Judul: Analysis on sustainability of organic farming in rice intensification
Abstrak: Indonesia and some other countries in Asia are still striving for food security. This is due to the fact that the world food supply has indicated a critical condition where rice, as the staple food of the majority of Asian population, is one of the critical foods. System of Rice Intensification (SRI) claimed with high productivity and less water requirement might be one of the possible solutions to overcome the world food as well a water crisis. This method has been developed in some Asian countries including Indonesia although some researches still have to be conducted concerning the sustainability of this farming method in increasing rice production. A study was conducted in the District of Sukabumi as a case study with the objective to analyze the potential sustainability of organic rice farming using the SRI method in that area. Study on agricultural sustainability usually concerns with at least three components such as social, economic and environmental aspects. In this study, the three components were stressed on willingness of farmer to adopt new method as social factor, productivity as economic factor and utilization of agricultural wastes for fertilizer as the component that indirectly related to environmental factor. The analyses on the potential agricultural sustainability were conducted based on modeling approach. Several models were developed for uses in the calculation and prediction of the factors considered, which basically were based on Cobb-Douglas production function and Verhulst growth model. The result of this study indicated that the District of Sukabumi had the potential to develop a sustainable organic rice farming using SRI method. However, some factors involving the sustainability still had to be improved for better result of development.
Keyword: Rice production

Judul: Pengaruh Perbedaan Karakteristik Kimia dan  Mineral serta Penambahan Bahan Organik terhadap Pertumbuhan dan Produksi  Padi yang Ditanam dengan Metode SRI
Abstrak: The necessity of food especially rice increase with increasing in human population. One of a very popular system in the cultivating of paddy is the System of Rice Intensification (SRI). Although SRI is believed can increase the paddy production without inorganic fertilizer and optimizing water use, but there are several problems which has not been fully understand yet in order to apply SRI, especially about the land condition. This research was aimed to study mineralogical and chemical soil characteristics and organic matter application in order to support the growth and the production of paddy cultivating by comparing SRI and conventional method. Soil samples were collected from four locations i.e: Cihideung, Bogor (Chd, Bgr), Sindangbarang, Bogor (Sbr, Bgr), Margakaya, Karawang (Mgk, Krw) and Bobojong, Cianjur (Bbj, Cjr), two water management levels, i.e: convensional (K) and SRI with irrigation during five days (S). Each water management levels were combined with two treatments of organic matter applications, i.e: plus compost application (B1) and without compost application (BO). Treatments were desained in Factorial Completely Random Design with 16 treatments and three times replications. Totally there were 48 experimental units. Chemical properties (C-organic, total N, and K) of Bobojong soil showed better result than the other soils, and the texture of Cianjur soil was silty clay. Quartz was the most dominant mineral in sand fraction for all soils, and kaolinite was the most abundant mineral in clay fraction. It was also found easily weathered mineral which show that natural fertility in the research location were high, especially on Sindangbarang and Cianjur soils. Compost application 7 ton/ha was not significantly different in increasing the production and the growth of paddy. Water irrigation using SRI method during five days also can not increase the production and the growth of paddy, except if both treatments were combined. Meanwhile, based on the production and the growth parameters, Sindangbarang (Bogor) soil showed better response for SRI application than other soil. SRI application in different soils gave variety results for paddy production.
Keyword: 

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf