Agropyron Desertorum Research Articles

Competition, light quality and seedling growth of Russian wildrye grass (Psathyrostachys juncea)

The low seedling vigour of Russian wildrye grass ( Psathyrostachys juncea ) (RWR) limits its use. Shading from durum wheat ( Triticum turgidum ) reduced RWR leaf number, tiller number, leaf area and seedling dry weight in a growth room experiment. Treatments with similar shading differed in tiller number and dry weight, which suggested that light quality may have also contributed to these responses. In a second growth room experiment, light intensity (PAR) and red:far-red light ratio (670:730 nm) were altered by coloured plastic filters suspended above seedlings of Russian wildrye, crested wheatgrass ( Agropyron desertorum ) (CWG) and Dahurian wildrye grass ( Elymus dahuricus ) (DWR). Leaf area, tiller number and dry weight of RWR seedlings were reduced by declining red:far-red light ratio while light intensity differences at similar red:far-red ratio did not affect these variables. CWG exhibited similar responses to declining red:far-red light ratio as RWR, except that it exhibited a seedling weight response to light intensity. DWR tiller number was not responsive to low red:far-red light ratio but rather to low light intensity. However, DWR seedling weight, tiller weight and leaf area were responsive to declining red:far-red light ratio. These results indicate that RWR seedlings are sensitive to light quality changes caused by neighbouring plants.

Livestock Forage Conditioning Among Six Northern Great Basin Grasses

Studies of Anderson and Scherzinger's forage conditioning hypothesis have generated varied results. Our objectives were: 1) to evaluate late summer/early fall forage quality of crested wheatgrass (Agropyron desertorum [Fisch. ex Link] J. A. Schultes), bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love), Idaho fescue (Festuca idahoensis Elmer), bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), Thurber's needlegrass (Achnatherum thurberianum [Piper] Barkworth), and basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Love) from ungrazed paddocks and paddocks grazed at vegetative, boot, and anthesis; and 2) test hypotheses that postgrazing regrowth yields were correlated with soil moisture content when grazing occurred. Crop–year precipitation for 1997 and 1998 was 134% and 205% of average. Crude protein (CP) and in vitro dry matter digestibility (IVDMD) of ungrazed grasses displayed expected declines in quality. Among ungrazed grasses, late summer/early fall CP was 5.7% in 1997 and 3.6% in 1998; IVDMD was 47% and 41%, respectively. Late summer/early fall forage quality was elevated by vegetative, boot stage, or anthesis grazing. The phenologically youngest regrowth always ranked highest in CP and IVDMD. Among grasses, respective 1997 CP and IVDMD means were 9.0% and 55% for regrowth following anthesis grazing. No regrowth followed anthesis grazing in 1998, but CP and IVDMD means from boot stage treatments were 5.5% and 47%, respectively. With CP measures, a species by treatment interaction occurred in 1997, but species reacted similarly in 1998. Vegetative, boot stage, and anthesis grazing in 1997 caused respective late summer/early fall standing crop reductions of 34%, 42%, and 58%; and 34%, 54%, and 100% reductions in 1998. Forage conditioning responses were lower for bluebunch wheatgrass and crested wheatgrass than other grasses. Soil moisture content was a poor predictor of regrowth yields. Managed cattle grazing can successfully enhance late season forage quality.

Nutritive Quality of Four Perennial Grasses as Affected by Species, Cultivar, Maturity, and Plant Tissue

Improved perennial grasses provide ranchers with high‐quality forage for grazing and hay. However, in the Northern Great Plains of the USA, nutritive quality information is limited on both established and new cultivars. This study compares the nutritive quality of established and more recently released cultivars of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes] (CWG), intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth and Dewey] (IWG), western wheatgrass [Pascopyrum smithii (Rydb.) Love] (WWG), and smooth bromegrass (Bromus inermis Leyss.) (SBG); evaluates the effect of plant maturity on tissue quality; compares nutritive quality differences among species; and evaluates nutritive quality relationships. Smooth bromegrass leaf tissue had the highest (P < 0.05) in vitro dry matter digestibility (IVDMD) and lowest neutral detergent fiber (NDF), but IWG and WWG had higher stem IVDMD. Few quality differences were detected between cultivars within a species, but ‘Rosana’ WWG had higher (P < 0.10) stem and whole plant IVDMD than the more recently released ‘Rodan’. Leaf percentage differed significantly (P < 0.05) among species, with WWG (49.8%) having the highest, and CWG (21.2%) the lowest. Correlation coefficients between quality measurements suggest that if grass leaf tissue were selected for higher IVDMD, leaves should also have higher crude protein (CP) and lower NDF. This relationship was best illustrated with WWG for all three tissue types. The apparent lower quality of Rodan WWG compared with the older cultivar, Rosana, should caution plant breeders to monitor forage quality to ensure that selection for improved agronomic traits does not compromise nutritive quality.

Response of Water Vapor and CO2 Fluxes in Semiarid Lands to Seasonal and Intermittent Precipitation Pulses

Abstract Precipitation pulses are important in controlling ecological processes in semiarid ecosystems. The effects of seasonal and intermittent precipitation events on net water vapor and CO2 fluxes were determined for crested wheatgrass (Agropyron desertorum), juniper (Juniperus osteosperma), and sagebrush (Artemisia tridentata) ecosystems using eddy covariance measurements. The measurements were made at Rush Valley, Utah, in the northern Great Basin of the United States. Data were evaluated during the growing seasons of 2002 and 2003. Each of these communities responds to precipitation pulses in all seasons, but these responses vary among season and ecosystem, and differ for water vapor and CO2. The degree and direction of response (i.e., net uptake or efflux) depended upon the timing and amount of precipitation. In early spring, both evapotranspiration (ET) and CO2 fluxes responded only slightly to precipitation pulses because soils were already moist from snowmelt and spring rains. As soils dried later in the spring, ET response to rainfall increased. The summer season was very warm and dry in both years, and both water and CO2 fluxes were generally reduced as compared to fluxes in the spring. Water vapor fluxes increased during and immediately after periodic summer rain events at all sites, especially at juniper, followed by the sagebrush and crested wheatgrass sites. Net CO2 exchange changed significantly at the juniper and sagebrush sites but changed very little at the crested wheatgrass site due to senescence of this grass. However, in the wetter summer of 2003, the grass species maintained physiological activity and responded to rain events. In the fall of both years, responses of ET and CO2 fluxes to precipitation were very similar for all three communities, with only small changes, presumably due to significantly lower temperatures in the fall. This research documents the importance of the temporal distribution of rainfall on patterns of ET and CO2 fluxes and suggests that soil moisture and stand-level leaf area index (LAI) are critical factors governing ET and CO2 responses to precipitation in these communities.

Meiotic behaviour in natural diploid, tetraploid, and commercial diploid crested wheatgrass

Chiasma frequencies and chromosome associations at diakinesis and first metaphase (MI) were studied in natural and commercial diploid Ag‐ropyron cristatum and natural tetraploid Agropyron desertorum crested wheatgrass plants. The frequencies of bivalents were 6.988 and 6.980 at diakinesis and 6.980 and 6.976 at MI in the natural and commercial diploids, respectively. The frequencies of bivalents and quadrivalents in the natural tetraploid were 7.728 and 3.072 at diakinesis, and their frequencies at MI were 7.880 and 2.984, respectively. A few univalents were formed at diakinesis and MI in the three crested wheatgrasses, and these were generally associated with trivalents at the two stages in the tetraploid. There were positive and significant correlations between the frequencies of chiasmata at diakinesis and those of chiasmata at MI in the three crested wheatgrasses. Tetraploid A. desertorum, in particular, is thought to be an important breeding material for future studies when growth performance and meiotic regularity are taken into consideration.

