Reseeding in the Falkland Islands: seed rate and fertilizers for establishment

Five experiments were carried out to measure the effects of seed rate and fertilizers on the establishment and early growth of reseeded grass mixtures in the Falkland Islands.
Experiments 1 and 2 compared seed rates within the range 7·5-35kg ha⁻¹. Experiment 3 assessed the effects of three levels of each of nitrogen (N), P₂O₅, K₂O and CaCO₃ applied as seedbed fertilizers. Experiments 4 and 5 were similar in intent to Experiment 3, but treatments consisted of either nil or a very heavy application of the same fertilizer elements. In all experiments, the grass seed mixtures were sown in late summer after rotavation and burning of Cortaderia pilosa dominant indigenous vegetation on peaty soils. Percentage ground cover was estimated in the following spring and dry matter production through the first year was determined by sample harvests.
Initially, heavier seed rates resulted in higher percentage ground cover of sown species, but dry matter production over the season following sowing showed a significant increase only between the 25 and 35 kg ha⁻¹ rates in Experiment 2. The modest levels of seedbed fertilizers applied in Experiment 3 had no significant effect on either percentage ground cover of sown species or dry matter production. Even at the higher levels used in Experiments 4 and 5, only N consistently increased dry matter yields, although a significant positive response was also obtained from CaCO₃ in the final harvests.
The implications of the results to farmers in the Falkland Islands who may be contemplating reseeding are discussed.     

Herbage productivity of a range of grass species in association with white clover

Red fescue ( Festuca rubra L.) cvs Reptans, Dawson and Ruby, perennial ryegrass ( Lolium perenne L.) cvs Perma and Sprinter, crested dogstail ( Cynosurus cristatus L.) cv. Southlands, smooth meadow-grass ( Poa pratensis L.) cvs Parade and Arena, Yorkshire fog ( Holcus lanatus L.) commercial types I and II, creeping bent ( Agrostis stolonifera L.) cv. Penncross and rough meadow-grass ( Poa trivialis L.) cvs Omega Øtofte, Dasas and Sabre were each sown with white clover ( Trifolium repens L.) cv. Donna and the productivity of the fourteen mixtures assessed under simulated grazing (six harvests per year) for 3 years. A single fertilizer-N rate (50 kg ha⁻¹) in early spring was applied to all treatments each year.
Over the 3 years, mean annual dry matter (DM) production of the swards ranged from 5·25 t ha⁻¹ (creeping bent) to 8·71 t ha⁻¹ (red fescue cv. Reptans), with the species ranking order of: red fescue > perennial ryegrass > crested dogstail > smooth meadow-grass > Yorkshire fog > creeping bent. Rough meadow-grass only persisted over the first harvest year. Mean annual organic matter digestibility (OMD) values of the swards ranged from 0·712 (creeping bent) to 0·782 (ryegrass cv. Sprinter). Mixtures with the lowest proportion of grass (crested dogstail and smooth meadow-grass) generally gave the highest proportions of white clover. The creeping bent mixture had exceptionally low production of both components.
Red fescue, crested dogstail and smooth meadow-grass showed compatibility with clover and, therefore, have potential for use in grass/clover swards. Yorkshire fog had lower compatability with clover. Some breeding effort to improve selected characteristics of promising species, e.g. improvement of low OMD in red fescue, seems warranted.     

Herbage production from swards containing a range of grass, forb and clover species and under extensive management

Three small plot experiments were conducted to investigate the effects of species of grass and forbs, defoliation regime, inclusion of white clover and forb blend on the herbage dry matter (DM) yield, botanical composition and mineral content of swards managed with zero fertilizer inputs. The results of all three experiments were characterized by decline in herbage production and large variations in treatment effects over the harvest period.
When sown singly with a standard grass mix the species that competed well with grasses and produced annual forb herbage yields greater than 20 t DM ha⁻¹ were black knapweed, oxeye daisy, ribwort plantain, burnet, birdsfoot trefoil, chicory, kidney vetch, red clover and white clover. When sown singly with a standard forb mix, grass species significantly affected the annual yield of total ( P <005). grass ( P <001) and forb ( P <0.001) herbage. The species that most surpressed the yield of forbs were common bent, Yorkshire fog and perennial ryegrass. Those that allowed for the highest yield of forbs were rough meadow grass, sweet vernal grass and crested dogstail. Averaged over the three harvest years, defoliation regime did not significantly affect herbage production, but the inclusion of white clover in mixtures increased the yield of grasses ( P <0.01) The use of rosette-type forb blends increased forb yield ( P <0.01), compared with erect-type blends.
The effects of treatments on herbage N and mineral contents and yields were inconsistent. However, there was some evidence to support the view that the presence of forb species in swards can result in greater contents of minerals in herbage, compared with grass-only swards.     

Herbage production and quality of a range of secondary grass species at five rates of fertilizer nitrogen application

The productivity of ten grasses was measured under six cuts per annum for 3 years and three cuts for a fourth harvest year in comparison with a perennial ryegrass (Lolium perenne) control. The grasses were Yorkshire fog (Holcus lanatus), two red fescues (Festuca rubra), creeping bent (Agrostis stolonifera), bent (Agrostis castellana), bent (Agrostis capillaris), smooth meadow-grass (Poa pratensis), crested dogstail (Cynosurus cristatus), sweet vernal (Anthoxanthum odoratum) and timothy (Phleum bertolonii). Another grass sown, rough meadow-grass (Poa trivialis), did not persist after the first harvest year. Annual N rates were 0, 120, 240, 360 and 480 kg ha^?1. Classified by DM production, the grasses grouped into: high (perennial ryegrass, Yorkshire fog and red fescue), intermediate (creeping bent, bent (A. castellana), crested dogstail and smooth meadow-grass) and low (bent (A. capillaris), sweet vernal and timothy. With frequent cutting, production ranking interacted with N rate: Yorkshire fog. red fescue and creeping bent were more productive than ryegrass at the 0 N and 120 N rates but not at higher N rates; crested dogstail and sweet vernal outperformed ryegrass at 0 N; ryegrass and smooth meadow-grass performed relatively better at moderate to high N. DM production of ryegrass was matched or exceeded by some of the other grasses during different parts of the season particularly at low N rates. Notable features from the 3-cut regime were the outstanding DM production of Yorkshire fog at all N rates and the poor production of bent (A. capillaris) and crested dogstail. High DM response to applied N in both cutting regimes was given by perennial ryegrass. smooth meadow-grass, red fescue cv. Boreal, timothy, crested dogstail and Yorkshire fog. N concentrations were highest in less productive grasses such as the bents and lowest in highly productive ryegrass and Yorkshire fog. Ryegrass was superior in digestibility to the other grasses, but especially to the red fescues, bents and smooth meadow-grass. The other grasses, especially Yorkshire fog and bent (A. capillaris) were superior to ryegrass in P, K and Mg concentrations, but not Ca. It is concluded that the annual and/or seasonal production of some of the secondary grasses at low to moderate N rates, e.g. the performance of Yorkshire fog and red fescue, warrant a reconsideration of their poor reputation, particularly within the context of increasing grassland extensification. Breeding to improve selected characteristics, such as digestibility in red fescue, seems justified. Assessment of the grazing and ensiling qualities of secondary grasses require further study.     

Herbage productivity of a range of grass species under a silage cutting regime with high fertilizer nitrogen application

The productivity of fourteen grasses was measured under a silage cutting regime of four harvests per year for 3 years (1984-86) with an annual fertilizer N rate of 360 kg ha⁻¹, applied at 120, 100, 80 and 60 kg ha⁻¹ for successive harvests. The grasses were: red fescue (Festuca rubra) cvs Reptans, Dawson and Ruby, perennial ryegrass (Lolium perenne) cvs Perma and Sprinter, Yorkshire Fog (Holcus lanatus) commercial types I and II, smooth meadow-grass (Poa pratensis) cvs Parade and Arena, creeping bentgrass {Agrostis stolonifera) cv. Penncross, crested dogstail {Cynosurus cristatus) cv. Southlands and rough meadow-grass (Poa trivialis) cvs Dasas, Omega Øtofte and Sabre.
Red fescue gave the highest dry-matter (DM) production over the 3 years but because of low organic matter digestibility (OMD), its production of digestible organic matter (DOM) was lower than that of perennial ryegrass. Rough meadow-grass was relatively low yielding in the first year and did not persist thereafter. Three-year mean DM production ranged from 9-22 kg ha"'(crested dogstail) to 14-37 kg ha-1 (red fescue cv. Reptans), while mean annual OMD values ranged from 0-660 (smooth meadow grass cv. Arena) to 0766 (ryegrass cv. Sprinter). The mineral composition (P, K, Ca and Mg) differed among species; creeping bentgrass, crested dogstail, perennial ryegrass and Yorkshire fog had moderate to high mineral concentrations while smooth meadow-grass had low concentrations. Mean two-year (1985-86) mineral composition (g kgDM⁻¹) ranged from 3-1 to 40 (P), 234 to 31-0 (K), 3-8 to 6-0 (Ca) and 1-6 to 2-6 (Mg),
It was concluded that while red fescue and Yorkshire fog showed considerable potential for silage DM production, there is scope for breeding red fescue cultivars with improved digestibility and more winterhardy Yorkshire fog; characterization of their ensiling qualities would also be useful.     

Growth and production of a Cortaderia ptlosa (Gramineae) community in the Falkland Islands

Above ground production of a typical Cortaderia pilosa dominant sward in the Falkland Islands was estimated over one growing season by summing significant positive increments in DM production of various sward components and by sequential cutting to ground level. The standing crop was characterized by a high proportion of standing dead matter at all times of the year. Net herbage production was estimated as 2200 kg ha^-1 and 1440 kg ha^-1 by the 'difference' and "sequential culling" techniques, respectively. The pattern of leaf growth was determined on another site by regular linear measurements of a population of physiologically similar C. pilosa leaves. There was very little early season growth and most of the DM was produced in a short period in the middle part of the growing season. The poor early season growth was attributed to adverse climatic conditions. A significant increase in green matter digestibility in October and November was masked by the low digestibility and high contribution to the overall DM by the standing dead component of the herbage.
The implications of these findings are briefly discussed in relation to the increased utilization of C. pilosa by improved pasture management, including burning and possibly reseeding areas with improved species. Tissue turnover studies combined with more knowledge of sheep nutrition cycles would enable grazing systems to be developed on a sounder basis than previously.     

Differences in lamina wettability in some permanent pasture grass species and two Lolium perenne cultivars

Lamina wettability, assessed using water droplet contact-angle and surface water-retention measurements on excised leaves, was examined in Lolium perenne cv. Melle, cv. Condesa and an indigenous population from an old pasture, Holcus lanatus, Poa trivialis and Agrostis stolonifera. The species fell into two significantly distinct categories, those with unwettable laminae, namely H. lanatus and A. stolonifera , and those with highly wettable laminae, P. trivialis and the three L. perenne populations. There was no significant difference between the L. perenne populations, which had the most wettable laminae overall. The possible implication of these differences in lamina wettability on animal production is discussed.     

Herbage productivity of prairie grass, reed canary-grass and phalaris

The herbage production and quality of swards of three grass species, prairie grass (Bromus willdenowii Kunth), reed canary-grass (Phalaris arundinacea L.) and phalaris (Phalaris tuberosa L.) were compared with perennial ryegrass (Lolium perenne L.) and hybrid ryegrass (L. perenne L. ×L. muitiflorum Lam.) under 6–cut (experiment 1) and 4–cut (experiment 2) regimes over 3 years at Ayr; annually, 360 kg ha^-1 fertilizer N were applied. At Edinburgh prairie grass was compared with Italian ryegrass (L. multiflorum Lam.), timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.) under an annual 4–cut regime for 3 years (experiment 3); fertilizer N application totalled 350 kg ha^-1 annually. Prairie grass gave the highest annual dry matter (DM) production at Ayr, averaging 11·99 t ha^-1 in experiment 1 and 15·62 t ha^-1 in experiment 2. Reed canary-grass was much less productive whilst phalaris did not persist after harvest year 1. On average, prairie grass gave 8–10% more DM than the three ryegrasses in the 6-cut system but its advantage was much less under the 4-cut regime. In experiment 3, the DM production of prairie grass and Italian ryegrass were similar in year 1, but following winter damage prairie grass gave the lowest production in subsequent harvest years. Prairie grass had digestibility (OMD) values lower than the ryegrass but higher than reed canary-grass, timothy and cocksfoot. The water soluble carbohydrate (WSC) concentrations in prairie grass were markedly higher than in timothy and cocksfoot but lower than those in Italian ryegrass. Prairie grass had relatively low P and Mg concentrations. Reed canary-grass had relatively low OMD and Ca, but high N, P, K and Mg contents. It is concluded that prairie grass may have potential in the UK as a special-purpose species for conservation management but mainly in the milder climatic areas. The Phalaris species evaluated had disappointing agronomic potential.     

The production and persistency of different grass species cut at different heights

The effect of two heights of cutting (5 and 8 cm) on the dry matter harvested and persistency of a range of different grass species and varieties were monitored over a 3-year period (1976 to 1978). Dry matter harvested was measured in the second and third harvest year and persistence of sown grass was assessed at the end of the first and third harvest year. The grasses were managed under a frequent cutting system, i.e. simulated grazing. Results showed that at the low cutting height tetraploid hybrid ryegrasses and diploid Italian ryegrasses in the third harvest year gave lower annual dry matter harvests of sown grass and were less persistent than at the high cutting height, whilst, in contrast, perennial ryegrasses gave higher annual harvests of sown grass but persistency was unaffected. In general at the low cutting height varieties of cocksfoot, meadow fescue and tall fescue gave comparatively higher annual harvests of sown grass in the second harvest year but lower yields of sown grass in the third harvest year. A notable exception was Cambria cocksfoot which in the second harvest year gave higher yields of sown grass and was more persistent at the low cutting height.
However, at 5 cm cutting height, the proportions of weed grasses (mainly Poa spp.) in swards sown to tetraploid hybrid ryegrasses and diploid Italian ryegrasses were generally greater, particularly in mid-season.     

Herbage intake and N excretion by sheep grazing monocultures or a mixture of grass and white clover

In 1988 and 1989, swards of grass (G0), while clover (C0) and grass/white clover (GC0) receiving no N fertilizer, and a grass sward supplied with 420 kg N ha^?1 (G420), were grazed by non-lactating sheep to maintain a sward surface height of 6 cm. Herbage organic matter (OM) intakes averaged between 1200 and 1700 g OM ewe^?1 d^?1. For treatments G0, C0, GC0 and G420 respectively, the ewes' live weight gain was 102, 112, 100 and 110 g d^?1 and changes in body condition scores were +0·28, +0·52, +0·36 and +0·44 units season^?1. However, the effect of treatment was not significant for either variable. There were similar levels of output of faecal N ewe^?1 but significantly more urinary N ewe^?1 was excreted on treatments C0 and G420, where the concentrations of N in herbage laminae were also higher. For example, in 1989, total daily N excreted was 39·7, 64·4, 44·0 and 63·3 g N ewe^?1 for G0, C0, GC0 and G420 respectively. Taking into account the mean daily stocking rates, which were 19·4, 26·6, 27·2 and 36·5 ewe ha^?1, the total faeces and urine returns over the season were 161, 358, 249 and 484 kg N ha^?1 for each treatment respectively. The herbage OM intakes ewes^?1 d^?1 measured in September and October were similar for C0 and G420, and so the intake of herbage OM ha^?1 d^?1 was related to stocking rate, i. e. the estimated herbage intake ha^?1 over the growing season for the white clover monoculture was 73% of that for N-fertilized grass. Excretal nitrogen returns to the pasture from grazed mono-cultures of clover were high, and similar to those from a grass sward receiving 420 kg fertilizer N ha^?1. Consequently potential losses of N to the environment are high under these management systems.     

