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Canola (Brassica napins L.) has the potential for being used in a double‐cropping system (two crops grown in 1 yr) as a winter crop in the humid subtropical southeastern U.S. climate, but little information is known about its nitrogen (N) management when grown in this region. Thus, a field study was conducted at two locations (Shorter, AL: Compass loamy sand; Prattville, AL: Lucedale fine sandy loam) in 2016 to determine the effect of different rates of N fertilizer on plant growth, seed yield, and N uptake of canola. The experimental design was a randomized complete block with four replications. The N rates included were 0, 68, 135, 180, 202, and 270 kg N ha−1. Linear‐plateau regression was used to evaluate the response of plant growth, seed yield, and N uptake to N rate. Overall, canola growth, yield, and N uptake were highly dependent on N fertility. Applying 180 kg N ha−1 or more for canola production significantly increased plant height, plant biomass accumulation, seed yield, and N uptake compared with the unfertilized control at both locations. The linear‐plateau regression model indicated that the optimal N rate was 197–232 kg N ha−1 for these southeastern U.S. soils. This study suggests that winter canola grown in a humid subtropical region of the United States can be a successful winter crop for a double‐crop production system and provide seed yields comparable to yields from major winter canola production areas. [ABSTRACT FROM AUTHOR]

Canola (Brassica napins L.) has the potential to be used as a winter crop in the southeastern United States, but little is known about its nitrogen management when grown in this region. Increasing fertilizer costs have increased interest in using poultry litter (PL) as an alternative nutrient source for crops in this region. However, evaluation of the use of PL on canola growth and yield is lacking. Thus, a field study was conducted at Shorter, AL (loamy sand soil) and Prattville, AL (fine sandy loam soil) using a randomized complete block design with four replications. Fertility treatments consisted of an unfertilized control (P0U0), commercial fertilizer N (urea, 180 kg N ha−1, P0U180), PL at 68 kg N ha‐1 with 112 kg N ha−1 urea (P68U112), PL at 112 kg N ha−1 with 68 kg N ha−1 urea (P112U68), and PL at 180 kg N ha−1 (P180U0). Overall, the combination of PL and urea application significantly increased canola growth (plant height and aboveground biomass) and elevated grain yield compared with PL application alone or with the control. The P68U112 treatment resulted in an equivalent aboveground biomass, grain yield, and N uptake compared with the recommended urea treatment. This study suggests that a combination of PL and commercial fertilizer N could provide sustainable canola yield production in the southeastern United States. [ABSTRACT FROM AUTHOR]

Gypsum has a long history as a soil amendment. Information on how flue gas desulfurization (FGD) gypsum affects soil, water, and plant properties across a range of climates and soils is lacking. We conducted a meta-analysis using data from 10 field sites in the United States (Alabama, Arkansas, Indiana, New Mexico, North Dakota, Ohio, and Wisconsin). Each site used three rates each of mined and FGD gypsums plus an untreated control treatment. Gypsum rates included a presumed optimal agronomic rate plus one rate lower and one rate higher than the optimal. Gypsum was applied once at the beginning of each study, and then data were collected for 2 to 3 yr. The meta-analyses used response ratios (R) calculated by dividing the treatment value by the control value for crop yield or for each measured element in plant, soil, and vadose water. These R values were tested for their significance with z values. Most R values varied only slightly from 1.00. Gypsum significantly changed more R values from 1.00 for vadose water than for soil or crop tissue in terms of numbers of elements affected (11 for water, 7 for soil, and 8 for crop tissue). The highest R value for soil was 1.57 (Ca) which was similar for both mined and FGD gypsum, for crop tissue was 1.46 (Sr) for mined gypsum, and for vadose water was 4.22 (S) for FGD gypsum. The large increase in Ca and S is often a desired response to gypsum application. Lowest R values occurred in crop tissue for Mg (0.89) with FGD gypsum and for Ni (0.92 or 0.93) with both gypsums. Although some sites showed crop yield responses to gypsum, the overall mean R values for mined gypsum (0.987) and for FGD gypsum (1.00) were not significantly different from 1.00 in this short-term study. [ABSTRACT FROM AUTHOR]

There are concerns regarding the fate of nutrients from surface application of animal manure. One approach to reduce losses of P is to treat manure with industrial byproducts such as flue gas desulfurization (FGD) gypsum. However, concerns regarding potentially toxic elements contributed to the environment have arisen based on previous element-rich forms of FGD gypsum that included fly ash, whereas "new" FGD gypsum without fly ash is much lower in contaminants. This study examined the impact of FGD gypsum application on soil, plants, and runoff when applied alone or with poultry litter (PL) to soil. The study consisted of a plant response study (four rates of FGD gypsum of 0, 2.2, 4.4, and 8.9 Mg ha-1 and four rates of PL of 0, 4.4, 8.9, and 13.4 Mg ha-1) and a rainfall simulation study (3.4 Mg PL ha-1 with four rates of FGD gypsum of 0, 2.2, 4.4, and 8.9 Mg ha-1 and controls). Plant, soil, and runoff samples were analyzed for As, Ba, Be, Ca, Cd, Ba, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Sb, Se, Tl, V, and Zn. Results indicated that FGD gypsum application would not result in increased potentially toxic elements in plants, soil, or runoff. In addition, the application of FGD gypsum significantly reduced P, As, and Fe concentrations in runoff, indicating that FGD gypsum can reduce the negative impact of manure surface application on surface water degradation. [ABSTRACT FROM AUTHOR]

Controlling the threat that pastures intensively managed with poultry litter (PL) pose to accelerating eutrophication is a major issue in the southeastern United States. Gypsum (CaSO4) has been identified as a promising management tool for ameliorating litter P losses to runoff. Thus, research was conducted to elucidate gypsum's residual effects on P losses from a bermudagrass (Cynodon dactylon L.) pasture. Runoff events (60 min) were created using rainfall simulations. Treatments consisted of applying four flue gas desulfurization (FGD) gypsum rates (0, 2.2, 4.4, and 8.9 Mg ha-1) to bermudagrass fertilized with 13.4 Mg ha-1 PL plus a nonfertilized check (no litter or gypsum) and 8.9 Mg ha-1 FGD gypsum only as controls. Rainfall simulations (~ 85 mm h-1) were conducted immediately, 5 wk, and 6 mo (i.e., at the end of growing season) after PL application to determine gypsum's effectiveness at controlling P loss over successive runoff events. The greatest dissolved P (DP) in runoff occurred immediately after PL application. Gypsum effectively reduced cumulative DP concentration losses (54%) compared with PL alone in initial runoff events. Gypsum reduced DP concentrations in succeeding runoff events also regardless of timing, suggesting that its effect is persistent and will not diminish over a growing season. Generally, maximum DP reductions were achieved with 8.9 Mg ha-1. However, it was surmised from this study that optimal P reduction in a bermudagrass pasture can be achieved with 4.4 Mg ha-1. Information ascertained from this study may be useful in aiding land managers making prescriptions for management practices that reduce DP losses from agricultural fields. [ABSTRACT FROM AUTHOR]

Excessive phosphorus (P) loss from agricultural fields is a major cause of eutrophication to rivers, lakes, and streams. To mitigate P loss after poultry litter (PL) applications, technology is being developed to apply litter below the soil surface. Thus, research was conducted to evaluate the effects of subsurface PL banding on soil P under pasture management. Treatments consisted of surface-broadcasted or subsurface-banded PL (38 cm apart) at 9 Mg ha-1, surface-broadcasted commercial fertilizer (CF; urea and triple superphosphate blend) at N (330 kg N ha-1) and P (315 kg N ha-1) application rates equivalent to PL, and a nonfertilized control. Runoff events lasting 40 min were simulated in bermudagrass (Cynodon dactylon L.) pastures on common soil types of the Coastal Plain and Piedmont regions. One day later, Mehlich-1 and water-soluble P concentrations in soil were measured at depths of 0 to 5 cm and 5 to 10 cm to determine P distribution and movement. The greatest P concentrations were observed at the shallow depth for all treatments. Phosphorus measurements at the point of application for PL bands were greater than for the surface-applied treatments (PL and CF) and control. Measurements between subsurface PL bands were slightly higher than the control but were statistically similar, suggesting that this application method can abate shortterm P movement. Results obtained from this study show that subsurface band applying PL could increase P retention and reduce movement by precluding contact between surface water and litter nutrients. [ABSTRACT FROM AUTHOR]

