Judul: Kajian Agronomi Pemanfaatan Biomulsa Kacang Hias (Arachis pintoi) pada Budidaya Jagung Manis (Zea mays saccharata Strurt.) di Lahan Kering
Abstrak: The aim of the experiment was to observe the effect of the utilization of legum cover crop Arachis pintoi as bio-mulch on sweet corn production (Zea mays saccharata Sturt) compared with Centrosema pubescens and Calopogonium mucunoides. The experiment was held at Cikabayan Eksperimental Field, Bogor in February-September 2013. Randomized completey block design (RCBD) was used in this experiment with a single factor and three repitions. The factor is the difference of mulch variety that consist of control (natural vegetation with weeding), natural vegetation (without weeding), plastic mulch, A. pintoi, C. pubescens, and C. mucunoides. The use of A. pintoi bio-mulch influenced weeds variety replacement that grown in the treatment field. The treatment of A. pintoi is more effective to decrease the growth of grass weeds than that of C. pubescens and C. mucunoides. The treatment of A. pintoi bio-mulch increased the content of C-Organik, N-Total, and K2O in the soil. Based on the result, the difference of mulch variety showed a significant effect on all of observed sweet corn characters, except cob long and circle. The result also showed no significant difference among the treatments of A. pintoi, C. pubescens, and C. mucunoides on sweet corn production. The treatment of plastic mulch showed a higher rate than another treatment in increasing sweet corn production.
Keyword: production, weeds, bio-mulch, Arachis pintoi

Judul: Utilization of Arachis pintoi Krap. & Greg. as Biomulch to Suppress Weeds and Increase Soil Chemical Properties in Guava Plantations
Abstrak: Salah satu penyebab penurunan produksi jambu kristal adalah keberadaan gulma. Arachis pintoi dapat ditanam sebagai biomulsa karena mampu menambah kesuburan tanah dan menekan gulma. Penelitian bertujuan untuk mengetahui efektivitas A. pintoi sebagai biomulsa dalam menekan gulma dan meningkatkan sifat kimia tanah pada pertanaman jambu kristal. Percobaan disusun dalam Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan 7 perlakuan dan 4 ulangan. Faktor yang diuji yaitu: tanpa A. pintoi tanpa penyiangan (P0), tanpa A. pintoi dan penyiangan manual setiap 1 bulan sekali (P1), populasi A. pintoi 20% (P2), populasi A. pintoi 40% (P3), populasi A. pintoi 60% (P4), populasi A. pintoi 80% (P5), populasi A. pintoi 100% (P6). Hasil penelitian menunjukkan A. pintoi sebagai biomulsa dapat menekan gulma spesies A. conyzoides, B. alata, A. gangetica, C. diffusa, dan S. nodiflora (golongan daun lebar) serta spesies C. kyllingia (golongan teki), namun tidak dapat menekan gulma spesies R. exaltata dan O. nodosa (golongan rumput). A. pintoi sebagai biomulsa dapat meningkatkan pH, C-organik, N-total, dan K-total., One of the causes of the decrease in guava production is the weeds disturbances. Arachis pintoi can be planted as a biomulch because it is able to increase soil fertility and suppress weeds. The objective of this research was to study the effectiveness of A. pintoi as a biomulch in suppressing weeds and increasing the soil chemical properties in guava plantations. This study used a single factor randomized complete block design (RKLT) with 7 treatments and 4 replications. Factors tested were: without A. pintoi without weeding (P0), without A. pintoi and manual weeding every 1 month (P1), population A. pintoi 20% (P2), population A. pintoi 40% (P3), population A. pintoi 60% (P4), population A. pintoi 80% (P5), population A. pintoi 100% (P6). The results showed the application of A. pintoi as a biomulch could suppress the weeds of species A. conyzoides, B. alata, A. gangetica, C. diffusa, and S. nodiflora (broad leaf group) as well as species C. kyllingia (sedges group), but were not could in suppressing weed species R. exaltata and O. nodosa (grass group). The application of A. pintoi as biomulch could increase pH, C-organic, N-total, and K-total.
Keyword: mulsa, tanaman penutup tanah, kacang hias, pengelolaan gulma, mulch, cover crops, ornamental peanute, weeds management

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
Keyword: