Cut Swards Research Articles

The impacts of different management practices on botanical composition, quality, colour and growth of urban lawns

Mulching has increasingly become a standard method used in maintaining low-input lawns. This can be attributed to cost-savings, as these maintenance systems do not require loading and hauling of grass clippings. It is also possible to reduce the amount of nitrogen (N) fertilization and thus save on fertilizer costs. The effects of mowing management and rate of nitrogen fertilization on quality and growth of urban lawns were studied in a field trial during 2007–2012 on lawns newly sown in autumn 2006 and consisting of a grass–legume mixture (Lolium perenne 25%, Poa pratensis 25%, Festuca rubra 30%, Festuca ovina 5%, Anthoxanthum odoratum 5%, Cynosurus cristatus 5%, Trifolium repens 3%, Lotus corniculatus 2%). Nitrogen was used at three application levels: 0, 50 and 100kg of N ha−1year−1. Swards were cut to a height of 40mm five times annually and mulched to the same height. Mulching significantly affected the botanical composition of lawns, wherein a decrease in the portion of legumes (from 32% to 19.1%) was observed. The returned grass matter supported a significant increase in the grass component in the lawns (from 57.8% to 69.7% of total). When the clippings were returned, quality remained the same. Returned clippings had a positive impact on colour and increased the height of cut swards significantly. Application of nitrogen decreased the share of legumes, supported the grass component, statistically increased quality, improved colour, and increased sward height. The results show that returning grass clippings through mulching is beneficial. In any case, it is necessary to apply at least a basal amount of mineral fertilizer in order to preserve the quality of urban lawns over the long term.

Complementary effects of red clover inclusion in ryegrass–white clover swards for grazing and cutting

AbstractIncreasing plant species diversity in grasslands may improve productivity and stability of yields. In a field experiment, we investigated the herbage dry‐matter (DM) yield and crude protein content of two‐species swards of perennial ryegrass–white clover (Lolium perenne L.–Trifolium repens L.) and three‐species swards of ryegrass–white clover with red clover (Trifolium pratense L.). Five different managements represented cutting, grazing and combinations thereof, with different slurry fertilization treatments in 1‐ to 4‐year‐old swards. The three‐species mixture out‐yielded the two‐species mixture in years 1 and 2. Across all 4 years, yields were 8–10% higher in cut swards. Inclusion of red clover increased the yields of clover across the 4 years by 51% without fertilizer and by 90% when fertilized. Responses to slurry fertilization were similar in both mixtures and were mainly independent of sward age. There was a complementary effect over the season and across managements. Red clover dominated in the first and third cuts; white clover dominated in the second and fourth cuts. Red clover dominated in cut swards and white clover in grazed swards. Future prospects of the inclusion of red clover in sown swards are discussed. These may include higher nitrogen‐use efficiency in ruminants, increased soil fertility and improved sward flexibility to cope with changing managements. The findings also suggest positive yield effects of alternating between cutting and grazing within the season or between years.

Creating ephemeral resources: how long do the beneficial effects of grass cutting last for birds?

CapsuleBeneficial effects of cutting grass are relatively short-lived for a range of bird species. AimsTo investigate how cutting affects a range of birds occurring on farmland, how long these effects last, and whether there is any effect of the timing of cutting operations. MethodsWe surveyed birds on 33 grass fields on three farms in northern England, both before and after agricultural cutting operations. The data were then modelled using generalized linear mixed models (GLMMs). Results Species relying on below-ground invertebrates (e.g. corvid species) prefer cut swards, while some species make greater use of longer grass swards (e.g. pheasant). Use of fields after cutting declined by 50 % by day 11 for corvids, by day 8 for aerial feeders (e.g. hirundines), by day 6 for gulls, and by day 4 for kestrels. ConclusionsWe recorded mainly common, generalist species that make use of agricultural grassland. The foraging behaviour of these species is similar to other, rarer or declining species, and so our findings can be extrapolated to a range of farmland birds. However, it is important to note that some studies indicate direct negative effects of cutting on some species not found in our surveys.

