Native Mixed Prairie Research Articles

A non-native agronomic legume (Astragalus cicer L.) alters multiple ecosystem-services in mixed prairie grassland

Cicer milkvetch (Astragalus cicer L.), and other non-native agronomic legumes, are used extensively for forage in North America, but, despite their abundance, few studies have examined their effects when they colonize native grasslands. Cicer milkvetch provides excellent forage for livestock, but given its large size and ability to fix nitrogen, it is likely to affect other ecosystem services provided by grasslands. We have observed cicer milkvetch in the dry mixed-grass prairie of southern Alberta, Canada. The objective of this study was to examine the effects of cicer milkvetch on forage production, carbon storage and plant community diversity after it colonizes native mixed prairie grasslands and further examine whether these effects increase with cicer milkvetch patch size. We compared the ecosystem functions among plots located within a cicer milkvetch patch, beside a patch and 5 m distant from the patch. The plant, as expected has positive effects on forage quantity and quality, reduced plant species diversity and richness, and altered numerous components of the carbon pool, as well as nitrogen availability. Furthermore, larger patches of cicer milkvetch had lower concentrations of soil carbon and nitrogen, and differentially affected other ecosystem properties. Given the potentially large propagule pressure of non-native legumes from agricultural lands, surrounding native grasslands in North America, and our results demonstrating effects on multiple grassland ecosystem services, further consideration and investigation of non-native legumes in grasslands is warranted.

Grassland vegetation and bird communities in the southern Great Plains of North America

Structure and composition of vegetation and abundance of breeding birds in grasslands seeded to Old World bluestem (Bothriochloa ischmaeum) were compared to native mixed prairie in the southern Great Plains of North America. Abundance of birds was determined using fixed-radius point counts. Detrended correspondence analysis was used to compare plant community composition and canonical correspondence analysis was used to examine the relationships between plant species composition and vegetation structure with the bird community. Plant species composition differed distinctly between seeded grassland and native mixed prairie, but the differences were not reflected in habitat structure, bird community composition, or abundance of bird species. Seeded grassland was inferior to native mixed prairie in terms of diversity of plant species, but that difference did not translate into meaningful differences in structure that drove habitat selection by breeding birds. Conservation programs that promote establishment of seeded grassland and do not allow for suitable disturbance regimes will selectively benefit a narrow suite of birds regardless of plant species composition.

Changes in soil microbial community structure with tillage under long-term wheat-fallow management

Fatty acid methyl esters (FAMEs) were used to ‘fingerprint’ soil microbial communities that evolved during 25 years of wheat-fallow cropping following native mixed prairie sod at Sidney, Nebraska, USA. Total ester-linked FAMEs (EL-FAMEs) and phospholipid-linked FAMEs (PL-FAMEs) were compared for their ability to discriminate between plots remaining in sod and those cropped to wheat or left fallow under no-till, sub-till or plow management. Cropped plots were higher in microbial biomass than their fallowed counterparts, and did not differ significantly with tillage for the 0–15 cm depth. Under fallow, microbial biomass was greatest in no-till and least in plow. Both cluster and discriminant analysis of PL- and EL-FAMEs clearly separated the remaining native sod plots from the existing wheat-fallow plots. This separation was particularly pronounced for the EL-FAMEs and was largely driven by high amounts in sod of a single FAME, C16:1( cis11), which has been cited as a biomarker for arbuscular mycorrhizal (AM) fungi. Within wheat-fallow, C16:1( cis11) declined significantly from no-till to plow, which supports the origin of C16:1( cis11) from extraradical mycelium and spores of AM fungi known to be sensitive to soil disturbance. Although discriminant analysis of PL- and EL-FAMEs differentiated wheat and fallow systems by tillage, discrimination among tillage treatments was expressed most strongly during fallow. FAME profiles from fallow plow were most dissimilar from cropped soils which suggests a relationship between tillage management and the long-term resiliency of the microbial community developed under the wheat crop.

