Judul: The Role of Resistant Organic Materials Bromelain Extraction Waste and Brown Coal on Penetration Resistance of Podzolic and Regosol
Abstrak: Pengolahan tanah secara intensif dapat menyebabkan terjadinya pemadatan tanah. Pemadatan tanah merupakan indikator penurunan kualitas tanah. Pemadatan tanah dapat diatasi dengan pemberian bahan organik. Pelapukan bahan organik yang cepat mengakibatkan kebutuhan bahan organik hanya akan terpenuhi di awal masa pertumbuhan. Untuk tanaman berumur panjang dengan kerapatan tinggi seperti nanas, penambahan bahan organik sulit dilakukan di tengah musim tanam. Dalam kasus seperti demikian perlu dilakukan pemberian bahan organik tahan lapuk diantaranya adalah limbah ekstraksi bromelin asal bonggol nanas dan batubara muda. Penelitian bertujuan mengetahui ketahanan penetrasi pada jenis tanah yang memiliki kelas tekstur berbeda akibat pemberian bahan organik tahan lapuk limbah ekstraksi bromelin asal bonggol nanas dan batubara muda. Parameter yang diamati adalah paramater terkait kepadatan tanah yaitu ketahan penetrasi. Penelitian dilakukan di rumah kaca dengan menggunakan rancangan acak lengkap tiga faktor, yaitu dua jenis tanah, dua jenis bahan organik, dan lima dosis bahan organik. Sebaran nilai ketahanan penetrasi Podsolik dan Regosol pada bulan pertama berkisar 0–0.46 kg/cm2 , pada bulan ketiga berkisar 0.46–0.79 kg/cm2 , dan bulan kelima berkisar antara 0.58–0.88 kg/cm2 . Perlakuan limbah ekstraksi bromelin asal bonggol nanas dan batubara muda belum memberikan pengaruh nyata terhadap ketahanan penetrasi pada Podsolik dan Regosol selama lima bulan inkubasi., Intensive tillage seems to be more crucial in causing soil compaction. Soil compaction can be overcomed by adding organic matter. The rapid weathering of organic matter results in the need for organic matter application at the very beginning of the growth season. The addition of organic matter is difficult to be applied in the middle of the growing season for high density perennial plants, such as pineapple. In such cases, it is necessary to apply a weather-resistant organic matter, namely pineapple based bromelain extraction waste and brown coal. The aim of this study was to determine the penetration resistance of soil on different texture classes due to the application of weather-resistant organic matter pineapple based bromelain extraction waste and brown coal. The parameter observed ware related to soil density i.e. penetration resistance. The study was conducted in a greenhouse using a completely randomized design with three factors, namely two types of soil, two types of organic matter, and five doses of organic matter. The result showed that the penetrability values of Podzolic and Regosol soils in the first month of application ranged from 0–0.46 kg/cm2 , in the third month of application it ranged from 0.46–0.79 kg/cm2 , and in the fifth month of application it ranged from 0.58–0.88 kg/cm2 . Treatment of pineapple based bromelain extraction waste and brown coal had no significant effect on the penetration resistance of Podzolic and Regosol during five months of incubation.
Keyword: Brown coal, Bromelain extraction waste, Penetration resistance

Judul: Soil Penetrability in Podzolic and Latosol due to the Addition of Bromelain Extraction Waste and Chopped Bamboo
Abstrak: Peningkatan ketahanan penetrasi menyebabkan pertumbuhan akar tanaman terhambat sehingga mengakibatkan penurunan produksi tanaman. Oleh karena itu, mempertahankan ketahanan penetrasi tanah agar tetap rendah merupakan salah satu syarat untuk mempertahankan produksi tanaman. Salah satu upaya yang dapat dilakukan untuk mempertahankan penetrabilitas tanah adalah pemberian bahan organik. Suatu penelitian yang bertujuan untuk mengetahui ketahahanan penetrasi tanah akibat penambahan bahan organik dengan dosis yang berbeda pada tanah Podsolik dan Latosol telah dilakuan di rumah kaca kebun Pendidikan Cikabayan IPB. Bahan organik berasal dari limbah industri perkebunan berupa limbah ekstraksi bromelin dan bambu cacah. Penelitian ini menggunakan rancangan acak lengkap yang terdiri atas dua perlakuan jenis tanah, dua perlakuan bahan organik dan lima perlakuan dosis bahan organik dengan inkubasi selama lima bulan. Hasil penelitian menunjukkan bahwa nilai ketahanan penetrasi tanah pada perlakuan bahan organik limbah ekstraksi bromelin dan bambu cacah selama lima bulan inkubasi belum berubah nyata. Nilai ketahanan penetrasi untuk tanah podsolik pada bulan pertama, ketiga dan kelima adalah berturut-turut berkisar 0.29-0.54 kg/cm2, 0.75-0.92 kg/cm2, 0.71-0.87 kg/cm2 sementara untuk Latosol adalah 0.33-0.71 kg/cm2, 0.54-0.88 kg/cm2, dan 0.46-0.79 kg/cm2. Ketahanan penetrasi akan meningkat dengan menurunnya kadar air, namun peningkatan ketahanan penetrasi akibat penurunan kadar air pada Podsolik lebih besar daripada Latosol., Increased penetration resistance causes stunted plant root growth resulting in decreased crop production. Therefore, maintaining low penetration resistance is one of the efforts for maintaining crop production. One effort that can be done to maintain soil penetrability is the application of organic matter. A study aimed at determining soil penetrability as response to the addition of organic matter at different doses in Podzolic and Latosol soils was carried out in the greenhouse of the education garden Cikabayan IPB. The organic material used came from industrial plantation waste in the form of bromelain extraction waste and chopped bamboo. This study used a completely randomized design consisting of two treatments of soil type, two treatments of organic matter, and five doses of organic matter with incubation time for five months. The results showed that the value of soil penetrability in the treatment of organic matter from bromelain extraction waste and chopped bamboo with five months incubation had not changed significantly. Penetration resistence values for podzolic soils in the first, third, and fifth months ranged from 0.29-0.54 kg/cm2, 0.75-0.92 kg/cm2, 0.71-0.87 kg/cm2 respectively while for Latosol were 0.33-0.71 kg/cm2, 0.54- 0.88 kg/cm2, and 0.46-0.79 kg/cm2. Penetration resistance will increase with decreasing water content, but the increase in penetration resistance due to decreased water content in Podzolic is greater than that in Latosol.
Keyword: Bromelain Extraction Waste, Chopped Bamboo, Soil Penetrability

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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