Further studies on the effect of phosphate fertilizer and propyzamide on the growth of white clover slot-seeded into permanent pasture

Assessments were made of the clover yield and clover content between early June and late July 1984 of white clover in a permanent pasture which had been slot-seeded in spring 1982.
Past reserves of phosphate or application of propyzamide alone only slightly increased clover dry matter yield but together they increased it from 13 to 785 kg dry matter ha^-1 and gave 31% clover in the total herbage yield. Applications of P₂O₅ during the experiment, alone or together with past reserves of phosphate, Iased clover yield from 13 to 242 kg dry matter ha^-1 and the proportion of clover from 1 to 10%. However, highest yields (1282 kg) and clover content (37%) were attained when P₂O₅ and propyzamide were applied to treatments with past reserves of phosphate.
These results confirmed the trends evident during the second year and also indicated a potential role for grass-suppressants in increasing management options during the early years after slot-seeding.     

Cattle slurry as a source of nutrients for red clover: herbage production and clover contribution

An established sward of red clover cv. Hungaropoly sown pure received approx. 30 kg P ha^-1 and 200 kg K ha^-1 each year for 3 successive years. The P and K were applied either as cattle slurry, inorganic fertilizer or combinations of these. Treatments were applied either in spring or after the first harvest. There were a total of six treatments and these were harvested three times each year. The average yields of total herbage DM over all the treatments in the first, second and third years were 15·2, 14·2 and 14·2 t ha^-1 respectively and the various treatments had no significant effect on the overall yields.
Treatments had a significnt effect on red clover DM yields and percentage red clover in one harvest in each of the first 2 years and all three in the third year. Yields of red clover were lower and grass higher in treatments receiving cattle slurry only. On this treatment there was a total yield of 23·2 t ha^-1 red clover DM in the 3 years compared with 30·2 t ha^-1 on the inorganic fertilizer treatments. However, by applying P and K fertilizer in the spring, followed by cattle slurry after the first harvest, it was possible to maintain a high proportion of red clover in the sward and to produce yields of red clover DM similar to those on the inorganic fertilizer treatments.     

The influence of surface and sub-surface application methods for pig slurry on herbage yields and nitrogen recovery

Experiments were conducted on a grassland site at Wrest Park, Silsoe, Bedfordshire between 1987 and 1989, to compare herbage yields from slurry applied by deep and shallow injection, low trajectory and conventional vacuum tanker methods. Slurry application rates for all spreaders were calibrated at 86 ± 5 t ha^-1, an equivalent of c. 200 kg NH₄⁺-N ha^-1 applied in autumn or in spring.
As expected, herbage yields following spring applications were higher than from autumn applications, with average mineral fertilizer equivalents of 122 and 89 kg N ha^-1 respectively. Yields from the conventional and low trajectory spreaders showed no consistent differences. However, in both years, first cut yields from plots were significantly lower ( P < 0·05) where slurry had been injected than where surface applications had been used by an average of 0·7 t DM ha^-1. Subsequent cuts in 1988 demonstrated higher residual effects from injection so that annual total yields were similar from all slurry applications irrespective of spreader type.
Analysis of N content revealed high N levels in herbage from deep injection plots. Mean concentrations of N in the herbage, expressed as a percentage of the dry matter, were 1·43 for surface treatments and 1·79 for deep injection in 1988, and 1·84 for surface treatments, 2·13 for shallow injection and 2·68 for deep injection in 1989.     

The effect of fertilizer nitrogen rate, white clover variety and closeness of cutting on herbage productivity from perennial ryegrass/white clover swards

Four varieties of white clover (small-leaved cv. Aberystwyth S184. medium-leaved cv. Grasslands Huia and large-leaved cvs Linda and Olwen) were sown at 3 kg ha^-1 together with 10 kg ha^-1 perennial ryegrass cv. Talbot. Herbage productivity was measured for three harvest years, 1979-81, over four annual rates of fertilizer N (0,120,240 and 360 kg ha^-1) and two closeness of cutting treatments (80 and 40 mm from ground level). A simulated grazing regime of six cuts per year at 3- to 6-week intervals was used.
Production of total herbage DM was increased by increasing N rate; mean annual DM production ranged from 783 1 ha^-1 with no N to 11701 ha^-1 at 360 kg ha^-1 N. Mean herbage response to N (kg DM per kg N applied) was 73,90 and 108 for the three successive N increments relative to no N. Mean white clover DM production was reduced from 4 14t ha^-1 with no N to 051 t ha^-1 at 360 kg ha^-1 N.
The large-leaved clover varieties were more productive than the small- or medium-leaved varieties at all N rates. Close cutting increased total herbage and white clover by a mean annual 16% and 31%. respectively. White clover varieties did not interact with either N rate or closeness of cutting.
It is concluded that repetitive N application over the growing season is incompatible with white clover persistence and production, even with large-leaved clover varieties or with close cutting, two factors which improved clover performance in the experimental swards.     

