Effect of Seasons and Sticker thickness on Sclerocarya birrea (Humied) Wood Drying in Kadogli Area, South Kordofan State, Sudan.

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Ismail Amin Yousif, Moatassim
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The effect of seasons and sticker thickness on Sclerocarya birrea (Humied) wood drying in Kadogli area, South Kordofan State, Sudan. The aim of this study was to investigate the variation between seasons (autumn, winter and summer) and sticker thickness on the air drying of Sclerocarya birrea (humied) wood. The study was undertaken in Kadogli Town, South Kordofan State. The wood material was collected from mature and healthy trees growing in Kegga-jerro natural forest. The logs were cut from three hundred and ten trees, about 30 cm above the surface of ground. The logs were flat-sawn, 1080 planks were prepared and 360 planks were used in each season. The stacks of the wood were piled on the drying yard, loaded on a firm foundation, built by using bricks, cement and sand. Nine stacks were piled for the study, three stacks in each season, using three sticker sizes (1.25 cm, 2.5 cm and 3.75 cm). Each stack was built using 120 randomly selected planks, which were sawn in equal dimensions of about 5 cm ×15 cm×200 cm. Each stack was divided into fifteen rows and each row consists of eight planks Fifty four test blocks, measuring 2.5 cm×5 cm×15 cm, were cut from twenty seven sample planks, about 30 cm from either end of the planks to determine the initial moisture content using the oven dry method. The data were obtained by weighting the twenty seven sample planks which were randomly selected and placed in three different locations within the drying stacks (three sample planks in each stack) every three days until a constant weight was attained. The relationship between the moisture content and the drying time (days) was investigated using regression analysis. Although this relationship could be significantly explained by second, third or fourth-order polynomial equations, the fourth order had the best fit. The statistical analysis of variance indicated 5 that there were significant differences between the trends of the relationship between the seasons (autumn, summer and winter) in terms of the equilibrium moisture content and the drying time. Summer had the highest equilibrium moisture content and longest drying time compared with autumn and winter seasons. No significant differences were found among sticker thicknesses in the equilibrium moisture content and the drying time. The percentage of warping defect was higher in winter season than the other two seasons, while the magnitude of the warped planks was greater in autumn. However, the percentage of surface-checked planks was greater in summer than in winter and autumn, while the percentage of end-checked planks was very high in autumn compared with winter and summer. The high number and percentage of drying defect was expected to be associated with stacks for sticker 3.75 cm thickness, but the defect was found unevenly distributed between the three sticker sizes. The magnitude of drying defects (warping, checking) and the numbers of the defected planks indicate that Sclerocarya birrea wood can successfully be air-dried, with acceptable level of drying.
Effect,Seasons,Sticker,thickness,Sclerocarya,birrea,Wood, Sudan