Heated air by solar collector has high variation in temperature because it is depend on time. Therefore, a rock-bed was used to regulate the air temperature and to damp out the large fluctuation of air temperature, although it causes a change in the phase and the amplitude temperature of the inlet air. The rock-bed could be used then to store day-heat for night use. The purpose of this paper was to mathematically model the rock-bed performance using SAS language. This modeling utilizes; (1) rock-bed characteristics, (2) Fourier series, and (3) statistical procedures for predicting the outlet air temperature. A computer program was developed to achieve this purpose. An air flow of 4.66 m 3 /min was used to test the computer model and air temperatures at 0, 0.375, and 0.70 m of the rock bed height were recorded by time for 24 h. It was found that Fourier series was more efficient for predicting the air temperature at any vertical location of the rock-bed. The correlation coefficient using the rock-bed characteristics and Fourier series was 0.905 for predicting the outlet air temperature. The determination coefficients were found to be above 0.98 between observed and predicted air temperatures at any vertical location of the rock-bed.

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Because the most soils in Saudi Arabia can not maintain water being sandy soils. This. soil characteristic leads to the loss of water by gravity. In addition, the high degree of temperature also can cause high evaporation rate for water after irrigation especially in summer. A thought was developed toward a method to increase soil bulk density that leads to raise the capability of water to maintain water. This was achieved by designing and constructing a machine for compacting and making holes in soil. These holes will act as small water tanks in soil and save water to growing seeds. This machine consisted of 44 cm diameter cylinder with 245 cm width to make 8 rows of holes on the ground with 30 cm apart. The cylinder bas 5 groups of metal cones (10 cm diameter with 10 cm height) welded on the cylinder circumference. Thus, lay out holes on the ground have a distance of 30 cm apart and 40 cm apart in the other direction. Mainly two field treatments were camed out, one with holes and one without holes. Variables such as soil moisture content and soil bulk density of soil were measured at different depths and times. The other variables such soil penetration resistance and organic matter as well as the clay percent were determined affer the 4" inigation for both treatments. The results showed that soil moisture content was higher in hole soil treatment than soil without treatment due to the coUection of clay particles and organic matter by water droplets during inigation. The collection of clay and organic matter in these holes made the holes very well sealed and increased the soil storage for water. It is obvious that the developed machine decreased the soil hydraulic conductivity that leads to an increase in soil water content.