Some changes associated with the field drying of lucerne and timothy

Lucerne (approximately 10% flowering, 270 g dry matter kg⁻¹) and timothy (boot stage, 310 g dry matter kg⁻¹) were harvested and allowed to wilt for a period of 52·5 h. During the early stages of wilting of lucerne there were increases in the proportion of leaf material (dry weight basis), as well as increases in total available carbohydrate and water soluble carbohydrate concentrations. Approximately 50% of the leaf material in lucerne and in timothy was lost after a drying period of 52·5 h and after tedding and raking operations prior to baling of the hay. This resulted in considerable reduction in the protein content of both lucerne and timothy.     

Effects of an established sward of Lolium perenne L. on the growth and development of Rumex obtusifolius L. seedlings

Seedlings of Rumex obtusifolius L. were grown in gaps (11 cm diameter) in an established sward at Lolium perenne L., Root competition from the surrounding sward was controlled by PVC tubes and shoot competition was controlled by cutting the sward frequently. All combinations, with and without root competition and with and without shoot competition, were used.
Plants received either 40 or 80 kg N ha⁻¹ month⁻¹ and 0 or 300 kg K₂O ha⁻¹ and were harvested 39 d after emergence; a second harvest was made 12 d later, after shading to 20% of full sunlight.
The shoot dry weight per plant of R. obtusifolius was much more affected by root competition than by shoot competition, especially at low nitrogen applications. Potassium supply had no effect.
More dry matter was allocated to the leaf petioles under shaded conditions and the specific leaf area was greater. This morphological plasticity enabled R. obtusifolius to grow well under shading and to be affected only slightly by shoot competition from L. perenne.
The results suggest that competition for nitrogen was the main factor limiting the initial grown of R. obtusifolius in a ryegrass sward and that the morphological characteristics of R. obtusifolius make it less susceptible to competition for light in the early stages of its development.     

Growth performance, appetite and plasma ammonia concentrations in heifers fed inoculated lucerne prior to ensilage, then supplemented with sodium bicarbonate

A study was conducted to explore the possibility of a synergistic effect of an inoculum of lactic acid bacteria and sodium bicarbonate in improving the nutritive value of lucerne silage. Twenty Holstein heifers (live weight 183 ± 9·4 kg) were assigned to four dietary treatments consisting of: lucerne uninoculated or inoculated prior to ensilage and then either unsupplemented or supplemented with NaHCO₃ (40 g kg⁻¹ dry matter (DM)). The lucerne silage contained 320 g kg⁻¹ DM and constituted 600 kg⁻¹ diet DM. The animals were fed once daily for 90 d and samples of jugular blood were analysed for plasma ammonia and indices of blood acid-base status. Inoculation of Lucerne reduced ( P <0·01) silage pH but had no other effect on silage composition. In the absence of NaHCO₃, liveweight gain and organic matter intake were improved by inoculating lucerne prior to ensilage; however, in the presence of NaHCO₃, inoculation reduced growth rate but had no major effect on intake. Dietary treatment did not (P>0·05) affect the concentration of plasma ammonia or measures bf blood acid-base status. The results suggest that NaHCO₃ may have nullifled any potential benefit of inoculating lucerne silage to improve its nutritive value for heifers.     

Fermentation and nutritive value of Zea mays and lucerne forage ensiled with added rolled barley

The effect of adding rolled barley on the ensiling characteristics and nutritive value of lucerne and corn ( Zea mays ) forage was studied using 19-1 plastic mini-silos. Other factors evaluated with lucerne were the effect of wilting and added lactic acid bacteria. Rolled barley was added at rates of 0, 50, 100 and 150gkg⁻¹ (wet weight) to lucerne or corn forage. Lucerne was ensiled at 170–330 g kg⁻¹ dry matter (DM) and lactic acid bacteria were applied at 10⁵g⁻¹ wet forage. Addition of rolled barley consistently improved the fermentation of lucerne by lowering the pH and decreasing the concentration of acetate and ammonia nitrogen. Wilting of lucerne had variable effects on fermentation in two experiments. The addition of lactic acid bacteria improved fermentation by decreasing the concentrations of acetate and ammonia nitrogen, improved the nutritive value by increasing the in vitro dry matter digestibility (IVDMD), and was associated with decreased amounts of lactic acid. Corn was ensiled at 250 g kg⁻¹ DM, and added rolled barley had little effect on the fermentation of corn silage. The digestibility of all silages determined in vitro was improved by the addition of rolled barley.     

Growth and water relations of field-grown tall fescue as influenced by drought and endophyte

Field plots were established in autumn 1992 in which endophyte [ Neotyphodium coenophialum Glenn. Bacon, Price and Hanlin (formerly Acremonium coenophialum )]-infected (E⁺) and endophyte-free (E⁻) isolines of three tall fescue [ Festuca arundinacea Schreb.) genotypes were planted. Plants were subjected to three water-withholding periods in 1993 and one in 1994, or were kept well watered throughout the experiment. There were no consistent endophyte effects for leaf elongation, tiller density or dry weight per tiller. There were genotype X endophyte interactions ( P <001) for tiller density and shoot dry weight per area and genotype X water X endophyte interactions ( P <005) for cumulative leaf elongation in 1993. These interactions indicated the highly specific effect of host genotype-endophyte association on the expression of plant growth. Leaf rolling in the stressed treatments was more severe in E⁻ than in E⁺ plants in 1993, but there were no differences in 1994, and stomatal conductance tended to be lower in E⁻ than in E⁺ plants in 1993. Fractional water content of the lower 3 cm of the youngest fully developed leaf sheath was usually greater, and never less, in E⁺ than in E⁻ plants. The leaf rolling and stomatal conductance results suggest that E⁻ plants were more severely stressed in the summer after planting. Thus, the endophyte may induce greater water retention in the leaf sheath and therefore better protect the internal growing zone from lethal desiccation.     

A study of the potential of lucerne as a silage crop in a high-rainfall area

The results are reported of a 2-year plot experiment investigating the potential of lucerne as a silage crop in a comparatively high-rainfall area (annual average of about 900 mm). The performance of the lucerne on the remainder of the field in which the plot experiment was located is also discussed. With below-average rainfall in the sowing year a good establishment was obtained and a single cut to a stubble height of 75 mm in August gave a dry matter yield of 3 t ha^-1. In the first harvest year, summer rainfall was again below average and a total dry matter yield of 13·8 t ha^-1 resulted from three cuts to 75 mm above ground level. However, the total yield was reduced to 10·11 ha^-1 in the second year when the rainfall was considerably above average. Attempts to increase the feeding value of the lucerne herbage by increasing cutting frequency and by increasing cutting height showed little effect over the standard system of three cuts to a stubble height of 75 mm. The effects of applying potassium fertilizer at rates supplying 100,200 or 300 kg K ha^-1 either as a single spring dressing or in equally divided dressings were not significant in either of the two years     

小麦苗期抗旱相关形态指标的灰色关联度分析

为了系统研究小麦苗期形态指标与抗旱性的关系并筛选有效的抗旱性指标,使用PEG-6000模拟干旱胁迫,采用灰色关联度分析法分析了28份小麦品种苗期干旱胁迫下的苗高、最长根长、根数、地上部鲜重、地上部干重、根鲜重、根干重、叶片数、根冠比等9个形态指标与抗旱系数的关联程度,并以所得加权抗旱系数对各品种进行聚类分析.结果显示,各形态指标与抗旱系数的关联度依次为:叶片数(0.817)>苗高(0.766)>地上部干重(0.746)>地上部鲜重(0.729)>根数(0.699)>根干重(0.688)>根鲜重(0.681)>根冠比(0.645)>最长根长(0.399).研究还表明,9个形态指标可分为叶片相关因子、地上部生物量因子和根部生物量因子三大类,地上部生物量因子的关联度大于根部生物量因子;不能只通过差异显著度检验来判断某一指标是否可以用作抗旱性鉴定;聚类结果能较好地反映各小麦品种的地域分布.因此,进行小麦品种苗期抗旱性鉴定时,应加强对地上部形态指标的选择和鉴定,以提高选择效率.     

The contribution of different white clover cultivars to the nitrogen yield of mixed swards

The annual contribution of clover to a mixed sward for 5 years was compared for a range of cultivars, viz. S1OO, Sabeda, Blanca and Olwen, in order of increasing leaf size. The contribution referred to as'clover-derived nitrogen N', was measured as the difference between N harvested in mixed swards and that in similarly treated swards devoid of clover. The swards were harvested four or five times each year and received N fertilizer, annually, at 0, 30, 60 or 90 kg N ha⁻¹ in March.
Blanca swards had the highest clover-derived N yield in the second year and lowest in the fourth year. By the fifth year Sabeda and S100 (medium leaved cultivars) were contributing more N than the other two cultivars. When related to the amount of clover harvested, S100 had the highest value in the second year and S100 and Sabeda in the third year. Relating the total lover-derived N harvested over the 5 years to the amount of clover harvested, S100 had an efficiency of contribution of 54-3 kg N t⁻¹ dry matter (DM) compared to a mean of 49 0 kg N t⁻¹ clover DM for the other three cultivars. Nitrogen fertilizer reduced the contribution of clover N in the first 3 years owing to a reduction in clover yield, but it did not affect clover's efficiency to contribute N.
It is concluded that although the smallest leaved type of the four (S100) made the most efficient N contribution to the sward more information is required to relate morphology of clover to its capability to contribute N directly or indirectly to the sward.     

Influence of bacterial inoculant and substrate addition to lucerne ensiled at different dry matter contents

Field-wilted lucerne was chopped with a forage harvester at 33 ± 1·5, 43 ± 2·0 and 54 ± 1·8% dry matter, treated and ensiled in laboratory silos during four cuttings in each of two years. Treatments were control (C), sugar addition at 2% of fresh weight (S), inoculum applied at 3 × 10⁵ bacteria g⁻¹ herbage (I), and sugar and inoculum combined (IS). Duplicate silos were opened and analysed after 1, 2, 3, (4 or 5), 7, 14 and 60 d of fermentation. The initial rate of proteolysis of lucerne protein decreased with increasing dry matter (DM) content of the lucerne, and was not influenced by the year, cutting or silage treatment. Inoculation increased ( P <0·05) the rate of pH decline for all silage dry matters, and shortened the lag time prior to pH decline with 33 and 43% dry matter silages. Sugar addition had no effect on rate of pH decline or lag time. Inoculation and sugar addition both lowered final pH, acetic acid, ammonia (NH₃), free amino acids (FAA) and soluble non-protein N (NPN) in silages ( P <0·01) and increased lactic acid content with 33 and 43% dry matter silages. Only inoculation was beneficial at 54% DM with no difference between I and IS. The influence of forage characteristics (epiphytic lactic acid bacteria, buffer capacity and sugar:buffer capacity ratio) on treatment effectiveness varied with dry matter content.     

Leaf number as a criterion for determining defoliation time for Lolium perenne, 1. Effect of water-soluble carbohydrates and senescence

This study sought to define the optimum defoliation interval for Lolium perenne , with the maximum interval being determined by the onset of senescence, as reflected by the number of fully expanded leaves, and the minimum interval set by the replenishment of water-soluble carbohydrates (WSCs).
In a glasshouse set at 13°C/23°C night/day temperature and at a plant spacing of 94 m⁻² (3290 tillers m⁻²), the accumulation of dry matter against leaf number and days was exponential to the four-leaf stage of the regrowth cycle. Senescence commenced at the 3·5-leaf stage.
WSCs in roots, stubble and leaf showed a very significant linear relationship with leaf number. Levels of WSCs in leaves were restored to predefoliation values by the one-leaf stage, after which WSCs accumulated preferentially in the stubble, rising to 22% at the four-leaf stage.
Regrowth after 6 d was significantly greater for plants defoliated at the three-leaf stage than at the one-leaf stage, but this difference disappeared at the end of the regrowth cycle. This questions the importance of WSCs in determining the yield of ryegrass under normal rotational grazing management.
Regrowth at 6 d was related positively to stubble WSCs (r²= 0·66) and to stubble DM per tiller(r²=0·71)     

Initial bacteria] numbers on lucerne prior to ensiling

Populations of lactic acid bacteria (LAB) on lucerne before and after havesting were extensively monitored over a two-year period and correlated with weather data, various wilting parameters and equipment used for harvest. The LAB on standing lucerne were below detectable levels (<10 colony forming units (CFU) g lucerne⁻¹). Immediately after mowing, low levels of LAB (51 CFU g⁻¹) were found on over half the samples. During wilting, the population of LAB generally increased. The amount of increase was affected primarily by the average air temperature during wilting, the length of wilting and the drying rate. The first two variables were positively correlated with bacterial growth whereas increased drying rate adversely affected LAB numbers. If the LAB numbers in the swath were below 100 CFU g⁻¹ prior to chopping, the forage harvester inoculated the chopped lucerne an level of 10² to 10⁴ CFU g⁻¹, depending on air temperature. Considering these factors, LAB counts on chopped lucerne could be predicted within one order of magnitude approximately 95% of the time.     