The sulphur status of intensive grassland sites in southern Scotland

Field trials were carried out at five sites in southern Scotland to examine the sulphur status of intensively grown grass under varying Inputs of atmospheric and rainfall sulphur. Sulphur budgets were prepared by comparing amounts of sulphur removed at harvest with sulphur inputs from rainfall, the atmosphere and fertilizers.
No yield responses to added sulphur were obtained, although soil-derived sulphur was essential for the maintenance of optimal sulphur levels in herbage. Where no fertilizer sulphur was added, mineralization of soil organic sulphur supplied approximately 8 to 18 kg S ha^-1 annually during the growing season. Maintenance requirements of 5 to 10 kg S ha^-1 annually were indicated at the Dumfriesshire and Midlothian sites and 20 kg S ha^-1 annually at the Berwickshire sites to prevent a decline in soil sulphur reserves. Total sulphur concentrations of less than 2 g S kg^-1 dry matter were observed in herbage at some samplings indicating marginal sulphur sufficiency. Sulphate levels in herbage, expressed as a percentage of total sulphur, also indicated that sulphur supplies barely matched crop requirements.     

Effect of regrowth interval on the productivity of swards defoliated by cutting and grazing

Over three grazing seasons (1984-1986) a sward of perennial ryegrass, cv. Talbot, which received a total of 336 kg N ha^-1 each season, was cut or grazed with ewes at 3- or 4-week intervals on a rotational basis.
Sward productivity was higher under cutting than under grazing irrespective of the interval between defoliations. Under cutting, mean herbage organic matter (OM) yields over both intervals were 8·66, 9·62 and 8·17 t ha-¹ in 1984, 1985 and 1986 respectively while under grazing the corresponding yields were 7·65, 8·63 and 7·50 t ha^-1. The mean annual yield of herbage defoliated at 3-week intervals was 7·50, 8·64 and 7 ·20 t OM ha^-1 compared with 8·80, 9·60 and 8·46 t OM ha^-1 for swards defoliated at 4-week intervals in the three years respectively.
The nitrogen (N) content of both the available and the residual herbage was consistently higher under grazing than under cutting. Available herbage contained 31·3 and 27·7 g N kg OM^-1 and residual herbage 26·1 and 22·7 g N kg OM^-1 under grazing and cutting respectively.
The mean yield of N under cutting was 284 kg ha^-1 compared with 304 kg ha^-1 under grazing. Defoliation interval had no effect on N yield, the overall mean yield being 294 kg ha^-1 under both 3- and 4-week defoliation intervals. The effect of the treatments on tiller population was slight and inconclusive.
The process of grazing reduced yield probably as a result of damage to the sward through trampling; the positive effect of excretal N on yield was minimal on account of the short grazing periods.     

Grass production studies in the uplands of north-east Scotland 1. The effects of soil parent material, altitude and soil major group

Sites were established on good quality grass swards in areas representative of three of the most extensive soil parent materials in north-east Scotland and covering an altitudinal range of 260–460 m. Overall yields of herbage dry matter in 1975 were high, ranging from 6280 kg ha^-1 with no fertilizer to 9190 kg ha^-1 with an application of 100, 26 and 50 kg ha^-1 N, P and K respectively. Differences in production between parent material and altitude groupings were found to be associated with differences in major soils group and past land use, with long-enclosed brown earths outyielding podzols recently reclaimed from heather moorland by about 30% overall. Increasing inputs of fertilizer appeared to reduce the effects of soil and climatic conditions. Brown earths showed higher apparent recoveries of N fertilizer than did podzols.     

