Judul: Surface runoff and Soil Erosion in Pineapple  Plantation Land at PT Great Giant Pineapple, Central Lampung
Abstrak: Aliran permukaan dan erosi tanah sering menjadi masalah pada lahan pertanian karena dapat menyebabkan penurunan produktivitas tanah, pendangkalan badan air, dan penurunan kualitas air. Masalah yang dihadapi oleh PT Great Giant Pineapple (GGP) adalah pendangkalan badan air atau lebung, yang diduga disebabkan oleh erosi tanah di area perkebunan nanas. Aliran permukaan dan erosi tanah berkaitan erat dengan curah hujan dan tutupan tajuk tanaman. Oleh karena itu, perlu dilakukan identifikasi terhadap aliran permukaan dan erosi tanah di lahan perkebunan nanas PT GGP. Penelitian ini bertujuan untuk mengidentifikasi karakteristik aliran permukaan dan erosi di lahan perkebunan nanas PT GGP, Lampung Tengah. Pengukuran aliran permukaan dan erosi dilakukan pada petak erosi lahan perkebunan nanas umur tanaman 6 BST (Bulan Setelah Tanam), 9 BST dan 12 BST dengan kemiringan lahan 5 % - 10 %. Jenis tanah yang mendominasi lahan nanas di PT GGP adalah Ultisol. Aliran permukaan dan erosi memiliki hubungan yang lebih erat dengan curah hujan dibandingkan dengan tutupan tajuk tanaman. Semakin besar curah hujan maka aliran permukaan dan erosi tanah semakin besar. Aliran permukaan yang dihasilkan pada masing masing petak erosi dengan umur yang berbeda beda yaitu sebesar 6,43 liter untuk 6 BST, 2,93 liter untuk 9 BST dan 2,01 liter untuk 12 BST. Jumlah erosi yang terukur pada masing masing petak umur tanaman yaitu sebesar 6,35 ton/tahun/ha pada 6 BST, 2,76 ton/tahun/ha pada 9 BST, dan 1,37 ton/tahun/ha pada 12 BST., Surface runoff and soil erosion often pose problems on agricultural land because they can lead to decreased soil productivity, siltation of water bodies, and deterioration of water quality. The issue faced by PT Great Giant Pineapple (GGP) is the siltation of water bodies or ponds, which is suspected to be caused by soil erosion in the pineapple plantation area. Surface runoff and soil erosion are closely related to rainfall and plant canopy cover. Therefore, it is necessary to identify surface runoff and soil erosion in the pineapple plantation land of PT GGP. This study aims to identify the characteristics of surface runoff and erosion in the pineapple plantation land of PT GGP, Central Lampung. Measurements of surface runoff and erosion were conducted on erosion plots in the pineapple plantation land with plant ages of 6 months after planting (MAP), 9 MAP, and 12 MAP, with land slopes ranging from 5% to 10%. The type of soil that dominates the pineapple land at PT GGP is Ultisol. Surface runoff and erosion have a closer relationship with rainfall than with plant canopy cover. The greater the rainfall, the greater the surface runoff and soil erosion. The surface runoff produced on each erosion plot with different plant ages was 6.43 liters for 6 MAP, 2.93 liters for 9 MAP, and 2.01 liters for 12 MAP. The measured erosion amount on each plot for different plant ages was 6.35 tons/year/ha for 6 MAP, 2.76 tons/year/ha for 9 MAP, and 1.37 tons/year/ha for 12 MAP
Keyword: erosi tanah, aliran permukaan, perkebunan nanas, tutupan tajuk tanaman, surface runoff, soil erosion, pineapple plantation, canopy cover

Judul: Permeability and Shear Strength of PT GGP Pineapple Land after Eleven Months of Resistant Organic Matter Application
Abstrak: Penurunan produktivitas pertanian pada umumnya disebabkan oleh penurunan kualitas tanah akibat penggunaan terus-menerus. Penelitian ini dilakukan pada lahan PT Great Giant Pineapple (GGP) yang mengalami penurunan produktivitas buah nanas seiring terjadinya penurunan kualitas tanah. Penurunan kualitas tanah terjadi karena rendahnya pemberian bahan organik yang sesuai dengan usia tanaman nanas, sehingga mengakibatkan pemadatan tanah. Dalam penelitian ini, limbah ekstraksi bromelain dan bambu cacah dipilih sebagai sumber bahan organik tahan lapuk karena mampu mempertahankan residence time pada pengaplikasian nya di lahan. Tujuan penelitian adalah menguji pengaruh bahan organik tahan lapuk setelah 11 bulan aplikasi terhadap permeabilitas dan kuat geser tanah. Metode penelitian yang digunakan adalah rancangan acak kelompok (RAK) di lokasi lahan 88 C2, PT GGP, Lampung Tengah. Hasil penelitian menunjukkan bahwa perlakuan limbah ekstraksi bromelain menghasilkan nilai laju permeabilitas yang lebih rendah dibandingkan dengan perlakuan bambu cacah. Laju permeabilitas pada kedua perlakuan mengalami penurunan setelah 11 bulan aplikasi bahan organik dibandingkan dengan setelah aplikasi 5 bulan. Nilai Kekuatan geser tanah meningkat seiring bertambahnya usia tanaman pada bulan 11, terutama pada kedalaman 0-10 cm, 10-20 cm, dan 20-30 cm. Pemberian dosis bahan organik yang lebih tinggi memberikan perbaikan sifat fisik tanah yang lebih baik., The decline in agricultural productivity is generally caused by a decrease in soil quality due to continuous use. This research was conducted on PT Great Giant Pineapple (GGP)’s land which experienced a decrease in pineapple productivity along with a decrease in soil physical quality. The decline in soil quality occurred due to the low provision of organic matter in accordance with the age of pineapple plants, resulting in soil compaction. In this study, bromelain extraction waste and chopped bamboo were chosen as a source of resistant organic matter since they are able to maintain quite long residence time in land after application. The research objective was to examine the effect of resistant organic matter after 11 months of application on permeability and soil shear strength. The research was held based on Randomized Block Design (RBD) at the location of 88 C2 land of PT GGP, Central Lampung. The results showed that the bromelain extraction waste treatment produced a lower permeability rate than the chopped bamboo treatment. The permeability rate in both treatments decreased after 11 months of organic matter application compared to the 5 months of application. Soil shear strength values increased with plant age of month 11, especially at depths of 0-10 cm, 10-20 cm, and 20-30 cm. Application of higher doses of resistant organic matter provided better improvements in soil physical properties.
Keyword: bromelain, organic matter, permeability, shear strength

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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