Judul: Pengelolaan hayati tanah untuk meningkatkan peran fauna tanah dalam proses dekomposisi jerami padi pada budidaya System of Rice Intensification (SRI) di Kecamatan Cibungbulang, Kabupaten Bogor
Abstrak: Recently, low agricultural production is becoming a main problem in agricultural sector in Indonesia, especially for food crop. System of Rice Intensification (S.R.I.) is a method of rice cultivation which is able to increase crop yield through soil, crop and water management system. The principles of the S.R.I. technique include planting of young and single seedlings with shallow-root planting, wide spacing and maintain unflooded soil condition with intermittent irrigation. Soil biological management can be applied to support the creating of more conducive environment for improving population and role of soil fauna, especially on organic matter decomposition. Modification of bund distance in rice field is one of those methods. This research aimed to study the effect of bund distance (4 meters and 8 meters) on the role of soil fauna in rice straw decomposition in S.R.I. cultivation technique by using litterbag method. The research was conducted in NOSC (Nagrak Organic S.R.I. Center) field in Cijujung Village, Cibungbulang Subdistrict, Bogor Regency. This research was designed according to bund distance treatment, two levels (short, 4 meters and long, 8 meters) and four replications. Measurement of the decomposition rate of rice straw performed by using litterbag in coarse mesh (10 mm), medium mesh (0.25 mm) and fine mesh (0.038 mm), which contained 10 g rice straw per litterbag. These litterbags were exposured to the rice field with humid soil condition and retrieved after 30, 60 and 90 days. Decomposition rate was measured by counting the difference weight of before and after exposure time. The result showed that decomposition rate of the rice straw in the field with short bund distance (4 meters) is higher than in the field with long bund distance (8 meters). Decomposition rate based on the difference of litterbag showed that in field with short bund distance, coarse mesh litterbag have the higher rate with 93.91%, meanwhile medium mesh size about 89.07% and fine mesh about 81.58%. In long bund distance field, percentage of coarse -, medium - and fine mesh sizes are 88.98%; 85.87% and 78.53%, respectively. This result showed that the field with short bund distance have the higher decomposition rate, indicated that field with short bund distance has more soil fauna population that involved in decomposition process, compared to field with long bund distance.
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Judul: Populasi dan keragaman organisme tanah pada budidaya padi System of Rice Intensification (SRI) di Kecamatan Yanjung Sari, Kabupaten Bogor
Abstrak: Upaya peningkatan kebutuhan akan pangan khususnya padi sebagai kebutuhan pokok masyarakat Indonesia, memerlukan suatu teknologi yang dapat menunjang kebutuhan tersebut. Kemajuan ilmu pengetahuan telah menghasilkan berbagai sistem pertanian padi untuk meningkatkan produksi padi, antara lain SRI (System of Rice Intensification). SRI adalah teknik budidaya padi inovatif untuk meningkatkan produksi padi. Melalui sistem ini diharapkan produksi padi meningkat sehingga akan mencukupi kebutuhan pangan masyarakat Indonesia. Prinsip dasar dari metode SRI antara lain penggunakan bibit muda berumur 5-10 hari, dengan jarak tanam 30 cm x 30 cm, mempertahankan tanah agar tidak tergenang dan penanaman dilakukan dengan tanam bibit tunggal. Beberapa keunggulan metode SRI antara lain dapat meningkatkan produksi padi lebih dari 50%, menghemat penggunaan air antara 25-50%, meminimalkan penggunaan pupuk anorganik atau sintesis dan menghemat penggunaan benih padi antara 80-90%. Keadaan tanah yang tidak tergenang atau macak-macak pada sistem ini akan meningkatkan keragaman dan kepadatan populasi organisme tanah, selain itu pada sistem ini sangat dianjurkan menggunakan pupuk organik seperti kompos sehingga kebutuhan organisme tanah tersedia. Penelitian ini bertujuan untuk mempelajari populasi serta keragaman organisme tanah yaitu fauna tanah, total mikrob, total fungi, Azotobacter dan mikrob pelarut fosfat pada beberapa sistem pertanian padi yaitu sistem konvensional dan SRI ( System of Rice Intensification) baik organik maupun anorganik. Penelitian ini dilaksanakan di Kecamatan Tanjung Sari, Kabupaten Bogor dan di Laboratorium Bioteknologi Tanah, Departemen Ilmu Tanah dan Sumberdaya Lahan, Institut Pertanian Bogor. Penelitian dirancang berdasarkan Rancangan Acak Kelompok dengan empat perlakuan yaitu perlakuan penanaman padi dengan metode Konvensional (T0), SRI-anorganik (T1), SRI-organik (T2) dan SRI-semiorganik (T3). Perlakuan diulang empat kali. Parameter yang diamati adalah fauna tanah, total mikrob, total fungi, Azotobacter dan mikrob pelarut fosfat. Hasil penelitian menunjukkan bahwa perlakuan SRI-organik cederung meningkatkan populasi fauna tanah, total mikrob, total fungi, Azotobacter dan mikrob pelarut fosfat dibandingkan perlakuan konvensional, bahkan untuk jumlah fauna tanah pada perlakuan SRI-organik secara signifikan meningkat dibandingkan perlakuan konvensional.
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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