An individual-based, stochastic and spatial model to simulate the ramification of grass tillers and their distribution in swards

Understanding the vegetation dynamics of a grass sward at fine-scale requires breaking the interplay between density-dependent processes and environmental variability. Simulation of one of these interacting processes may be a powerful tool. SISTAL is a spatially explicit, object-oriented model of the spatial distribution and spatio-temporal dynamics of individual grass tillers in cut swards. It focuses both on the spatial movement of existing tillers and on the birth and death of tillers. The time management is based on discrete events, and the system dynamics is computed with thermal time. The space management uses both a spatial grid and real coordinates. The paper exposes implementation choices that have been carefully selected: inputs and outputs; edge effects; implementation of the memory management and the handling of pseudo-parallelism. The simulation diary is described since it was found a very useful tool for verification. Essential results and comparisons with real observations allowing the validation of the model are presented.

Estimation of N2‐fixation by grass–white clover mixtures in cut or grazed swards

Abstract. Formulation of nitrogen balances on farms requires accurate information on all inputs of the nutrient. N2‐fixation by legumes, particularly forage legumes, is an important input which is difficult to measure. Simple regression models have been established from the literature for predicting N2‐fixation by grass–white clover (Trifolium repens) mixtures using dry matter yields.Linear relationships were obtained between the N2‐ fixation (Nfix) and the extra dry matter production of mixed swards (Md) compared with pure grass swards. Nitrogen fixation was given by Nfix= A + 0.067Md where A is the intercept having a value of 6.8 for cut swards and ‐168.1 for grazed swards. A common slope was adopted because the F statistics showed that slopes fitted separately were not significantly different. The value of the negative intercept represents the supply of N to the grazed sward from soil and excreta‐derived N. The regression equation for the cut sward gave reasonable predictions (r2= 0.953) of values of N2‐fixed for experimental data not used in establishing the relationship. For grazed grass, the approach over‐estimated the N2‐ fixation by an average of 15%.

The spatial pattern of vegetation in cut and grazed grass/white clover pastures

AbstractThe spatial patterns of white clover and sward surface height (SSH) that developed In established perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pastures undercutting lent every 4 weeks to 5 cm) and gracing (continuously grazed with sheep to 5 cm) were measured. While clover cover was recorded in 1000 contiguous 5 × 5‐cm quadrats down 50‐m permanent transects from early spring to late autumn. Measurements of SSH were made at 10‐cm intervals down the same transect. Spatial pattern was analysed using two‐term local quadrat variance and patch‐gap analysis. At least two scales of spatial pattern existed for white clover when defoliation treatments began. White clover was not distributed at random but found in patches (mean size = 1.1 m) where it was finely intermixed with grass. Patches, separated by gaps (regions of no clover) (mean size = 2.3 m), were in turn aggregated into ‘patches of patches’, separated by larger gaps (mean size = 4.1 m). Under grazing the pattern of patches and gaps did not alter. Under cutting, patch size increased and gap size decreased, explaining in part the greater mass and cover of white clover that arose in cut than grazed swards during the experiment. No new patches of white clover due to seedling establishment or clonal growth were observed in either cut or grazed swards. The intensity of pattern increased in both cut and grazed swards, but the increase was greater m cut swards. The initial single scale of spatial pattern of SSH of tall patches (mean size = 1.2 m) separated by short patches (mean size = 2.7 m) did not change under grazing. SSH became uniform under cutting. It is suggested that the response of plants to selective (spatially heterogeneous) grazing is a crucial factor in the development and maintenance of spatial pattern in grasslands. The importance of spatial pattern to our understanding and interpretation of plant‐plant and plant‐animal interactions and to the composition of temperate grasslands is considered.

Concentrations of N, P, K, Ca, Mg and Na in perennial ryegrass and white clover leaves of different ages

AbstractLeaf blades of perennial ryegrass (Lolium perenne) at five developmental stages, from unemerged to dead, were collected from cut swards grown under field conditions. Similarly, leaflets of white clover (Trifolium repens) at four developmental stages, from tightly folded to proximal to the youngest fully developed leaf, were collected. The leaves were analysed for N, P, K, Ca, Mg and Na.In perennial ryegrass, the concentration of N declined by about half and those of P and K declined by about two‐thirds, as leaves aged. By contrast, the concentration of Ca increased more than fivefold and that of Mg about twofold as leaves aged. The concentration of Na initially increased more than twofold but then declined as leaves died. In white clover the concentration of N declined by about 20% as leaves aged, while the concentrations of P and K declined by about 50%; the concentration of Ca increased about fivefold, that of Mg declined by about 15% and that of Na increased by about 15%.The application of N increased the concentrations of N and K in ryegrass leaf blades at all stages of development. The application of P increased the concentrations of P and Na in the leaves of both species.

