Permanent Swards Research Articles

Accumulation of SOC and Carbon Fractions in Different Age Red Fescue Permanent Swards

One of the practices often mentioned to achieve climate change mitigation is the long-term cultivation of perennial plants. The objective of the study was to estimate changes in the accumulation of soil organic carbon (SOC) and its fractions in 0–10, 10–20, 20–30 cm, and within 0–30 cm soil layer of red fescue (Festuca rubra L.) swards that differ in age (5, 10 and 15 years) as well as to compare them with the arable field. Our results show that SOC accumulation at 5-year-old cultivation of red fescue is high, later this SOC increase slowed down from 71% in the 0–30 cm soil layer when land use was converted from arable field to 5-year-old sward to 1% from 10 to 15 years. The level of water extractable organic carbon (WEOC) in the 0–30 cm soil layer of swards was significantly higher compared to the arable field. The positive effect of these swards in the accumulation and stabilization of organic carbon during humification in the soil was also determined. The largest amounts of mobile humic substances (MHS) and mobile humic acids (MHA) accumulated in the 0–10 cm layer of sward soil (3.30–4.93 and 1.53–2.48 g kg−1, respectively). In conclusion, the findings suggest that a conversion from arable to soil under permanent grass cover significantly improves carbon status.

Milk production and quality from ewes grazing a plantain-chicory mixture or a grass-based permanent sward

Fat lamb production systems in humid-temperate regions rely heavily on grass-based permanent swards with a seasonal growth pattern: scarce in winter, copious in spring and slow or nil growth in dry summers. Plantain (Plantago lanceolata L.) and chicory (Cichorium intybus L.) are summer-active, tolerate water deficit and present a high nutritional quality. They start to grow in late winter (especially plantain) and can be grazed in mid-lactation by ewes suckling their lambs. This work compared milk production and quality of suckling ewes grazing a mixture of plantain-chicory (PCH) or a grass-based permanent sward (GBS) by early spring in two consecutive years. Nine Austral ewes (a local meat breed) in their 8th week post-partum were allocated to PCH and GBS treatments with three replications in two consecutive years. After a pre-experimental period, milk production was determined by the oxytocin method. Milk samples were obtained in the second year and analysed for fat, protein, total solids and urea. Pastures were sampled and analysed for nutritional composition. No effects of treatments were detected for milk production (average 1.43 L/d). PCH milk had lower total solids than GBS milk (19.57 vs. 21.80%, P < 0.01), lower fat (6.97 vs. 9.60%, P < 0.01) and lower urea (47.00 vs, 58.22 mg/100 g, P < 0.05), but protein concentration was higher for PCH than GBS milk (5.71 vs 5.18%, P < 0.05). In forage, total ash was higher (P < 0.05) in PCH than GBS (125.8 vs. 89.9 g/kg dry matter, DM), but lower in year 2016 than 2015 (97.9 vs. 117.7 g/kg DM, respectively). Differences (P < 0.05) were found between swards for NDF (PCH: 245.6; GBS: 394.1 g/kg DM) and years (2015: 372.3; 2016: 267.3 g/kg DM). Apparent DM intake was similar (P > 0.05) between years and swards, averaging 2.15 and 1.78 kg/d for PCH and GBS, respectively. It is concluded that plantain and chicory can be grazed by suckling ewes in mid-lactation without detrimental effects on their milk production or composition.

Variability in the critical phase of stem elongation of perennial ryegrass genotypes: a source for breeding progress?

SUMMARYPhenological development and its variation during reproductive growth have important effects on the yield and quality of forage grasses. In perennial ryegrass (Lolium perenne L.) genetic variation in heading date is well recognized, but there are no reliable studies about the variability in the length of the stem elongation phase. To determine the variation in phenological traits of single plants of perennial ryegrass genotypes, a field trial was conducted over three growing seasons (2011–2013) using plant material from eight different ecotype populations, sampled from old permanent grassland swards in Northern Germany. In addition to the phenological stages of jointing, heading and flowering, the critical phase of stem elongation was considered as a new phenological trait. It was hypothesized that the length of the critical phase between jointing and heading differs significantly among genotypes and thus offers a new tool for selecting for specific purposes, e.g. adaption to changing climatic conditions, cutting or grazing as well as yield and quality. The study revealed significant genotypic variation in the observed traits, which was highest for the critical phase (GCV = 0·21). Moderate heritability in jointing (h2 = 0·72) revealed a large environmental impact. In contrast, high heritability (h2 &gt; 0·86) in heading, flowering and the critical phase imply a strong genetic effect. Moderate to high genotypic and phenotypic coefficients of correlation revealed a substantial linkage among the phenological traits. Results are discussed in the context of providing different approaches and strategies in forage crop production, especially with regard to regional weather conditions and future climate change. Significant differences among the tested ecotype populations indicate that existing diversity in permanent grassland can provide source material for further progress in grass breeding.

Little grazer species effect on the vegetation in a rotational grazing system

To maintain and enhance phytodiversity of complex permanent swards, the choice of livestock is still being debated. In this study, vegetation composition, diversity and sward structure of permanent grassland were investigated in response to cattle, sheep or mixed grazing on two sward types differing in composition. The study was conducted in the Solling Uplands in Lower Saxony, Germany, in a triplicate randomized block design. The experimental site belongs to the plant association Lolio-Cynosuretum and is moderately species-rich. One half of the paddocks was treated with herbicides to achieve grass-dominated, species-poor swards (2007: 6.9±1.5speciesm−2, means±sd) in contrast to the diverse controls (10.3±2.9speciesm−2). Paddocks were grazed rotationally in three grazing cycles per year from 2007 to 2011; the vegetation was analyzed from 2007 to 2012. Vegetation composition showed a clear effect of herbicide-treatment, but was not significantly influenced by grazers within or after five years of grazing. With respect to vegetation composition and sward structure, there was no indication of complementary grazing between cattle and sheep in mixed stocking. The effects of grazers in this study were relatively minor and not consistently found. Sward structure, measured as coefficient of variation of sward height, was more heterogeneous in the second grazing cycle 2011 under cattle grazing in contrast to sheep grazing. In addition, the cattle-grazed diverse swards contained more species than the sheep-grazed ones in 2012. These results point toward a slight advantage of cattle grazing for the diversity of European grasslands in common agricultural practice.

Impact of floor vegetation on the abundance of nematode trophic groups in vineyards

This study examined the effect of two floor vegetation management strategies on the abundance of nematode trophic groups in two Australian vineyards (one cool and one warm climate) for three consecutive years. Throughout the grape growing season floor vegetation was managed either as a perennial sward by regular mowing/snipping (permanent sward) or eliminated by spraying herbicide (spray/bare soil). Soil from both treatments was inhabited by five nematode trophic groups namely bacteria feeders, predators, omnivores, fungal feeders and plant parasites. Of these, bacteria feeder nematodes were predominant, comprising 60–70% of the total population in each site. Predators and plant parasites comprised ca. 3% and 17% of the total population respectively at Wagga Wagga, and ca. 17% and 4% at Tumbarumba. In the sward plots by the end of the experiment, the populations of non-plant parasitic ‘beneficial’ nematodes (bacteria feeders, predators, omnivores and fungal feeders) had generally increased linearly with time whereas plant parasitic nematode populations had decreased. On the last sampling date, the total bacteria feeder nematode populations were ca. 3–4-fold and ca. 2–3-fold greater in the sward than the spray plots at Wagga Wagga and Tumbarumba vineyard respectively. Over three years, the omnivore nematode (primarily Dorylaimidae) populations were also significantly increased by ca. 2–6-fold and 3-fold in the sward plots compared to the spray plots at Wagga Wagga and at Tumbarumba vineyard respectively. Similarly, predatory nematodes in the sward plots were ca. 32–57% higher at Wagga Wagga and ca. 60–164% at Tumbarumba compared to the spray plots. In contrast, plant parasitic nematodes were ca. 4-fold greater in inter-row sward plots than the spray plots at Wagga Wagga but 3-fold lower at Tumbarumba. The plant parasitic nematode populations were decreased consistently over time for both treatments and soil layers until at the termination of the experiment when its populations were reduced below 100 m −2 in undervine soil in the Tumbarumba vineyard. Therefore, the overall results from this study showed that non-plant parasitic ‘beneficial’ nematodes were increased generally in plots with permanent swards, which in turn suppressed pest nematodes.

Permanent swards increase soil microbial counts in two Australian vineyards

This study examined the effect of permanent swards and bare soil (by repeated herbicide treatment) on soil microbial counts in Australian cool and warm climate vineyards. In both climates, hot water extractable soil C (HWC) in the vine row was increased by 73% after 3 years of sward development. Most of the soil bacterial counts were greatly decreased by the herbicide treatment and principal components analysis was able to clearly discriminate between microbial populations from the grassed and bare soil. In both the under-vine and inter-row soil, HWC was positively correlated with fungal counts and with cellulolytic, pseudomonad, copiotrophic and oligotrophic bacterial counts. HWC was also negatively correlated with soil bulk density. The grapevine rhizosphere bacterial population was dominated by cellulolytic bacteria in both climates. Many cellulolytic bacteria were slow growing, requiring up to 84 days of laboratory incubation. This study shows that permanent swards can significantly enhance the microbial community in vineyard soil.

