Judul: Pengaruh Cara Pemberian dan Dosis Bahan Humat Terhadap Produksi Tanaman Padi (Oryza sativa L) di Desa Sidosari, Kecamatan Natar, Lampung Selatan
Abstrak: Demand of rice in Indonesian will continuously increase following the population growth. Increasing demand of rice must be balanced by improvement of rice productivity. One of efforts that can be done to increase rice productivity is by improving soil properties either physically, chemically and biologically. Addition of organic matter may improve soil properties, but organic matter such as compost and manure is needed in large amounts. Humic substance is known able to replace a part of organic matter role. Treatment of humic substance on soil and plant is expected to be able to improve productivity of rice. The aim of this research was study effect of humic substance on growth and productivity of rice by different method and dosage application. The research was conducted at Sidosari village, Natar District, South Lampung Regency using Ciherang rice variety. Fertilizers used were 350 kg/ha Phonska, 200 kg/ha Urea, and 100 kg/ha SP-18. The treatments were composed of treatment of without humic substance, humic substance addition to soil, and humic substance addition to soil and leaves. Addition of humic substance to soil conducted on land preparation, while addition of humic substance to the leaves was done when the plants were 2 to 8 week after transplanting with an interval of two weeks. Humic substance dosages were 15 l/ha that diluted to 4 ml/l for soil and 2 ml/l for leaves. The results showed that the growth and yield components increased in plants treated with humic substance. The weight of grain yield of the plant without humic substance equivalent to 6.7 ton/ha, whereas that of plant with humic substance addition to soil was 7.14 ton/ha, and that of plant with humic substance addition to soil and leaves was 7.86 ton/ha.
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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.
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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