The effect of strategic fertilizer nitrogen and date of primary harvest on the productivity of a perennial ryegrass/white clover sward

Four management systems involving different dates for first harvest (simulated grazing, early silage, late silage and hay) and two fertilizer N rates in spring (0 and 80 kg ha^-1) were imposed on a perennial ryegrass cv. Talbot/white clover cv. Blanca sward during 1981-82. In each year, annual total herbage DM was increased by spring application of N but white clover production and content in the total herbage were reduced; however, white clover, which was depressed in the harvests immediately after N application, recovered during the season to amounts and contents in the total herbage similar to those given no spring N.
Annual total herbage DM production increased as the date of primary harvest was delayed (935 to 1197 t ha^-1 over two years) but mean organic matter digestibility values for the same period decreased (0-769 to 0700). First-harvest production made up substantial proportions of the annual production in the conservation systems. White clover, as shown by its production and the amount of stolon present, was tolerant of conservation systems, especially with no applied N.
It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. The use of strategic spring N seems a viable option, but more knowledge of rates would be valuable since this experiment only compared 80 kg ha^-1 with no applied N.     

Long-term effects of fertilizer on soil nutrient concentration, yield, forage quality and floristic composition of a hay meadow in the Eifel mountains, Germany

A long-term fertilizer experiment, which was set up in 1941 on extensively grazed heathland, naturally dominated by Calluna vulgaris L. and Nardus stricta L., is presented. The turf layer was grubbed and reseeded with a grass/legume mixture, and plots were fertilized with (a) lime only as calcium (including magnesium), (2) lime and nitrogen (Ca/N), (3) lime, nitrogen and phosphorus (Ca/N/P₂O₅) and (4) lime, nitrogen, phosphorus and potassium (Ca/N/P₂O₅/KCl and Ca/N/P₂O₅/K₂SO₄). Since 1941 these experimental plots have been mown but not grazed.
After 50 years of imposing the experimental treatments, dry-matter (DM) yield was found to be positively affected by N, P and K application. Soil N and P concentrations were significantly higher in fertilized than in unfertilized plots. No differences in soil K concentration were found between the two treatments with KCl and K₂SO₄. Net energy concentration in the plant DM was highest with the Ca/N treatment, but differences were slight. Crude protein concentrations varied from about 110 to 170 g kg^–1 DM. In all plots and all years protein concentrations were lower in the first cuts than in the second cuts.
Considerable differences in floristic composition were found between different fertilizer treatments. The treatments receiving only Ca contained more than sixty species, many of them representative of oligotrophic extensively managed grassland. In fully fertilized plots, herbs were suppressed by tall-growing grasses. In these plots the number of species was low.     

The herbage intake and performance of set-stocked suckler cows and calves

Groups of eight Hereford × Friesian cows and their South Devon cross calves were set stocked over a 24-week grazing season at 3·23 (low), 3·21 (medium) or 4·24 (high) cows ha^-1 together with their calves. For the first 8 weeks only two-thirds of the total area was grazed. Increasing the stocking rate from low to medium reduced daily milk yield and cow and calf liveweight gains by 1·2, 0·24 and 0·29 kg d^-1 respectively, and from medium to high by 1·2, 0·24 and 0·23 kg d^-1. The main sward factor influencing faecal output and herbage intake was the quantity of organic matter on the pastures but the digestibility of the herbage selected also exerted a significant effect on the intake of cows. Major depressions in the herbage intake of cows occurred once the average sward height fell below 7 cm. Output of calf live weight was 628, 658 and 743 kg ha^-1 for the 3 stocking rates from low to high, and for cows 246, 179 and 30 kg ha^-1. It was concluded that decisions on pasture management should be taken in relation to the cow rather than the calf on set-stocked swards.     