Effects of separation, dilution, washing and acidification on ammonia volatilization from surface-applied cattle slurry

SUMMARYTreatments which lowered the rate of ammonia volatilization from surface-applied cattle slurry were evaluated in three field experiments during 1989/90 at the Agricultural Research Institute of Northern Ireland. The relative effects of separation, dilution with water before application and washing with a water spray after application, on ammonia volatilization rates were compared over 4 days using ventilated enclosures. As the loss rate of ammonia during the first 4 days after application was highly correlated with the loss rate over the first 4 hours after application, the loss rate in the first 4 hours was used as a rapid method to assess the efficacy of various combinations of separation, dilution and acidification. Ammonia volatilization loss rates from treatment combinations were compared to the loss rate from whole slurry.A 50% decrease in ammonia volatilization was achieved by separation through a 0·4 mm mesh, separation through a 10·0 mm mesh plus dilution with 86% by volume of water, or separation through a 2·0 mm mesh plus washing with 53% by volume of water.A 75% decrease in ammonia volatilization was achieved by acidification to pH 6·5, or combinations of separation and dilution, namely separation through a 0·4 mm mesh plus 50% dilution or separation through a 5·0 mm mesh plus 100% dilution.A 90% decrease in ammonia volatilization was achieved by acidification to pH 6·0, dilution by 50% plus acidification to pH 6·5, or separation through a 0·4 mm mesh plus acidification to pH 6·5.The effects of separation and acidification on ammonia volatilization were cumulative. There was a highly significant inverse linear relationship between ammonia volatilization rate and volume of nitric acid used. Adding 10 M nitric acid at 1·4% by volume lowered volatilization by 75% of that from whole slurry and increased the nitrogen content of the slurry by 2 g N/l, making it a more balanced NPK fertilizer for cut swards. Because the variable value of cattle slurry is due to loss of nitrogen as ammonia and smothering of the sward with slurry solids, a combination of separation or dilution to lower sward contamination and acidification with nitric acid to lower volatilization may be the best practical option for improving cattle slurry as a fertilizer for cut grass.

An assessment of the contribution of net mineralization to N cycling in grass swards using a field incubation method

Measurements of net mineralization using a field incubation method were made over a full growing season (180 d). Soil cores, taken from cut swards which for many years had been previously grazed by cattle, were placed in jars in the field for successive incubation periods of 14 d. Acetylene was added to the incubation jars to inhibit nitrification in the soil cores and thereby prevent losses of N through denitrification. Net mineralization over 180 d amounted to 415, 321 and 310 kg N ha−1 under grass/clover, unfertilized grass and grass receiving 420 kg N ha−1 y−1, respectively. At the start of the growing season, an index of potentially mineralizable N in the soil was estimated by a chemical extraction method, but this index was <50% of the estimates obtained by field incubation. The amount of N in herbage harvested regularly from the swards also under-estimated the supply of N from the soil, with apparent recoveries of 53, 82 and 74% and total yields of N of 240, 263 and 538 (kg N ha−1) from grass/clover, unfertilized grass and fertilized grass, respectively. Mineralization rates varied significantly with seasonal soil temperature fluctuations, but the incubation method was apparently less sensitive in relation to changes in soil water content. Rates of N-turnover (as % of total soil N) were highest under grass/clover (9%), but similar under fertilized and unfertilized grass swards (approximately 5%).

