Judul: Analysis of water sufficiency in a star fruit (Averrhoa carambola L) orchads
Abstrak: Problem faced by star fruit farmers in Depok, West Java, is water availability relying only on rainfed which the quantity is always unevenly distributed in each year. The abundant water availability during the rainy season has not been optimally utilized so that water stress often occurs during the dry season. Therefore, research related to water conservation technique for optimum utilization of rain water and runoff for star fruit in that area was conducted. The objectives of the research were: 1) to develop water balance analytical model with and without runoff for the sweet star fruit orchard, 2) to find out the effectiveness of water harvest technique using infiltration canal and silt pit to control runoff and change soil water content at the star fruit orchard, and 3) to find out the relationship of evapotranspiration and star fruit productivity. In this experiment the water table was approximately 16 m from the soil surface, no irrigation was used and infiltration canals equipped with silt pits were constructed so that runoff component and contribution of water capillarity movement were zero. The research results showed that: 1) the water balance analytical model without runoff could nicely simulate the soil water content at the rooting zone with R2 of 0.83 and RSME of 0.001; 2) the water balance analytical model with runoff could nicely simulate the soil water content at the rooting zone with R2 of 0.82 and RSME of 0.007; 3) the water harvest technique was effective in controlling runoff which was indicated by the higher soil water content at the rooting zone ranging from 0.429 to 0.458 m3/m3 with an average of 0.452 m3/m3 as compared to control (with no water harvest technique) ranging from 0.362 to 0.458 m3/m3with an average of 0.417 m3/m3; 4) productivity of the star fruit increased with the increase of evapotranspiration as expressed by the following linear regression equation: Y = 0,299X – 13,93 with R2 of 0.74, F value of 5.56 at p~0.81, indicating that evapotranspiration had influence on the star fruit productivity.; and 5) with water harvest technique treatment (infiltration canal with silt pit), the value of soil water content at the star fruit orchard was in good condition for the growth and year-round production of the star fruit plants.
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Judul: Pemanfaatan Water Absorbent untuk Meningkatkan Retensi Air Tanah dan Pertumbuhan Tanaman Jagung (Zea mays L.)
Abstrak: Water availability is one of principal problem in the system of dry-land farming, especially for food crops. Every plants needs constant water supply to grow, but this is not obtained in dry land farming that rely mainly on rain as a water resource. The lack of water availability in dry season caused decreasing of plant’s growth and productivity. In order to increase water availability, this research is using super water absorbent (SWA) from cassava’s starch to hold water and release it slowly. The purposes of this research are analyzing the impact of cassava’s starch SWA to the volume of water that is retained by soil and growth of corn (zea mays L). The result showed that application of water absorbent tend to increase the ammont of water retained by soil, eventhough the effect was not significant. Application of water absorbent result in significanly better corn growth as compared to control (no water absorbent). Nevertheless the application of water absorbent fail to maintain crop growth at optimum level. The treatment that retained most water is cassava starch SWA with 0.2 g/kg the dosages of spread mix in soil make every 14 days watering. While, application of cassava’s starch with 0.1 g/kg the dosages of concentrate in soil make every 14 days watering has a significant with the high and leaves’s wide, but not with the number it.
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Judul: Sintesis Paduan Ti-6Al-4Nb sebagai Matrial Implan Pengganti Komponen Tibial
Abstrak: Synthesis of Ti-6Al-4Nb alloy was done by melting using Tri Arc Melting Furnace. Each sample was remelted five times to ensure the homogenity. Aluminum and niobium addition were expected to stabilize α phase and β phase until the αβ-titanium alloy was resulted. Yet based on the experiment, it was α-titanium alloy resulted. α-titanium alloy was a Hexagonal Close Packed (HCP) crystalline structure which would be cracked if deformation non-uniaxial happens. The presence of oxygen in pure titanium significantly increased the hardness of titanium. The addition of aluminum was also able to increase the hardness of titanium alloy because aluminum more stabilize the α phase in the α-titanium alloy. The corrosion ressistance of titanium could be increased by adding aluminum and niobium. Titanium coating with HA/chitosan composite was also proved in decreasing the corrosion rate because it barried direct interaction between titanium alloy and corrotion solution.
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