Sequence Grazing Systems on the Southern Plains

Eastern gamagrass (Tripsacum dactyloides (L.) L.) is a perennial warm-season bunchgrass that starts growth earlier in the spring than most other warm-season grasses. This suggests that combining eastern gamagrass with other warm-season grasses in a sequence grazing system could lengthen the period of rapid livestock gain. We studied sequence grazing systems consisting of eastern gamagrass and Old World bluestem (Bothriochloa ischaemum L.) (EG-OWB) as compared to native mixed prairie and Old World bluestem (Native-OWB) from 1993 to 1997. Crossbred beef steers averaging 239 kg grazed eastern gamagrass or native pasture from early May to early June and again from late July through August. Old World bluestem was grazed in mid season. We measured forage yield and nutritive value and steer gain. Standing forage of eastern gamagrass above a 15-cm stubble height averaged 895 kg ha-1 at the start of the first grazing period and 2,430 kg ha-1 at the start of the second grazing period. Dry, cold winter and spring weather reduced this amount to 80 kg ha-1 in May 1996 and precluded grazing the eastern gamagrass that season. Crude protein content of eastern gamagrass was greater than 14% and in vitro dry matter disappearance (IVDMD) was greater than 65% in May. By August, crude protein content had dropped to 5-8% and IVDMD was 45-50%. Peak standing crop of Old World bluestem averaged 4,580 kg ha-1 over years. Steer gain over the entire grazing season, 103 days, did not differ between forage systems, averaging 1.02 kg head-1 day-1 in both systems. Steer gain was higher on native pasture than eastern gamagrass in the late grazing season (0.91 versus 0.60 kg head-1 d-1, p=0.02). As a result of higher stocking rates, steer gain was 257 kg ha-1 for the EG-OWB system and 103 kg ha-1 for the Native-OWB system (p<0.01).

Soil microbial activity, nitrogen cycling, and long-term changes in organic carbon pools as related to fallow tillage management

Two experiments were established in 1969 and 1970 near Sidney, NE, to determine the effect of moldboard plow (plow), sub-tillage (sub-till), and no-tillage (no-till) fallow management on soil properties, biological activities, and carbon and nitrogen cycling. One experiment was on land which had been broken from sod in 1920, seeded to crested wheatgrass [ Agropyron cristatum (L.) Gaertn.] from 1957 to 1967, and cultivated for wheat again in 1967 (Previously Cultivated site). The second experiment was established on land that was in native mixed prairie sod until 1969 (Native Sod site), and compared the three tillage management practices listed above in a winter wheat-fallow system as well as replicated plots remaining in sod. Soil sampling done 10–12 years after these experiments were initiated, indicated that the biological environment near the soil surface (0–30 cm) with no-till was often cooler and wetter than that with conventional tillage management practices, especially moldboard plowing. Biological activity and organic C and N reserves were concentrated nearer the soil surface (0–7.6 cm) with no-tillage, resulting in greater potential for tie-up of plant available N in organic forms. However, regardless of tillage practice with wheat-fallow management at either site, long-term (22–27 years) losses of soil organic C from surface soil (0–30 cm) ranged from 12 to 32% (320–530 kg C ha −1 year −1), respectively, for no-till and plowing. These soil C losses were closely approximated by losses measured to a depth of 122 cm, indicating that under the cropping, tillage, and climatic conditions of this study, soil C changes were adequately monitored by sampling to a depth of 30 cm within which most C loss occurs. No-till management maintains a protective surface cover of residue and partially decomposed materials near the soil surface. However, the decline in soil organic matter, and associated degradation in soil quality, will likely only be slowed by increasing C inputs to soil through use of a more intensive cropping system which increases the time of cropping and reduces the time in fallow.

Nitrogen transformations, utilization, and conservation as affected by fallow tillage method

While we know that fallow tillage method affects water conservation and soil erosion control, effects on soil and fertilizer N dynamics are less well known. In this paper, we summarize results from our investigations of N transformation and cycling for two experiments established in 1969 and 1970 near Sidney, NE. In this research, the effects of three fallow tillage methods (moldboard plow, sub-till, and no-till) on changes in soil properties, N dynamics, and subsequent crop growth were studied. One experiment was on land, that had been broken from sod before 1920, seeded to crested wheatgrass [ Agropyron cristatum (L.) Gaertn.] in 1957, and cultivated again since 1967 with the above three fallow tillage methods. Wheat ( Triticum aestivum) was grown in a wheat-fallow sequence with and without 45 kg fertilizer N ha −1. The second experiment was on land that was in native mixed prairie sod until 1969, and included a comparison of the three above tillage methods in a wheat-fallow system with plots remaining in native sod. During the first 13 years of study, total soil N loss from the surface 30 cm of soil (compared to the native sod) was only about 3% for the no-till system, compared to 8 and 19% for the sub-till and plow systems, respectively. For both experiments, considerable mineralization and nitrification of organic N occurred during the fallow period, with greatest rates for plowed fallow. No-till immobilized more labeled and total N in soil organic matter and in visible and partially decomposed crop residues on and near the soil surface. However, by harvest of the second crop grown after N-labeled fertilizer N was applied, little if any of the labeled N was found in visible and partially decomposed crop residues or as soil inorganic N, suggesting that most of the fertilizer N applied was immobilized in soil organic N or was lost. Deep sampling (to 15 m) of the Native Sod plots showed that several hundred kg of NO 3–N ha −1 had leached beneath the crop root zone, presumably during wet years after fallow. For plowed plots, the quantity of NO 3–N beneath the root zone approximated the loss in total soil N from the root zone, suggesting there was a little net loss of soil N by denitrification or ammonia volatilization. For no-till, quantities of NO 3–N beneath the root zone exceeded the loss of total soil N during cultivation, suggesting significant N-fixation occurred by unknown mechanisms. These results show that fallow tillage system does affect soil and fertilizer N cycling and transformations and the availability of N to crops.

Crop production and soil water storage in long-term winter wheat–fallow tillage experiments

Soil water is the major limiting factor in dryland crop production in the Central Great Plains. No-till fallow management increases soil water storage and reduces soil erosion potential. Two experiments were initiated in 1969 and 1970 near Sidney, NE to compare effects of moldboard plow (Plow), sub-tillage (Sub-till) and no-tillage (No-till) fallow systems on winter wheat ( Triticum aestivum L.) grain yield, grain protein, residue production, and soil water accumulation during fallow. The first experiment was established in 1969 on an Alliance silt loam that had been previously cultivated prior to study initiation. This experiment contained a nitrogen (N) fertilizer split of 0 and 45 (kg N) ha −1 within each tillage treatment. The second experiment was established in 1970 on a Duroc loam that was in native mixed prairie sod. No fertilizer was applied at this site. At both sites, soil water storage was greatest with the no-till and least with the plow system. Winter wheat grain yields failed to consistently respond to increased soil water storage in the no-till system during the 24–26 years of the experiments. Grain yields with the plow system were 8% greater than with sub- and no-till systems at the Previously Cultivated site when N was not applied. The addition of N at this site eliminated yield differences due to fallow tillage systems. Grain protein averaged 13.8, 13.3 and 12.8% for all plow, sub- and no-till treatments, respectively. The addition of N at the Previously Cultivated site increased residue dry weights by an average of 5% in all tillage systems. Neither grain protein nor residue dry weights were affected by tillage system at the Native Sod site. Winter wheat–fallow is probably not a sustainable production system for the Central Great Plains, regardless of the fallow management system used.

Effect of Native Prairie, Crested Wheatgrass (Agropyron Cristatum (L.) Gaertn.) and Russian Wildrye (Elymus Junceus Fisch.) on Soil Chemical Properties

Crested wheatgrass and Russian wildrye are used extensively as seeded pastures in the prairie region of western Canada. Their long-term impact on soil quality was studied at 4 sites, each including plant communities of native mixed prairie rangeland and 17to 27-year-old monocultures of crested wheatgrass and Russian wildrye, in southern Alberta, Canada. Root mass and soil chemical properties were determined on the soil samples collected. Native rangeland had about 7.6 times more root mass than the seeded species from the 0to 7.5-cm depth and about equivalent mass from the 7.5to 40-cm depth. For the seeded species, root mass was significantly less between rows than within rows. Soils in the native rangeland community had significantly greater soil organic matter and lower NO3-N, chemical index, urease activity, and available phosphorus than those in the seeded pastures. Altering the plant community from native mixed prairie to either a sequence of cropping followed by an introduced grass monoculture, or directly to an introduced grass monoculture, resulted in decreased root mass and organic matter, and monosaccharide content of dry aggregates. The seeded grasses could neither return nor maintain the chemical quality of the soils in relation to that of the native rangeland.