Effect of fertilizer nitrogen on six-year-old red clover/perennial grass swards

Three diploid red clover cultivars—Sabtoron, Violetta and Essex—and three tetraploid, Hungaropoly, Teroba and Red Head, were sown separately in pure culture and with each of three companion grasses: timothy (Aberystwyth S48), tall fescue (Aberystwyth S170) and perennial ryegrass (Aberystwyth S24).
The effects of fertilizer N on yield and on clover/grass ratio over a 2-year period (seventh and eighth harvest years) subsequent to 6 harvest years during which no N fertilizer was applied were investigated. The data for productivity and persistence have already been published (McBratney, 1981; 1984).
Application of fertilizer N increased DM yields in the eighth year. In this year, the highest yield, 11·9t ha^-1, averaged over the six clover cultivars, was given in association with tall fescue. Tall fescue contributed 90% of this yield. Clover content continued to decrease in all swards but the decrease was greatest in the swards receiving fertilizer N. The yield of clover DM averaged over the six cultivars under N treatment declined from 5·6t ha^-1 in the seventh year to only 0·4t ha^-1 in the eighth year.
The results from this trial demonstrate the potential of red clover sown either pure or in mixture with a suitable perennial grass, to maintain high output of quality herbage over a 6-year period without the aid of fertilizer N. They further demonstrate that following decline in red clover content, both herbage yield and quality may be restored by the application of N fertilizer, particularly where the clover was seeded with a highly productive companion grass.     

Interactions between fertilizer use and leatherjacket control in grassland

A coordinated experiment was set up in eight fields of established grass; four In Northern Ireland and four in the West of Scotland. At each site one of three different fertilizer rates (0, 75 and 150 kg N ha^-1) were applied to plots that had previously either received a 0.72 kg ha^-1 chlorpyrifos treatment to control leatherjackets or no spray. Both fertilizer and insecticide applications increased herbage yields. Yield increases in response to chlorpyrifos treatments were equivalent to that obtained from 75 kg N but were not linearly related to leatherjacket numbers. A curvilinear function relating loss per leatherjacket to population size was derived and its validity is discussed. It is concluded that herbage yield increases resulting from chlorpyrifos and nitrogen applications were independent and cumulative.     

Sodium fertilizer application to pasture. 6. Effects of combined applications with sulphur on herbage production and chemical composition in the season of application

The effect of sulphur and sodium fertilizers on the response of a perennial ryegrass ( Lolium perenne ) sward was examined over 2 years. Sulphur fertilizer was applied as ammonium sulphate at 0 or 97·5 kg S ha⁻¹ year⁻¹ and sodium fertilizer as sodium nitrate at 0 (nil), 31 (low), 62 (medium) or 94 (high) kg Na ha⁻¹ year⁻¹, with nitrogen input balanced across all treatments. Both sulphur and sodium increased herbage yield. Sodium fertilizer increased herbage sulphur concentration and sulphur fertilizer slightly increased herbage sodium concentration, but there were no major interactions between the two fertilizers on herbage yield or composition in the season of application. Sodium fertilizer increased dry-matter digestibility, water-soluble carbohydrate concentration and the live proportion of the herbage. Herbage sodium and magnesium concentrations were increased and potassium concentration decreased by sodium fertilizer. Sulphur fertilizer increased herbage dry-matter digestibility and water-soluble carbohydrate concentration. Sulphur and potassium concentrations were also increased and non-protein nitrogen, magnesium and phosphorus concentrations decreased in response to sulphur fertilizer. It is concluded that, although there was evidence of facilitation of sodium uptake by sulphur fertilizer and vice versa, this was not sufficient to produce synergistic effects on herbage growth in the season of application.     

The response of Lotus uliginosus L. grown on hill soils to inoculation with Rhizobium

The response of marsh birdsfoot trefoil ( Lotus uliginosus ) to inoculation with appropriate Rhizobium spp. was compared over 2 years. Inoculated and uninoculated seed was sown at 5 kg ha^-1 on three soil types, brown earth, peaty podsol and deep peat. Perennial ryegrass cv. Perma was sown at 20 kg ha^-1 as a companion species. Plots received either no N or a light starter dressing of 30 kg ha^-1 N. Significant benefits from inoculation were recorded for Lotus germination and nodulation, Lotus and non- Lotus herbage DM harvested and Lotus cover on the deep peat, and to a lesser extent on the other soil-types. Due to particularly uneven early establishment, work on the peaty-podsol site was discontinued at an early stage. There was a trend towards depression of Lotus where N had been applied to inoculated plots.     