Nitrous oxide emissions from artificial urine patches applied to different N‐fertilized swards and estimated annual N2O emissions for differently fertilized pastures in an upland location in Germany

Abstract. Artificial urine containing 20.2 g N per patch of 0.2 m2 was applied in May and September to permanent grassland swards of a long‐term experiment in the western uplands of Germany (location Rengen/Eifel), which were fertilized with 0, 120, 240, 360 kg N ha−1 yr−1 given as calcium ammonium nitrate. The effect on N2O fluxes measured regularly during a 357‐day period with the closed‐chamber technique were as follows. (1) N2O emission varied widely among the fertilized control areas without urine, and when a threshold water‐filled pore space &gt;60% was exceeded, the greater the topsoil nitrate content the greater the flux from the individual urine patches on the fertilized swards. (2) After urine application in May, 1.4–4.2% of the applied urine‐N was lost as N2O from the fertilized swards; and after urine application in September, 0.3–0.9% of the applied urine‐N was lost. The primary influence on N2O flux from urine patches was the date of simulated grazing, N‐fertilization rate being a secondary influence. (3) The large differences in N2O emissions between unfertilized and fertilized swards after May‐applied urine contrasted with only small differences after urine applied in September, indicating an interaction between time of urine application and N‐fertilizer rate. (4) The estimated annual N2O emissions were in the range 0.6–1.6 kg N2O‐N per livestock unit, or 1.4, 3.6, 4.1 and 5.1 kg N2O‐N ha−1 from the 0–360 kg ha−1 of fertilizer‐N. The study demonstrated that date of grazing and N‐fertilizer application could influence the N2O emission from urine patches to such an extent that both factors should be considered in detailed large‐scale estimations of N2O fluxes from grazed grassland.

Influence of sward botanical composition on performance of cool temperate grassland under contrasting nitrogen fertilization regimes

Eight field experiments, which tested the effects of lime, phosphorus (P), and two rates of nitrogen (N) on a range of permanent grassland swards in Northern Ireland (NI), were re‐examined to investigate the influence of sward botanical composition on aerial dry matter (DM) productivity under ‘low’ and ‘high’ levels of ? input. The aim of the investigation was to verify results previously obtained using ‘pure’ single‐species swards, which suggested that secondary grasses are more productive than perennial ryegrass at low levels of ? input (i.e., < 100 kg ? ha‐1 a‐1)#lb The swards used in the investigation varied considerably in botanical composition, but were largely dominated by three main species: perennial ryegrass (Lolium perenne L.), creeping bent (Agrostis stolonifera L.), and rough stalked meadow grass (Poa trivialis L.), all of which were characteristic of fertile habitats. The results confirmed that under reduced ? input management, swards dominated by these secondary grasses are capable of out‐performing those in which perennial ryegrass is a major component. The superior (aerial) productivity of the secondary grasses was attributed to their ability to conserve resources and maintain high shoot‐to‐root ratios under ‘moderate’ ? stress conditions.

Long-term fertilization effects on soil carbon under permanent swards

In a long-term study with four rates each of fertilizer N, P, and K in factorial combination on timothy (Phleum pratense L.), soil C concentration in the 0- to 15-cm layer of an Orthic Dystric Brunisol in New Brunswick ranged from 25 to 37 g C kg−1 after 26 yr, and from 26 to 44 g C kg−1 after 35 yr. Soil C concentration was not related to the wide range of aboveground net productivity resulting from contrasted long-term fertilization treatments. Soil C concentration, however, was negatively correlated to soil pH. Key words:Phleum pratense L., timothy, carbon, fertilization

Introduction of Annual Forage Species (Secale cereale L. and Lolium multiflorum Lam.) into Permanent Swards: A Technique to Improve Early Season Herbage Production and Nitrogen Uptake