Terman Environmental Study Area

Terman Environmental Study Area (TESA) is owned and maintained by Dr. Max R. Terman, professor of biology at Tabor College, Hillsboro, Kansas. The area is managed for a diverse wildlife population and is used as an outdoor laboratory for the science division of the college. Established in 1980 and located 5/2 miles south of Hillsboro in Marion County, the rectangular 15 acre area consists of approximately 70% native mixed prairie, 10% hedge row, 5% aquatic (pond, marsh), and 15% residential area (naturally landscaped earth sheltered home and yard). Bounded on the west by a road and cropland, the north by agricultural land, and on the south and east by pasture and riparian woodland, TESA is a terminal habitat point on a network of wildlife movement corridors formed by streams and woodlands associated with the South Cottonwood River drainage system. Dominant species in the grassland are big bluestem (Andropogon gerardii), little bluestem (Schizacchrium scoparius), switchgrass (Panicum virgatum), side-oats grama (Bouteloua curtipendula), Indiangrass (Sorghastrum nutans), dropseed (Sporobolus asper), western wheatgrass (Agropyron smithii), and cheat (Bromus secalinus). Common forbs include sage (Artemesia ludoviciana), aster (Aster spp.), catsclaw (Schrankia nuttalli), light poppy mallow (Callirohoe alceoides), gayfeather (Liatris punctata), death camus (Zygadenus nuttalli), false indigo (Baptisia australas), wild indigo (B. lucantha), prairie clover (Pentalostem spp.), yarrow (Achillea millefolium), ground plum milk vetch (Astragalus crassicarupus), spiderwort (Tradescantia ohiensis), green antelope horn milkweed (Asclepias viridis), ironweed (Vernonia baldwinii), ragweed (Ambrosia spp.), yellow goatsbeard (Tragopogon dubius), daisy fleabane (Erigeron spp.), snow-on-the-mountain (Euphorbia marginata). Hedgerows consist primarily of osage-orange (Maclura pomifera). The pond edge supports mainly various species of sunflower (Helianthus spp.), sumpweed (Iva spp.), and an introduced cover plant, crown vetch (Coronilla varia) (which also surrounds much of the house and sewage lagoon). Grasses surrounding and on the earth-sheltered house are mainly fescue (Festuca spp.) and buffalograss (Buchloe dactyloides). Major faunal species are small mammals (Peromyscus maniculatus, P. leucopus, Microtus ochrogaster, Sigmodon hispidus, Reithrodontomys montanus, R. megalotis, Blarina hylophaga, Cryptotis parva, Sylvilagus floridanus, Scalopus aquaticus, Didelphis virginiana), and 28 species of birds, mostly passerines and raptors. Dominant reptiles include great plains skink