The effect of environmental change on vascular plant and cryptogam communities from the Falkland Islands and the Maritime Antarctic

Background  

Antarctic terrestrial vegetation is subject to one of the most extreme climates on Earth. Currently, parts of Antarctica are one of the fastest warming regions on the planet. During 3 growing seasons, we investigated the effect of experimental warming on the diversity and abundance of coastal plant communities in the Maritime Antarctic region (cryptogams only) and the Falkland Islands (vascular plants only). We compared communities from the Falkland Islands (51°S, mean annual temperature 7.9°C), with those of Signy Island (60°S, -2.1°C) and Anchorage Island (67°S, -2.6°C), and experimental temperature manipulations at each of the three islands using Open Top Chambers (OTCs).     

Identifying suitable temperate grass species and cultural practices for herbage production in the mountain regions of North Vietnam

In North Vietnam, during winter, shortage of herbage constrains the profitability of dairy farming. The first objective of this study was to evaluate the potential of alternative temperate (C₃) forage species, namely common oat ( Avena sativa L.), lop-sided oat ( Avena strigosa Schreb.), Italian ryegrass ( Lolium multiflorum L.) and a commercial forage mixture (Avex), to address the shortage of herbage during winter in the mountain regions of North Vietnam. The second objective was to measure the effects of cultural practices (sowing rate, harvest interval and irrigation level) on yield of dry matter (DM), chemical composition, digestibility of DM and metabolizable energy (ME) concentration of herbage from the best adapted C₃ species previously tested (lop-sided oat). Four experiments were conducted. Oat species proved to be the best adapted species and produced the highest annual yield of herbage (7600 kg DM ha⁻¹) with a high nutritive value. Yields of DM of lop-sided oat were not affected by sowing rate of seed but increased as the length of harvest intervals increased from 30 to 45 and 60 d ( P  <   0·001). Crude protein concentration, digestibility of DM and ME concentration decreased as the harvest interval increased ( P  <   0·01). Irrigation increased the yields of DM of lop-sided oats by 1·3 ( P  <   0·05) but had no effect on the nutritive value of herbage. It is concluded that both common oat and lop-sided oat are suitable species to provide herbage in the winter for the mountain regions of North Vietnam.     

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

The 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.     

Seasonal patterns of diet composition, herbage intake and digestibility limit the performance of cattle grazing native pasture in the Falkland Islands

The botanical composition, intake and digestibility of the diet consumed by mature lactating and non‐lactating cows grazing a native white grass (Cortaderia pilosa) plant community in the Falkland Islands was measured in four periods between September 1998 and June 1999. Five lactating and five non‐lactating cows were used in the summer, autumn and winter; five non‐lactating cows were used in the spring. Different cows were used in each period. Plant cuticle patterns in the faeces of cattle were used, in conjunction with the patterns of concentrations of n‐alkanes in the faeces, to estimate the botanical composition of the diet and predicted concentrations of C₃₂‐ and C₃₃‐alkanes in the herbage allowed herbage intake and digestibility to be estimated using the n‐alkane technique. White grass, sedges and rushes comprised 0·78, 0·64 and 0·63 of the diet in autumn, winter and spring respectively. Fine grasses, smooth‐stalked meadow grass (Poa pratensis L.), annual meadow grass (Poa annua L.), bent grass (Agrostis capillaris L.), native fescue (Festuca magellanica Lam.), Yorkshire fog (Holcus lanatus L.), wavy hair grass [Deschampsia flexuosa (L) Trin.] and early hair grass (Aira praecox L.), were consumed at the expense of sedges and rushes in summer and this coincided with the period of greatest estimated metabolizable energy and crude protein intakes by cows. Lactating cows suffered substantial liveweight loss during autumn and winter and this reflected the low quality of the diet consumed. Phosphorus intakes were insufficient and there was an estimated deficiency of vitamin D in the winter and early spring in cattle that were grazed with the experimental cows. The nutrient restrictions imposed on cattle by the low quality of native pasture during autumn and winter are likely to impair the reproductive potential of breeding females and methods should be investigated to improve the diet consumed by cows during these critical periods if cattle systems are to become sustainable in the Falkland Islands.     