A model of nitrogen flows in grassland

Abstract. The model comprises three submodels, which together give an integrated picture of nitrogen pools and fluxes in grassland under grazing or cutting. The first submodel represents the interaction of the grazing animal with the sward through intake and the production of excreta: the second is concerned with the growth of the vegetative grass crop and its response to light, temperature and nitrogen; these two submodels are interfaced with a submodel of soil carbon and nitrogen pools and processes, including dead shoot and root material, dead and live soil organic matter, and three pools representing mineral nitrogen. No account is taken of water, which is assumed to be non‐limiting, or the possible effects of soil pH and soil aeration. The model is used to simulate a range of management strategies as applied to stocking density and fertilizer application, examining both steady‐state and non‐steady‐state conditions. The model highlights the long time scales associated with grassland systems, the role of the grazing animal in modifying carbon and nitrogen flows, and the importance of soil conditions to grassland productivity and fertilizer response. The productivity of grazed swards may be greater or less than that of cut swards depending on stocking density and fertilizer application, although nitrogen recovery (as calculated here) is always lower in grazed swards. The model is able to stimulate mineralization and immobilization, and place these in the context of plant processes and the grazing animal.

The influence of nitrogen and early drainage on production from grazed and cut grassland restored after opencast mining

AbstractA review of past and present grassland management on land restored from opencast mining suggests that the most noticeable changes have been increased nitrogen fertiliser use and earlier installation of permanent under‐drainage.A programme of research is described which aimed to examine the effect of early drainage on perennial ryegrass (Lolium perenne S23) grown for grazing, frequent cutting or silage production on sites previously opencast mined for coal, and to consider how these options affected both the short‐term productivity and the long‐term restoration of the soil.The results demonstrate that satisfactory herbage production is possible on restored land provided moderate levels of fertiliser are applied. Grass was utilised at high levels of intensity with no detrimental effects on sward or soil. Highest yields were obtained when grass was cut for silage, and under this regime early drainage led to a significant increase in herbage production each year of the study. When grazing was practised, drainage only led to increased total herbage production in wet years although benefits were seen in spring and in the overall sheep carrying capacity of the land. Clover inclusion in the cut swards only increased yield when less than 200 kg N ha−1 year−1 was applied.

Study of the population dynamics of dipterous stem‐borer larvae of ryegrass swards under rotationally grazed or cut conditions

AbstractObservations made between 1980 and 1982 showed that dipterous stem‐borers were more common in grazed than cut swards. The two forms of Oscinella frit were particularly prevalent in grazed swards but O. vastator was more evenly distributed and dominated the larval populations of the cut sward in 1981. The population dynamics of all species were probably affected by the number of days on which weather was suitable for high stem‐borer adult activity. It was also found that stem‐borer larval numbers could expand rapidly after periods suitable for high adult activity even when adult numbers had been low for long periods. Despite low numbers of O. vastator being present in winter 1981, their numbers increased markedly and built up to a large population which peaked in September 1981.

Predicting the response of perennial ryegrass to fertilizer nitrogen in relation to cutting interval, climate and soil

AbstractThis paper describes the derivation of a series of equations for estimating mean grass production on cut swards under different fertilizer nitrogen, soil and climatic regimes. Using data from the National Grassland Manuring Trial GM20 for a late flowering perennial ryegrass, equations have been estimated for the individual cuts. On the basis of data from cutting trials at Hurley, equations for extrapolating yields under cutting strategies with different first cut dates and regrowth intervals have been derived. The resultant model for predicting yields has then been tested against data obtained from two separate cutting trials. Although in individual cases significant differences between predicted and observed mean yields were noticed, in general the predicted yields were a reasonable approximation to observed yields. Comparison of the predicted yields with those derived from an earlier study by the authors indicated an improvement in the accuracy of prediction.

Influence of age and year of growth on the botanical composition and productivity of swards