Prescribed Burning in the Loess Hills Mixed Prairie of Southern Nebraska

Abused rangelands dominated by introduced cool-season grasses and warm-season shortgrasses are common over much of the Mixed Prairie. Native decreaser species are primarily warm-season grasses and are present at only insignificant levels on abused rangeland in the Loess Hills of southcentral Nebraska. A single, latespring, prescribed fire was evaluated as a method of improvement. The study area consisted of 3 tracts of plots located on Holdrege silt loam soil (Typic Argiustall) with an average annual precipitation of 550 mm. The vegetation on the tracts was in low range condition, with cooland warm-season components being present in varying proportions on all tracts. In general, the dominant cool-season species were Kentucky bluegrass (Poa pratensis) and annual bromes (Bromus spp.), and the dominant warm-season species were blue grama (Bouteloua gracilis) and buffalograss (Buchloe dactyloides). Burning reduced the basal cover and herbage yields of cool-season species. This favored the warm-season component. The increaser short grasses generally exhibited higher herbage yields and basal cover on burned as compared to unburned plots. These results indicate that a single, late-spring, prescribed burn may have a limited potential as a range improvement practice in the Loess Hills of south central Nebraska. The Loess Hills of Southern Nebraska west of 980 30' west longitude were described by Weaver (1965) as Mixed Prairie. The dominant native vegetation was a mixture of primarily warmseason tall, mid, and shortgrasses. Currently, over one-third of the Loess Hills is classified as native range. Due to mismanagement, approximately 60% of this rangeland (1.6 million ha) is in poor to fair range condition (Bose 1977). Improper grazing management has caused a shift in species composition from the native warmseason plant community to a mixture of warm-season shortgrasses, i.e., blue grama (Bouteloua gracilis)' and buffalograss (Buchloe dactyloides), and undesirable cool-season grasses, i.e., Kentucky bluegrass (Poapratensis), Canada bluegrass (Poa compressa), and annual bromes (Bromus spp.). This species composition shift results in a reduction of the quantity and quality of forage produced during the summer months. There are numerous methods of improving rangeland in low condition, but one of the simplest and least expensive practices is prescribed burning. The ability of prescribed fires to selectively suppress or promote particular species depends primarily upon the date of the fire in relation to the phenology of the particular species. As a general rule, those species actively growing when the area is burned are much more susceptible to injury and death than dormant species or those initiating growth (Anderson et al. 1970). Fire severity, which is closely related to fuel loading, size and distribution of fuel, weather, and moisture content of soil and fuel, is also a major factor affecting fire damage to living plants (Wright and Bailey 1982). A late-spring fire has been a particularly effectve Authors are graduate research assistant and professor (range ecology), Department of Agronomy, University of Nebraska, Lincoln 68583. Mr. Schact is currently graduate teaching assistant, Range Science Department, Utah State University, Logan 84322. Published as Paper Number 7087, Journal Series, Nebraska Agricultural Experiment Station. Manuscript accepted March 25, 1984. 'Nomenclature follows Gould and Shaw 1983. method of controlling Kentucky bluegrass (Hensen 1923, Ehrenreich 1959, and Launchbaugh and Owensby 1978), Canada bluegrass (Curtis and Partch 1950), and Japanese brome (Bromus japonicus) (McMurphy and Anderson 1965). In many mesic areas of the Mixed Prairie, prescribed burning has been used to control cool-season grasses without reducing herbage yields or cover of warm-season grasses (Kirsch and Kruse 1972, Gartner and Thompson 1972), although total herbage yield has been reduced the first year following the burn (Dwyer and Pieper 1967). The primary purpose of this study was to determine the potential of a single late-spring prescribed burn in one part of the Mixed Prairie as a means to shift species composition from low yielding warm-season shortgrasses and introduced cool-season grasses to species more indicative of the native Mixed Prairie vegetation, such as big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), switchgrass (Panicum virgatum), and sideoats grama (Bouteloua curtipendula).

Long‐Term Recovery of Fertilizer Nitrogen Applied to a Native Mixed Prairie

AbstractPrevious research on perennial grassland soils has generally shown that a large part of any fertilizer nitrogen (N) added is immobilized in grass roots or in soil organic matter. Few studies have measured the amount of such immobilized N that eventually becomes mobilized and taken up by plant growth in subsequent years. In this experiment, up to 540‐kg fertilizer N/ha was applied to native mixed prairie in North Dakota during a 1‐ to 6‐year period, and residual effects of these treatments on grass production were followed until no further plant growth response was measured. When a total of 270‐ or 540‐kg N/ha had been applied, plant growth responses were measured for up to 9 years after fertilization ceased. As fertilizer N rate decreased, length of residual effects likewise decreased. Part of the residual response may have resulted from increased density of cool‐season grasses where higher N rates were applied. Growth responses after fertilization ceased were often greater when fertilizers were applied over a 6‐year period, rather than applying an equal quantity of fertilizer N all in 1 year. For the 540‐kg N/ha treatment, as much as 12% of the fertilizer N applied was recovered in top growth after fertilization ceased. Assuming that all increased inorganic N in the soil resulting from fertilization was used by plants during the residual period, and that the remaining fertilizer N taken up by top growth after fertilization ceased came from mobilization of fertilizer N present in grass roots in 1968, then an estimate can be made of availability of fertilizer N in roots. Maximum value for such an estimate was 44‐kg N/ha, leaving 60‐ to 160‐kg fertilizer N/ha permanently immobilized as this root material decomposed. Thus, when 270‐ or 540‐kg fertilizer N/ha was applied, typically about 30% was permanently immobilized by absorption into root material during the period of fertilization, 35% was removed in top growth, and 35% was either immobilized permanently in soil organic matter or lost by gaseous means.