Enhanced-efficiency N fertilizers (EENFs) have the potential to increase crop yield while decreasing soil N loss. However, the effect of EENFs on greenhouse gas (GHG) emissions from different agricultural systems is not well understood. Thus, studies from a variety of locations and cropping systems are needed to evaluate their impact. An experiment was initiated on a Coastal Plain soil under cotton (Gossypium hirsutum L.) production for comparing EENFs to traditional sources. Nitrogen sources included urea, ammonia sulfate (AS), urea-ammonia sulfate (UAS), controlledrelease, polymer-coated urea (Environmental Smart Nitrogen [ESN]), stabilized granular urea (SuperU), poultry litter (PL), poultry litter plus AgrotainPlus (PLA), and an unfertilized control. Carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes were monitored regularly after fertilization through harvest from 2009 to 2011 using a closed-chamber method. Poultry litter and PLA had higher CO2 flux than other N treatments, while ESN and SU were generally lowest following fertilization. Nitrous oxide fluxes were highly variable and rarely affected by N treatments; PL and PLA were higher but only during the few samplings in 2010 and 2011. Methane fluxes were higher in 2009 (wet year) than 2010 or 2011, and N treatments had minimal impact. Global warming potential (GWP), calculated from cumulative GHG fluxes, was highest with PL and PLA and lowest for control, UAS, ESN, and SU. Results suggest that PL application to cotton increases GHG flux, but GHG flux reductions from EENFs were infrequently different from standard inorganic fertilizers, suggesting their higher cost may render them presently impractical. [ABSTRACT FROM AUTHOR]

Interest in the use of enhanced-efficiency nitrogen fertilizer (EENFs) sources has increased in recent years due to the potential of these new EENF sources to increase crop yield, while at the same time decreasing N loss from agricultural fields. The efficacy of these fertilizer sources on cotton (Gossypium hirsutum L.) production in southeastern U.S. upland soils has not been well documented. Thus, a field study was conducted on a Coastal Plain soil (Marvyn loamy sand; fine-loamy, kaolinitic, thermic Typic Kanhapludult) in Central Alabama from 2009 to 2011 to compare EENFs to traditional N sources in a high-residue conservation cotton production system. Nitrogen fertilizer sources evaluated included urea (U), ammonium sulfate (AS), urea-ammonium sulfate (UAS), Environmentally Smart Nitrogen (ESN) (Agrium Advanced Technologies, Loveland, CO), stabilized urea (SuperU [SU] [Agrotain International, St. Louis, MO]), poultry litter (PL), poultry litter + AgrotainPlus (PLA) (KOCH Agronomic Services LLC, Wichita, KS), and an unfertilized control (C). Generally, no significant differences in cotton lint yield were observed between the traditional sources and EENFs. Nitrogen source affected fiber quality; however, effects varied among years and generally would not have impacted discount/premium values. In the present study, EENFs produced cotton lint yields similar to conventional fertilizers, suggesting their higher cost may render them uncompetitive at present. However, if EENFs reduce N loss through leaching, runoff and N2O flux from agricultural fields they could become viable alternative fertilizer sources. More research is needed on the benefits of enhanced-efficiency fertilizer use as a tool in agricultural production systems. [ABSTRACT FROM AUTHOR]

There are growing concerns regarding the fate of nutrients, especially phosphorus (P), from land application of animal waste. One approach being studied to reduce runoff losses of P is to treat manure or the soil receiving manure with chemical amendments such as gypsum. This study used rainfall simulations to examine the impact of flue gas desulfurization (FGD) gypsum application on runoff nutrient losses on a Coastal Plains soil (Luverne sandy loam; fine, mixed, semiactive, thermic Typic Hapludults). Four rates of FGD gypsum (0, 2.2, 4.4, and 8.9 Mg ha-1) were applied to plots of Coastal Bermudagrass (Cynodon dactylon L.) that had received application of 13.4 Mg ha-1 poultry litter. Plots with 8.9 Mg ha-1 FGD gypsum but no poultry litter and plots with neither poultry litter nor FGD gypsum were also used. Rainfall simulation was used to generate water runoff for 60 min, and samples were analyzed for soluble reactive P (SRP) and soluble Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, and Zn. Total concentration of Ca, Mg, K, Na, Fe, Mn, and Zn and concentration of heavy metals Ar, Hg, Al, Sb, Ba, Be, Cd, Cr, Co, Cu, Pb, Ni, Si, V, Se, Tl, and hexavalent chromium were also analyzed. Results indicated a maximum of 61% reduction in SRP concentration in runoff with the application of 8.9 Mg ha-1 FGD gypsum. This translated to a 51% reduction in total SRP load during the 60-min runoff event. Concentrations of heavy metals in runoff were all found to be below detection limits. The results indicated that use of 4.4 Mg ha-1 FGD gypsum on Coastal Plains pastures receiving poultry litter could be an effective method of reducing SRP losses to the environment. [ABSTRACT FROM AUTHOR]

