, bentuk signal yang dipancarkan transmitter, pengaruh jarak transmitter dan receiver, nilai efisiensi serta efek alat terhadap perangkat lain. Hasil pengamatan menunjukkan bahwa semakin besar daya input maka semakin besar daya yang dipancarkan oleh transmitter. Bentuk sinyal yang dipancarkan oleh transmitter berupa gelombang listrik AC sinusoidal dengan frekuensi ~2.9 MHz. Semakin jauh jarak receiver terhadap transmitter maka semakin kecil amplitudo gelombang AC yang diterima oleh receiver, menyebabkan semakin kecil daya yang diterima oleh receiver. Adapun nilai efisiensi terbesar penangkapan daya oleh receiver yaitu sebesar 0.00516 % serta terdapat gangguan pada alat-alat tertentu seperti monitor komputer dan radio.
Keyword: rangkaian LC, receiver, tesla coil, transistor C1970, transmitter