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: Utilization of Resistant Organic Materials to Improve Soil Physical Properties (Infiltration and Penetrability)
Abstrak: Permasalahan utama tanah di kebun PT. Great Giant Pineapple (GGP) yaitu kandungan bahan organik yang rendah dan terjadinya pemadatan tanah. Pemadatan tanah sampai tahap tertentu dapat diatasi dengan perlakuan mekanik yang memaksa partikel tanah saling menjauh dan pemberian bahan organik untuk memicu proses agregasi tanah dan meningkatkan kemampuan menahan air, meningkatkan nilai infiltrasi tanah dan menurunkan nilai ketahanan penetrasi tanah. Penelitian ini bertujuan mengidentifikasi pengaruh aplikasi serat limbah ekstraksi bromelain dan bambu cacah terhadap infiltrasi dan ketahanan penetrasi tanah pada berbagai dosis bahan organik. Pengukuran infiltrasi konstan dilakukan dengan menggunakan alat infiltrometer dan pengamatan ketahanan penetrasi dilakukan dengan menggunakan alat penetrometer saku dan penetrologger. Kapasitas infiltrasi pada perlakuan limbah ekstraksi bromelain memiliki nilai awal sebesar 44,73 cm/jam pada bulan ke-1 dan nilai akhir sebesar 9,32 cm/jam pada bulan ke-5, sedangkan pada perlakuan bambu cacah memiliki nilai awal sebesar 47,26 cm/jam pada bulan ke-1 dan nilai akhir 15,18 cm/jam pada bulan ke-5. Ketahanan penetrasi tanah pada petak perlakuan bambu cacah memiliki nilai relatif lebih rendah dibandingkan dengan petak perlakuan limbah pemrosesan bromelain pada semua kedalaman pada bulan ke-1, bulan ke-3 dan bulan ke-5. Kurva penetrologger menunjukkan bahwa petak perlakuan limbah ekstraksi bromelain pada bulan ke-3 dan bulan ke-5 memiliki nilai relatif lebih tinggi dibandingkan petak perlakuan bambu cacah. Berdasarkan pengamatan, petak limbah ekstraksi bromelain dan bambu cacah berdampak baik terhadap infiltrasi konstan dan penetrasi tanah., The main problem of soil in PT. Great Giant Pineapple (GGP) namely are low of organic matter content and the occurrence of soil compaction. Soil compaction to a certain extent can be overcome by mechanical treatment which forces soil particles away from each other and the application of organic matter to trigger the soil aggregation process and increase the ability to hold water, to increase the infiltration and lowering the penetration resistance of soil. This study aims to identify the effect of the application of bromelain extraction waste product and chopped bamboo on soil infiltration and soil penetration resistence. Constant infiltration measurements were carried out using an infiltrometer and penetration resistance observations were carried out using a pocket penetrometer and a penetrologger. The infiltration capacity in the bromelain extraction waste product had an initial value of 44.73 cm/hour in the 1st month and a final value of 9.12 cm/hour in the 5th month, while in the chopped bamboo treatment it had an initial value of 43.78 cm/hour in the 1st month and a final value of 15.18 cm/hour at the 5th month. The soil penetration resistance of the chopped bamboo treatment plots had a relatively lower value compared to the bromelain extraction waste product treatment plots at all depths either at the 1st, 3rd or 5th month. The penetrologger curve shows that the plots treated with bromelain extraction waste product at the 3rd month and the 5th month had a relatively higher value than the plots treated with chopped bamboo. Based on observations, bromelain extraction waste product and chopped bamboo application had a positif effect on constant infiltration and soil penetration resistance.
Keyword: amelioran, bromelain extraction waste, chopped bamboo, penetrologger, soil compaction

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.
Keyword: