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ASABE Standard S410.2 specifies that 200 g samples of peanuts should be dried in an oven until a constant weight is achieved. The standard recommends oven-drying at 100°C for 72 h or at 130°C for 6 h for samples with up to 30% wet basis moisture content. In previous research to calibrate instruments for measuring single-kernel moisture, the moisture content of single peanut kernels was determined using the same time and temperature recommendations as for 200 g samples. This study was conducted to determine if shorter oven-drying times could be used for single-kernel moisture determination. Shelled peanut kernels were rehydrated to five different moisture levels by placing samples over saturated salt solutions in closed containers for 18 d. A sample of 20 kernels was removed from the rehydration chamber, the wet weight of each kernel was recorded, and the kernels were then placed in individual containers in a convection oven at 130°C. The weight of each kernel was recorded at approximately 90 min intervals for 8 h and then again at 24 h. The apparent dry basis (d.b.) moisture content was calculated using the weight recorded at each observation. The error was calculated as the difference between the apparent moisture content calculated at each time step and the final moisture content calculated after 24 h in the oven. The data were fit to an exponential decay function to estimate the error as a function of drying time. The regression function was then used to estimate the drying time required to achieve various levels of accuracy. The drying time required to achieve an accuracy of ±0.5% d.b. averaged 300 min for peanuts between 9% and 15% d.b. moisture content, and this drying time was approximately 150 min for peanuts at 4% d.b. moisture content. This research shows that drying at 130°C for 6 h (360 min) is adequate for determining the moisture content of single peanut kernels and that ASABE Standard S410.2 is suitable for single-kernel moisture measurements.

Drying, cleaning, and shelling peanuts represents approximately one-third of the costs of growing, harvesting, and processing peanuts for oil extraction. A conventional two-row peanut combine normally used to thresh windrowed peanuts was modified to shell the peanuts as they were harvested. Peanuts were dug, windrowed, and allowed to partially dry in the windrow. They were then harvested using either the modified peanut combine or a conventional grain combine. As a control treatment, peanuts were harvested using the modified peanut combine with the shelling grates removed from the sheller. The modified peanut combine successfully captured 91% of the peanut kernels threshed by the control and shelled 99% of the kernels harvested. The grain combine captured only 62% of the peanut kernels compared to the control. The grain combine shelled 93% of the peanuts harvested. Peanuts harvested with the grain combine had 30% foreign material, compared to 11% foreign material harvested with the modified peanut combine or the control. Allowing the peanuts to dry in the windrow and shelling with the modified peanut combine reduced the estimated postharvest oil production costs by as much as 36%, from $611 to $391 per 1000 L of oil.

The ability to determine how long a crop utilizes a given amount of water either from an applied irrigation or from a precipitation event would have great potential in improving irrigation decision systems. However, technical methodologies available to accomplish this measurement are almost entirely unavailable and untested. Experiments were conducted to quantify water movement through soil and peanut plants using deuterium-labeled water applied to simulate a typical irrigation or rainfall event. Soil at four depths and stem tissue samples were collected after the deuterium was applied. The first experiment in Greenville soil was conducted over a 24 h period in order to determine how much water was utilized in a fully charged soil profile. The second experiment in Tifton soil was conducted over a four-day period starting with a relatively dry soil profile in order to determine how long a peanut plant could utilize applied water. Differences in soil water infiltration between overhead irrigation and subsurface drip irrigation were observed, but there was no effect on subsequent peanut water uptake patterns between the two peanut cultivars, Georgia Green and Andru II. The duration of water uptake after a simulated irrigation or precipitation event appears to be between 48 and 72 h for peanut plants. The study demonstrated the utility of applying deuterium-labeled water in order to follow soil infiltration and plant water uptake patterns in a peanut agricultural system.

Moisture content (MC) in peanuts is an important parameter to be measured and monitored at various stages in the peanut industry. In previous research, peanut MC was estimated by placing a sample between a set of parallel-plate conductors to measure capacitance and phase angle of the system with commercially available, expensive impedance analyzers. In this work, a low-cost impedance analyzer called the CI meter (Chari's impedance meter) was designed and developed to measure impedance and phase angles at frequencies 1, 5, and 9 MHz using the parallel-plate sensor. The average MC values predicted by the CI meter for peanut samples harvested during two different years were compared with the standard air-oven values. In-shell peanut sample MC ranged between 6% and 23%. Over 90% of estimated in-shell MC values were within 1% of the air-oven values. Ability to determine the average MC of in-shell peanuts without shelling and cleaning them can be of considerable use in the peanut industry.