ABSTRACT Permanent grassland soils can release surplus nitrogen (N) in autumn and winter but herbage growth is reduced by soil N deficiency in spring. The hypothesis that winter-growing rye or Italian ryegrass, oversown (strip-seeded) in autumn into permanent swards, might reduce these limitations was investigated in field trials in western Britain. Introduction of Italian ryegrass did not increase spring production and N recovery at any site. At two sites (on brown earth and sandy loam soils) rye introduction led to greater (p < 0.05) first-harvest (early April) herbage yield: DM yield was increased by 0.5 and 1.3 t ha−1 compared with unfertilized control and by 0.8 and 0.5 t ha−1 compared with swards receiving fertilizer N at 50 kg ha−1 without significant adverse effects on herbage digestibility. Herbage N uptake was increased by up to 17 kg ha−1. Soil inorganic-N concentrations in early spring were low. Reduced second-harvest herbage yields offset the production advantage of the rye treatment at the first harvest. Rye introduction had no significant effect at two other sites which had imperfectly drained clay/silty loam soils. Oversowing was associated with reduced white clover in the summer after oversowing. The technique is considered appropriate for providing early season forage in some situations, but the effects of soil type, sowing date and winter management require further investigation.

Response of permanent and reseeded grassland to fertilizer nitrogen. 2. Effects on concentrations of Ca, Mg, K, Na, S, P, Mn, Zn, Cu, Co and Mo in herbage at a range of sites

AbstractThe concentration of mineral elements in herbage from permanent swards of mixed species composition (predominantly Agrostis spp., Holcus lanatus, Festuca rubra, Lolium perenne, Poa spp., etc.) was compared with that from sown perennial ryegrass (Lolium perenne) at two fertilizer rates (0 and 300kg N ha−1 year−1, both with P and K) and with L. perennel Trifolium repens (at 0 N with P and K). The investigation was conducted over four years at sixteen contrasting sites in England and Wales. Herbage samples for mineral analysis were taken at first and fourth harvests (May and August) each year from plots under 4‐weekly cutting. There was a wide degree of variation between sites, particularly for concentrations of Ca, Mg, Na and all trace elements analysed. Herbage from L. perenne reseeds had significantly higher concentrations of Ca, Mg, Na, Co and S, but K, Mo, Zn, Cu and P were generally lower than in the permanent swards. L. perennel T. repens swards had the highest concentration of major cations, but trace element levels were generally intermediate between those for 0 N permanent and L. perenne swards. Fertilizer N reduced concentrations of Ca, Mn, Mo and S, and increased Mg, Na and Zn, with no consistent effects on K, Co and Cu. Herbage at harvest 4, compared with harvest 1, had higher Ca, Mg, Na, Mn, Zn and S. Permanent and L. perenne swards responded similarly to fertilizer N and between harvest dates. Results are discussed in relation to previous reports of botanical and fertilizer effects on mineral concentrations, and the mineral requirements of livestock. Changes in mineral concentration resulting from reseeding permanent swards are considered unlikely to increase mineral‐related livestock disorders, and in many cases could be beneficial, though problems might arise on sites where some elements, e.g. Cu and Mg, are low.

A comparison of the output from permanent swards containing clover or receiving nitrogen fertilizer when continuously grazed by ewes and lambs

AbstractA 2‐year experiment was designed to compare the output from a permanent grass sward, either containing clover (GC) or receiving 200kg N ha‐1 (GN), when continuously grazed by sheep stocked at 12 and 15 ewes ha‐1 on GC and 15 and 18 ewes ha‐1 on GN. Sward surface height (SSH) was controlled within designated guidelines by adjusting the size of the grazing area with an electrified ‘buffer’ fence; the herbage surplus to grazing requirement was cut and conserved. A dried grass supplement was offered to the sheep during periods of low herbage availability.The experiment was carried out during 1989 and 1990. No silage was made on GC15 in either year compared with 28 and 90kg DM ewe‐1 on GN15 in 1989 and 1990 respectively; supplementation was consistently and significantly greater on GC15 than on GN15. Clover proportion was generally higher on GC12 than GC15 (significant (P &lt;0·01) in September 1989) and reached a maximum level of 14%on GC12 in August 1990. Herbage organic matter digestibility was little affected by the inclusion of clover in the sward. Differences in lamb growth rate were not significant and, at the common stocking rate, there was no difference in lamb output between GC and GN.In 1990, GC12 and GN15 treatments proved to be successful after weaning in balancing the increasing nutritional requirements of the ewes during the period prior to mating, the requirements of a declining lamb population as the lambs satisfied the criteria for slaughter and were sold, and a continuing need to conserve surplus herbage. The metabolizable energy requirements of the ewes and lambs over 2 years were 75·8 and 74· 7 GJ ha‐1 for GC15 and GN15 respectively, and the differences in total utilized metabolizable energy output of the two systems were due to the amounts of herbage conserved and supplement consumed. The 2‐year mean total UME output on GC15 was 80% of that on GN 15 (67·8 and 84·4 GJ ha‐1 for GC15 and GN15 respectively) and the experiment provided further evidence that grass/white clover swards with no fertilizer N applied are capable of producing about 80% of the total output of grass swards receiving 200 kg N ha‐1.

