Environmental impacts of grazed clover/grass pastures

peer-reviwedGrazed clover/grass pastures are important for animal production systems and the clover component is critical for its contribution to N inputs via biological fixation of atmospheric N2. The resource efficiency and environmental emissions for clover/grass pastures can differ from that of N-fertilised grass-only pastures. Fixation of N2 by clover uses photosynthetically- fixed carbon, whereas fertiliser N production consumes fossil fuels and has net greenhouse gas (GHG) emissions. Clover has a higher phosphorus (P) requirement than grass and where extra P fertiliser is used for clover/grass pastures the risk of P loss to waterways is greater than for grass-only pastures. Nitrogen leaching from grazed pasture increases exponentially with increased N inputs and urinary-N contributes 70 to 90% of total N leaching. However, the few studies comparing clover/grass and N-fertilised grass-only pastures at similar total N inputs indicated similar N leaching losses. Nitrous oxide emissions from grazed pastures due to N-cycling of excreta are similar for clover/grass and N-fertilised grass-only pastures at similar total N inputs. However, grass-only pasture requires the application of N fertiliser, which will result in additional specific losses that don’t occur from clover-fixed N. Thus, total N2O emissions are generally higher for N-fertilised grass pastures than for clover/grass pastures. A summary of various whole-system and life cycle assessment analyses for dairy farms from various countries indicated that at similar total N inputs, clover/grass pasture systems can be more efficient than N-fertilised grass systems per kilogram of milk produced from an energy use and GHG perspective whereas results for nutrient losses to waterways were mixed and appear to be similar for both pasture types. In practice, other management practices on farm, such as crop integration, supplementary feeding strategy and winter management, can have a larger overall effect on environmental emissions than whether the N input is derived from fertiliser N or from N2 fixation

Environmental impacts of grazed pastures

Large nitrogen (N) surplus and return of excreta-N in localised patches at high N rates in intensively grazed pasture systems markedly increases the risk of N losses to waterways and the atmosphere. Here are described the main routes of N input to grazed pastures, losses via N leaching, methane (CH4) and nitrous oxide (N2O) emissions. Furthermore farm N budgets and N use efficiency in relation to management strategies that can be applied to reduce N losses are discussed. Nitrate leaching increases exponentially with increased inputs and is closely related to urine patches, which also influence the leaching of dissolved organic N. High N2O emission rates in grazed pastures are related to fertiliser-N or N in excreta combined with compaction by animal treading. Grazing may considerably reduce CH3 emissions compared to indoor housing of cows. Pastures are occasionally cultivated due to sward deterioration followed by a rapid and extended period of N mineralization, contributing to an increased potential for losses. Good management of the pasture (e.g. reduced fertiliser input and reduced length of grazing) and of the mixed crop rotation during both the grassland and the arable phase (e.g. delayed ploughing time and a catch crop strategy) can considerably reduce the negative environmental impact of grazing. It is important to consider the whole farm system when evaluating environmental impact. In particular for green house gasses since the pasture may serve as a source of N2O and indirectly of CH3, but also as a sink of CO2 influenced by management practices on the farm

The Change in Macroalgal Assemblages through the Saldanha Bay/Langebaan Lagoon Ecosystem (South Africa)

Saldanha Bay and Langebaan Lagoon form together one of the few sheltered habitats within the Benguela Marine Province; a wide gradient in environmental factors is found here. The West Coast National Park was established to protect this unique ecosystem, but at the same time an industrially expanding harbour marks this area. In an effort to understand the biological composition of the Saldanha/Langebaan ecosystem, the intertidal macroalgal assemblages were studied in relation to the relatively well-known South African West Coast flora. Three distinct floral entities were identified using various analytical techniques (similarity coefficients, CCA and TWINSPAN): (i) the species poor, though distinct, salt marshes; (ii) the Lagoon sites; and (iii) the Bay and West Coast sites. The transition between the latter two is located at the mouth of the Lagoon. The species richness of the Bay/West Coast entity is larger than in the Lagoon. The change in algal composition can be explained in terms of the environmental variables of which wave exposure is the most significant. Other important environmental parameters are water surface temperature and salinity, which were found to be negatively correlated with wave exposure. Biogeographical affinities of the different algal entities of the Bay/Lagoon system were also determined in relation to the entire South African shoreline. The Bay/West Coast entity supports a typical West Coast flora, with some noticeable effects of uplift of subtidal species into the infralittoral fringe and morphological variation in less exposed areas. The algal flora of the Lagoon is also dominated by West Coast species, but is typified by species characteristic of sheltered habitats, and with a number of species which otherwise only occur on the geographically distant South Coast (east of Cape Agulhas). The algae from the salt marshes occur widely in tropical mangroves and warm temperate salt marshes

