An automated computer-based system was developed to control field scale controlled-drainage/subirrigation (CD-SI). The control system was designed to maintain the optimum soil water conditions in the root zone by monitoring the soil water potential and adding or removing water or remaining idle as needed.

Conventional techniques for the determination of moisture content in grain often use small static samples to represent several tons of material. A more desirable alternative would be a method which utilizes continuous dynamic moisture measurement of the grain. The potential for making density-independent moisture content measurements in both static and flowing grain using microwave frequencies was evaluated in tests with soft red winter wheat over moisture contents from 11% to 19% (w.b.). Moisture measurements were predicted within +/-0.7% for the static samples and within +/-1.2% for wheat in a dynamic solid-flow condition. For suspended flow (aerated sample of grain) scatter became more apparent and the system accuracy decreased.

A model was developed to simulate germination of loblolly pine in nurseries. The model inputs included sowing depth, mulch type, amount of mulch, daily mean temperature, length of seed stratification period, seed quality (germination determined by a seed testing laboratory), and temperature used by the seed testing laboratory to determine seed quality. The model simulated daily germination as percent of the total number of seeds sown. Germination data observed by Boyer et al. (1987) in 1984 at Jake Stauffer Alabama Forestry Commission nursery near Opelika, Alabama, was used to test the model. The cumulative germination curve predicted by the model closely followed the observed data. An analysis of the model indicated that the predicted germination rate was more sensitive to the input values of sowing depth, length of seed stratification period, laboratory determined germination, and amount of mulch than to the other model input parameters.

A radar-based distance marking system was developed, constructed, and evaluated. The velocity dependent frequency of a radar-based speed sensor was the primary reference signal used in generating a distance dependent pulse. Errors of - 2.67% or less were obtained when speeds were from 1.6 to 6.4 km/h on a variety of surfaces.

ABSTRACT Adensity-independent function of grain dielectric properties was developed for use in measuring the moisture content of grain. A microwave system operating at 10.5 GHz was developed and evaluated that is capable of accurate and independent simultaneous measurement of the attenuation and phase shift introduced by grain occupying the space between two horn antennas. The dielectric parameters needed to predict moisture content can be calculated from attenuation and phase-shift data. Measurements of the dielectric properties of soybeans were made with the new system.

ABSTRACT THE results of this project indicate that there are no technical problems which would prevent the use of schedule 40 polyvinyl chloride (PVC) pipes for panel heating. The major consideration when using PVC is the insulating properties of the PVC material. The water temperature must be increased to compensate for the use of PVC pipes. Once the temperature is increased, the system should function similar to a conventional system. The large thermal expansion of the PVC material did not create any difficulties.

ABSTRACT THE operating characteristics of several non-conventional grain drying systems are presented. Specific attention is paid to the energy efficiency and the drying rate of the systems.