SUMMARYAn account is given of vegetational and yield changes occurring in sown swards of Lolium perenne L. to which four alternative management treatments were applied for 8 years.With infrequent cutting (four cuts per year), and a fertilizer nitrogen rate of 188 kg/ha per year, there was a substantial invasion by Agrostis spp. At 376 kg N/ha under cutting the main invader was Agropyron repens (L.) Beauv. with a lower proportion of Agrostis. After cutting at 752 kg N/ha, the swards became dominated by A. repens. With rotational sheep grazing, at 376 kg N/ha, the main invader was Poa annua L., although the proportion was low and L. perenne remained the dominant species. The plant successions which occurred with each type of management as the swards became older had little influence on the yield or quality of herbage under grazing or cutting.Because sward age is confounded with the influence of year-to-year environmental variation, the experiment was designed to enable independent assessments of these factors to be made. Sequential sowings were made to produce an array of swards between 1 and 7 years old. Year-to-year fluctuations in the pattern of herbage production were quantified after allowing for the progressive increase in sward age. Similarly, the influence of age was investigated by adjusting yields for year effects, and comparing swards of different ages in the same year.Year-to-year variation in the total yield of dry matter was much greater than variation attributable to sward age. There was similarly more variation due to year than to age in the yield of D.M. at any one season. In the most extreme comparison, the D.M. yield at an individual defoliation in one year was 2·8 times the lowest yield at the same season in a different year, whereas the yield at the same season varied by a factor of up to 1·5 between swards of different ages.The influence of age on quality was quantified for cut swards only. There was an age effect only at the first cut, when the percentage of digestible organic matter (DOM) declined with age, and herbage nitrogen concentration increased, at the lowest level of fertilizer N, but these changes did not occur at higher N levels. Annual yields of DOM declined significantly with age, but only at the highest N level, and there were no significant changes in the annual yield of herbage N.Comparisons were made of the cumulative D.M. yields for several years of young swards, resown every 3 years, and undisturbed swards, up to 7 years old. Young swards gave a higher yield during the first two years after sowing, but the advantage was lost in the period of ploughing and establishment, during which time the undisturbed swards achieved a small advantage in cumulative yield. Cumulative yields of DOM and N from young swards were not sufficiently different from those of older swards to suggest that there would be an advantage from regular resowing. A theoretical analysis was made to predict the long-term yields of D.M. and DOM from different renovation strategies at yearly steps from 2 to 7 years. This suggested that ploughing and resowing gave little or no advantage in productivity over swards which were not renovated before age 7, and resowing too frequently gave a loss of yield.The paper contains an appendix by A. Smith and R. E. Deriaz describing a method used for the correction of analytical results obtained for variable contamination of herbage samples by extraneous materials.

Nitrate leaching from grassland

Increased awareness of the economic importance of losses of nitrogen (N) from agricultural land, together with the recognition that nitrate in drinking water is potentially detrimental to human health, have stimulated research on nitrate leaching1–4. Various reports5–7 have suggested that the leaching of nitrate from arable land is the major source of nitrate to water supplies in east and south-east England. In contrast, leaching from grassland is thought to he small5,8–10. However, this conclusion has been based largely on studies of leaching below cut swards, which exclude the effect of ruminants (cattle and sheep) on nitrate loss. This effect is likely to be substantial as <20% of the input of N to grassland systems is recovered in products of the ruminant animal11. Our study demonstrates that the amount of nitrate leached below a grass sward grazed by cattle was 5.6 times greater than that leached below a comparable cut sward and exceeded the losses normally observed from arable land.

The utilized metabolizable energy output of grassland on hill farms in Northern Ireland

AbstractForty hill farms in Northern Ireland were surveyed to obtain information on stocking rates and output and to identify factors affecting output. The mean farm area of 194 ha was composed of 155 ha hill land and 39 ha inbye land with a mean stocking rate of 0–7 cow‐equivalents ha−1.On the average farm most of the grassland (88%) was over 20 years old. The preferred species content of the swards averaged 22% over the whole farm and 42% in cut swards. This latter result may be attributed to the relatively high level of fertilizer N applied to these swards (131 kg ha−1) compared to the mean application rate over the whole farm of only 29 kg N ha−1 and 93 kg ha−1 applied to the inbye land.Output data calculated as utilized metabolizable energy (UME) per unit area for the whole farm and separately for hill and inbye components showed that although only 21% of the farm area was inbye land almost half the annual total metabolizable energy requirements of stock had to be met by grazing inbye. The capacity of herbage to meet stock energy demands was much lower on the hill with supplementary feed having to be provided over the winter.Calculated output from inbye land was 39 GJ ha−1 compared to 7 GJ ha−1 from the hill and 15 GJ ha−1 from the whole farm. UME output of the whole farm was negatively correlated with farm size (r=−0 55) and positively correlated with stocking rate (r = 0 89), applied N level (r = 0 63)

Nematodes associated with dipterous stem‐boring larvae (Chloropidae and Opomyzidae) in ryegrass

