Andropogon Gerardii Research Articles

115 Nitrogen fertilizer effects on above ground sward characteristics and beef heifer performance from native warm-season grass blends

Abstract A 2-yr study was conducted at Black Belt Research and Extension Center in Marion Junction, AL, to evaluate the effect of nitrogen (N) fertilizer application rate on forage production characteristics, nutritive value, and animal performance of beef heifers grazing a mixture of native warm-season grasses (NWSG) including big bluestem, little bluestem, and indiangrass. Six, two-hectare plots were randomly assigned to one of two treatments (0 or 67 kg N ha-1 applied in early April; n = 3 replications per treatment). Paddocks were continuously stocked with four weaned Angus × Simmental beef heifers (initial BW 288 ± 7 kg) from late May/early June through mid-to-late August during 2018 (73 grazing d) and 2019 (70 grazing d), respectively. Put-and-take cattle were used to manage forage to a target of 38 cm. Forage mass and canopy heights were collected every two weeks during the trial. Visual ground cover ratings, canopy light interception, and botanical composition were measured at the beginning and end of the trial in each year. Hand-plucked samples were collected every two weeks during the grazing trial to determine forage nutritional value. Data were analyzed using the PROC MIXED procedure in SAS 9.4, and differences were declared significant when P ≤ 0.05. Nitrogen fertilized NWSG had greater crude protein (P < 0.0001), sward heights (P = 0.0003), and canopy light interception at the beginning of the season (P = 0.0049) compared to non-fertilized paddocks. However, there were no differences (P ≥ 0.05) among N-fertility treatments for mean forage mass, heifer ADG, or BCS across the 2-yr study. Botanical composition data indicated that indiangrass decreased from 64% to 61% (P = 0.0022) and weed pressure increased from 11% to 15% (P = 0.0064) across the summer grazing season. Canopy light interception decreased by 51% from early June to August in fertilized NWSG and 26% in unfertilized paddocks, respectively. These data illustrate that NWSG systems may provide a viable grazing system in the summer months under reduced N inputs.

Super‐abundant C4 grasses are a mixed blessing in restored prairies

Forbs comprise most of the plant diversity in North American tallgrass prairie and provide vital ecosystem services, but their abundance in prairie restorations is highly variable. Restoration practitioners typically sow C4 grasses in high abundances because they are inexpensive, provide fuel for prescribed fires, can dominate reference sites, and suppress weeds that suppress sown forbs. However, C4 grasses can also suppress sown forbs, calling this practice into question. We evaluated how C4 grasses influence the abundance and diversity of sown forbs in 78 restored prairies across Illinois, Indiana, and Michigan. We found that the direct negative effects of C4 grasses on sown forbs outweighed indirect positive effects that occurred as C4 grasses suppressed nonsown species, which in turn suppressed sown forbs. This pattern was especially strong for the C4 grass big bluestem (Andropogon gerardii). Therefore, strategies to promote big bluestem and other C4 grasses would not promote sown forbs. Although C4 grass cover was not strongly related to two hypothesized drivers (time since fire or site age), seeding density of C4 grasses increased their cover. Sown forb cover also increased with forb seeding density, increased indirectly with fire (through its negative effect on nonsown species), and decreased indirectly with soil water‐holding capacity (through its positive effect on nonsown species). These results highlight the complex interplay of species groups during grassland restoration and show how managers can promote sown forbs in restored prairies: increasing forb seeding density and reducing time since fire and the abundance of C4 grasses and weeds.

Evaluation of Five East Texas Forages under Differing Shade Levels

A pot study was conducted to measure the establishment success of five forages under 0%, 30% or 60% shade levels. The forages evaluated were ‘Pensacola” Bahia grass (Paspalum notatum Fluegge), “Texas Tough” Bermuda grass (Cynodon dactylon L. Pers.), “Alamo” switch grass (Panicum virgatum L.), “San Marcos” Eastern Gama grass (Tripsacum dactyloides L.), and a native mix containing by weight 45% “Texas” little bluestem (Schizachyrium scoparium Michx Nash), 15% sand love grass (Eragrostis trichodes Nutt. L. Alph. Wood), 15% “Blackwell” switch grass (Panicum virgatum L.), 10% “Lometa” Indian grass (Sorgastrum nutans L. Nash), 10% “Haskell” sideoats grama (Bouteloua curtipendula Michx Torr) and 5% “Earl” big bluestem (Andropgon gerardii Vitman). Mean biomass under 60% shades for all forages was less than under the other shade treatments, but did not differ among shade treatments within forages. Mean nutrient tissue concentration showed significant differences among treatments and forages for several nutrients. Shade treatments had no effect on plant density, but low germination of several forages appears to have influenced plant density. Based on these results, Bahia grass, eastern Gama grass and Bermuda grass may be suitable species if maximum biomass production were the goal of a silvopasture management system in east Texas.

