Infective larvae of Haemonchus contortus found from the base to the top of the grass sward

The resistance of gastrointestinal nematodes (GIN) of sheep to anthelmintic treatment has motivated researchers to seek alternatives to reduce the use of these drugs in sheep farming and decontaminate pastureland based on knowledge about the survival dynamics of larvae. The aim of this work was to evaluate the migration of the infective larvae (L3) of Haemonchus contortus at different times of the day, strata, and sward heights, with and without shade after the deposition of contaminated sheep feces. The grass species used here was Cynodon dactylon cv. Tifton 85 in four treatments: low sward height shade; low sward height sunshine; high sward height shade; and high sward height sunshine. The number of L3 recovered from the pasture at different times of the day did not differ. The highest number of L3 recovered was in shade. The number of L3 at different times and strata occurred uniformly, confirming that L3 remain in the same place after migrating from dung at the hottest times of the day. Infective larvae of H. contortus were able to migrate across all the strata regardless of the time of day in the summer season in humid subtropical climate.

Performance and nutrient utilisation of dairy cows offered silages produced from three successive harvests of either a red clover–perennial ryegrass sward or a perennial ryegrass sward

The need to reduce reliance on imported protein feeds within the UK and Ireland has stimulated interest in locally grown forage legume crops, including red clover ( Trifolium pratense L.). This 13-wk study examined the performance of 28 dairy cows offered silages produced from three successive harvests (H) of either a pure grass sward (GS) receiving 315 kg N/ha per annum or a red clover–perennial ryegrass sward (RCGS) receiving 22 kg N/ha per annum. The crops of H1, H2 and H3 were wilted for 48, 72 and 72 h, respectively. Silages from H1, H2 and H3 were offered for 5, 5 and 3 wk, respectively, with cows supplemented with 8.0 kg concentrate/d throughout the experiment. Digestibility of DM and the effectively degradable protein content were lower, while protein degradability was higher, for RCGS than for GS. Silage DM intakes (DMIs) were higher for RCGS than for GS at H1 and H2, with no differences at H3. Milk yield was higher with RCGS than with GS at H3, with no differences at H1 and H2. Milk fat and milk protein contents were lower with RCGS than with GS at H3 but did not differ at H1 and H2. Faecal N/N intake was higher in the RCGS group than in the GS group at H1, with no differences at H2 and H3. Gross energy digestibility was lower for RCGS than for GS at H2. Although cow performance was higher with RCGS treatment, the responses were variable between harvests, largely reflecting the changing proportion of RC in the swards as the season progressed.

Effect of Pasture Management System Change on In-Season Inorganic Nitrogen Pools and Heterotrophic Microbial Communities

It has been assumed that the system of long-term pasture management exerts a significant impact on the soil microorganisms count, subsequently affecting the availability of mineral nitrogen (Nmin). This hypothesis was tested in a three-year experiment on a long-term pasture with two distinct systems of grass sward management, i.e., grazing and mowing. Mowing significantly increased the microorganisms count by 13%, 28%, 86%, and 2% for eubacteria (EU), actinobacteria (AC), molds (MO), and Azotobacter (AZ), respectively. The main reason was drought in 2006, which resulted in the domination of Dactylis glomerata L. in the grass sward, instead of Lolimum perenne L. and Poa pratensis L. The content of Nmin decreased through the vegetative growing season, reaching its lowest value after the 3rd grazing cycle. The impact of microorganisms on the Nmin pools increased in the order: molds < eubacteria < actinobacteria. The count of actinobacteria in the alkaline organic soil increased in response to drought, contribution of Dactylis glomerata L. in the sward, and the shortage of available phosphorus. The sound pasture management system is possible by introducing alternate grazing and mowing cycles. The core of sustainability is the enhanced activity of actinobacteria after changing the system from grazed into mowed.

Effects of grassland renewal and submerged drains on greenhouse gas exchange at an intensively managed bog peat soil

&lt;p&gt;Intact peatland ecosystems are efficient sinks of atmospheric carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;). Disturbance, e.g. by drainage to transform peatlands into agricultural land, causes high emissions of the greenhouse gases (GHG) CO&lt;sub&gt;2&lt;/sub&gt; and nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O). Our Project &amp;#8220;Gnarrenburger Moor&amp;#8221; focuses on the evaluation of the effects of submerged drains on GHG emissions and dissolved solute losses from bog peat under intensive grassland management. Due to installation of the water management system, grassland renewal was necessary at one of our two experimental grassland sites, both being located in Northwest Germany and subjected to similar management in the past. Here, we report on the initial year of the project, which was dominated by the impact of grassland renewal as target groundwater levels were only reached after several months.&lt;/p&gt;&lt;p&gt;The reference site, representing common region-specific grassland management on peat, is deeply drained by tile drains, while submerged drains were installed at the project site to achieve constantly high water levels of 30 to 40 cm below ground. Both sites are equipped with eddy covariance towers for CO&lt;sub&gt;2&lt;/sub&gt; measurements and 6 plots for manually measuring N&lt;sub&gt;2&lt;/sub&gt;O and methane (CH&lt;sub&gt;4&lt;/sub&gt;) with closed chambers. Water samples for the analysis of phosphorus and nitrogen species are collected from ditches, tile drains and suction plates at 15, 30 and 60 cm depths. Measurements started in March 2019, i.e. approximately one month before the grassland renewal. The mechanical renewal involved mulching of the old grass sward and grading the surface of the site. Due to very dry conditions, growth of grass species was poor and the site was mulched and re-seeded again in July 2019. Target groundwater levels were reached in September 2019.&lt;/p&gt;&lt;p&gt;During the initial year of our study, grassland renewal substantially dominated the response of the system. From April to November, net ecosystem exchange of the project site was approximately 400&amp;#160;g&amp;#160;C&amp;#160;m&lt;sup&gt;-2&lt;/sup&gt; higher than that of the reference site. When including carbon input and output from organic fertilizer and harvest on the reference site, the project site is still by far (around 140 g C m&lt;sup&gt;-2&lt;/sup&gt;) a larger source. When the bare soil and raising groundwater levels coincided between July and September, N&lt;sub&gt;2&lt;/sub&gt;O fluxes and dissolved nitrogen and phosphorus concentrations drastically increased at the project site. N&lt;sub&gt;2&lt;/sub&gt;O fluxes were partially 100 times higher than at the reference site. The next years will show whether an operational water management system and a fully developed grass sward will turn the project site with submerged drains into a smaller source of GHGs than the reference site.&lt;/p&gt;