There is currently much interest in developing crop management practices that will decrease N2O emissions from agricultural soils. Many different approaches are being investigated, but to date, no studies have been published on how microbial inoculants affect N2O emissions. This study was conducted to test the hypothesis that microbial-based inoculants known to promote root growth and nutrient uptake can reduce N2O emissions in the presence of N fertilizers under controlled conditions. Carbon dioxide and CH4 fluxes were also measured to evaluate microbial respiration and determine the aerobic and anaerobic conditions of the incubated soil. The microbial-based treatments investigated were SoilBuilder (SB), a metabolite extract of SoilBuilder (SBF), and a mixture of four strains of plant growth-promoting Bacillus spp. Experiments included two different N fertilizer treatments, urea and urea--NH4NO3 32% N (UAN), and an unfertilized control. Emissions of N2O and CO2 were determined from soil incubations and analyzed with gas chromatography. After 29 d of incubation, cumulative N2O emissions were reduced 80% by SB and 44% by SBF in soils fertilized with UAN. Treatment with Bacillus spp. significantly reduced N2O production on Days 1 and 2 of the incubation in soils fertilized with UAN. In the unfertilized treatment, cumulative emissions of N2O were significantly reduced 92% by SBF. Microbial-based treatments did not reduce N2O emissions associated with urea application. Microbial-based treatments increased CO2 emissions from soils fertilized with UAN, suggesting a possible increase in microbial activity. Overall, the results demonstrated that microbial-based inoculants can reduce N2O emissions associated with N fertilizer application, and this response varies with the type of microbialbased inoculant and fertilizer. [ABSTRACT FROM AUTHOR]

Reduced tillage, poultry litter applications, crop rotations, and winter cover cropping are management practices that could be used with conservation tillage systems to increase yields compared to conventional monoculture systems. This study evaluated cropping sequences of corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and corn-soybean rotations with wheat (Triticum aestivum L.) covers in conventional, strip, and no-tillage (no-till) systems, following poultry litter additions to wheat cover. The study was conducted from 1991 to 2001 on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Poultry litter (112 kg N ha-1) was applied to wheat each year in fall. Wheat not receiving poultry litter received equivalent inorganic N. Corn was fertilized with inorganic fertilizer in spring with 56 kg N ha-1 at planting followed by 168 kg N ha-1 3 wk after emergence; soybean received no fertilizer. Corn yields were influenced by tillage in 1991, 1992, 1993, 1994, 1996, 1997, 1998, and 2001 with conventional tillage producing greater yields, except in 1993 (strip tillage) and 2001 (no-till). Poultry litter increased corn yield in 1991, 1997, and 1998. Crop rotations increased corn yield for all years, except 2001. Soybean yields were not impacted by differences in tillage. Crop rotations significantly impacted soybean yield in 1992, 1995, and 1998, with higher yields observed in 1992, and 1995, and lower yields in 1998. Poultry litter significantly increased soybean yield 8 of the 9 yr evaluated. This study suggests that poultry litter use for these crop rotations in conservation tillage systems could increase sustainable yield production. [ABSTRACT FROM AUTHOR]

The article discusses research investigating the growth of tropical spiderwort (Commelina benghalensis L.) under elevated atmospheric carbon dioxide (CO2) conditions. The researchers note that despite considerable efforts to study exotic plant pests, few researchers consider how invasive plants might react to the increasing CO2 concentration in the atmosphere. Topics include a brief overview of the economic impact on agriculture in the U.S. from the invasive plant C. benghalensis L. and results from a study measuring growth responses of C. benghalensis L. using plants grown in containers with soilless potting medium under ambient and elevated levels of CO2 in open-field chambers.