Minder klaver en lagere groei bij low-input systeem in 1996

Vanaf najaar 1994 wordt op de Waiboerhoeve onderzoek gedaan naar de ontwikkeling van een low-input schapenhouderij systeem. Op dit bedrijf ligt het dek- en aflamseizoen enkele maanden later dan op de traditionele schapenbedrijven. Verder krijgen zowelde ooien als de lammeren geen krachtvoer en is er geen huisvesting. In eerdere artikelen is al ingegaan op de proefopzet en de geboorte resultaten. In dit artikel gaan we in op het graslandgebruik, klaveraandeel, gezondheidszorg, en de groei en classificatie van de lammeren op de Waiboerhoeve tijdens het tweede weideseizoe

Low-input systeem schapen: voederwaarde gras/klaver, groei lammeren en classificatie op hoog niveau

In dit artikel gaan we in op het graslandgebruik, samenstelling van het grasklavermengsel de gezondheidszorg, groei en classificatie van de lammeren in het afgelopen jaar

Emissies van lachgas, methaan en ammoniak uit mest na scheiding = Emissions of nitrous oxide, methane and ammonia from manure after separation

It is expected that separation of animal slurry in the Netherlands in coming years will increase as a result of the manure legislation. Against this background the effect of slurry separation on the emission of greenhouse gasses and ammonia during storage and after field application was studied. It is expected that due to slurry separation in the Netherlands in 2020 the greenhouse gas emissions will be slightly lower than the current level. Slurry separation has no effect on the emission of ammonia

Low-inputsysteem schapen: de groei van gras en lammeren in 1998

De groei van lammeren in dit systeem is vooral afhankelijk van de graslandproductie, de kwaliteit van het gras en de gezondheidsstatus van de lammeren

Stikstofwerking van runderdrijfmest bij gebruik zodebemester

Ongeveer de helft van de totale ammoniakemissie in de Nederlandse rundveehouderij is afkomstig van verliezen tijdens of na de mestaanwending

Phylogenomic assessment prompts recognition of the Serianthes clade and confirms the monophyly of Serianthes and its relationship with Falcataria and Wallaceodendron in the wider ingoid clade (Leguminosae, Caesalpinioideae)

The Indo-Pacific legume genus Serianthes was recently placed in the Archidendron clade (sensu Koenen et al. 2020), a subclade of the mimosoid clade in subfamily Caesalpinioideae, which also includes Acacia, Archidendron, Archidendropsis, Falcataria, Pararchidendron, Paraserianthes and Wallaceodendron. Serianthes comprises ca. 18 species, five subspecies and two varieties that are characterised by bipinnately compound leaves with alternate sessile leaflets, branched axillary corymbiform panicles and woody indehiscent pods. Generic relationships, as well as species relationships within genera in the Archidendron clade, remain uncertain. While the sister relationship between Serianthes and the genus Falcataria is strongly supported by molecular data, the distinction between Serianthes and the monotypic genus Wallaceodendron has been questioned, based on their similar flower and fruit morphologies. We combined three gene-enriched hybrid capture DNA sequence datasets (generated from the 964 mimobaits v1 probe set, the expanded 997 mimobaits v2 probe set and the GoFlag angiosperm 408 probe set) and used their overlapping markers (77 loci of the target exonic and flanking regions) to test the monophyly of Serianthes and to investigate generic relationships within the Archidendron clade using 55 ingoid plus two outgroup taxa. We show that Serianthes is monophyletic, confirm the Serianthes + Falcataria sister relationship to Wallaceodendron and recognise this combined clade as the Serianthes clade within the Archidendron clade. We also evaluated the use of overlapping loci across datasets in combination with concordance analyses to test generic relationships and further investigate previously unresolved relationships across the wider ingoid clade. Concordance analysis revealed limited gene tree conflicts near the tips of the Archidendron clade, but increased discordance at the base of the clade, which could be attributed to rapid lineage divergence (radiation) and/or incomplete lineage sorting