Response of Semiarid Grassland Sites to Nitrogen Fertilization: I. Plant Growth and Water Use

AbstractAlthough it has been repeatedly demonstrated that most perennial grassland ecosystems respond to N fertilization, knowledge of factors controlling N transformations involved in such responses is fragmentary. Eight rate‐of‐N‐fertilizer experiments were conducted for 5 or 6 years on established perennial grass sites near Mandan, North Dakota. Experiments were conducted within essentially the same precipitation and temperature regimes on sites differing in soil type, exposure, and grass species to determine their influence on N response. Above‐ground vegetation response to N fertilization depended primarily upon species — smooth bromegrass (Bromus inermis) was generally more responsive than crested wheatgrass (Agropyron desertorum) or native mixed prairie. No consistent patterns of root biomass response to N fertilization were obvious. At some sites or in certain years root biomass responses were fairly consistent, whereas at other sites or in other years, little response to N occurred. Water use efficiency (WUE) was greatest for bromegrass and least for native grasses, and was generally increased by N fertilization. WUE increased as aboveground growth increased, whether as a result of N fertilization or because of less evaporation at more protected sites. Cumulative dry matter response to N fertilization was highly correlated with cumulative fertilizer N added, with a different curvilinear relationships for each site.These results indicated that the magnitude of fertilizer N responses by perennial grasslands is site specific. Although the same general mechanisms seem to operate at the different sites, magnitude of response was controlled by the plant species present and by some soil type × location factors that are presently ill‐defined. These latter factors appear to influence the capacity of the soil to immobilize fertilizer N, capability of above‐ground plant growth to take up fertilizer N, and many other N transformations, and may be related to relative availability of water. Consequently interpretations of fertilizer experiments conducted on only one soil type or with only one species must be interpreted with caution.

Use of Slow‐Release N Fertilizers on Native Mixed Prairie1

AbstractAlthough it is known that the native mixed prairie grasses will respond to N fertilization, little is known concerning the recovery and fate of different fertilizer N sources applied to this ecosystem. Possibly by using slow‐release N fertilizers, changes in stands of the different grass species could be controlled in a manner that would improve productivity. Consequently, a 4‐year field experiment was conducted at Mandan, North Dakota, to compare the effects of S‐coated urea and ureaformaldehyde with ammonium nitrate on production of mixed native prairie vegetation. In general, all fertilizers at all rates of application decreased Boulettoua gracilis (blue grama) density, while Agropyron smithii (western wheatgrass) density generally increased at rates above 56 kg N/ha annually. Dry matter production from all rates of N application was greatest for ammonium nitrate and least for ureaformaldehyde, with intermediate production for the S‐coated ureas. Fertilizer N recovery in harvested forage followed this same order. Assuming that about 100 kg fertilizer N was immobilized in grass roots, and that fertilizer N not accounted for in tops, roots, and soil inorganic N forms estimates gaseous losses, presumed gaseous losses varied from less than 10% of the amount of N applied as ammonium nitrate to about 60% for ureaformaldehyde. In general, the mixed prairie grasses used N from urea‐containing fertilizers less efficiently than that from ammonium nitrate.

Solar radiation interactions with mixed prairie rangeland in natural and denuded conditions

Adjacent plots of native mixed prairie rangeland and bare soil near Sidney, Montana, were studied during the 1973 growing season for reflected solar radiation (albedo) variations induced by variations in surface soil water content. Results for the bare soil were nearly identical to those obtained for a bare soil at Phoenix, Arizona, where albedo variations were linked to the three classical stages of soil drying. Results from the vegetated plot, however, did not show the characteristic water content dependency patterns. Thus, the utility of the albedo technique for assessing soil water status seems limited to the remote sensing of essentially vegetation-free soils and thein situ assessment of soil water evaporation via miniature solarimeters placed below the plant canopy or in small open spaces between plants.