Stockpiled Forage Kochia to Maintain Beef Cows During Winter

Extending grazing into the winter, as opposed to feeding of harvested forages, can increase the sustainability of ranching in the western US. This study was conducted to determine the economic value of grazing stockpiled forage kochia ( Kochia prostrata [L.] Scrad.) and crested wheatgrass ( Agropyron desertorum [Fisch. Ex Link] Schultes) during the fall and winter. Changes in cow body weight, body condition score, and ultrasound backfat were compared for late-gestation cows grazing forage kochia–crested wheatgrass pastures vs. those fed alfalfa ( Medicago sativa L.) hay in drylot. The study was conducted from early November to late January for 2 consecutive years near Promontory, Utah. Forage availability and nutritional quality were monitored throughout the experiment. Cows grazing stockpiled forages did not receive any protein or energy supplements. Forage kochia comprised approximately 70% of available forage, with November crude protein content of 116 and 76 g·kg −1 in years 1 and 2, respectively. Nutritional quality declined throughout the season, presumably mostly because of removal of higher-quality forage by preferential grazing as opposed to weathering. Averaged over years, cows grazing forage kochia–grass gained body weight (19 kg), increased in body condition (0.3 points), and maintained backfat thickness, finishing well within the range considered optimum for onset of calving and return to estrus . Pasture- vs. drylot-fed cows did not differ with regard to changes in body weight or body condition score. Both treatments increased backfat in year 1, when initial backfat was less than 0.5 cm, but both treatments resulted in loss of backfat in year 2, when initial backfat was greater than 1.0 cm. Grazing was more economical, costing $0.24·cow −1 ·d −1 less than feeding alfalfa hay in drylot. Forage kochia can be used on western rangelands to extend grazing into the fall and winter, thereby improving the profitability of beef production. Extender el apacentamiento hasta el invierno, como estrategia opuesta a la alimentación con forrajes cultivados, puede incrementar la sostenibilidad de las operaciones ganaderas del oeste de Estados Unidos. Este estudio se condujo para determinar el valor económico de apacentar forraje acumulado en pie de “Kochia” ( Kochia prostrata [L.] Scrad.) y “crested wheatgrass” ( Agropyron desertorum [Fisch. Ex Link] Schultes) durante el otoño e invierno. Cambios en el peso corporal, la condición corporal y grasa del lomo medida con ultrasonido fueron comparados entre vacas en estado final de gestación apacentando praderas de “Kochia”–“Crested wheatgrass” versus vacas alimentadas en corral con heno de “Alfalfa” ( Medicago sativa L.). El estudio se llevo a cabo cerca de Promontory, Utah de inicios de Noviembre a fines de Enero durante dos años consecutivos. La disponibilidad de forraje y la calidad nutricional fueron monitoreadas a lo largo del experimento. Las vacas apacentando los forrajes acumulados en pie no recibieron ningún suplemento ni proteico ni energético. El forraje de “Kochia” aportó aproximadamente el 70% del forraje disponible, con un contenido de proteína cruda en Noviembre de 116 y 76 g·kg −1 en el año 1 y 2, respectivamente. La calidad nutricional disminuyó a través de la estación de apacentamiento, presumiblemente debido en gran parte a la remoción de forraje de alta calidad por el apacentamiento preferencial como opuesto al intemperismo. Promediado a través de los años, las vacas apacentando “Kochia-zacate” ganaron peso corporal (19 kg), incrementaron su condición corporal (0.3 puntos) y mantuvieron el espesor de la grasa del lomo, terminando bien dentro del rango considerado como optimo para el inicio de la época de pariciones y regresar al estro. Las vacas apacentando las praderas versus las alimentadas en estabulación no difirieron en los cambios de peso o condición corporal. Ambos tratamientos incrementaron la grasa del lomo en el primer año, cuando la grasa inicial fue menos de 0.5 cm, pero en el segundo año, ambos tratamientos resultaron en perdida de grasa del lomo cuando la grasa inicial del lomo fue mayor a 1 cm. El apacentamiento fue más económico, costando $0.24·vaca −1 ·día −1 menos que la alimentación con alfalfa en corral. El forraje de “Kochia” puede ser utilizado en los pastizales del oeste para extender el apacentamiento hasta otoño e invierno, por lo tanto mejorando la rentabilidad de la producción de carne.

Do Pasture-Scale Nutritional Patterns Affect Cattle Distribution on Rangelands?

Heterogeneous distribution of ungulates about the landscape can be a particularly vexing problem for resource managers. Although livestock preferences for leaves over stems among plants and patches of herbage are well documented, effects of senescent forage (herbage supporting both green and cured materials) on cattle distribution and nutrition at pasture scales have not been investigated. Our primary objective was to determine the proportions of time cattle spent foraging within senescent and conditioned sectors (areas supporting only current season’s herbage) of pastures. Other endeavors included the following: comparing velocities of foraging cattle in conditioned and senescent sectors, determining diet quality of cattle confined to conditioned and senescent treatments, and quantifying levels of forage utilization by cattle in conditioned and senescent treatments. Global positioning system collars were used to track cattle movement and activity in treated crested wheatgrass (Agropyron desertorum [Fisher ex Link] Schultes) pastures. Over a 7-day trial, cattle were found in senescent and conditioned areas 41% and 59% of the time, respectively. When cattle were grazing, 32% of observations were in senescent sectors and 68% were in conditioned areas. With a decline in standing crop in the conditioned treatment, cattle switched to senescent herbage (73% of observations) on day 7. Standing crop was reduced by 13% to 40% in conditioned sectors and increased by 10% in senescent areas. Despite disparities in the crude protein of standing crops in senescent ( x ¼ 6.5%) and conditioned ( x ¼ 11.3%) treatments, cattle confined to treatment harvested diets of similar quality ( x ¼ 13.6% CP) at turn-out. Cattle walked farther when making transitions between treatments, and walked farther each day as the trial progressed. A preference of foraging cattle for portions of pastures grazed (conditioned areas) during the previous growing season suggests that utilization patterns established by livestock are self-sustaining.

Regionalisation of suitable herbages for grassland reconstruction in agro‐pastoral transition zone of northern China

To provide a sound basis for selecting suitable herbages for grassland reconstruction in the farming‐pastoral zone of northern China, the zone was divided into regions using the lowest annual temperature, water regimes represented by a moisture index (the ratio between annual rainfall and accumulated temperature >0°C), soil types, and terrain. Suitable herbages of Gramineae (G), Legu‐minosae (L) and other families (O), representing native species (NS) and non‐native cultivars (CR) were recommended for the zone based on the following four principles: a) matching species with the site; b) giving precedence to ecological conservation; c) providing economic benefit to production; and d) taking into account the integrity of local administrative division. The main findings from this study were as follows. The farming‐pastoral zone was divided into seven regions: I. Western Songliao Plain and Daxinganling Mountain Region; II. Upper Liaohe River Sandy Region; III. Mid‐Eastern Mongolia Plateau and Northwestern Heibei Mountain Region; IV. Luliang, Taihang and Yanshan Mountains Region; V. Ordos Plateau Sandy Region; VI. Northern Shaanxi to Eastern Ganxu Loess Plateau Region; and VII. Mid Gansu to Eastern Qinghai Plateau Loess Region. Among the herbages recommended for selection, Stipa grandis and Leymus chinensis were particularly suggested for controlling wind erosion in Region I; Leymus chinensis and Elymus dahuricus for lessening soil alkalisation in Region II; Stipa glareos, Elymus dahuricus and Agropyron deserto‐rum for retarding land desertification in Region III; Elymus nutans and Bromus inermis for preventing water erosion in Region IV; Agropyron desertorum and Elymus dahuricus for reducing wind erosion and land desertification for Region V; Medicago sativa and Onobrychis viciaefolia for improving soil fertility in Region VI; Medicago varia and Melilotoides rethenica for controlling erosion and improving soil fertility in Region VII.

Soil response to long-term grazing in the northern Great Plains of North America

Grazing management affects ecosystem function through impacts on soil condition. We investigated the effects of long-term (over 70 years) grazing on soil properties and nitrous oxide (N2O) emission within a moderately grazed native vegetation pasture (MGP), heavily grazed native vegetation pasture (HGP), and a fertilized crested wheatgrass (Agropyron desertorum (Fisch. ex. Link) Schult.) pasture (FCWP) near Mandan, ND, USA. Grazing-induced changes in species composition and N fertilizer application contributed to differences in soil properties and N2O emission between pastures. Soil organic C (SOC) was 5.7 Mg ha−1 greater in FCWP and HGP than MGP at 0–5 cm, whereas HGP had 2.4 Mg ha−1 more SOC than FCWP and MGP at 5–10 cm. At 30–60 cm, SOC in FCWP was 4.0 and 7.5 Mg ha−1 greater than in HGP and MGP, respectively. Particulate organic matter (POM) C and N in the surface 5 cm of FCWP were three- and five-fold greater, respectively, than in HGP and MGP. Acidification from N fertilization in FCWP decreased soil pH and cation exchange capacity compared to HGP and MGP in the surface 5 cm. Annual N2O emission was over three-fold greater in FCWP compared to HGP and MGP, and was positively associated with POM-C across all pastures (P ≤ 0.0001; r2 = 0.85). Results from this study suggest fertilized crested wheatgrass enhances deep storage of SOC, but contributes to surface acidification and greater N2O emission relative to native non-fertilized pastures in the northern Great Plains.

Do Pasture-Scale Nutritional Patterns Affect Cattle Distribution on Rangelands?

Heterogeneous distribution of ungulates about the landscape can be a particularly vexing problem for resource managers. Although livestock preferences for leaves over stems among plants and patches of herbage are well documented, effects of senescent for- age (herbage supporting both green and cured materials) on cattle distribution and nutrition at pasture scales have not been investigated. Our primary objective was to determine the proportions of time cattle spent foraging within senescent and con- ditioned sectors (areas supporting only current season’s herbage) of pastures. Other endeavors included the following: comparing velocities of foraging cattle in conditioned and senescent sectors, determining diet quality of cattle confined to conditioned and senescent treatments, and quantifying levels of forage utilization by cattle in conditioned and senescent treatments. Global positioning system collars were used to track cattle movement and activity in treated crested wheatgrass (Agropyron desertorum [Fisher ex Link] Schultes) pastures. Over a 7-day trial, cattle were found in senescent and conditioned areas 41% and 59% of the time, respectively. When cattle were grazing, 32% of observations were in senescent sectors and 68% were in conditioned areas. With a decline in standing crop in the conditioned treatment, cattle switched to senescent herbage (73% of observations) on day 7. Standing crop was reduced by 13% to 40% in conditioned sectors and increased by 10% in senescent areas. Despite dispa- rities in the crude protein of standing crops in senescent (x= 6.5%) and conditioned (x= 11.3%) treatments, cattle confined to treatment harvested diets of similar quality (x= 13.6% CP) at turn-out. Cattle walked farther when making transitions between treatments, and walked farther each day as the trial progressed. A preference of foraging cattle for portions of pastures grazed (con- ditioned areas) during the previous growing season suggests that utilization patterns established by livestock are self-sustaining.

Stockpiled Forage Kochia to Maintain Beef Cows During Winter

Extending grazing into the winter, as opposed to feeding of harvested forages, can increase the sustainability of ranching in the western US. This study was conducted to determine the economic value of grazing stockpiled forage kochia (Kochia prostrata [L.] Scrad.) and crested wheatgrass (Agropyron desertorum [Fisch. Ex Link] Schultes) during the fall and winter. Changes in cow body weight, body condition score, and ultrasound backfat were compared for late-gestation cows grazing forage kochia- crested wheatgrass pastures vs. those fed alfalfa (Medicago sativa L.) hay in drylot. The study was conducted from early November to late January for 2 consecutive years near Promontory, Utah. Forage availability and nutritional quality were monitored throughout the experiment. Cows grazing stockpiled forages did not receive any protein or energy supplements. Forage kochia comprised approximately 70% of available forage, with November crude protein content of 116 and 76 g kg-1 in years 1 and 2, respectively. Nutritional quality declined throughout the season, presumably mostly because of removal of higher-quality forage by preferential grazing as opposed to weathering. Averaged over years, cows grazing forage kochia-grass gained body weight (19 kg), increased in body condition (0.3 points), and maintained backfat thickness, finishing well within the range considered optimum for onset of calving and return to estrus. Pasture- vs. drylot-fed cows did not differ with regard to changes in body weight or body condition score. Both treatments increased backfat in year 1, when initial backfat was less than 0.5 cm, but both treatments resulted in loss of backfat in year 2, when initial backfat was greater than 1.0 cm. Grazing was more economical, costing 0.24 cow-1 d-1 less than feeding alfalfa hay in drylot. Forage kochia can be used on western rangelands to extend grazing into the fall and winter, thereby improving the profitability of beef production.

Establishing Native Grasses in a Big Sagebrush–Dominated Site: An Intermediate Restoration Step

AbstractMany semiarid rangelands in the Great Basin, U.S.A., are shifting dominance to woody species as a consequence of land degradation including intense livestock grazing and fire suppression. Whereas past rehabilitation efforts in Big sagebrush (Artemisia tridentata) steppes removed the shrub and added introduced forage grasses to successfully shift communities from shrublands to grasslands, current consensus is that native species should be included in restoration projects and that retention of some woody plants is desirable. We examined the potential for interseeding grasses into dense shrub communities as a precursor to thinning shrubs and releasing grasses from shrub interference. We compared seedling establishment of the native grass, Bluebunch wheatgrass (Pseudoroegneria spicata), with that of the Eurasia grass, Crested wheatgrass (Agropyron desertorum), in denseAr. tridentatastands. Shrubs may play an important role as nurse plants for seedling establishment (reduced solar radiation, “island of fertility” effect) but result in highly contrasting light environments and root interference for seedlings. In experimental plots, we examined effects ofAr. tridentatashade levels (0, 40, 70, and 90% reduction of solar radiation) and initial root exclusion (present/absent) on the establishment and growth ofP. spicataandAg. desertorumseedlings. With this design we evaluated the interference effects ofAr. tridentataon the two grasses and identified the most beneficial microsites for grass restoration inAr. tridentata–dominated communities. We predicted seedling survival and growth to be greater under moderate shade (40% reduction) and limited root competition than under no or strong shade conditions (0 and 90%) and unrestricted root interactions. Fifty to 85% of theP. spicataandAg. desertorumseedlings survived the dry summer months of 1995 and 1996 and the intervening winter. Neither shading nor root exclusion fromAr. tridentataaffected final seedling survival of either species. Seedling biomass of both grass species was negatively affected by initial root interactions withAr. tridentata.However, the analysis of seedling biomass variability (coefficient of variation) indicated that in all shade and root‐exclusion treatments, some seedlings of both species developed to large individuals to survive inAr. tridentata–dominated rangelands. Thus, the use of interseeding techniques shows promise for restoring herbaceous species in denseAr. tridentatastands and should be given further consideration when shrub retention is an important consideration.

Cesium Desorption from Illite as Affected by Exudates from Rhizosphere Bacteria

Biogeochemical processes in the rhizosphere can significantly alter interactions between contaminants and soil minerals. In this study, several strains of bacteria that exude aluminum (Al)-chelating compounds were isolated from the rhizosphere of crested wheatgrass (Agropyron desertorum) collected from the Idaho National Laboratory (INL). We examined the effects of exudates from bacteria in the genera Bacillus, Ralstonia, and Enterobacter on cesium (Cs) desorption from illite. Exudates from these strains of bacteria significantly enhanced Cs desorption from illite. In addition, Cs desorption increased with increasing Bacillus exudate concentrations. Cesium desorption from illite as a function of both exudate type and concentration was positively correlated with Al dissolution, suggesting that the Al-complexing ability of the exudates played an important role in enhancing Cs desorption. The density of frayed edge sites (FES) on illite increased as a result of treatment with bacterial exudates, while the Cs/K selectivity of FES decreased. These results suggestthat exudates from bacteria isolated from the rhizosphere can enhance Cs desorption from frayed edges of illite and, therefore, can alter Cs availability in micaceous soils.

Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium chinese―Stipa grandis grassland of C 4 grasses. After 5000 a BP, C 4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Agropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 10000 and 8720 a BP, the Aneurolepidium chinese―Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 8720 to 7000 a BP, C 4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C 4 grasses and the presence of some trees (such as Pinus and Betula , and so on) in or near the study site. From 4200―3000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3000 and 2170 a BP, with a rapid development of Echinops type plants and a small expansion of C 4 grasses. From 2170 a BP to present, human activities accelerated the process of grassland degeneration.

Agronomic characteristics and nutritive value of 11 grasses grown with irrigation on a saline soil in southwestern Saskatchewan

Agronomic and nutritive characteristics of 11 grasses were studied at Swift Current, Saskatchewan on a moderately saline irrigated soil: [smooth bromegrass (Bromus inermis Leyss.), meadow bromegrass (Bromus riparius Rehmann), tall wheatgrass (Elytrigia elongata (Host) Nevski), crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.), intermediate wheatgrass (Elytrigia intermedia (Host) Nevski), slender wheatgrass (Elymus trachycaulus (Linke) Gould ex Shinners), Altai wild ryegrass (Leymus angustus (Trin. Pilger), Russian wild ryegrass (Psathyrostachys junceus (Fisch.) Nevski), Dahurian wild ryegrass (Elymus dahuricus Turcz ex Grieseb), reed canarygrass (Phalaris arudinaceae L.) and creeping foxtail (Alopecurus arundinaceus Poir.)]. Grasses were clipped at threeleaf, heading and seed set. Yield, leaf-to-stem ratio (LSR), botanical composition (BC), crude protein (CP), phosphorus, fibre and in vitro dry matter digestibility (IVDMD) were determined. There were differences (P < 0.05) between the grasses in yield at each growth stage with smooth bromegrass and creeping foxtail having high yields and meadow bromegrass low yields at all growth stages. The BC of most target grasses was greater than 60%. Exceptions were Dahurian wild ryegrass, crested wheatgrass, tall wheatgrass and meadow bromegrass. There were few significant differences between the grasses for LSR, except that Russian and Altai wild ryegrasses and meadow bromegrass had higher LSR (P < 0.05) than the other grasses. Differences in CP, P, neutral (NDF) and acid (ADF) detergent fibres were inconsistent and small at each growth stage but CP and P declined (P < 0.05) while NDF and ADF increased (P < 0.05) with plant maturation. There were differences (P < 0.05) between years and cuts for all traits except between years for yield, BC and LSR at seed set (P > 0.05). Dry matter intake (DMI) NDF and in vivo dry matter digestibility (DMD) were determined for hay cut from each plot using sheep. The relationship between forage NDF and DMI: DMI g kg BW-1 d-1 = 86.5 – 0.09 NDF (r2 = 0.87; RSD = 1.16; P < 0.001)]

Ploidy, water, and nitrogen effects on Russian wildrye chemical composition

Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], a cool-season introduced bunchgrass, offers producers an alternative to crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes] for spring and fall grazing in the Northern Great Plains. Tetraploid Russian wildrye with improved seedling establishment may offer even greater potential for seasonal grazing. This study investigates how the concentrations of some nutritive quality components in leaf, stem, and inflorescence tissue of diploid and tetraploid Russian wildrye were affected by growing season water (50 and 150% of average precipitation) and fertilizer (10 and 134 kg N ha−1). Plants were sampled at vegetative, boot, anthesis, and anthesis plus 10-day stages of maturity in 1994, 1995, and 1996. Tetraploid plants had slightly (P < 0.05) less crude protein (CP) in leaf, stem and inflorescence tissue than diploid plants. Plants grown at the 50% water treatment had higher CP and in vitro dry matter digestibility (IVDMD), and lower acid detergent fiber (ADF) and neutral detergent fiber (NDF) in leaf and inflorescence tissue, while in stem tissue only CP was affected by the growing season water treatment. Nitrogen fertilizer resulted in greater CP and IVDMD and lower ADF and NDF in all 3 plant tissues. Maturity affects were consistent over leaf, stem and inflorescence tissue, with CP and IVDMD declining and ADF and NDF increasing as plants matured. There were some differences in nutritive quality components between diploid and tetraploid plants, but overall their qualities were comparable and quite good. Crude protein at all stages of maturity in leaf and inflorescence tissue would have been adequate for most classes of beef cattle, while stem tissue CP would have only been adequate for lower producing animals.

Nutritive Quality of Cool‐Season Grass Monocultures and Binary Grass–Alfalfa Mixtures at Late Harvest

Nutritive quality of hay is compromised when harvest is delayed, but reproduction of upland nesting birds in the northern Great Plains would be improved if haying operations could be deferred until mid‐July or later to allow completion of nesting. This study was conducted to determine nutritive quality of hay at a single mid‐July cutting from three cool‐season grass species that were grown in monoculture and in binary mixtures with alfalfa [Medicago sativa subsp. × varia (Martyn) Arcang.] near Mandan, ND. Grasses were intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. &amp; Dewey], smooth bromegrass (Bromus inermis Leyss.), and crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.]. Annual applications of 0 and 50 kg N ha−1 had no effect on in vitro dry matter digestibility (IVDMD) or neutral detergent fiber (NDF) levels of grass or alfalfa. Grass monocultures and alfalfa averaged 612 and 624 g kg−1, respectively, for IVDMD and 651 and 567 g kg−1, respectively, for NDF. At 0 kg N ha−1, crude protein (CP) ranged from 71 to 78 g kg−1 in grass monocultures and from 92 to 131 g kg−1 in grass–alfalfa mixtures. At 50 kg N ha−1, CP ranged from 83 to 97 g kg−1 in grass monocultures and from 99 to 133 g kg−1 in mixtures. Feasibility of deferring hay harvest to allow reproduction of upland nesting birds in the northern Great Plains depends on maintaining alfalfa or other legumes with high nutritive quality in grass mixtures to reduce NDF and increase CP levels.

Grass Seedling Recruitment in Cattle Dungpats

Livestock seed dispersal (fecal seeding) is gaining recognition as a method to reintroduce desirable species to degraded rangelands. A field study was conducted to determine the influence of cattle dungpat thickness on the recruitment of Sandberg bluegrass (Poa secunda Presl.), bluebunch wheatgrass (Psuedoroegneria spicata [Pursh] A. Love), and ‘Hycrest’ crested wheatgrass (Agropyron desertorum [Fisch. ex Link] Schult. × A. cristatum [L.] Gaert.) in naturally and artificially deposited dungpats. Four Holstein heifers each were fed 60 000 seeds of each species. Twenty-four hours after feeding seeds, dung was collected from 2 animals receiving each plant species and formed into uniform, artificial dungpats (2 kg in mass) with thicknesses of 1, 2, and 4 cm, and respective diameters of 40, 28, and 20 cm, and deposited on bare soil. The other 2 animals receiving each plant species were used to deposit natural dungpats, varying in mass, thickness, and diameter, on bare soil. Seedling recruitment in all dungpat types was greatest for crested wheatgrass, followed by Sandberg bluegrass and bluebunch wheatgrass. Recruitment for all species was generally greatest in 1-cm-thick artificial dungpats, followed in order by 2-cm-thick artificial dungpats, natural dungpats, and 4-cm-thick artificial dungpats. Most seedlings, regardless of species, emerged and survived in the interior region of 1- and 2-cm-thick artificial dungpats and at the periphery of 4-cm-thick artificial dungpats. Most seedlings of crested wheatgrass and Sandberg bluegrass emerged and survived in cracks and depressions in the interior region of natural dungpats, whereas more bluebunch wheatgrass seedlings emerged and survived at the periphery of natural dungpats. Results indicate that the efficacy of cattle seed dispersal is influenced by the seedling vigor of species (seeds) consumed and the thickness of dungpats in which the ingested seeds are deposited. Grass species with weak seedling vigor (Sandberg bluegrass and bluebunch wheatgrass) have lower recruitment than species with strong seedling vigor (crested wheatgrass), particularly in dung &gt; 2 cm thick.

Ploidy, water, and nitrogen effects on Russian wildrye chemical composition

Abstract Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], a cool-season introduced bunchgrass, offers producers an alternative to crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes] for spring and fall grazing in the Northern Great Plains. Tetraploid Russian wildrye with improved seedling establishment may offer even greater potential for seasonal grazing. This study investigates how the concentrations of some nutritive quality components in leaf, stem, and inflorescence tissue of diploid and tetraploid Russian wildrye were affected by growing season water (50 and 150% of average precipitation) and fertilizer (10 and 134 kg N ha−1). Plants were sampled at vegetative, boot, anthesis, and anthesis plus 10-day stages of maturity in 1994, 1995, and 1996. Tetraploid plants had slightly (P < 0.05) less crude protein (CP) in leaf, stem and inflorescence tissue than diploid plants. Plants grown at the 50% water treatment had higher CP and in vitro dry matter digestibility (IVDMD), and low...

Ploidy, water, and nitrogen effects on Russian wildrye chemical composition

Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], a cool-season introduced bunchgrass, offers producers an alternative to crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes] for spring and fall grazing in the Northern Great Plains. Tetraploid Russian wildrye with improved seedling establishment may offer even greater potential for seasonal grazing. This study investigates how the concentrations of some nutritive quality components in leaf, stem, and inflorescence tissue of diploid and tetraploid Russian wildrye were affected by growing season water (50 and 150% of average precipitation) and fertilizer (10 and 134 kg N ha-1). Plants were sampled at vegetative, boot, anthesis, and anthesis plus 10-day stages of maturity in 1994, 1995, and 1996. Tetraploid plants had slightly (P 0.05) less crude protein (CP) in leaf, stem and inflorescence tissue than diploid plants. Plants grown at the 50% water treatment had higher CP and in vitro dry matter digestibility (IVDMD), and lower acid detergent fiber (ADF) and neutral detergent fiber (NDF) in leaf and inflorescence tissue, while in stem tissue only CP was affected by the growing season water treatment. Nitrogen fertilizer resulted in greater CP and IVDMD and lower ADF and NDF in all 3 plant tissues. Maturity affects were consistent over leaf, stem and inflorescence tissue, with CP and IVDMD declining and ADF and NDF increasing as plants matured. There were some differences in nutritive quality components between diploid and tetraploid plants, but overall their qualities were comparable and quite good. Crude protein at all stages of maturity in leaf and inflorescence tissue would have been adequate for most classes of beef cattle, while stem tissue CP would have only been adequate for lower producing animals.