Productivity of mixtures of Italian ryegrass and red clover

Two red clover ( Trifolium pratense ) cultivars, Red Head (tetraploid) and Kuhn (diploid), were sown at a seed rate of 13 kg ha⁻¹ either alone or in mixture with Italian ryegrass ( Lolium multiflorum ) cv. RvP sown at seed rates of 10, 15, 20 or 30 kg ha⁻¹. RvP was also sown alone at a seed rate of 30 kg ha⁻¹ and received nil or 300 kg ha⁻¹ fertilizer a⁻¹ fertilizer N. All plots were established using the barley cultivar Midas sown at a seed rate of 100 kg ha⁻¹ as a nurse crop.
Neither clover cultivar nor ryegrass seed rate significantly influenced either dry matter harvested or botanical composition over the 3 harvest years. On average over all years the grass-clover mixtures produced 75% of the yield of the N-fertilized RvP, 125% of the clover monocultures and 225% of the unfertilized RvP. The red clover contribution to the total dry matter harvested of the mixtures averaged 45–60%. The dry matter concentrations of the mixtures were considerably higher than those of the pure clover stands. In the third year yields were markedly reduced in comparison with those in the first and second years.
It was concluded that Italian ryegrass can be a suitable companion grass for red clover. Its superior yielding capacity over other grasses such as perennial ryegrass or timothy under a conservation management can be coupled to advantage with red clover to give a sward which Is essentially stable, at least over a 2- to 3-year cropping period, although giving slightly reduced yields in the third year. Italian ryegrass-red clover mixtures, without the use of fertilizer N, can produce high DM yields of good quality herbage.     

Effects of interval between harvests and application of fertilizer N in spring on the growth of perennial ryegrass in a grass/white clover sward

A perennial ryegrass/white clover sward, which had been grazed for over 2 years, was cut at 1-, 2-, 3- or 6-week intervals from 18 April to 28 November 1986. Two rates of fertilizer N application in spring, 0 and 66 kg N ha⁻¹, were compared. Perennial ryegrass growth was studied in three 6-week periods, beginning on 18 April, 18 July and 17 October. Clover growth was studied in the same three periods and described by Fisher and Wilman (1995) Grass and Forage Science , 50 , 162–171.
Applied N increased the number of ryegrass tillers m⁻², the rate of leaf extension and the weight of new leaf produced tiller⁻¹ and m⁻²per week. Increasing the interval between cuts reduced the number of ryegrass tillers m⁻² and increased the rate of leaf extension, weight tiller⁻¹and the weight of new leaf produced tiller⁻¹week⁻¹. Increasing the interval between cuts increased the weight of new ryegrass leaf produced m⁻² where N had recently been applied, but otherwise had little effect on the weight of new leaf produced m⁻². Applying N favoured the grass in competition with the clover in every respect, whereas increasing the interval between cuts only favoured the grass, compared with clover, where N had recently been applied; where N had not been applied, the ratio of ryegrass tillers to clover growing points in the sward was very little affected by the interval between cuts.     

The future of lucerne in British agriculture: an economic assessment

With its potential for high yields and high animal output, lucerne appears to be an underexploited crop in British agriculture. In this paper an attempt is made to assess the prospects for expansion of the area of lucerne in Britain from an economic viewpoint, concentrating on lucerne as a conservation crop. Under good management lucerne is shown to have lower production costs than grass and its inclusion in the diet of dairy cows, but not beef cattle, could significantly lower winter feed costs. However, under apparently similar growing conditions, lucerne yields on different farms vary significantly, ranging from 9 to 13 t dry matter ha⁻¹ a⁻¹. At the lower yields, the economic attraction of growing and feeding lucerne in place of grass is small. Moreover, since potential lucerne production is concentrated in the south and east of Britain, lucerne competes with other arable crops. For lucerne to offer a gross margin per unit area comparable with these, the price for conserved lucerne would have to be set at a level at which dairy farmers would derive little economic advantage from feeding it. Thus, although lucerne is a forage crop with some potential, at present it is likely to offer economic possibilities only where producers can combine high yields with on-farm utilization of the crop.     