SUMMARYAssociations between different species of nematodes and stem‐boring larvae were studied over two years. Howardula oscinellae was rarely found in stem‐boring larvae. Usually mermithids were also uncommon, but in one Italian ryegrass (Lolium multiforum) variety trial over 12.5% of stem‐boring larvae were attacked, with different levels of parasitism in larvae from the different ryegrass varieties. Panagrolaimus rigidus nematodes were also identified from stem‐boring larvae and Oscinella frit larvae were the most common host. Greater infestation levels of P. rigidus were found in larvae from grazed swards than from cut swards. P. rigidus may cause the death of some stem‐boring larvae.

Sward growth under cutting and continuous stocking managements: sward canopy structure, tiller density and leaf turnover

AbstractThe change in structure of continuously grazed versus infrequently cut swards of perennial ryegrass (Lolium perenne L), cv. S23, was investigated during their first full harvest year. Measurements were made from early May until late September. The intensity of stocking by sheep in the grazed sward was adjusted in an attempt to maintain a high level of radiation interception and the cut sward was harvested at approximately monthly intervals.The herbage mass, lamina area index and radiation interception of the cut sward varied in a cyclic pattern between harvests but in the grazed sward these parameters showed considerably less variation, although they all increased early in the season and then declined later. The proportion of dead material above ground increased throughout the season in both sward types but was more marked in the grazed sward.There were major differences between the grazed and cut swards in the number of tillers per unit ground area; the difference became more marked throughout the season and by September the tiller densities in the grazed and cut swards were 3·204 m‐2 and 6·203 m‐2 respectively. Divergence in tiller density was associated with differences in specific stem weight and leaf area per tiller.Rates of appearance and death of leaves on tillers in the grazed sward were determined. During May, leaf appearance exceeded leaf death but this was reversed in June. During the rest of the season as a new leaf appeared on a tiller so the oldest leaf died.

Residual effects of sulfur fertilizers on cut swards of a Stylosanthes guianensis and native grass pasture on a euchrozem soil in north Queensland

A field experiment was undertaken at Meadowbank Station between 1974 and 1980 to assess the residual effects of sulfur application, as gypsum and coarse elemental sulfur, on yields and composition of an established Stylosanthes guianensis cv. Graham and Themeda australis pasture. Sulfur rates ranged from 0-20 kg S ha-1 in years 2 and 3 and from 0-80 kg S ha-1 in year 4. The fertilizer was applied as a single dressing at the beginning of the growing seasons of 1975 (year 2), 1976 and 1977. Dry matter yield and concentrations of nitrogen and sulfur in the legume generally decreased to levels of unfertilized plots after two growing seasons when up to 20 kg S ha-1 was applied. With a rate of 80 kg S ha-1 at the beginning of the 1977 growing season, a response to residual sulfur was still evident in 1980. In each year when a sulfur application was made, there was a strong response by the legume component in terms of yield, legume content and concentrations of nitrogen and sulfur. Coarse elemental sulfur was generally not as effective as gypsum. Phosphate-extractable sulfur in the surface soil (0-10 cm) was low (1 -4 �g g-1) and did not change greatly as a result of sulfur applications up to 20 kg S ha-1. There was evidence of movement of sulfur down the soil profile in plots that received 80 kg S ha-1 as gypsum, but it was not so marked with elemental sulfur. It is suggested that an application of 40 kg S ha-1 as elemental sulfur or gypsum is sufficient to establish and maintain the legume component of the pasture for a period of 4 years.

The interaction of perennial ryegrass and timothy in mixtures and their reaction to clover and nitrogen in cut swards

AbstractResults of experiments where timothy, perennial ryegrass and mixtures of these two in the presence and absence of white clover and receiving various nitrogen treatments were compared, have been considered in the light of previous related experiments. There is evidence that under certain conditions greater yields of sown grass can be achieved from mixed seedings than from either of the two grasses on its own. No yield advantage was gained from mixtures of species when cut infrequently after a late first cut. Inclusion of white clover changed the balance of species in favour of perennial ryegrass and no yield advantage occurred with mixtures in the presence of clover. Yield advantage may be related to seasonal changes in the order of dominance of the two grass species in mixed seedings.