Assessment of management-dependent nutrient losses in tropical industrial tree plantations

Industrial tree plantations in the tropics usually follow short rotations and intensive site management including slash and burn, and the use of heavy machinery. We attempt to quantify the implied nutrient losses (harvest export, erosion, slash and burn, leaching) in order to give plantation managers a chance to understand the significance of their planning and decisions. We used the scarce globally available information and a case study plantation in East Kalimantan, Indonesia (Acacia mangium and Eucalyptus deglupta). Adaptation involves problems and is discussed in some detail. Results are approximate only. Assuming a harvest volume of 200 m(3) ha(-1), we assessed a loss of 427-680 kg ha(-1) N, 12-13 kg ha(-1) P, 178-252 kg ha(-1) Ca, 276-370 kg ha(-1) K, and 45-57 kg ha(-1) Mg per rotation. Of this overall loss, stand harvest accounted for 18-29% (N), 21-30% (P), 56-26% (K), 48-64% (Ca) and 22-37% (Mg). This means that the cumulative loss by erosion, slash and burn, and leaching exceeds that of the harvest. These losses can be influenced by management

TEKNIK REKONSTRUKSI ALJABAR UNTUK MENYELESAIKAN SISTEM PERSAMAAN LINEAR DENGAN SCILAB

Dalam artikel ini diuraikan program art.sci, sebuah program Scilab untuk menyelesaikan sistem persamaan linear berukuran sembarang. Program ini merupakan implementasi dari metode teknik rekonstruksi aljabar (TRA). Uji coba numerik TRA menggunakan sistem persamaan linear yang berasal dari diskretisasi persamaan integral jenis pertama. Salah satu obyektif tulisan ini adalah menyediakan alat untuk menyelesaikan sistem persamaan linear sembarang di Scilab sebagai sebuah lingkungan komputasional yang bebas (free)

Tinjauan Sosioekonomi Pemanfaatan Feses Sapi dengan Teknologi Vermicomposting

The Cibodas village is located in Pasir Jambu subdistrict at Bandung Regency, majority community livelihood edged is dairy cattle and agriculture. The problem of waste management in terms of cattle manure that could potentially produce methane (CH4) as one of the greenhouse gases (GRK), and when the cattle manure dumped into the River then it can pollute the rivers directly. The purpose of this study is to see how big the benefits of social and economic aspects of the utilization of cattle manure at the farmer scale. A series of Research include : 1) collect opinions and responses to ranchers, livestock farmers and administrators, by filling the questionnaire against the management of the cattle manure, 2) Observations of operational at the process of vermicomposting in two locations, namely in kampong Papak Manggu and kampong Injeman Cibodas village, during the activities of Demontration plot. The observed data covering 1) production process of vermicomposting (worm production and the weight of the raw materials, daily activities, results of casting, mass balance and quality of organic fertilizer) 2) Required total working hour of process of vermicomposting 3) Space and facilities requirement 4) cost and price analysis. The research show that vermicompost is suitable to be implemented in processing cattle manure, base on the following reason : a) cleaning of the environment b) minimum labor requirement c) providing additional income d) availability of organic fertilizer