Judul: Potato based sustainable vegetable farming systems planning in Siulak watershed, Kerinci district, Jambi
Abstrak: Established agricultural practices in upland vegetable growing areas in Indonesia are generally implementing up and down the slope cultivation with relatively high rates of fertilizers and pesticides applications. Combined with high rainfall intensity, these practices have contributed to high runoff and severe erosion and in turn gradually decreased land productivity and farmers income, thus unsustainable farming systems. The objectives of this research were : 1) to identify and describe existing conditions of the potato based vegetable farming systems, 2) to study soil conservation measures alternatives to control soil erosion and obtain optimal net farm income, and 3) to design potato based sustainable vegetable farming systems in Siulak Watershed, Kerinci District, Jambi Province. Land biophysical and farmers characteristics as well as agrotechnologies were identified through soil survey and farmers interview, while alternatives of soil conservation measures were studied through soil erosion plot experiments. Models of patato based sustainable vegetable farming system were formulated by simulation using Universal of Soil Loss Equation (USLE) model and multiple goal programming. Results of the research showed that up and down the slope vegetable farming practices and inadequate of soil conservation practices caused soil erosion rate of 39.25 - 229.14 ton/ha/year which was higher than the local soil tolerable loss (24.09 - 20.89 ton/ha/year), and net farm income was generally not enough to support life worthed living (Rp 28 000 000/year). Planting on ridges across the slope, or ridges constructed 15 degrees across the slope, or in ridges down the slope with a mound constructed across the slope in each 4.5 m distance and silt-pit, can be considered as alternatives soil conservation methods for vegetable farming systems. Potato based sustainable vegetable farming systems in Siulak Watershed could be accomplished by improving the cultivation practices by integrating the soil conservation methods (planting on ridges across the slope and mulch, or ridges down the slope with a mound constructed across the slope, mulch and silt-pit) into the existing systems. Potato based sustainable vegetable farming systems with the cropping pattern of potato-cabbage-tomato and recommended agrotechnologies performed the most optimum models in Siulak Watershed, Kerinci District, Jambi; this system generated soil erosion about 10.59 - 18.82 ton/ha/year and the net farm income about Rp 40 714 558 - Rp 52 745 652 per hectar per year on 0.44 ha farm area. Some farmers in Siulak Watershed have started applicating the recommended agrotechnologies right after the research was completed.
Keyword: farming systems, Siulak Watershed, Kerinci District, Jambi

Judul: Development of agroecological based horticultural crops on sloping land in Upstream of Jeneberang Watershed, South Sulawesi
Abstrak: The aims of this study were to evaluate the land capability and suitability for horticultural crops, to determine the suitable forest management method to minimize the erosion, to determine the sustainability of horticultural crops farming, and to formulate model design of agroecology-based horticultural crops development on sloping land in upstream of Jeneberang watershed, South Sulawesi, conducted from April 2009 until December 2009. The first step of this study was determination of land capability using USDA method. The second step was determination of land suitability using FAO method. The third step was erotion prediction using USLE method. The forth step was sustainability analysis using Multi Dimensional Scalling (MDS)-Rapfarm method. The last step was design the dynamical model using Stella 9.0.2 program analysis. Classes of land capability in upstream of Jeneberang watershed were class II, III, IV,VI and VII with limiting factors of drainage, root zone barrier, and erosion danger. Classes of actual land suitability for fruits commodity on land with elevation < 700 m above sea level (asl) were S2 and S3, with limiting factors of nutrient retention, root medium and erosion danger, and classes of potential land suitability were S1, S2, and S3. Classes of actual land suitability for vegetables commodity (potato, mustard, carrot, cabbage, and scallion) with elevation ≥ 700 m asl were S2, S3, and N, limiting factors of nutrient retention, root medium and erosion danger, and classes of potential land suitability were S1, S2, and S3. Erosion happened in upstream of Jeneberang watershed was 2.57 ton/ha/year until 5.764,82 ton/ha/year. Farming sustainability index of fruits about 41,90 – 54,41 and vegetables about 39,58 – 64,85. Ecology, economy, institution, and technology dimensions include to enough sustainable category, whereas social dimension include to less sustainable category. Result of leverage Rap-farm analysis showed that in 43 attributes, 9 attributes were sensitive to affect fruits farming and 23 attributes were sensitive to vegetables farming. Dynamical model simulation of fruits horticultural development showed erosion reduction, productivity and sales value improvement in year of 10, whereas vegetables commodity in year of 9. Moderate and optimistic scenario more effective in decreasing erosion and increasing productivity and sales value. Model scenario simulation in 2020 for rambutan commodity, erosion prediction at moderate scenario was 3,35 ton/ha/year, and optimistic scenario was 2,56 ton/ha/year, productivity was 6.222,3 kg/ha with sales value Rp. 34.512.298. Model scenario simulation in 2019 for potato commodity, erosion prediction that happened at moderate scenario was 27,80 ton/ha/year, and optimistic scenario was 21,07 ton/ha/year, productivity was 8.724,43 kg/ha with sales value Rp. 34.897.720. Base on, moderate scenario can use of development of agroecological based horticultural crops in Gowa Regency.
Keyword: South Sulawesi

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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