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Row crops normally grown in Southeast USA are cotton (Gossypium hirsutum L.), corn (Zea mays L.), and peanut (Arachis hypogea L.) with a focus on the higher economic value for peanut. Peanut is typ...

Currently, there are 13.9 million hectares of loblolly pine (Pinus taeda L.) in the Southern United States. Reforested hectares could be used for intercropping oilseed crops such as carinata (Brassica carinata) and white lupin (Lupinus albus L.). The oil obtained from these crops could be used for bio-jet fuel production to reduce the carbon footprint of the aviation sector. This study determines the profitability for three scenarios: loblolly pine with no intercropping (baseline), loblolly pine with carinata (once every three years), and loblolly pine with carinata and white lupin rotated annually. We ascertained the land expectation value (LEV) for three site indices of 15.3 m, 18.3 m, and 21.3 m. Carinata and white lupin were planted during the initial eight, seven, and six years for site indices 15.3 m, 18.3 m, and 21.3 m, respectively. Sensitivity and risk analyses were undertaken for determining the influence of input variables on LEVs and the probability of loss for intercropping production systems relative to a baseline production system, respectively. For site index 21.3 m, the LEV of loblolly pine with no intercropping was $2816/ha at a 21-years rotation period. Intercropping with carinata only and both carinata and white lupin yielded LEVs of $3346/ha and $3607/ha at a 21-years rotation period, respectively. The LEVs of production systems were sensitive to interest rate, price, and yield of carinata seeds. The intercropping approach had > 50% probability of being less profitable than loblolly pine alone in over half of the scenarios considered. Future research should focus on the impacts of intercropping on loblolly pine yield and adoption behavior of forest landowners.

Interest and focus on development of renewable biofuels has been increasing over the past decade leading to the introduction of a wide cadre of renewable feedstocks. As a result, numerous perennial warm-season grasses have been introduced and management practices evaluated to determine their suitability as biofuel feedstocks. “Merkeron” napier grass (Pennisetum purpureum) plots were established in 2010 and harvested during crop years 2011 through 2015 adjacent to an on-going peanut (Arachis hypogaea L.), corn (Zea mays L.), and cotton (Gossypium hirsutum L.) cropping systems study conducted at the USDA/ARS Multi-crop Irrigation Research Farm in Shellman, GA (84 36 W, 30 44 N) on a Greenville fine sandy loam (fine, kaolinitic, thermic Rhodic Kandiudults). Napier grass was produced in both non-irrigated and two irrigated levels with different levels of nitrogen and potassium fertilizers. Peanut, corn, and cotton were produced in non-irrigated and full irrigation regimes. Breakeven prices for napier grass ranged from $65 to $84 Mg−1 at variable and total costs. The breakeven napier grass price was estimated such that the net returns were equal between napier grass and peanut, cotton, corn cropping systems. At variable production cost, comparative breakeven napier grass prices for non-irrigated, 50% irrigated, and full irrigated regimes were $77, $117, and $112 Mg−1, respectively. Napier grass did not compete economically against traditional irrigated cropping systems. Depending on traditional crop prices and bioenergy feed stock prices, napier grass could offer economic opportunities in non-irrigated production environments, riparian buffer zone edges, or non-cropped marginal production areas.

Application of biochar to soils is hypothesized to increase crop yield. Crop productivity impacts of biochar application in southeastern cropping systems consisting of peanut (Arachis hypogaea L.), corn (Zea mays L.), and cotton (Gossypium hirsutum L.) produced under varying rates of irrigation have not been addressed. This research incorporated biochar at two different rates into a long-term irrigation and cropping systems study to compare yield and quality response of peanut, corn, and cotton. Biochar was incorporated into soil once at the beginning of the 4-year project at rates of 22.4 and 44.8 Mg ha−1. Peanut, corn, and cotton were produced under three sprinkler irrigation levels (100%, 66%, and 33%), shallow surface drip irrigation (100%), and a nonirrigated control. Crop input management followed best management practices. Sprinkler irrigation was scheduled by Irrigator Pro for Peanuts, Corn, and Cotton at the 100% level and the 66% and 33% levels were applied at the same time as the 100% l...

Aflatoxin contamination is a major constraint in food production worldwide. In peanut (Arachis hypogaea L.), these toxic and carcinogenic aflatoxins are mainly produced by Aspergillus flavus Link and A. parasiticus Speare. The use of RNA interference (RNAi) is a promising method to reduce or prevent the accumulation of aflatoxin in peanut seed. In this study, we performed high-throughput sequencing of small RNA populations in a control line and in two transformed peanut lines that expressed an inverted repeat targeting five genes involved in the aflatoxin-biosynthesis pathway and that showed up to 100% less aflatoxin B1 than the controls. The objective was to determine the putative involvement of the small RNA populations in aflatoxin reduction. In total, 41 known microRNA (miRNA) families and many novel miRNAs were identified. Among those, 89 known and 10 novel miRNAs were differentially expressed in the transformed lines. We furthermore found two small interfering RNAs derived from the inverted repeat, and 39 sRNAs that mapped without mismatches to the genome of A. flavus and were present only in the transformed lines. This information will increase our understanding of the effectiveness of RNAi and enable the possible improvement of the RNAi technology for the control of aflatoxins.

Crop yield response to biochar application may vary with biochar type/rate, soil, crop, or climate. The objective of this research was to identify yield response of cotton (Gossypium hirsutum L.), ...

With global increases in the production of cellulosic biomass for fuel, or “biofuel,” concerns over potential negative effects of using land for biofuel production have promoted attention to concepts of agricultural landscape design that sustainably balance tradeoffs between food, fuel, fiber, and conservation. The Energy Independence Security Act (EISA) of 2007 mandates an increase in advanced biofuels to 21 billion gallons in 2022. The southeastern region of the USA has been identified as a contributor to meeting half of this goal. We used a GIS-based approach to estimate the production and N-removal potential of three perennial biofeedstocks planted as conservation buffers (field borders associated with riparian buffers, and grassed waterways) on the Coastal Plain of Georgia, USA. Land cover, hydrology, elevation, and soils data were used to identify locations within agricultural landscapes that are most susceptible to runoff, erosion, and nutrient loss. We estimated potential annual biomass production from these areas to be: 2.5–3.5 Tg for giant miscanthus (Miscanthus × giganteus), 2–8.6 Tg for “Merkeron” napier grass (Pennisetum purpureum), and 1.9–7.5 Tg for “Alamo” switchgrass (Panicum virgatum). When production strategies were taken into consideration, we estimated total biomass yield of perennial grasses for the Georgia Coastal Plain at 2.2–9.4 Tg year−1. Using published rates of N removal and ethanol conversion, we calculated the amount of potential N removal by these systems as 8100–51,000 Mg year−1 and ethanol fuel production as 778–3296 Ml year−1 (206 to 871 million gal. US).

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.

Water-use efficiency is often genetically correlated with specific leaf area (SLA) and leaf C isotopic composition (d13C) in peanut (Arachis hypogaea L.). The objectives of this study were to examine the effects of environment, genotype, and genotype × environment interaction on SLA, d13C, harvest index (HI), and yield and to estimate heritability and the genetic relationships. Fifteen genotypes were tested at two locations with different drought intensities for 2 yr. The additive main effects and multiplicative interaction analysis based on yield data divided eight environments (locations × treatments × years) into four clusters, which reflected a gradient in drought stress, indicating yield trait is a good indication of drought stress. The genotype Exp8-12 was identified as a best drought tolerant germplasm across environments. Heritability estimates for HI (0.68 to 0.89) and d13C (0.75 to 0.89) were higher than those for SLA (0.31 to 0.88) and yield (0.12 to 0.65). A positive but small genetic correlation coefficient (rg) (0.26) was found between HI and yield, and low to moderate rg (0.14 to 0.55) were observed between HI and SLA. A relative high negative genetic correlation rg (-0.81 to -0.57) was found between d13C and yield. In theory, the high heritability and no G×E interaction for d13C make it possible a surrogate that can be used to assess drought tolerance in peanut breeding.

Aspergillus flavus accumulates carcinogenic aflatoxins in peanuts, mainly in immature kernels during drought. Aspergillus flavus invasion induces accumulation of phytoalexins, mostly stilbenoids in peanut, as a plant defence mechanism. Because fungal laccases are often related to pathogenicity and can degrade stilbenoids, this study reports for the first time the expression of A. flavus laccases in the presence of kernels, hulls and low water potential in relation to the accumulation of phytoalexins in peanut kernels. Packed-cell volume (PCV) of A. flavus biomass was significantly higher (P ≤ 0·01) in the presence of mature kernels, dead kernels, and mature and immature peanut hulls than the control. The presence of kernels and hulls lowered the level of expression of three A. flavus laccases by 4–6-fold (P < 0·01), whereas 3% sucrose up-regulated them by 35–304-fold, and low water potential (−1·1 MPa) up-regulated them by 85–248-fold (P < 0·01). Phytoalexins that accumulated in peanut kernels in the presence of A. flavus and were quantified by HPLC-DAD-MS were primarily the stilbenoids: 3′-isopentadienyl-3,5,4′-trihydroxystilbene (IPD), chiricanine-A, arachidin-2, arachidin-3 and arahypin-1. Apparent degradation of phytoalexins was observed when using a priori induction of phytoalexins in seeds in combination with a priori induction of laccases in A. flavus. The up-regulation of laccase expression observed at −1·1 MPa and at high sucrose concentration could be contributing to peanut invasion in immature kernels under drought conditions.