槟榔生物量预测模型建立与应用

以海南本地种槟榔植株为材料,测量槟榔叶长（leaf length, LL）、叶宽（leaf width, LW）、叶片数（leaf number, LN）、花苞数（bud number, BN）、节数（node number, NN）、茎粗（stem diameter, SD）、株高（plant height, PH）、茎高（stem height, SH）和节间长度（internode length, IL）等可简单测量的特征指标,通过建立估测模型预测槟榔植株单片叶片干物质量（leaf dry weight, LDW）、茎杆干物质量（stem dry weight, SDW）及地上部分干物质量（aboveground dry weight, ADW）。结果表明：通过模型拟合和择优得到槟榔茎杆干物质量的估测模型为：SDW=0.2518 SD₀+ 0.0423 PH-23.8883,槟榔茎杆干物质积累量主要受株高（PH）、0 m茎粗（SD₀）的综合影响,决定系数R²=0.7157,样本株数为36株,另外18株进行外部验证,相关系数r=0.9165;槟榔单片叶片干物质量的估测模为：LDW=3.9726 LL+2.8402 LW-297.6869,槟榔单片叶干物质积累量主要受叶长（LL）、叶宽（LW）的综合影响,决定系数R²=0.6054,样本叶片数量为177片,另外88片进行外部验证,相关系数r=0.7528;槟榔地上部分干物质量的估测模型为：ADW=0.3283 SD₀ + 0.0415 PH -23.7333,槟榔地上部分干物质积累量主要受0 m茎粗（SD₀）、株高（PH）的综合影响,决定系数R²=0.6932,样本株数为36株,另外18株进行外部验证,相关系数r=0.9028。通过大量数据的观测分析,建立的槟榔生物量预测经验模型,可以将其作为最优生物量预测模型用于槟榔地上部分生物量的估算,具有一定应用价值。     

Between-cultivar variability in breaking force of components of perennial ryegrass (Lolium perenne)

The variation in force required to break the leaves and pseudostems of perennial ryegrass ( Lolium perenne ) was measured on twelve New Zealand commercial and pre-release cultivars using a punch and die apparatus which enabled up to 100 simultaneous breaks per sample. Perennial ryegrass cultivars were sampled from 2-year-old pure swards in two studies carried out in spring and autumn. In the first study, the forces required to break old and young leaves, and pseudostems, of six cultivars ranging in heading date and ploidy were compared at a designated morphological stage during spring growth. Force was measured as Newtons (N) mg⁻¹ dry matter (DM) and the difference between the force required to break leaves and pseudostems was significant ( P  < 0·01). The youngest emerged leaf required a greater force by 0·13 than the oldest green leaf (5·60 and 4·90 N mg⁻¹ DM for young and old leaf respectively). The force required to break leaves (average of young and old leaves) of 5·25 N mg⁻¹ DM was 0·12 greater than the force required to break pseudostems (4·59 N mg⁻¹ DM). This difference was consistent across most cultivars. In the second study, the force required to break leaves of ten cultivars was tested daily over three autumn periods when all cultivars were sampled at a regrowth age of 2 weeks. The cultivar Nevis was used in each period whilst the other cultivars were used in one period. When averaged across periods, cultivars could be separated into three groups of high, medium and low forces required to break leaves. The difference between the means of the high and low groups was 0·33 with a range from 3·29 to 4·91 N mg⁻¹ DM.     

The productivity of four forage legumes sown alone and with each of five companion grasses

Four legumes—white clover cv. Blanca, red clover cvs Violetta (diploid) and Hungaropoly (tetraploid) and lucerne cv. Europe—were established as pure-sown swards and with each of five companion grasses: timothy cv. Timo, meadow fescue cv. Bundy, sweet brome cv. Deborah and perennial ryegrass cvs Talbot (diploid) and Barlatra (tetraploid), both ryegrasses being of 'intermediate' heading date. Two 'silage' crops and an 'aftermath grazing' crop were harvested in each of three successive years.
In the first harvest year, total herbage DM production of red clover ranged from 15·03 to 17·01 t ha^-1. White clover and lucerne swards produced considerably less at 7·12 to 11·01 t ha^-1. In the second harvest year, lucerne swards were the highest producing at 15·54 to 17·14 t ha^-1, while DM production from red clover and white clover swards ranged from 6·75 to 11·87 t ha^-1. Lucerne swards maintained their production superiority in the third year at 16·48 to 17·87 t ha^-1, while production from white clover swards ranged from 6·41 to 10·23 t ha^-1. However, red clover swards declined to 3·30 to 5·81 t ha ^-1; this above-average decline was mainly caused by the onset of red clover necrotic mosaic virus which affected all red clover plots uniformly in the second harvest year, and by winter conditions before the third harvest year. Total herbage DOM and CP yields of the swards were influenced in a similar manner to DM production.     