Yield and nitrogen concentration of above- and below-ground biomasses of red clover cultivars in pure stands and in mixtures with three grass species in northern Europe

Three red clover (Trifolium pratense) varieties differing in productivity and winter hardiness, Jokioinen, Betty and Ilte, were sown in a 2‐year (2003–2004) pot experiment in pure stands and mixtures with the grasses, timothy (Phleum pratense), tall fescue (Festuca arundinacea) and meadow fescue (Festuca pratensis). Grass growth dominated until fertilizer‐N, applied when the stands were sown, was depleted. Timothy was the least competitive of the grass species. Red clover variety Ilte produced the highest dry‐matter (DM) yields. Variety Betty yielded less, but allocated as much biomass to the root and stubble (soil‐bound) fraction as variety Ilte. Variety Jokioinen allocated least to the soil‐bound fraction. While the root structure and the starch concentration of the crown‐root area were similar in all varieties, the high ratio of soil‐bound: harvested fractions could be a key to the higher winter survival and higher DM yields of Betty under field conditions. At the end of the experiment, 3–5 g N pot^?1 (49–81 g m^?2) had been harvested and 0·7–1·5 g N pot^?1 (11–24 g m^?2) was left in the soil‐bound fraction, amounts depending on the red clover variety and grass mixture, with pure clover stands containing the highest N amounts. Because of the high N concentrations in the biomass of red clover, the proportion of red clover and conditions prevailing during canopy and root death in mixed stands are crucial for N mineralization and incorporation into new growth.     

An evaluation of a high-quality grass silage for milk production

Forty British Friesian cows with a mean calving date of 28 January were used in a randomized block design experiment to evaluate a high-quality grass silage for milk production. The high-quality silage was made from two consecutive cuts of a perennial ryegrass sward after regrowth intervals of 37 days, wilted to 51% dry matter, finely chopped and ensiled using 2.2 1 t^-1 (0.5 gallons per ton) of formic acid. The resulting silage had a dry matter digestibility of 72.9% and was fed ad libitum with 3.8 kg (8.4 lb) concentrates as a supplement. A medium-quality grass silage, of lower digestibility and dry matter content (70.0 and 25.4% respectively), was also fed ad libitum in addition to either 3.8, 5.7 or 7.6 kg (8.4, 12.5 or 16.7 lb) concentrates. The feeding treatments were commenced immediately after calving and were terminated on 9 April giving a mean period of 72 d on the treatments. Over the experimental period the animals on the high-quality silage consumed 15% more silage dry matter and produced 8% more milk that those on the medium-quality silage with the same level of concentrate supplementation. From the results it was estimated that 1.9 kg (4.3 lb) of additional concentrates would be required with the medium-quality silage to give an equivalent milk output to that achieved with the high-quality silage. Milk composition, liveweight change, ration digestibility and nitrogen balance data are also presented.     