Effect of stocking rate in early season on dairy cow performance and sward characteristics

A comparison was made of stocking rates of 4·7, 5·6 and 6·4 cows ha^-1 during the first 7 weeks (period 1) of the grazing season. Each group of British Friesian cows was continuously stocked on a day and a night field. In the subsequent periods 2 and 3 (each lasting 7 weeks) the three groups were maintained at the same stocking rate within periods (4·2 and 31 cows ha^-1, respectively). The differential stocking rates were achieved by the addition and removal of cows.
The stocking rates applied in period I had no significant effects on milk yield, milk composition, liveweight change or condition score, in any period. Milk production ha^-1 over the three periods totalled 12390,13 978 and 14986 kg, and the estimated utilized metabolizable energy totalled 773, 81·5 and 86·6 GJ ha^-1 for low, medium and high stocking rates, respectively.
Increased stocking rate in period I was associated with a decrease in sward height in periods 1 and 2. This led to an increase in herbage metabolizable energy, and crude protein contents, and to an increase in tiller population density. The lowest stocking rate gave greater live individual tiller weights throughout the experiment and a longer interval between defoliation of individual tillers in period 1.
The results indicate that high stocking rates in the spring are not necessarily detrimental to overall summer performance of spring calving dairy cows. However, high stocking rates in the early season ensure a high level of herbage utilization and milk output ha^-1 in that period. Although this practice leads to a reduced sward height in mid season, the sward has less rejected area, a higher tiller population density and a higher digestibility than swards stocked at a lower level.     

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     

The potential for control of the soft rush (Juncus effusus) in grass pasture by grazing goats

Two experiments were conducted to examine the effect of inter-tussock grass height and stocking rate on the utilization of the rush ( Juncus effusus ) by grazing goats. In the first experiment, on rush-infested Festuca rubralTrifolium repens pasture, the utilization of rushes by goats grazing at a sward height of 3–4cm or 5–6cm was compared with that occurring on plots grazed by sheep at a sward height of 3–4 cm. Sheep grazed minimal amounts of rush. In contrast, it was estimated that 90% and 75% of current seasons growth of rush was grazed by goats at sward heights of 3–4 and 5–6 cm respectively during the first year. With continued goat grazing at 5–6cm there was a dramatic reduction in the cover and vigour of the rushes, and at a sward height of 3–4cm established tussocks were eliminated from the pasture.
The second experiment compared the utilization of rushes invading predominantly Agrostis swards stocked with goals at 10, 20 or 30 ha^-1 and in which inter-tussock sward height was maintained at 4–5cm on all treatments, by adding or subtracting sheep. On one site rush utilization increased with the increase in stocking rate of goats and rush tussocks were eliminated within 3 years at 30 goats ha^-1. On another, there was no difference between plots stocked at 20 or 30 goats ha^-1 and viable tussocks remained. The influence of the composition and productivity of the inter-tussock herbage and the proportion of rush in the biomass are discussed.
Goats can be used lo control rushes in grassland but high stocking levels and low inter-tussock pasture heights are required to promote adequate levels of utilization.     

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.     

Some effects of added phosphorus on perennial ryegrass—white clover swards

The effect of applying 100kg P ha^-1 per year in the form of triple superphosphate to mixed swards of perennial ryegrass ( Lolium perenne ) and white clover ( Trifolium repens ) was examined on a soil of low P status.
The dry matter yield of total herbage was increased by 10'/i by added P. In the year of sowing the ryegrass benefited more than the clover from added P: in the subsequent four years the two species benefited equally. Both species responded 10 added P to a similar extent in terms of leaf size; the clover responded less well than the ryegrass in terms of rate of leaf emergence. However, clover responded positively to added P in terms of stolon internode length, length of stolon per m² and number of growing points per m². It is suggested that the application of P may promote the spread of white clover within an open sward, but that its application may not enhance the competitive power of white clover when growing with vigorous grasses.     

Further experiences of beef production on permanent pasture in 1976–78

Between 1976 and 1978 a further 154 beef animals were grazed in separate groups on Alberts and Far field at Begbroke Hill, the former being a paddock system and the latter being set-stocked. Each year part of Alberts received complete fertilizer (147–180 kg ha^-1 N) and part did not. All of Far field received complete fertilizer (140–190 kg ha^-1 N). Drought caused a reduction in output in 1976, but in 1977 and 1978 total production of live weight was 9·07 and 8·74 t respectively from 11·65 ha grassland. Calculations of corrected outputs show that maxima of 829 kg ha^-1 in Alberts and 908 kg ha^-1 in Far field were achieved from fertilized grass. The highest output in Alberts represented 929 livestock unit grazing days per ha or 87·9 GJ ha^-1 in 1978.