Judul: Analisis Salinitas dan Dampaknya terhadap Produktivitas Padi di Wilayah Pesisir Indramayu
Abstrak: Indramayu District is one of main rice production centre in West Java. Most of rice fields locate next to Java’s North Coast and some of the areas are influenced by salinity problem. The problem of salinity increases during dry season particularly when irrigation water is limited as salt water intrusion will increases under this condition. The salinity problem will be more severe when dry season extends. Under high salinity condition, yield of rice will decrease significantly. This study analyzed the spatial distribution of salinity and its changes in the rice field during dry season and its impact on rice yield. The salinity were measured during dry season (July, October and November) in a number of location and yield of rice was measured in the same location from a plot with size of area of size 2.5x2.5 m2 in November. It was found that the salinity decreased with distance from the coast. In some area near the cost, the salinity could go up to 9 dS/m and most this area had been converted to pond or salt mining or other uses. In most of paddy fields affected by salinity have salinity level of less than 5.5 dS/m. The area of paddy field affected by salinity expanded as the rainfall in the dry season decreased. The rice yield was not significantly affected by the salinity. This study suggests that the current rice variety used by farmers is tolerant to salinity. However, the risk of salinity may increase in the future due to change in sea level and coastal characteristics (e.g. degradation and conversion of mangrove forests). Current rice variety may be tolerant to salinity of not more than 5.5 dS/m. Adapting to increasing risk of salinity, it is very important to introduce alternative rice varieties which are more tolerant to salinity, restoration of mangrove forest and also improvement of irrigation facilities.
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Judul: Analysis and Seasonal Mapping of Rice Field Salinity Changes in Jumbleng Village, Losarang Subdistrict
Abstrak: Desa Jumbleng merupakan daerah pesisir di Kabupaten Indramayu yang rentan terhadap masalah salinitas tanah yang disebabkan oleh perbedaan curah hujan musiman dan sumber irigasi dengan kandungan garam yang tinggi di musim kemarau. Tujuan penelitian ini adalah mengetahui pengaruh curah hujan musiman terhadap kadar salinitas sawah dan memetakannya. Peneliti menggunakan data pengukuran electric conductivity di lapangan dan data curah hujan dari stasiun pemantauan hujan terdekat. Persamaan Taro Yamane dan Slovin digunakan untuk menentukan titik pengumpulan sampel. Metode interpolasi inverse distance weighting power 1, inverse distance weighting power 2, dan kriging digunakan untuk menentukan nilai EC prediksi yang paling akurat. Root Mean Square Error dan regresi linier digunakan untuk validasi data. Inverse distance weighting power 2 menunjukkan hasil yang paling signifikan dan akurat dengan penyebaran area salin tinggi dan sedang sebesar 5,09 ha (3,3%) dan 56,03 ha (36,1%) di musim kemarau dan 0 ha (0%) dan 1,86 ha (1,2%) di musim hujan. Tambahkan satu kalimat saran untuk penelitian ke depan, Jumbleng Village is a coastal area in Indramayu Regency that is vulnerable to the impact of soil salinity problems caused by seasonal rainfall differences and high salt content irrigation sources in the dry season. This study aims to understand the influence of seasonal rainfall on rice field salinity levels and map them. The analyst uses field measurement data (electrical conductivity) and precipitation data from the nearest rain monitoring station. The Taro Yamane and Slovin equations are used to determine the sample collection points. The interpolation methods: inverse distance weighting power 1, inverse distance weighting power 2, and kriging are used to determine the most accurate EC prediction value. Root Mean Square Error and linear regression are used for data validation. Inverse distance weighting power 2 shows the most significant and accurate results with a high and moderate saline area spread of 5.09 ha (3.6 %) and 56.03 ha (36.6 %) in the dry season and 0 ha (0 %) and 0.12 ha (1.2 %) in the rainy season.
Keyword: tanah, salinitas, musiman, variabilitas, interpolasi

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