Judul: Precision Fertilizer Automation System for Oil Palm Tree Driven by Six Wheel Drive Transporter
Abstrak: Tingginya produktivitas kelapa sawit perlu dipertahankan salah satunya dengan pemupukan. Kelemahan pemupukan manual yaitu aplikasi pupuk beragam dan tenaga kerja yang banyak. Penelitan ini pengembangan dari pemupukan mekanis sebelumnya. Penelitian bertujuan untuk merancang dan menguji kinerja sistem otomasi pemupuk presisi per pohon kelapa sawit berbasis deteksi sensor ultrasonik. Sensor diletakkan di bagian depan sisi kanan dan kiri pada ketinggian 1 meter. Kecepatan maju transporter yaitu 0.7 m/s. Pembacaan sensor yang bernilai 300 - 350 cm dan sebanyak 15 kali digolongkan sebagai kelapa sawit dalam waktu 300 ms. Dosis pupuk diatur motor listrik dengan kontrol PID. Penalaan PID dilakukan dengan metode IMC melalui pendekatan model Tustin. Nilai Kp, Ki, dan Kd yang didapat yaitu 0.04, 0.01916, dan 0.00107. Motor listrik diatur pada kecepatan 3000 rpm, 2300 rpm, 1700 rpm, dan 1100 rpm selama 7 detik. Pada pengujian statis, penjatah kanan dan kiri memiliki persamaan korelasi y = 0.4019x + 369.43 dan y = 0.4168x + 401.33. Pada pengujian dinamis, penjatah kanan dan kiri memiliki persamaan korelasi y = 0.4273x + 500.11 dan y = 0.4102x + 629.01. Hasil pengujian menunjukkan bahwa output pupuk mempunyai hubungan linier terhadap kecepatan putaran motor listrik. Berat pupuk pengujian dinamis lebih besar daripada statis. Perbedaan terbesar sisi kanan dan kiri yaitu 28.21% dan 30.37% pada kecepatan 1100 rpm. Perbedaan terkecil pada kecepatan 2300 rpm yaitu 9.40% dan 8.50%. Karena itu untuk aplikasi di lapangan, perlu dilakukan penyesuaian dalam pemrogramannya dengan persamaan kalibrasi agar didaptkan hasil yang sama antara output kiri dan kanan.
Keyword: palm oil, PID control, automatic placement, ultrasonic sensor

Judul: Rancang Bangun Mesin Pemupuk Kelapa Sawit dengan Metode Pembenaman ke Dalam Tanah
Abstrak: Fertilizer application methods for oil palm by spreading fertilizer on the soil surface need to be fixed, by immersion of fertilizer in the soil to make it more effective and more efficient in the use of fertilizer. The objective of this research was to design and construct a prototype of fertilizer immersion machine for oil palm, driven by a four-wheel tractor. The machine was designed using a rotor type metering device for fertilizer metering, and a rotary blades mechanism for immersion of fertilizer in the soil. The metering device and the rotary shaft were driven by the PTO of the tractor using a gear box and sprockets-chain power transmissions. The rotary unit consisted of four rotary blades mounted on two flanges which were welded to the rotary shaft with flanges spaced of 20 cm. Rotary diameter was 45 cm, working width was 20 cm, and the rotation speed was 200 rpm. The machine was mounted on a four-wheel tractor via the three point hitches. Based on the results of the design, a prototype was constructed and tested. The test results showed that the machine could immerse fertilizer into the soil at a depth of 10-15 cm and mixing with soil in fairly evenly. Fertilizing dose was about 1 kg per meter application.
Keyword: tractor, oil palm, immersion, rotary, fertilizer applicaort

Judul: Distribution and Diversity of Ectoparasite Mites on Geckos in Indonesia
Abstrak: Data on the diversity and dispersal of parasitic mites on house geckos in Indonesia are very scarce. In this work, the distribution and diversity of mites living on three species of house geckos, namely Cosymbotus platyurus, Hemidactylus frenatus, and H. garnotii collected throughout Indonesia, has been elaborated. Geckos and mites were captured and immediately preserved in 70% ethanol. Whole mount of the mites was prepared by clearing in lactophenol followed by mounting on polyvinyl lactophenol solutions. The SEM preparation was conducted to examine the detail morphological characters of the mites. The results showed that among 448 individuals of geckos, 221 geckos were infected by Geckobia mites. Prevalences of C. platyurus, H. frenatus, and H. garnotii infested by mites were 14.8%, 50.69%, and 79.6%, respectively. Three different spesies of Geckobia (G1, G2, and G3) could be differentiated; and based on similarities of their morphological characters to ones described in published literatures, Geckobia G2 is Geckobia glebosum and Geckobia G3 is Geckobia bataviensis while G1 could not be identified to the species level. The highest mean intensity of Geckobia G1 infestation was found on H. garnotii (I=7.0), G. glebosum infestation on H. frenatus (I=3.5), and G. bataviensis infestation on H. garnotii (I=11.8). In general, C. platyurus was infested by the least number of mites. Geckobia G1 were found living on the skin folds on the claws, G. glebosum were found mainly on the body and thigh, and G. bataviensis were found on almost all parts of the host’s body. Geckobia mites are distributed randomly throughout Indonesian Archipelago, following the pattern of distribution of their hosts. So it is concluded that Geckobia G1, G. glebosum, and G. bataviensis are sympatric.
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