Judul: Penilaian Opsi Budi Daya Padi Sawah Tadah Hujan Adaptif Kekeringan: Studi Kasus Kabupaten Subang
Abstrak: Extreme climate events, particularly drought significantly affectproduction of rainfed lowland rice in Indonesia. This might affect food security. This study aims to assess alternative technologies or crop management strategies of rainfed lowland rice more adaptive to drought in Subang, West Java. Technology options and strategies are determined through surveis and crop simulation models of DSSAT (Decision Support System for Agrotechnology Transfer). Input data for the model consists of a 21-year daily climate data (1991-2011), soil physic and chemical properties, genetic data of IR 64 rice varieties and rice cultivation technologies. The cultivation technology options being tested included soil management (fertilization) and crop management (varieties and planting time). Simulations was carried out according to the time of planting from January to December with 15 days interval. The results of field survei confirmed that the main problem in rainfed rice at Subang District was drought. The simulation results showed that the main options to address drought was to set appropriate planting time with the use of proper cultivation technology (balanced fertilizers). In general, the appropriate time for rainfed lowland rice planting was rainy season (October-April) the yield can reach 6.0 ton/ha, while dry season (May-September can be lower than 1.0 ton/ha. The use of SST Nino 34 index to see the phenomenon of ENSO which affecting rice yield variance of rain. So that farmers can appropriate started of planting time based on seasonal climate forecast to solve the drought problem. The recommended amount of fertilizer for the rainfed lowland rice at Subang was 300 kg/ha of inorganic fertilizer and 5 tons/ha of organic fertilizer with planting space of 40 × 40 cm. The use of this technology resulted in yield of more than 5 ton/ha with B/C ratio of about 1.76.
Keyword: simulation., rainfed rice system, rice farming system, DSSAT

Judul: PenilaianTeknologi Budidaya Padi Sawah Irigasi Adaptif Terhadap Keragaman Iklim (Studi Kasus: Subang, Jawa Barat)
Abstrak: In recent yearsm riceproductivitytended to decrease. Thisconditionis not only due to limited adoption of new technologies by farmers but also due to the increased in crop failure caused by extreme climate events. This study aimsto identify and assess crop management technologiesofirrigatedrice inSubang and to develop crop management strategies more adaptive to climate variability. Assessment of crop management technologies was done using crop simulation (DSSAT) and cost-benefitanalysis, and adaptivefarmingstrategies was developed based on interviews with farmers taking into consideration the results ofthe crop simulation. Crop management technologies being assessed were 18technologies consists of water management,fertilizer application, and crop spacing. The results showedthat theoptimumtechnology at Subang for the irrigated rice is puddlingwithnitrogen application of 150 kg Urea/ha and plant spacing of 40x40cm. The optimumplantingtime is betweenmid-Octoberand mid-January. The B/C ratio for this technology is the highest. Strategy to manage climate risk include not only with structural intervention such as development of community-based water reservoir, wells pump etc, but also with non-structural intervention such as enhancement of farmers capacity in using climate forecast information application for tailoring crop management and cropping pattern to the forecast information.
Keyword: DSSAT, Technology Choice, Rice Irrigation

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology