Mixed Species Seeding: A Means to Increase Production in Temperate Pastures

Seeding mixed species for forage production has been suggested as a means of increasing productivity and stabilizing yields under a changing climate. Forages have traditionally been sown as monocultures or binary mixtures only, with the emphasis being on species and not necessarily their function or compatibility. While natural plant communities typically may be dominated by a single species, they are comprised of several species and function-al groups. This paper provides the results of sowing multiple species at semiarid sites within the North American Great Plains and identifies a similar result from a more humid region reported within the literature

Land use change and ecosystem service provision in Pampas and Campos grasslands of southern South America

New livestock production models need to simultaneously meet the increasing global demand for meat and preserve biodiversity and ecosystem services. Since the 16th century beef cattle has been produced on the Pampas and Campos native grasslands in southern South America, with only small amounts of external inputs. We synthesised 242 references from peer-reviewed and grey literature published between 1945 and mid-2015 and analysed secondary data to examine the evidence on the ecosystem services provided by this grassland biodiversity hotspot and the way they are affected by land use changes and their drivers. The analysis followed the requirements of systematic review from the PRISMA statement (Moher et al 2009 Acad. Clin. Ann. Intern. Med. 151 264–9). The Pampas and Campos provide feed for 43 million heads of cattle and 14 million sheep. The biome is habitat of 4000 native plant species, 300 species of birds, 29 species of mammals, 49 species of reptiles and 35 species of amphibians. The soils of the region stock 5% of the soil organic carbon of Latin America on 3% of its area. Driven by high prices of soybean, the soybean area increased by 210% between 2000 and 2010, at the expense of 2 million ha (5%) of native grassland, mostly in the Pampas. Intensification of livestock production was apparent in two spatially distinct forms. In subregions where cropping increased, intensification of livestock production was reflected in an increased use of grains for feed as part of feedlots. In subregions dominated by native grasslands, stocking rates increased. The review showed that land use change and grazing regimes with low forage allowances were predominantly associated with negative effects on ecosystem service provision by reducing soil organic carbon stocks and the diversity of plants, birds and mammals, and by increasing soil erosion. We found little quantitative information on changes in the ecosystem services water provision, nutrient cycling and erosion control. We discuss how changing grazing regimes to higher forage allowance can contribute to greater meat production and enhancing ecosystem services from native grasslands. This would require working with farmers on changing their management strategies and creating enabling economic conditions. (Résumé d'auteur

Forage nutritive value and predicted fiber digestibility of Kernza intermediate wheatgrass in monoculture and in mixture with red clover during the first production year

Kernza intermediate wheatgrass is thefirst perennial grain crop in the world and has been de-veloped with conventional breeding to increase seed yield of forage intermediate wheatgrass(Thinopyrum intermedium(Host) Barkworth & D.R. Dewey). When managed for dual-use (grainand forage), Kernza intermediate wheatgrass can produce grain, crop residue (straw) in thesummer, and green forage in the spring and fall. Mixtures of this grass with legumes could in-crease forage yield and nutritive value and provide other environmental and economic benefits.Despite the growing interest in these dual-use production systems, forage nutritive value ofKernza intermediate wheatgrass forage in a dual-use system in the Upper Midwest is unknown. Areplicatedfield experiment was established in two locations in southern Wisconsin (Arlingtonand Lancaster) with two treatments: Kernza intermediate wheatgrass grown in monoculture andmixture with red clover (Trifolium pratenseL.). Forage samples were collected at late vegetativestage in the spring, at grain harvest in the summer, and at the end of the regrowth period in thefall. Forage nutritive value of the monoculture was greatest in the spring with 456, 249 and 225 gkg−1for neutral detergentfiber (NDF), acid detergentfiber (ADF) and crude protein (CP), re-spectively; lowest in the summer with 702, 427 and 51 g kg−1NDF, ADF and CP, respectively,and intermediate in the fall with 590, 337 and 119 g kg−1NDF, ADF and CP, respectively.Predicted total-tract neutral detergentfiber digestibility (ttNDFD) was 0.53 for the spring forageand averaged 0.37 for the summer and fall forage, with no differences between the mixture andmonoculture. The relative forage quality (RFQ) for the monoculture was 175 for the springforage, 65 for the summer residue, and 116 for the fall. Intercropping red clover with Kernzaintermediate wheatgrass increased CP of the summer crop residue by 69%, and increased CP andRFQ of the fall forage by 49% and 11%, respectively, while reducing NDF and ADF of the fallforage by 25% and 18%, respectively. Therefore, Kernza intermediate wheatgrass forage is sui-table for lactating beef cows, dairy cows, and growing heifers when harvested in the spring andfall, and it offers high potential for dual-use grain and forage systems

Methane emission and milk production of dairy cows grazing pastures rich in legumes or rich in grasses in Uruguay

Understanding the impact of changing pasture composition on reducing emissions of GHGs in dairy grazing systems is an important issue to mitigate climate change. The aim of this study was to estimate daily CH4 emissions of dairy cows grazing two mixed pastures with contrasting composition of grasses and legumes: L pasture with 60% legumes on Dry Matter (DM) basis and G pasture with 75% grasses on DM basis. Milk production and CH4 emissions were compared over two periods of two weeks during spring using eight lactating Holstein cows in a 2 × 2 Latin square design. Herbage organic matter intake (HOMI) was estimated by chromic oxide dilution and herbage organic matter digestibility (OMD) was estimated by faecal index. Methane emission was estimated by using the sulfur hexafluoride (SF6) tracer technique adapted to collect breath samples over 5-day periods. OMD (0.71) and HOMI (15.7 kg OM) were not affected by pasture composition. Milk production (20.3 kg/d), milk fat yield (742 g/d) and milk protein yield (667 g/d) were similar for both pastures. This may be explained by the high herbage allowance (30 kg DM above 5 cm/cow) which allowed the cows to graze selectively, in particular in grass sward. Similarly, methane emission expressed as absolute value (368 g/d or 516 L/d) or expressed as methane yield (6.6% of Gross Energy Intake (GEI)) was not affected by treatments. In conclusion, at high herbage allowance, the quality of the diet selected by grazing cows did not differ between pastures rich in legumes or rich in grasses, and therefore there was no effect on milk or methane production.Fil: Dini, Yoana. Universidad de la Republica; UruguayFil: Gere, José Ignacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Briano, Carolina. Universidad de la República; UruguayFil: Manetti, Martin Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Juliarena, María Paula. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Picasso, Valentin. Universidad de la República; UruguayFil: Gratton, Roberto. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Astigarraga, Laura. Universidad de la República; Urugua

Leys from a Nordic perspective

The project involved creating a popular scientific review of the cultivation and use of leys for livestock. Target groups are the agricultural sector and industry. The project had four work packages (WP): crop production, harvest and conservation, feed value for different animals, and economy. Within each work package, search strings were developed and inclusion criteria defined, and a database for each WP developed through searching in online databases. Each selected article was assessed first on the title (include or exclude), second based on reading the abstract, and third based on reading the article. The review provides an extensive list of literature related to ley production and use, a description of the most important findings, and suggestions for future research

Diversity, productivity, and stability in perennial polycultures used for grain, forage, and biomass production

The objective of this dissertation was to determine to what extent plant species diversity affects biomass and seed productivity, weed invasion, and stability in perennial herbaceous polycultures across three years, two harvest management regimes, and two locations in central Iowa, USA. Average biomass productivity consistently increased in polycultures with increasing species richness across all environment-years. In most situations, polycultures were more productive than the average of monocultures, but not more productive than the best adapted species in monoculture for each environment. Polyculture overyielding was due to complementarity among species in the community rather than to selection effects of individual species at all richness levels across environments and was likely explained by legume-grass facilitation. Polycultures with high richness had lower variability in yield (i.e., greater stability) than the highest yielding monocultures. Seeds of two perennial grain species were harvested; intermediate wheatgrass produced up to 65.8 ± 6.5 g m-2 of seed and Illinois bundleflower up to 55.0 ± 8.1 g m-2. Plant breeding and better agronomic management are needed to increase these yields in the near future to be practical for production situations. The mixture comprising both perennial grains produced as much seed as the best yielding monoculture each year. Polycultures of Illinois bundleflower with C4 grasses and polycultures of intermediate wheatgrass with legumes produced as much seed as the monocultures. Weed biomass decreased exponentially with seeded species richness in all environments. Most polycultures exerted greater weed suppression than perennial grain monocultures but also they had reduced seed yields. Breeding and management of crop mixtures to optimize the trade-off between seed yield and weed suppression is a central challenge for the development of perennial polyculture systems. The dialogue between Ecology and Agriculture provides a basis for designing sustainable production systems

Post-Harvest Management Practices Impact on Light Penetration and Kernza Intermediate Wheatgrass Yield Components

Kernza intermediate wheatgrass (Thinopyrum intermedium) is the first commercially developed perennial grain crop in North America, with multiple environmental and economic benefits. One of the major challenges for adoption of this dual-use forage and grain crop is the decline in grain yield in subsequent harvest years. Post-harvest management practices (e.g., chopping, burning, chemical, and mechanical thinning) could reduce the intraspecific competition for light and maintain Kernza grain yields over time. We aimed to identify management practices that improve light penetration and propose a conceptual model to explain the mechanisms contributing to Kernza grain yield. We applied 10 management practices after the first Kernza grain harvest in a randomized complete block design experiment with three replications, at two different locations in Wisconsin, USA. Light penetration increased when post-harvest management practices were applied. Mechanical or chemical thinning had relatively lower lodging and increased yield components per row, but not per area due to a reduction in the number of productive rows. Threshed grain yield per area in the second year of Kernza was similar among the treatments despite the differences in vegetative biomass generated. Further research is needed to optimize management practices to maintain Kernza grain yield over time

Post-Harvest Management Practices Impact on Light Penetration and Kernza Intermediate Wheatgrass Yield Components

Kernza intermediate wheatgrass (Thinopyrum intermedium) is the first commercially developed perennial grain crop in North America, with multiple environmental and economic benefits. One of the major challenges for adoption of this dual-use forage and grain crop is the decline in grain yield in subsequent harvest years. Post-harvest management practices (e.g., chopping, burning, chemical, and mechanical thinning) could reduce the intraspecific competition for light and maintain Kernza grain yields over time. We aimed to identify management practices that improve light penetration and propose a conceptual model to explain the mechanisms contributing to Kernza grain yield. We applied 10 management practices after the first Kernza grain harvest in a randomized complete block design experiment with three replications, at two different locations in Wisconsin, USA. Light penetration increased when post-harvest management practices were applied. Mechanical or chemical thinning had relatively lower lodging and increased yield components per row, but not per area due to a reduction in the number of productive rows. Threshed grain yield per area in the second year of Kernza was similar among the treatments despite the differences in vegetative biomass generated. Further research is needed to optimize management practices to maintain Kernza grain yield over time

Greenhouse Gas Emissions of Beef Cow-Calf Grazing Systems in Uruguay

Evaluating greenhouse gas (GHG) emissions at farm level is an important tool to mitigate climate change. Livestock account for 80% of the total GHG emissions in Uruguay, and beef cow-calf systems are possibly the largest contributors. In cow-calf grazing systems, optimizing forage allowance and grazing intensity may increase pasture productivity, reproductive performance, beef productivity, and possibly reduce GHG emissions. This study estimated GHG emissions per kg of live weight gain (LWG) and per hectare from 20 cow-calf systems in Uruguay, with different management practices. The GHG emissions were on average 20.8 kg CO2-e.kg LWG-1, ranging from 11.4 to 32.2. Beef productivity and reproductive efficiency were the main determinants of GHG emissions. Five farm clusters were identified with different productive and environmental efficiency by numerical classification of relevant variables. Improving grazing efficiency by optimizing the stocking rate and forage production can increase beef productivity by 22% and reduce GHG emissions per kg LWG by 28% compared to “low performance” management. Further improvements in reproductive efficiency can increase productivity by 41% and reduce GHG emissions per kg LWG by 23%, resulting in a “carbon smart” strategy. However, the most intensified farms with highest stocking rate and beef productivity, did not reduce GHG emissions per kg LWG, while increased GHG emissions per ha compared to the carbon smart. This analysis showed that it is possible to simultaneously reduce carbon footprint per kg and per ha, by optimizing grazing management. This study demonstrated that there is high potential to reduce cow-calf GHG emissions through improved grazing management