Continuous grazing of mixed native warm‐season grass in the fescue belt

AbstractContinuous, season‐long (May–August) grazing is the most commonly used grazing strategy among tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] belt beef (Bos taurus) producers. However, little information is available regarding the feasibility of managing native warm‐season grass (NWSG) pastures in this region with continuous, season‐long grazing. We compared stand sustainability, beef cattle performance, and pasture production between continuous (CONT), season‐long grazing and heavy‐early (HEAVY), a modified continuous grazing strategy, on mixed‐NWSG pastures. Heavy‐early was designed to match the growth curve of NWSG, with an initial stocking target of 1.25 times the CONT density until 25 June, at which time stocking was reduced to 0.75 times the CONT density. Pastures were mixed big bluestem (Andropogon gerardii Vitman), indiangrass [Sorghastrum nutans (L.) Nash], and little bluestem [Schizachyrium scoparium (Michx.)]. The plant population (plants m−2) was similar between treatments, but years differed (P < .001), with a 35% reduction from 2017, the third and final year of grazing, to 2018. Despite the decline in plant density, overall tiller density (tillers m−2) increased 14%, indicating that the grazing strategies were likely sustainable. The grazing strategies had similar (P > .05) average daily gain (ADG; kg d−1), animal‐days ha−1, and total gain (kg ha−1). Weaned steer ADG was 0.98 kg d−1 for CONT and 0.89 kg d−1 for HEAVY. Total gain was 379 kg ha−1 for CONT and 334 kg ha−1 for HEAVY. Continuous grazing appears to be an appropriate strategy for managing NWSG pastures in the Fescue Belt.

Water-Use Efficiency of Forage Crops in the Southeastern United States

Preparing agricultural producers to cope with volatile weather changes, specifically drought, requires a better understanding of forage water-use efficiency (WUE) potentials. Options to improve farm resiliency to drought may include the use of C4 annual and perennial forages, which have greater production efficiency during drought than commonly used C3 forages. Our objective was to measure WUE through real-time gas exchange measurements of photosynthesis and transpiration in (1) a greenhouse study and (2) under field-grazing conditions. Growth parameters, instantaneous water use efficiency (iWUE), and mass-based WUE (mWUE) data were collected under greenhouse conditions in Study 1 for the following species: crabgrass (Digitaria sanguinalis cv. ‘Red River’), switchgrass (Panicum virgatum cv. ‘Alamo’), big bluestem (Andropogon gerardii cv. ‘OZ-70’), indiangrass (Sorghastum nutans cv. ‘Rumsey’), eastern gamagrass (Tripsacum dactyloides cv. ‘Pete’), bermudagrass (Cynodon dactylon cv. ‘Vaughn’s #1’), sorghum-sudangrass (Sorghum bicolor (L.) × Sorghum sudanese (P.) cv. ‘Greengrazer’), and tall fescue (Schedonorus arundinaceus (Schreb.) Dumort). Study 2 occurred from 2014 to 2016, and evaluated iWUE of crabgrass, switchgrass, bermudagrass, eastern gamagrass, and a big bluestem/indiangrass mix under field conditions. Overall, in situ iWUE of crabgrass, switchgrass, eastern gamagrass, and bermudagrass did not differ, while iWUE of the big bluestem/indiangrass was less than switchgrass and crabgrass, an advantage for these species if the standardized precipitation index drops below zero. Bermudagrass, switchgrass, sorghum-sudangrass, pearl millet, and indiangrass had comparable mWUE values under greenhouse-simulated drought. These results will aid in the development of forage species recommendations for mitigating drought and improving resiliency.

Effect of pH on xylitol production by Candida species from a prairie cordgrass hydrolysate.

Using hydrolysates of the North American prairie grass prairie cordgrass buffered at pH 4.5, 5.0, 5.5 or 6.0, xylitol production, xylitol yield, cell biomass production and productivity were investigated for three strains of yeast Candida. Of the three strains, the highest xylitol concentration of 20.19g xylitol (g xylose consumed)-1 and yield of 0.89g xylitol (g xylose consumed)-1 were produced by Candida mogi ATCC 18364 when grown for 120h at 30°C on the pH 5.5-buffered hydrolysate-containing medium. The highest biomass level being 7.7gcells (kg biomass)-1 was observed to be synthesized by Candida guilliermondii ATCC 201935 after 120h of growth at 30°C on a pH 5.5-buffered hydrolysate-containing medium. The highest xylitol specific productivity of 0.73g xylitol (g cellsh)-1 was determined for C.guilliermondii ATCC 20216 after 120h of growth at 30°C on a pH 5.0-buffered hydrolysate-containing medium. Xylitol production and yield by the three Candida strains was higher on prairie cordgrass than what was previously observed for the same strains after 120h at 30°C when another North American prairie grass big bluestem served as the plant biomass hydrolysate indicating that prairie cordgrass may be a superior plant biomass substrate.

Adaptive genetic potential and plasticity of trait variation in the foundation prairie grass Andropogon gerardii across the US Great Plains' climate gradient: Implications for climate change and restoration.

Plant response to climate depends on a species’ adaptive potential. To address this, we used reciprocal gardens to detect genetic and environmental plasticity effects on phenotypic variation and combined with genetic analyses. Four reciprocal garden sites were planted with three regional ecotypes of Andropogon gerardii, a dominant Great Plains prairie grass, using dry, mesic, and wet ecotypes originating from western KS to Illinois that span 500–1,200 mm rainfall/year. We aimed to answer: (a) What is the relative role of genetic constraints and phenotypic plasticity in controlling phenotypes? (b) When planted in the homesite, is there a trait syndrome for each ecotype? (c) How are genotypes and phenotypes structured by climate? and (d) What are implications of these results for response to climate change and use of ecotypes for restoration? Surprisingly, we did not detect consistent local adaptation. Rather, we detected co‐gradient variation primarily for most vegetative responses. All ecotypes were stunted in western KS. Eastward, the wet ecotype was increasingly robust relative to other ecotypes. In contrast, fitness showed evidence for local adaptation in wet and dry ecotypes with wet and mesic ecotypes producing little seed in western KS. Earlier flowering time in the dry ecotype suggests adaptation to end of season drought. Considering ecotype traits in homesite, the dry ecotype was characterized by reduced canopy area and diameter, short plants, and low vegetative biomass and putatively adapted to water limitation. The wet ecotype was robust, tall with high biomass, and wide leaves putatively adapted for the highly competitive, light‐limited Eastern Great Plains. Ecotype differentiation was supported by random forest classification and PCA. We detected genetic differentiation and outlier genes associated with primarily precipitation. We identified candidate gene GA1 for which allele frequency associated with plant height. Sourcing of climate adapted ecotypes should be considered for restoration.

Compaction of chopped material in a mini silo

The aim of the study was to explain the effect of pressure and compaction time, number of layers and compaction cycles of biomass from six energy plant species intended for silage on the density of mini silos as well as energy consumption and compaction indicators. A mathematical model was developed to predict the silage density against changed process factors. Chopped biomass was compacted in four layers using three cycles at 17–63 kPa pressure and 6–10 s per cycle. The greatest changes in compacted density were achieved in the first cycle of the first layer. At subsequent stages, the recompression curves were steeper, and more stable and higher densities were obtained. For giant knotweed the required silage dry matter density of 225 kg m−3 was achieved for plants at the physiological maturity stage, with a lower moisture content of 23.6%, than that obtained for plants harvested in June. The silage density was greater for deciduous plants (Virginia mallow and Jerusalem artichoke, but not giant knotweed) than that for grasses (miscanthus, Spartina pectinata, and big bluestem); this result was due to the lower moisture and to differences in the structure of the shoots. Silage density describes the model well in terms of pressure, number of layers, compaction time, particle size and dry matter.

Runoff water quantity and quality data from native tallgrass prairie and crop–livestock systems in Oklahoma between 1977 and 1999

Erosion and sedimentation pose serious threats to soil and water quality worldwide, including in the U.S. southern Great Plains. To better understand these processes in agricultural landscapes, eight 1.6-ha watersheds were established and instrumented in 1976 at the USDA-ARS Grazinglands Research Laboratory, ∼50 km west of Oklahoma City near El Reno, OK, to measure precipitation and surface runoff quantity and quality. Prior to construction, all watersheds were in native grass, primarily big bluestem (Andropogon gerardii Vitman.), little bluestem [Schizachyrium scoparium (Michx.) Nash], and Indiangrass [Sorghastrum nutans (L.) Nash]; afterwards, four of the eight watersheds were cropped initially into winter wheat (Triticum aestivum L.) (two conventionally tilled and two minimally or no-till). Although there have been many peer-reviewed papers from the Water Resources and Erosion (WRE) watersheds, none included all the datasets collected during the period 1977-1999. The objectives of this paper were (a) to present and discuss all archived historical data, including methods of collection and analysis, (b) to provide summary analyses of the variability in each dataset, and (c) to provide details about how to access these datasets. These datasets are valuable resources to improve modeling in relation to land use and management changes, climate variability, and other environmental factors and may be useful in developing strategies to mitigate environmental impacts of agricultural systems. They are available at https://doi.org/10.15482/USDA.ADC/1518421.

Effects of Nitrogen and Phosphorus Limitation on Lipid Accumulation by Chlorella kessleri str. UTEX 263 Grown in Darkness.

Growing algae in darkness for biodiesel production eliminates the challenges of evaporation and light penetration reported for open ponds and the costs and fouling that plague photobioreactors. The current study demonstrated that Chlorella kessleri str. UTEX 263 could grow heterotrophically in the dark on pure sugars or lignocellulosic hydrolysates of plant biomass. Hydrolysates of a prairie grass native to Kansas, Big bluestem (Andropogon gerardii), supported the growth of C. kessleri in the dark. Nitrogen limitation stimulated the accumulation of biodiesel lipids by 10-fold in heterotrophic cultures grown on pure sugars or Big bluestem hydrolysate. Limiting P in the growth medium also was shown to increase cellular lipid accumulation in C. kessleri. Iron limitation was not sufficient to increase cellular lipid content. Crude biomass extracts may have levels of N that can't be easily removed, which are high enough to relieve N limitations in growth media. This initial study suggests that P might be more easily removed from biomass extracts than N for increasing cellular lipid production by nutrient limitation and further that native prairie grasses are potentially suitable as sources of lignocellulosic sugars.

No Difference in Herbivory Preferences Among Ecotypes of Big Bluestem (Andropogon gerardii)

Big bluestem (Andropogon gerardii), a dominant prairie grass, exhibits a wide distribution with several genetically distinct ecotypes. Each ecotype adapts to abiotic and biotic factors within its environment. These adaptations may prove more or less desirable to herbivores in the area. For instance, plants adapted to areas with greater rainfall tend to grow larger than those adapted to drier conditions. Wetter conditions might result in greater herbivore pressure, but according to the Resource Availability Hypothesis, individual plants tend to invest little in herbivore defenses when resources are abundant. Consequently, we hypothesized A. gerardii ecotypes adapted to wetter conditions might be more susceptible to herbivory and that ecotypes adapted to drier conditions might have evolved greater herbivore defense mechanisms. We tested this with feeding preference trials involving grasshoppers and leaves from five ecotypes of A. gerardii that represented plants adapted to wet and dry conditions. Scans of leaves before and after herbivory trials indicated 43 to 78 percent of leaf area remained, with no difference among ecotypes regarding which were favored by herbivores. We also hypothesized that leaves with more tannins would be less preferable to herbivores. This was tested by measuring leaf tannin concentration from five ecotypes of A. gerardii from four common gardens across a precipitation gradient. Leaf tannin concentrations ranged from 0.8 to 2.4% of leaf dry mass and were different among both sites and ecotypes. Site differences caused the biggest difference in leaf tannins, indicating a strong environmental influence on leaf tannin concentration. There was no correlation between tannin concentration and herbivory preference among ecotypes, indicating other factors are related to herbivore defense in A. gerardii.

Alternative Hosts in the Families Poaceae and Cyperaceae for Xanthomonas vasicola pv. vasculorum, Causal Agent of Bacterial Leaf Streak of Corn.

The bacterial pathogen Xanthomonas vasicola pv. vasculorum was first reported in the United States causing bacterial leaf streak on Nebraska corn (Zea mays) in 2016. The bacterium is also known to cause disease in sugarcane, grain sorghum, broom bamboo, and various palm species. The objective of this study was to identify alternative hosts for X. vasicola pv. vasculorum among plants commonly found in corn growing areas of the United States. In repeated greenhouse experiments, 53 species of plants found in the United States that had not been tested previously for susceptibility to X. vasicola pv. vasculorum were inoculated with the pathogen and monitored for symptom development. Eleven species in the family Poaceae exhibited symptoms: oat (Avena sativa), rice (Oryza sativa), orchardgrass (Dactylis glomerata), indiangrass (Sorghastrum nutans), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), timothy (Phleum pratense), sand bluestem (Andropogon hallii), green foxtail (Setaria viridis), bristly foxtail (Setaria verticillata), and johnsongrass (Sorghum halepense). Yellow nutsedge (Cyperus esculentus) in the Cyperaceae also was a symptomatic host. In addition, endophytic colonization by X. vasicola pv. vasculorum was found in three asymptomatic alternative hosts: downy brome (Bromus tectorum), tall fescue (Festuca arundinacea), and western wheatgrass (Pascopyum smithii). Experiments were also conducted in the field to determine the potential for alternative hosts to become infected by natural inoculum. Symptoms developed only in big bluestem and bristly foxtail in field experiments. These results suggest that infection of alternative hosts by X. vasicola pv. vasculorum can occur, but infection rates might be limited by environmental conditions.

Influence of Species Composition and Management on Biomass Production in Missouri

Perennial biofuel crops help to reduce both dependence on fossil fuels and greenhouse gas emissions while utilizing nutrients more efficiently compared to annual crops. In addition, perennial crops grown for biofuels have the potential to produce high biomass yields, are capable of increased carbon sequestration, and are beneficial for reducing soil erosion. Various monocultures and mixtures of perennial grasses and forbs can be established to achieve these benefits. The objective of this study was to quantify the effects of feedstock mixture and cutting height on yields. The base feedstock treatments included a monoculture of switchgrass (SG) and a switchgrass:big bluestem 1:1 mixture (SGBBS). Other treatments included mixtures of the base feedstock with ratios of base to native forbs plus legumes of 100:0, 80:20, 60:40, and 20:80. The study was established in 2008. Biomass crops typically require 2 to 3 years to produce a uniform stand. Therefore, harvest data were collected from July 2010 to July 2013. Three harvest times were selected to represent (1) biomass for biofuel (March), (2) forage (July), and (3) forage and biomass (October). Annual mean yields varied between 4.97 Mg ha−1 in 2010 to 5.56 Mg ha−1 in 2011. However, the lowest yield of 2.82 Mg ha−1 in March and the highest yield of 7.18 Mg ha−1 in July were harvested in 2013. The mean yield was 5.21 Mg ha−1 during the 4 year study. The effect of species mixture was not significant on yield. The cutting height was significant (p < 0.001), with greater yield for the 15 cm compared to the 30 cm cutting height. Yield differences were larger between harvest times during the early phase of the study. Yield difference within a harvest time was not significant for 3 of the 10 harvests. Future studies should examine changes in biomass production for mixture composition with time for selection of optimal regional specific species mixtures.

Tree species effects on understory forage productivity and microclimate in a silvopasture of the Southeastern USA

Ecosystem services provided by silvopastoral systems are mediated by specific management practices, environmental conditions, and overall design of the system. We hypothesized that selection of tree species affects understory forage nutritive value and productivity, light/shade environment, and microclimate. The silvopastoral system was located at the Center for Environmental Farming Systems in Goldsboro, North Carolina, USA. Three overstory tree-species were Pinus palustris (PP; longleaf pine), Pinus taeda (PT; lobloblly pine), and Quercus pagoda (QP; cherrybark oak). The understory forage component consisted of a four-way mixture of native warm-season grasses [big bluestem (Andropogon gerardii, ‘Eastern’, KY origin), eastern gamagrass (Tripsacum dactyloides, MO origin), indiangrass (Sorghastrum nutans, ‘NC ecotype’), and switchgrass (Panicum virgatum, ‘Alamo’)]. The experimental design was an RCBD with 3 replicates. There was no effect of seedbed preparation (till versus no-till) on forage establishment. Understory dry matter yield, crude protein and total digestible nutrient concentrations of the harvested forage were not affected by tree species, with the exception at the 3.5 south sampling point. Overstory effects on microclimate variables were not different among tree-species, but were more noticeable during the daytime of the summer months, and were at the most 1-degree point for temperature and temperature-humidity index and 3 points for relative humidity. The silvopasture design in our study provided year-round shade by the tree-component, with varying levels of shade (ranging from 90 to 6% of incident photosynthetic active radiation) due to geographic location, tree species, and season. Our results describe and highlight the potential of trees in a silvopasture design in the southeastern USA to mitigate changes in temperature, humidity, the temperature-humidity index, and forage productivity and as a function of tree species and at different distance from the trees.

Soil carbon increased by twice the amount of biochar carbon applied after 6 years: Field evidence of negative priming

AbstractApplying biochar to agricultural soils has been proposed as a means of sequestering carbon (C) while simultaneously enhancing soil health and agricultural sustainability. However, our understanding of the long‐term effects of biochar and annual versus perennial cropping systems and their interactions on soil properties under field conditions is limited. We quantified changes in soil C concentration and stocks, and other soil properties 6 years after biochar applications to corn (Zea mays L.) and dedicated bioenergy crops on a Midwestern US soil. Treatments were as follows: no‐till continuous corn, Liberty switchgrass (Panicum virgatum L.), and low‐diversity prairie grasses, 45% big bluestem (Andropogon gerardii), 45% Indiangrass (Sorghastrum nutans), and 10% sideoats grama (Bouteloua curtipendula), as main plots, and wood biochar (9.3 Mg/ha with 63% total C) and no biochar applications as subplots. Biochar‐amended plots accumulated more C (14.07 Mg soil C/ha vs. 2.25 Mg soil C/ha) than non‐biochar‐amended plots in the 0–30 cm soil depth but other soil properties were not significantly affected by the biochar amendments. The total increase in C stocks in the biochar‐amended plots was nearly twice (14.07 Mg soil C/ha) the amount of C added with biochar 6 years earlier (7.25 Mg biochar C/ha), suggesting a negative priming effect of biochar on formation and/or mineralization of native soil organic C. Dedicated bioenergy crops increased soil C concentration by 79% and improved both aggregation and plant available water in the 0–5 cm soil depth. Biochar did not interact with the cropping systems. Overall, biochar has the potential to increase soil C stocks both directly and through negative priming, but, in this study, it had limited effects on other soil properties after 6 years.

Early‐season grazing of native grasses offers potential profitable benefit

AbstractA grazing trial was conducted in Mississippi during 2016 and 2017 to compare pasture, animal, and economic performance of three perennial, warm‐season grass systems. Grass treatments included: (i) Argentine bahiagrass (Paspalum notatum Fluegge; BAH); (ii) KY Ecotype big bluestem (Andropogon gerardii Vitman; BBS); and (iii), KY Ecotype indiangrass [Sorghastrum nutans (L.) Nash], big bluestem and little bluestem [Schizachyrium scoparium (Michx.) Nash; MIX]. Paddocks were continuously stocked using weaned beef (Bos taurus) steers across three grazing intervals (I, II, and III) during late spring and summer. Pasture measurements included forage mass (FM) and nutritive value. Greatest FM was observed during grazing interval II in 2016 (931.70 kg ha–1). Nutritive values declined as the season progressed. The BAH had greater CP and TDN, and lower ADF and NDF concentrations than BBS and MIX in 2016. Differences were not as discernable in 2017. Greatest ADG were observed for BBS interval I in 2017 (1.34 kg d–1), MIX interval I 2017 (1.21 kg d–1), and BBS interval I 2016 (1.19 kg d–1). Beef yield per hectare (GAIN) was greatest for interval I across both years (464.78 kg ha–1). By species, GAIN was greatest for BBS in interval I (451.32 kg ha–1). For economic analysis, BBS had the lowest total annual pasture cost (US$142.65 ha–1), and had the greatest NET returns for 2016 ($268.96 ha–1) and 2017 ($249.98 ha–1). Implementing native warm‐season grasses (NWSG) in stocker cattle systems for early‐season grazing can be productive in Mississippi.

Performance evaluation of three different grasses for use as willows in greywater treatment in semi-arid Ghana

The focus of this experimental study was to identify appropriate grass for use as willows for greywater treatment in constructed wetlands. Cymbopogon flexuosus (lemon grass), Pennisetum purpureum (elephant grass) and Andropogon gerardi (giant bluestem) were planted separately and watered with greywater for a period of fifteen weeks. Growth measurements were recorded weekly and the quality of the effluents from each of these grasses assessed using standard methods to determine their treatment efficiency. Elephant grass recorded the highest plant height of 88.9mm and the highest number of new leaves of 49, while lemon grass recorded the largest surface area of 5502mm2. With regards to treatment performance, lemon grass recorded the highest efficiency with reductions of 80% in TDS, 81% in NO3-N, 30% in PO4-P and 82% in BOD. Except for BOD that was missed by elephant grass and giant bluestem, all the other effluent parameters met the WHO guidelines. A scaling up of the experiment for continuous greywater feed and over a longer period is recommended in order to ascertain the performance over time.Keywords: Greywater treatment, willows efficiency, growth measurements

Do Nymphs of the Treehopper Stictolobus minutus (Funkhouser) (Hemiptera: Membracidae) Specialize on Grasses?

The ceresine treehopper Stictolobus minutus (Funkhouser), described by Thomas Say in 1830 as Membracis subulata (a junior primary homonym), is seldom collected; museum specimens typically are represented by singletons. In July 2016, nymphs of S. minutus were discovered on big bluestem (Andropogon gerardii Vitman; Poaceae) in the Buck Creek Serpentine Barrens of western North Carolina. This bunchgrass was sampled periodically in 2016, 2017, and 2019, and weekly in 2018, by using an ax handle to strike basal stems and crowns, and collecting dislodged nymphs and adults from an enamel pan or net bag placed at the base of plants. First instars appeared as early as 1 June, with the first adult, a male, found on 8 July. A fifth instar was taken as late as 12 August. Adults of this univoltine species typically were not observed on big bluestem after early August, perhaps having dispersed to woody plants for oviposition. Late instars also were collected from little bluestem (Schizachyrium scoparium [Michx.] Nash) in 2018 and 2019. The presence of all five instars in crowns of big bluestem devoid of small forbs, coupled with a review of treehopper-grass associations, suggests that S. minutus might be the first North American membracid known to specialize on Poaceae. The adult is diagnosed and described; color images of the adult male, female, male genitalia, and all nymphal instars are provided.

Competition Indices Identify Forb Species That Promote Overyielding of a Dominant Grass in Grassland Restoration

Overyielding is a common phenomenon. Overyielding of dominant grasses when in competition with common forbs during grassland restoration could lead to lower plant diversity. My objective was to characterize overyielding of Andropogon gerardii in competition with fcommon forbs. I collected soils representing different stages of restoration (0, 4, and 16 years restored) and conducted a pairwise competition experiment with a dominant grass, Andropogon gerardii, in competition with four subordinate forbs (Oligoneuron rigidum L., Liatris punctata Hook, Lespedeza capitata Michx., or Desmanthus illinoensis Michx.). Relative yield indices (RY) were calculated by comparison with a two-individual monoculture of A. gerardii with both per grass biomass and per grass net absolute tiller appearance rate (TAR). Overyielding of A. gerardii was in competition with Oligoneuron rigidum was indicated by RY values (greater than1) using both biomass and TAR measurements. These findings suggest that O. rigidum should be given low priority for inclusion in tallgrass prairie restoration seed mixes.

Dead Rhizophagus irregularis biomass mysteriously stimulates plant growth.

Arbuscular mycorrhizal (AM) fungi establish symbiotic associations with many plant species, transferring significant amounts of soil nutrients such as phosphorus to plants and receiving photosynthetically fixed carbon in return. Functioning of AM symbiosis is thus based on interaction between two living partners. The importance of dead AM fungal biomass (necromass) in ecosystem processes remains unclear. Here, we applied either living biomass or necromass (0.0004 potting substrate weight percent) of monoxenically produced AM fungus (Rhizophagus irregularis) into previously sterilized potting substrate planted with Andropogon gerardii. Plant biomass production significantly improved in both treatments as compared to non-amended controls. Living AM fungus, in contrast to the necromass, specifically improved plant acquisition of nutrients normally supplied to the plants by AM fungal networks, such as phosphorus and zinc. There was, however, no difference between the two amendment treatments with respect to plant uptake of other nutrients such as nitrogen and/or magnesium, indicating that the effect on plants of the AM fungal necromass was not primarily nutritional. Plant growth stimulation by the necromass could thus be either due to AM fungal metabolites directly affecting the plants, indirectly due to changes in soil/root microbiomes or due to physicochemical modifications of the potting substrate. In the necromass, we identified several potentially bioactive molecules. We also provide experimental evidence for significant differences in underground microbiomes depending on the amendment with living or dead AM fungal biomass. This research thus provides the first glimpse into possible mechanisms responsible for observed plant growth stimulation by the AM fungal necromass.