The Southeast U.S. receives an average of 1300 mm annual rainfall, however poor seasonal distribution of rainfall often limits production. Irrigation is used during the growing season to supplement rainfall to sustain profitable crop production. Increased water capture would improve water use efficiency and reduce irrigation requirements. Furrow diking has been proposed as a cost effective management practice that is designed to create a series of storage basins in the furrow between crop rows to catch and retain rainfall and irrigation water. Furrow diking has received much attention in arid and semi-arid regions with mixed results, yet has not been adapted for cotton production in the Southeast U.S. Our objectives were to evaluate the agronomic response and economic feasibility of producing cotton with and without furrow diking in conventional tillage over a range of irrigation rates including no irrigation. Studies were conducted at two research sites each year from 2005 to 2007. Irrigation scheduling was based on Irrigator Pro for Cotton software. The use of furrow diking in these studies periodically reduced water consumption and improved yield and net returns. In 2006 and 2007, when irrigation scheduling was based on soil water status, an average of 76 mm ha−1 of irrigation water was saved by furrow diking, producing similar cotton yield and net returns. Furrow diking improved cotton yield an average of 171 kg ha−1 and net return by $245 ha−1 over multiple irrigation rates, in 1 of 3 years. We conclude that furrow diking has the capability to reduce irrigation requirements and the costs associated with irrigation when rainfall is periodic and drought is not severe.

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.

This research was conducted in experimental plots in Georgia from 2004 through 2006 and assessed the prospects for transitioning to a totally organic management system for cotton. The seasonal abundance of insect pests and their natural enemies over the 3-yr transitional period are reported herein. The heliothines, Heliothis virescens (F.) and Helicoverpa zea (Boddie), and stink bugs, mainly Nezara viridula (L.), Euschistus servus (Say), and Euschistus quadrator (Rolston), were the 2 groups of insect pests found on cotton. Heliothine larvae were observed each year of the study but, in general, infestations of heliothines were higher in 2004 than in the other 2 yrs. Stink bugs were observed in relatively high numbers, and the percent of cotton bolls damaged by these pests was high only during year 2 of the study. Over the 3-yr period, the red imported fire ant, Solenopsis invicta Buren, various spiders, including Oxyopes scalaris Hentz and Peucetia viridans (Hentz), the big-eyed bug, Geocoris punctipes (Say), and the pirate bug, Orius insidiosus (Say), were the most abundant predators of the heliothines and stink bugs. The endoparasitoid Toxoneuron nigriceps Viereck and an ascovirus also contributed to larval mortality of H. virescens. The endoparasitoid Trichopoda pennipes (F.) parasitized adults of N. viridula.

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.

The effect of marketing quotas and price supports on technology adoption are examined for peanut production in the southeastern United States using a real options model of investment with output price and yield uncertainty. The optimal choice of peanut production technology (dryland versus irrigated) in the southeast is shown to depend on price supports and how they change. The manner in which price supports change will have an effect on the choice and rates of abandonment or adoption of production technologies.

Tillage to disrupt root-restricting, consolidated soil zones can improve rooting capacity and crop production, but costs increase with the need for more powerful tractors. Between 1992 and 1996, agronomic and economic consequences of annual or less frequent soil disruption treatments were evaluated for cotton (Gossypium hirsutum L.) on a Typic Kanhapludult. Two soil-disruptive treatments, fall paratillage (PT) and in-row chisel (IC) at planting (spring), were compared with two shallow-tillage treatments, coulter planting plus weed control with sweeps (ST) and conventional disk tillage (DT). The IC, PT, and ST treatments were applied annually or in Years 3, 4, and 5. Lint yield with annual IC was 15 to 20% greater than with DT each year. In 1994, yields ranged from 0.53 to 0.84 Mg ha -1 with annual IC and were better than with annual ST or PT. In 1995, yields ranged from 0.92 to 1.29 Mg ha -1 , with the top yield associated with current-year IC application. In 1996, no differences in yield were observed among tillages; however, yields of two IC treatments were among the top five. For Years 3, 4, and 5, cotton yields were numerically greater with annual IC than with annual PT and ST. Yields with PT, ST, and DT were not different. Average annual net returns from annual IC were $450, $403, and $287 ha -1 greater than those with annual DT, PT, and ST, respectively. In-row chisel appears to be a more economically viable production practice for heavy Piedmont soils compared with PT, ST, and DT.

Aspergillus flavus is the major producer of carcinogenic aflatoxins worldwide in crops. Populations of A. flavus are characterized by high genetic variation and the source of this variation is likely sexual reproduction. The fungus is heterothallic and laboratory crosses produce ascospore-bearing ascocarps embedded within sclerotia. However, the capacity for sexual reproduction in sclerotia naturally formed in crops has not been examined. Corn was grown for 3 years under different levels of drought stress at Shellman, GA, and sclerotia were recovered from 146 ears (0.6% of ears). Sclerotia of A. flavus L strain were dominant in 2010 and 2011 and sclerotia of A. flavus S strain were dominant in 2012. The incidence of S strain sclerotia in corn ears increased with decreasing water availability. Ascocarps were not detected in sclerotia at harvest but incubation of sclerotia on the surface of nonsterile soil in the laboratory resulted in the formation of viable ascospores in A. flavus L and S strains and in homothallic A. alliaceus. Ascospores were produced by section Flavi species in 6.1% of the 6,022 sclerotia (18 of 84 ears) in 2010, 0.1% of the 2,846 sclerotia (3 of 36 ears) in 2011, and 0.5% of the 3,106 sclerotia (5 of 26 ears) in 2012. For sexual reproduction to occur under field conditions, sclerotia may require an additional incubation period on soil following dispersal at crop harvest.