复种复筛法在煮炼过程中的应用初探

通过复种复筛法在煮炼过程中的应用与探讨，提出了提高甲种、甲膏纯度，提高糖分收回和产品质量的方法。     

Growth of white clover in eight grass species and the effects of propyzamide, a grass-suppressing herbicide

Seedlings of white clover (cv. Grasslands Huia) were introduced as spaced plants into 3-year-old monoculture plots of eight grass species ( Agrostis capillaris, Agrostis stolonifera, Dactylis glomerata, Festuca rubra, Holcus lanatus, Lolium perenne, Phleum pratense and Poa pratensis ) during June 1984. In mid-April 1985 plots were split for application of propyzamide at the following concentrations: 0, 0·2, 0·4, 0·6 kg a.i. ha^-1.
During 1984 differences between clover seedling growth in the different grass species became apparent within 2 weeks; growth was greatest in F. rubra, P. pratensis and H. lanatus and smallest in D. glomerata, L. perenne and P. pratense. During 1985, when more N fertilizer was given, H. lanatus and D. glomerata, were equally competitive and clover contributed only 16–18% of the total herbage yield of 10·4 t ha^-1 in them, compared with 33–50% of yields ranging from 9·6 to 119 t ha^-1 in the other six species. Propyzamide decreased grass growth in mid-season by more than 50% but there was little overall persistent benefit to clover yield, except for A. stolonifera and P. pratense with 0·4 and 0·6 kg ha_-1 treatments. Dactylis glomerata and perenne were least and H. lanatus, F. rubra and P. pratensis most suppressed by the herbicide.
Possible reasons for the overall large clover contribution from a very sparse seedling population and the relatively small effects of propyzamide are discussed as well as future work required to improve the predictability of effects of grass suppression.     

Seasonal patterns of diet composition, herbage intake and digestibility identify limitations to performance of weaner sheep grazing native pasture in the Falkland Islands

The botanical composition, intake and digestibility of the diet consumed by 1‐year‐old weaner sheep grazing a native white grass plant community in the Falkland Islands was measured in five periods between June 1998 and March 1999. Five different sheep were used in each period. Two methods were used for estimating the botanical composition of the diet: plant cuticle patterns in the faeces of the sheep and the patterns of concentrations of n‐alkanes in the faeces of sheep. These methods were used to predict the concentrations of C₃₂‐ and C₃₃‐alkanes in the herbage to allow the estimation of herbage intake and digestibility using the n‐alkane technique. It was concluded that the n‐alkane technique gave more accurate estimates of diet composition based on the comparison with estimates of nutrient intake derived from liveweight gains of sheep. The dominant pasture species, Cortaderia pilosa, was the predominant species consumed during the cooler periods of the year. In the summer, when the highest liveweight gains of sheep occur, the proportion of fine grass species, including Poa spp., Festuca magellanica and Agrostis capillaris, and herbs and sedges in the diet was highest. Herbage intake was the highest during the summer periods when digestibility was also at its peak. Estimated nutritional deficiencies of metabolizable energy, crude protein, phosphorus and vitamin D₃ that limit the growth and development of weaner sheep were evident for up to 9 months of the year. Targeted supplementation regimes that counter specific nutrient deficiencies could be developed on the basis of these results to address critical periods in the growth of young sheep.     

Seed characterization and direct sowing of native grass species as a management tool

There is insufficient information about germination, seed biology and seedling establishment of native grass species of the cerrado (Brazilian savannah) to recommend their use in restoration of disturbed areas. We evaluated the production, percentage of fertile seeds, germination, seedling growth and establishment in the field of eighteen native grass species and one exotic invasive species (Melinis minutiflora) and also the effects of different storage periods on germination. The percentage of fertile seeds varied from 6·0 to 94·2% among native species. Ten species produced a minimum of 800 fertile seeds per gram. Germination rate was in the range of 11·0 to 98·8%. Storage for 1 year reduced the germination rate in one species, did not affect germination of three species and increased germination (by 2–10 times) in 14 species. After 2 years of storage, six species showed reductions in germination. Three different patterns of resource allocation were observed and might provide mechanisms for increasing seedling establishment under different environmental conditions. In the field, only two species flowered in the first year after sowing and an additional eight in the second year of observation. Melinis minutiflora is an aggressive species with more than three times the fertile seed production of native species (2820 seeds per gram), high germination rate (55%) and a high number of germinable seeds (1551 per gram). Despite the wide variation in seed characteristics and the delay in flowering, it is concluded that most native grass species can be used in projects aiming at the restoration and management of degraded areas.