Natural fibres, such as flax and hemp, are typically chosen as reinforcing elements in composites to replace traditional glass fibres due to their high stiffness, strength and low strain to failure. Some plant fibres such as coir and celery however possess high strains to failure, which could be utilised in a composite to enhance toughness. This paper reports on the use of Raman spectroscopy to follow the molecular deformation of single fibres of coir and celery. The technique is also used to characterise the orientation of the cellulose structure within the fibres. It is shown by mechanical testing of fibres that both celery and coir possess a non-linear stress-strain curve. Coir fibres however exhibit high strain to failure, whereas celery fibres are shown to have a much lower value of this parameter, despite having a similar coiled fibrillar structure. It is shown by using polarised Raman spectroscopy, and rotating the specimens with respect to the polarisation axis of the laser and measuring the intensity of the 1095 cm -1 Raman band, that both celery and coir fibres combine both axial and transverse orientation, due to their coiled structures. This is also confirmed by birefringence measurements. By following the shift in the central position of this Raman band as a function of cyclic deformation of the fibres, it is shown that the coir fibres recover their molecular deformation, whereas the celery does not show the same level of recovery. This difference between the fibres is postulated to be due to the fact that coir possesses an interlaced fibrillar structure, which remains intact, whereas the celery sub-fibrils unravel and orient towards the fibre axis during deformation.

No abstract

Watermelon cultivation is one of the appropriate alternatives in order to increase farmers' income from tidal lowland agriculture. Research into crop adaptation to wet soil conditions is required to enable farmers to decide the best planting time under various conditions within the existing land classification. The research to determine crop physiological response during the initial growth period was conducted in a greenhouse. This was combined with field treatments based on groundwater table depths at 15, 10 and 5 cm‐surface, respectively. Analysis of crop potential based on the water status conditions in the root zone was conducted by using secondary and primary data (daily records). Results of crop adaptation at shallow groundwater table depth showed that the treatments with groundwater table depth of 10 and 5 cm‐surface were not significantly different in terms of plant height, with a size of 12.6 and 12.3 cm, having three leaves. However, it had a significant effect on root length, with a length of 11.9 and 3.1 cm, respectively. Maximum plant height of 15.2 cm and four leaves were found for the treatment with a groundwater table depth of 15 cm‐surface. It may be concluded that it is best for farmers to plant at a groundwater table depth of 10 cm‐surface. © 2019 John Wiley & Sons, Ltd.

<p>The main problem for agriculture at tidal lowland swamp is low soil quality and high acidity of soil and high water. The research objective was to investigate how far the effort in increasing tertiary canal network to improve water quality (increasing pH and reducinf iron) in channel and tertiary plot. Field study was conducted at Bandarjaya Village of Jalur 25, Delta Sugihan Kanan, South Sumatra. Field activities were consisted of network investigation  land use and farm enterprise system which located at Primr 13 of Sugihan Kiri and Primer 25 of Sugihan Kanan. The network improvement perfomance was conducted by constructing micro water management (installed the tertiary gate and developen quartey canal) at tertiary plot which consisted of collector channel, sub tertiary channel and control plot which was outfall at quarterly channel downstream end. Water gate having goose neck pipe system was constructed to control water table in tertiary channel. Results of field study showed that land use at the study area was still dominated by rice crop with magnitude of 83% and the rest of 17% was used for rubber plantation, orange planation and mix plantation. The depth of phyrite layer was in the range of 60 to 100 cm below soil surface. Water table surface in October was in the range of 10 to 35 cm. Field adaptation showed that water gate was operated in closed condition (water retention) during vegetative phase. Water retention showed significant to improve rice yield in which water table since November had increased from -10 cm to flooding condition of 15 cm in January. This condition provide sufficient water for rice crop which was similar as the result found at irrigation area. The addition of ameliorant substances such as coconut fiber, and sand semen block at outfall of tertiary and kuartely channels also increase water quality in which water pH was increased from  2.95 to 3.7 and iron concentration was decreased from 4.01 to 0.32 mg/liter. Rice yield was increased from average production of 2 ton/ha to 3 ton/ha. This low production was due to land flushing process which need longer time process for at least 2 to 3 years from current condition as well as other production inputs such as fertilization and ameliorant substances.</p>

Natural fibres as reinforcement of composite have been applied during the last decade. One of natural fibre has been used as reinforcement is coir fibre. As reinforcement of composite, such fibre needs treatment to improve compatibility with its matrix with suitable treatment. In this paper, surface treatment of such fibre was conducted using sodium bicarbonate (NaHCO3) solution with various densities and soaking time differences. Mechanical and morphological properties of coir fibre were investigated. Coir fibres were soaked in the 8 wt.%, 10 wt.%, and 12 wt.% sodium bicarbonate solution for 24 hours and 120 hours.  After treatment, coir fibres were characterized with tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FTIR) and x-ray diffraction (XRD). The results suggested that mechanical properties of coir fibre after sodium bicarbonate solution changed for all densities and soaking time. The coir fibre treated in 12 wt.% sodium bicarbonate for soaking time 120 hours has highest tensile strength. The surface morphology of fibre was analyzed by using SEM. It showed micropores on the fibre surface which may influence the mechanical properties of coir fibre.