Judul: Turnover Bahan Organik Tanah pada Berbagai Tipe Vegetasi di Ekosistem Mangrove Desa Blanakan, Kecamatan Blanakan Kabupaten Subang
Abstrak: Soils on mangrove ecosystem generally contain higher C-org than mineral soils on terrestrial ecosystem. The organic matter remained in soil as carbon deposit should be protected for its existence. This research aims to determine litter production, soil organic matter (SOM) content and how long SOM persists on mangrove ecosystem under various main vegetations. Materials used in this research include litters of various main vegetation on mangrove ecosystem i.e. Rhizophora, Avicennia, Sonneratia, and Bruguiera, and also disturbed soil samples from each mangrove vegetation. Those materials were analysed in laboratory, especially for measuring C-org content. The results showed that the average of litter production on mangrove ecosystem at Desa Blanakan, Kecamatan Blanakan, Kabupaten Subang is 10.02 ton/ha/year. The highest litter production was found for Sonneratia i.e. 18.38 ton/ha/year, followed by Bruguiera i.e. 10.14 ton/ha/year, Avicennia i.e. 6.96 ton/ha/year, and Rhizosphora i.e. 4.61 ton/ha/year. Soil C-org under Bruguiera vegetation in each soil depth was higher than soil Corg under Rhizophora, Avicennia, and Sonneratia vegetations. Soil C-org per hectare within 0-50 cm ranges between 59.38-67.25 ton in each main vegetation area. Average litter productions contribute 1.29-4.75 ton/ha organic carbon every year. Soil organic matter turnover under Sonneratia was faster than other main vegetations on mangrove ecosystem. Organic matter turnover on Sonneratia was 13 years, followed by Bruguiera, Avicennia, and Rhizospora i.e. 24, 27, and 48 years, respectively
Keyword: turnover, organic carbon, mangrove, litter production

Judul: Turnover Bahan Organik Tanah pada Tegakan Akasia (Acacia mangium Willd.) di RPH Maribaya dan RPH Jagabaya, BKPH Parung Panjang Bogor
Abstrak: Akasia memiliki produksi serasah yang tinggi dan susunan kimia serasah yang tidak mudah terdekomposisi. Penelitian ini bertujuan untuk mengetahui kadar BOT dan lama turnover di bawah tegakan Acacia mangium Willd. di kawasan HTI RPH Maribaya dan RPH Jagabaya, BKPH Parung Panjang Bogor. Bahan yang digunakan yaitu contoh tanah utuh dan terganggu yang diambil dari setiap horison pada 6 profil tanah di lokasi penelitian. Selanjutnya dilakukan analisis tanah di laboratorium meliputi sifat kimia dan fisik tanah, terutama C-organik tanah dengan menggunakan metode Walkey and Black, N total dengan metode Kjeldahl, bobot isi, dan tekstur. Kadar C-organik di bawah tegakan Akasia berkisar antara 0,42% – 3,00%. Turnover BOT pada tegakan Akasia di RPH Maribaya dan RPH Jagabaya pada kedalaman 0–50 cm yaitu 25–39 tahun, 0–66 cm yaitu selama 31–46 tahun, 0–81 cm yaitu 37–52 tahun, dan 0–100 cm yaitu selama 43–60 tahun. Faktor yang menyebabkan keragaman turnover BOT pada penelitian ini adalah rasio C/N dan rasio klei/C, dimana semakin tinggi rasio C/N maka bahan organik lebih lama bertahan di dalam tanah, dan semakin rendah rasio klei/C maka semakin banyak C-organik yang diikat oleh klei, sehingga turnover BOT menjadi semakin lama.
Keyword: Acacia mangium, C-organik, rasio klei/C, turnover BOT

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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