Grass species selection to control for concentrated flow erosion in grassed waterways.

&lt;p&gt;Grassed waterways reduce water runoff, prevent scouring and encourage sediment deposition from erosion prone land. The aim of this study was to assess the efficacy of conventional and novel grass species (as monocultures and mixtures) to control erosion, at an early establishment stage (6 weeks), within grassed waterways. The experimental treatments included bare soil (B), a conventional mix of Lolium perenne and Festuca rubra (C), Festulolium cv prior (F1), Festulolium cv prior and Festulolium bx511 (F1+F2), and all grass species combined (F1+F2+C). F1 is adapted to flooded conditions, whilst F2 is adapted to drought conditions. With climate change in the UK likely to result in drier summers and wetter winters these Festulolium species will be adapted to future climatic conditions. However, little is known about their efficacy within grassed waterways. The grasses were established in 1.2 x 1 x 0.5m macrocosms in a sandy clay loam soil during June-Aug, 2019. A sub sample of each experimental treatment was taken (0.3 x 0.1 x 0.1m) from the macrocosms within a stainless steel box. Tests were replicated in quadruplicate.&lt;br&gt;The following above ground trait (Stem area density) and the following below ground traits (Total root length of fine roots &lt;0.25mm, root diameter and root surface area) were determined for each experimental replicate. Prior to testing, the grass was cut to circa 3.0 cm height to represent a mowed grass sward before being placed into a fully instrumented hydraulic flume. The hydraulic flume simulated a concentrated flow event and treatment performance was assessed in terms of turbidity, sediment concentration, soil loss and flow velocity.&lt;br&gt;The effects of roots+shoots and of roots only on performance indicators were determined to quantify the relative contribution of above ground vs below ground traits in controlling erosion. One set of replicates was tested only with roots whilst another set of replicates was tested with roots+shoots and then with roots only. This was done to isolate the effect of below ground and above ground traits.&lt;br&gt;All replicates were subjected to a concentrated flow event with increasing incremental flow velocities from 0.2-0.6l s-1 for bare soil, 0.2-0.8l s-1 for roots+shoots treatments and 0.2-1.4l s-1 for roots only treatments. Each flow rate velocity was run for 60 seconds. For each flow rate, duplicate water samples were taken downslope of the treatment and water depth was measured, upstream of the treatment, in the centre of the treatment and downstream of the treatment. &amp;#160;The water samples were used to determine sediment concentrations. The water depth measurements were used to determine runoff velocity. Furthermore, a turbidity meter continuously measured turbidity during the concentrated flow event. Soil detachment and transport rates were significantly reduced for all experimental treatments as compared to the bare soil (p&lt;0.05). Final treatment efficacy will be assessed based on a ranking of the key performance indicators. The knowledge gained from this research can be used and applied to other grassed soil erosion mitigation features such as in field and riparian buffer strips, swales as well as grassed waterways.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Establishment gaps in species-poor grasslands: artificial biodiversity hotspots to support the colonization of target species

Sowing of grass seed mixtures is a feasible and cost-effective method for landscape-scale grassland restoration. However, sowing only grasses usually leads to species-poor and dense grass sward, where the establishment of target forbs is hampered both by microsite and propagule limitation. To overcome these limitations and increase the diversity of species-poor sown grasslands we developed a novel method by creating ‘establishment gaps’. We used tillage to open gaps of 1 m2, 4 m2 and 16 m2 size in the dense grass sward of six species-poor sown grasslands in the Great Hungarian Plain. We sowed high-diversity seed mixtures of 35 native species into all gaps. We analyzed vegetation development during the first five years after setting up the trial. We also studied the colonization dynamics of the sown species along four 20-m transects around each gap, resulting in a total of 1440 plots of 1 m2 size that were studied. Our results indicated that most of the sown species were able to establish permanently in the establishment gaps. The total cover and the cover of perennial sown species increased independently of gap size. Meanwhile the cover of short-lived sown species decreased during the five years. There was only a moderate level of weed abundance in the gaps, and weed cover decreased over the years. The sown target species started to colonize the species-poor grasslands surrounding the establishment gaps within five years. The highest number of species and individuals dispersed from the 4 m2-sized gaps, as they had a more stable development than small gaps and were exposed to lower grazing pressure than large ones.Implications for practiceEstablishment gaps are widely applicable tools to increase the diversity of species-poor grasslands. Gaps of 4 m2 represent a more feasible solution compared to larger openings also for the farmers, because there is only a moderate level of weed encroachment and smaller soil disturbance occurs during their creation.We recommend sowing high-diversity seed mixtures containing both short-lived species that can establish in the first year and perennial species, which guarantee a high cover of target species later on.Gaps sown with high-diversity seed mixture are highly resistant to unfavorable climatic conditions: increasing grass abundance in dry years does not hamper the recovery of target grassland species in the following years.