Proteolysis and amino acid degradation during ensilage of untreated or formic acid-treated lucerne and maize

Lucerne ( Medicago sativa ), field wilted to 330 g dry matter (DM) kg⁻¹, and whole-plant maize ( Zea mays ), 383 g DM kg⁻¹, were treated with formic acid (FA) at the rate of 4-5 1 t⁻¹ fresh forage. The effects of FA treatment on proteolysis and amino acid degradation was investigated at several intervals over a 90-d period of ensilage in laboratory silos. Formic acid treatment produced different patterns of pH decline during ensilage of the two forages, suggesting some degree of crop specificity in response to FA treatment. After 7 d of ensilage of lucerne there were increases of 81% in nonprotein nitrogen (NPN), and 104% in free amino acid nitrogen (FAA-N), but with FA-treated lucerne the increases were 39% and 31%, respectively. FA treatment resulted in a reduction in the concentration of most free amino acids in lucerne silage, with the exception of glutamic acid and serine; the branched chain amino acids as well as glycine, tyrosine and proline were significantly (P<0·05) reduced after 3 d of ensilage. By contrast, FA treatment of maize did not significantly ( p <0·05) affect the NPN content nor was there a consistent pattern in the changes in FAA-N. Formic acid treatment of maize did produce a significant reduction ( P <0·05) in the concentration of most individual free amino acids at 90 d of ensilage. Overall, FA treatment had a more predictable effect on proteolysis and amino acid degradation in ensiled lucerne than in ensiled whole-plant maize.     

Laboratory studies on the effect of potassium carbonate solution on the drying of cut forage

The potential drying rate of cut forage grasses and legumes, following treatment with a 2% potassium carbonate (K₂CO₃) solution, were compared with those of untreated crops under laboratory conditions. Material was fully exposed to a flow of conditioned air (20°C; 50% relative humidity). Treatment with K₂CO₃ had little effect on the drying rate of a range of cultivated grass species. The drying of legume species, particularly lucerne was accelerated. The average reduction in lucerne drying time, following K₂CO₃ treatment, was 63% and was similar for a range of varieties. The differential drying of lucerne leaf and stem fractions was reduced following treatment, and reduced further by selective treatment of the stem. Potassium carbonate treatment was superior to traditional mechanical conditioning for accelerating water loss from cut lucerne. The practical implications are discussed.     

Seasonal variation in white clover content and nitrogen fixing (acetylene reducing) activity in a cut upland sward

The seasonal variation in herbage mass and nitrogen fixing (acetylene reducing) activity of white clover in an upland sward, cut weekly to 3·5 cm from mid-May until mid-October, was measured. Acetylene reducing activity (ARA) was measured over a 24-h period at 3-weekiy intervals starting on 3 March 1983. Clover leaf and Stalon biomass was measured by harvest of the assay truces, and from mid-May quadrat euts to 3·5 cm above the soil surface provided estimates of herbage accumulation.
Little A RA was detected in March, but activity increased substantially after 10 cm soil temperatures reached > 3°C, and peak activity per unit of clover leaf dry weight occurred in June and July; standing clover leaf dry matter increased during the season to a maximum of 60·5 g m⁻¹ in June. Acetylene reducing activity was positively correlated with the number of rooted nodes, and Stalon and leaf dry weights in early spring. Thereafter, except during a period of summer drought, ARA was positively correlated with the amount of clover leaf material.
Clover population density increased during the season and maximum growing point numbers (5540 m⁻¹) occurred in September; maximum leaf number per unit area (12 984 m⁻¹) was found in October, prior to the final cutting of the site.
Results suggest that higher levels of nitrogen fixation in upland swards should be obtained if sward management regimes, which encourage a high clover leaf area, are adopted.