Harvest Date Effect on Forage Yield, Botanical Composition, and Nutritive Value of Novel Legume-Grass Mixtures

The potential for novel forage mixtures to address reduced herbage for late season grazing was investigated. Forage legumes, sainfoin (Onobrychis viciifolia Scop.) (SF) cvs. AC Mountainview, Shoshone, and Nova (MountainSF, ShoshoneSF, and NovaSF), cicer milkvetch (Astragalus cicer L.) cv. AC Veldt (CMV), Canadian milkvetch (Astragalus canadensis L.) cv. Great Plains (CaMV), and alfalfa (Medicago sativa L.) cv. AC Yellowhead (ALF) were evaluated in binary mixtures with meadow bromegrass (Bromus riparius Rehm.) cv. Admiral (MBG), hybrid bromegrass (B. riparius × B. inermis Leyss.) cv. AC Success (HBG) and Russian wildrye [Psathyrostachys junceus (Fisch.) Nevski.] cv. Tom (RWR) for yield, botanical composition, and nutritive value on July and September harvest dates at Saskatoon and Swift Current, Saskatchewan, Canada from 2016 to 2018. Hybrid bromegrass-legume mixture produced 16–38% greater forage compared to RWR-legume (7.5 vs. 5.6 Mg ha−1 in July and 6.1 vs. 5.1 Mg ha−1 in September at Saskatoon, and 3.2 vs. 2.0 Mg ha−1 in July at Swift Current). MountainSF and ALF had the greatest legume contribution to total yield at July harvest at Swift Current (67.7 ± 3.2%) and Saskatoon (62.1 ± 2.1%), respectively, while CaMV had lowest composition at Swift Current (20.2 ± 2.5%) and Saskatoon (12.6 ± 3.5%). The CMV and ALF-grass mixtures at Saskatoon and legume-RWR mixtures at both sites in July had greatest CP content. The July harvest had greatest yield, legume content and nutritive value compared to the September harvest at both sites. Study results suggest if yield is the objective, then either ALF or CMV with HBG may be considered. If nutritive value is the goal, any legume with RWR is an option. Finally, ALF or CMV in mixture with either HBG or RWR could be summer or fall stockpile forage in the Northern Great Plains of western Canada.

Effects of clipping frequency on tiller development of crested wheatgrass and hybrid bromegrass at vegetative and reproductive stages

Information on the tiller development of hybrid bromegrass (Bromus inermis × Bromus riparius Rehm) is limited. The objective of this study was to evaluate the effect of clipping frequency at the vegetative and reproductive stages on the tiller development and concentrations of sugars of ‘AC Knowles’ hybrid bromegrass compared to ‘Kirk’ crested wheatgrass (Agropyron cristatum L.). This experiment was conducted in the greenhouse using the tillers of the vernalized plants dug from the field. The experimental design was a randomized complete block design. Grasses were clipped once or four times at either vegetative or reproductive stage. Regardless of the growth stage, four clippings reduced the tiller number of hybrid bromegrass by 25.9% compared to the undefoliated control while single clipping had no impact. The four clipping had no impact on the tiller number of crested wheatgrass, while single clipping increased its tiller number on average by 50.4% at both growth stages. Crested wheatgrass produced 16.6% more tillers than hybrid bromegrass under the single clipping. The two grass species had a similar number of axillary buds under different clipping treatments. The axillary bud size of crested wheatgrass was larger than hybrid bromegrass. All axillary buds were viable under the two clipping treatments for both grasses. Four clippings significantly decreased the stem base glucose concentration of the two grasses and the root sucrose concentration of crested wheatgrass. Hybrid bromegrass was less tolerant to frequent clippings than crested wheatgrass. Therefore, intensive grazing of hybrid bromegrass pasture may result in a thin stand.

Introduction of four native legumes of the Canadian Prairies in monoculture and in mixtures with meadow bromegrass (Bromus riparius)

Many questions remain concerning the viability and productivity of seeding native legumes in the Canadian Prairies for forage production. Field research was conducted with four native legume species (Astragalus flexuosus, Dalea purpurea, Hedysarum boreale and Vicia americana) to evaluate performance in Swift Current and Saskatoon, SK. The experimental design was a Randomized Complete Block Design with four replicates to evaluate legume-grass mixtures and monoculture performance, botanical composition and effect of harvest dates (July and August) from 2016 to 2018. The native legume-grass mixtures performed differently at the sites, with greater foliar cover at Saskatoon but greater proportion of legumes in mixtures at Swift Current. The mixtures had similar forage nutritive value as monoculture Bromus riparius, with legumes contributing 10% or less of the forage dry matter yield (DMY) at both sites. A. flexuosus showed the greatest foliar cover and produced the greatest DMY in monoculture at both sites. Based on this study, native legumes would need to make up a larger proportion of forage dry matter yield to change the nutritional value of mixtures. In a subsequent seeding rate evaluation, the four legume species were planted at three seeding rates (300, 200 and 100 pure live seeds [PLS] per metre) and tested for DMY one year following establishment near Swift Current. Increasing seeding rates up to 300 PLS m-1 corresponded with an increase in seedling density and foliar cover, but DMY was not affected. Additional research with A. flexuosus is needed to demonstrate its value as a forage.

Establishment and productivity of cicer milkvetch (Astragalus cicer L.) in alfalfa (Medicago sativa L.) or alfalfa- hybrid bromegrass mixtures

Cicer milkvetch (Astragalus cicer L.) (CMV) is a non-bloating, perennial legume that has shown persistence under grazing. Limited information is available on its seedling establishment and subsequent forage yield and nutritive value in alfalfa (Medicago sativa L.) mixtures. Field plots were seeded in May 2013 at Melfort, SK, Canada to evaluate ‘Oxley II’ cicer milkvetch performance in ‘AC Grazeland’ alfalfa or alfalfa and ‘AC Success’ hybrid bromegrass (Bromus riparius × B. inermis) mixtures from 2014 to 2017. Two controlled environment tests were also conducted by treating seeds of CMV using alfalfa root aqueous extract. Seed germination and seedling height of CMV were significantly reduced in aqueous extract. In field, establishment of CMV in a mixture containing alfalfa was reduced, and CMV dry matter proportion in the mixture increased only 3.5% over three years. Increasing CMV seeding rate did not increase its DM percent in the mixtures, indicating a high allelopathic effect of alfalfa. Forage DM yield of all mixtures was linearly correlated to the proportion of alfalfa, and adding hybrid brome did not increase the DM yield. Forage DM yield was higher for the three-cut than the two-cut treatments for CMV-alfalfa mixtures, but there was no difference between the cutting frequency for CMV-alfalfa- hybrid brome mixtures. Fiber concentrations decreased linearly with increased CMV seeding rate in the mixtures. This study showed CMV establishment in alfalfa mixtures was reduced in a same row seeding, and the allelopathic effect was not reduced by lower alfalfa seeding rates or adding a grass.

Silvertop in perennial grass seed production: Effects of type and timing of biotic stresses

Seed production of perennial grasses is an important industry in Canada, but many fields exhibit high proportions of sterile heads with characteristic symptoms in a condition known as silvertop. In a 3-yr field study, biotic stress treatments were applied to caged plots of Kentucky bluegrass (<i>Poa pratensis</i>) and meadow bromegrass (<i>Bromus riparius</i>) to assess their effects on silvertop incidence. Treatments were: 1) control, 2) addition of grass-feeding insects, primarily grass plant bugs (Miridae), 3) inoculation with <i>Fusarium poae</i> spores, 4) both insects and spores, and in one year, 5) mechanical piercing of seed heads above the last node. Additionally, cores of the two grass species were potted and removed from the field in spring in each of 2 years. After 2-, 4-, and 6-wk intervals in a cold room at 4° C to stagger plant development stage, the five treatments were applied to caged plants of both grasses, which were maintained in a greenhouse until seed harvest. In both studies, the numbers of healthy seed heads, percentage of heads with silvertop, and seed weights were determined. In the field, stress treatments infrequently and inconsistently affected silvertop levels. Regression showed that the relationship between silvertop and seed yield, although significant, explained little of the variability in yield. Silvertop developed in all treatments in the greenhouse; treatments had no effect on silvertop levels, which were highest in plants treated at the R1 (boot) growth stage. This suggests that the boot stage of the two grass species is most vulnerable to silvertop occurrence.

Annual ryegrass and Festulolium as companion crops in the establishment of perennial forage crops

Annual companion crops are often used in new seedings of perennial forages in western Canada. Fast-establishing grass species that do not overwinter in this region have potential as companion crops to increase seeding year yields without reducing perennial forage establishment. Trials were seeded in two different years at Saskatoon and Melfort, SK, in the Dark Brown and Black soil zones, respectively. Crested wheatgrass [Agropyron cristatum (L.) Gaertn.], meadow bromegrass (Bromus riparius Rehm.), and alfalfa (Medicago sativa L.) were seeded in pure stands and mixtures with or without an annual ryegrass (Lolium multiflorum Lam.) or Festulolium (Lolium × Festuca) companion crop at two seeding rates. Forage dry matter yield in the establishment year was increased with annual ryegrass companion crops compared with no companion crop regardless of seeding rate, but was increased only with the higher rate of Festulolium at Saskatoon. Despite using low companion crop seeding rates, stand densities of most of the perennial forage stands were lower than with no companion crop at Saskatoon, but in Melfort, most stand densities did not differ. The annual ryegrass companion crop reduced yields the year after seeding at both sites, while the Festulolium also reduced yields, but not at Melfort for the lower companion crop seeding rate. Dry matter yields were usually not different between companion and no companion crop treatments in the second year after seeding and for 3-yr total yields. The use of these companion crops increased the percentage of the 3-yr total yield produced in the seeding year.

An economic analysis of resting versus nonresting perennial pastures during the critical acclimation period

Economic evaluations were carried out on stochastically simulated production systems using data from a grazing systems’ trial, which evaluated the impact of resting (i.e., grazing cessation) alfalfa (Medicago sativa L.) – bromegrass (Bromus riparius Rehm. ‘Fleet’) and grass-only (G) pastures during the critical prefrost period on beef cattle (Bos taurus) productivity. Grazing systems were compared on the basis of calculated net present value of returns analysis. Lower production costs through reduced fertilization requirements resulted in alfalfa–grass (AG) preference over G pastures, while returns from increased calf sale weights resulted in nonrested systems being preferred over rested systems. However, low presence of alfalfa in the AG pastures likely limited the potential for resting pastures to improve production through increased alfalfa persistence. This evaluation found nonrested grazing of AG pastures to be preferred over other treatments on the basis of increased returns and reduced risk.

Forage yield of simple and complex grass–legume mixtures under two management strategies

Foster, A., Vera, C. L., Malhi, S. S. and Clarke, F. R. 2014. Forage yield of simple and complex grass–legume mixtures under two management strategies. Can. J. Plant Sci. 94: 41–50. Limited information is available on the dry matter production, protein content and species composition of complex mixtures of introduced perennial forage crop species for hay and pasture in the moister regions of Saskatchewan. A field experiment was sown on 2008 May 27 at Melfort, Saskatchewan, Canada, on a thick Black Chernozem (Udic Boroll) silty clay soil, to compare the effects on dry matter yield (DMY), protein content and species composition of perennial forage crop monocultures and mixtures, under a two-cut and a three-cut management system, in 2009, 2010, 2011 and 2012. Eleven treatments consisted of monocultures of hybrid bromegrass (Bromus riparius Rehm.×Bromus inermis Leyss.), smooth bromegrass (Bromus inermis Leyss.), crested wheatgrass [Agropyron cristatum (L.) Gaertn], intermediate wheatgrass [Agropyron intermedium (Host.) Beauv.] and alfalfa (Medicago sativa L.); simple mixtures of each of these individual grass species with alfalfa; a more complex mixture of all these grass species and alfalfa, and a very complex mixture consisting of the complex mixture plus meadow bromegrass (Bromus riparius Rehm.), orchardgrass (Dactylis glomerata L.), tall fescue [Festuca arundinacea (Schreb.) Wimm.], timothy (Phleum pratense L.) and slender wheatgrass [Elymus trachycaulus (Link) Gould ex Shinners]. The alfalfa was inoculated with rhizobium, and no fertilizer was added to any treatment during the course of the study. The two-cut system yielded higher than the three-cut system in all years. In 2009, the first cutting year, all treatments, especially under the two-cut system, produced similar forage DMY, with monoculture grasses yielding as much as that of their mixture with alfalfa. In 2010, 2011 and 2012, however, monoculture alfalfa and grass–alfalfa treatments had higher DMY than the monoculture grasses. Monoculture alfalfa also showed superior DMY than most grass–alfalfa mixtures, especially during the last 2 yr of the study. In conclusion, the inclusion of alfalfa in forage mixtures, grown in unfertilized soil, significantly increased forage yield, especially after the first production year, and these grass–alfalfa mixtures yielded almost as much as monoculture alfalfa. Also, the inclusion of alfalfa significantly increased the forage protein content over the grass alone treatments. Hybrid bromegrass, grown alone or in mixture with alfalfa, yielded similar to the other grasses tested, while crested wheatgrass did not compete as well as other main grasses, grown alone or in mixture with alfalfa. In this study, the use of complex or very complex mixtures of introduced grasses with alfalfa did not increase DMY over the simple grass–alfalfa mixtures.

Responses of Three Bromegrass (Bromus) Species to Defoliation under Different Growth Conditions

Bromegrass species are important forage crops in temperate regions of world. This study compared responses of three bromegrass species to defoliation in the greenhouse and field to determine if the former could predict responses in the latter. Experiments were conducted in 2006 and 2007 in Saskatoon (52°07′N,106°38′W), Canada on meadow bromegrass (Bromus ripariusRehm.), smooth bromegrass (Bromus inermisLeyss.), and hybrid bromegrass (B. ripariusX B.inermis) following defoliation to 5 cm stubble height. When defoliated at the vegetative stage, above-ground biomass was similar among the three species in the field, but meadow bromegrass produced greater above-ground biomass than smooth bromegrass in the greenhouse. When defoliated at the stem elongation stage, meadow bromegrass produced greater above-ground biomass than smooth bromegrass in both environments. In the field, for all defoliation treatments, tiller number was greatest in meadow bromegrass, intermediate in hybrid bromegrass, and least in smooth bromegrass. In the greenhouse, however, the three species did not differ in tiller number. Similar results were found for below-ground biomass. Thus, testing the effect of defoliation in the greenhouse environment did not accurately predict the effect in the field environment.