Rumen degradation of the main forage species harvested from permanent mountain meadows in North-western Spain

SUMMARYHerbage samples were collected in late June, and again in early September (1987) from permanent mountain meadows situated in North-western Spain (León). Botanical composition was determined by grouping the species into grasses, legumes and herbaceous ‘weeds’. Rumen degradability of the dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of the botanical groups in each harvest season was determined by the nylon-bag technique.Grasses and legumes differed in their degradation characteristics, and the comparisons between forage species were different for the two harvest seasons. There were no significant differences between September grasses, June legumes and September legumes in the potential degradabilities of the DM (86·9, 87·1 and 88·4%) and CP (94·2, 92·4 and 93·8%). The NDF of grasses harvested in September was degraded to a greater extent (80·6%) than that of legumes from both harvests (70·9 and 73·6% in June and September respectively). However, June grasses showed significantly lower potential degradabilities for the DM (77·0 %), CP (84·3%) and cell wall (65·9%). Legumes were degraded at a faster rate than grasses (mean DM degradation rates of 0·143 and 0·057 respectively), and lag times were longer for grasses (4·7 h) than for legumes (2·5 h). Rumen degradation characteristics of the herbaceous ‘weeds’ were estimated, but it should be remembered that many other factors may limit their utilization by ruminants.It was concluded that the major constraint to the nutritive value of these permanent swards would be the maturity of the grasses harvested in June, which markedly reduced the rumen degradability of the forages.

Response of permanent and reseeded grassland to fertilizer nitrogen. 1. Herbage production and herbage quality

AbstractThe productivity of permanent swards of mixed species composition was compared with that of sown Lolium perenne, cv. Melle at five fertilizer‐N rates (0, 150, 300, 450 and 900 kg N ha−1) and with L. perenne/Trifolium repens, cv. Grasslands Huia at 0 kg N ha−1. The investigation was conducted under two cutting frequencies at sixteen sites in England and Wales, representing a range of grassland environments.Annual total herbage dry matter (DM) production from both permanent and reseeded swards increased with successive increments of fertilizer‐N up to 450 kg N ha−1. Herbage DM production from reseeded swards in the first year after sowing was signficantly higher than from the permanent swards, at all fertilizer‐N treatments. In subsequent years the production advantage of the L. perenne reseeds was maintained only at the higher N rates, though sown L. perenne/T. repens was the most productive sward type at 0 N. Average differences in modified acid‐detergent fibre suggested small advantages in herbage quality to the reseeded swards.It is concluded that, while reseeded swards are more productive in the year after sowing, many permanent swards are capable of high levels of production and that reseeding to a L. perenne sward cannot always be justified, particularly for grassland receiving low or moderate inputs of fertilizer‐N.

Beef production from silages produced from Lolium multiflorum, Lolium perenne and permanent grassland swards

Grass forms a major component of the total ruminant feed in both Ireland and the UK. Much of the grassland consists of permanent swards of diverse botanical composition with many of the grass species present considered ‘secondary’ or ‘undesirable’ (Frame and Tiley, 1987). The objective of this study was to compare reseeded Lolium multiflorum and Lolium perenne swards with an old permanent grassland sward managed under intensive silage conservation systems, and to determine the annual production of grass silage and subsequent beef carcass output per hectare when the silages were offered to finishing cattle.

The invertebrate population and response to pesticide treatment of two permanent and two temporary pastures

SUMMARYDuring 1979 and 1980 the herbage yields of two permanent pastures and two temporary swards were compared. All four swards received 250 kg N/ha per yr. The invertebrate population of all four swards was studied. Pot‐worms (Enchytraeidae) and some species with long life cycles, e.g. wireworms (Agriotes spp.) were more numerous in the permanent swards, but aerial species were more numerous in the temporary swards. A range of pesticide treatments was applied. At one temporary sward site, application of the broad‐spectrum pesticide aldicarb increased total annual yield of herbage by 16% in 1979 and 33% in 1980. Insecticide application at the same site resulted in no increase in herbage yield in 1979 and 12% yield increase in 1980. At the other three sites no significant increases in total annual yield were recorded in either year, but there were significant responses at one harvest or more at every site.