THE EFFECT OF COMPANION GRASS AND SEED RATE ON THE PRODUCTIVITY OF A TALL-FESCUE SWARD

The effects of sowing from 10 to 50 lb/acre of tall-fescue seed on plant establishment and on the annual and seasonal distribution of DM yield of tall fescue and its companion grasses were measured through two growing seasons. Increasing the seed rate increased plant numbers per unit area and decreased per cent establishment. Adding Scots timothy as a companion grass depressed both plant number and per cent establishment. S37 cocksfoot and New Zealand perennial ryegrass reduced both still further. Total annual dry-matter production was relatively unaffected by varying either the seed rate or the companion grass. The contribution of tall fescue to total production was highest when sown alone and was successively reduced by timothy, perennial ryegrass and cocksfoot. When sown alone there were only slight differences in contribution of tall fescue due to seed rate. With any companion grass the contribution from tall fescue increased with increasing seed rate. Early growth was not reduced by modifying seed rate but was reduced by all the companion grasses. It is concluded that increasing the seed rate of tall fescue above 30 lb is not justified, that Scots timothy can be sown at 3 lb/acre with tall fescue without affecting total production or early growth of the mixture, with the advantages of control of unsown species and improved palatability of the herbage.     

THE EFFECT OF TIME AND RATE OF N APPLICATION ON THE PRODUCTIVITY OF GRASS SWARDS IN TWO ENVIRONMENTS

Six identical experiments (3 in Devon and 3 in Suffolk) investigated the effect of 200, 300 and 400 lb N/ac (224, 336 and 448 kg/ha), given in 1, 2, 4 or 8 equal applications, on the yield and seasonal production of perennial ryegrass swards cut every 25 days. Each rate of N Increased DM and N yields. Giving the N in 4 or 8 dressings gave higher DM, bnt rather lower N yields, than applying the N in 1 or 2 dressings. The effect on DM yield of splitting the N was most marked at 400 lb NJac (448 kgJha). Seasonal production was closely related to the time of N application and most uniform where N was given in 8 dressings. Differences between Devon and Suffolk were most evident where the N was given in 4 or 8 dressings and occurred in the second half of the season when the low rainfall in Suffolk apparently restricted N uptake and DM yield. The efficiency with which N taken up by the plant was used for DM production was affected by sunshine. It is concluded that rainfall and sunshine will limit the extent to which fertilizer N can he used to control herbage production.     

THE TESTING OF GRASS VARIETIES IN SWARDS WITH CLOVER: THE EFFECT OF GRASS SEED-RATE ON COMPARISONS OF GROSS YIELD

Three experiments were carried out to examine the influence of grass seed-rate upon the amount of clover growing with different varieties of perennial ryegrass. The bred varieties S23 and S24 were compared with Irish ryegrass. A larger quantity of clover grew with Irish ryegrass than with bred varieties at any given seed-rate. If the varieties were to be compared in terms of herbage of similar clover content, then Irish ryegrass sown at 20 lb/ac had to be compared with S23 or S24 sown at about a quarter of that rate. Reducing the seed-rate of the bred varieties from 20 to 5 lb/ac had only a small effect upon yield of ryegrass, and this was offset by an increase in yield of clover. Since weed grasses also took advantage of low grass seed-rate, it is concluded that other factors in the management of variety trials must be so controlled as to produce a satisfactory clover content without too drastic a reduction in the seed-rate of any variety. The relationship between grass seed-rate and yield of clover varied markedly with the availability of moisture.     

THE CONSUMPTION OF PERENNIAL RYEGRASS AND RED CLOVER BY GRAZING LAMBS

Groups of six-month old lambs, which were either experienced or inexperienced grazers, strip-grazed swards of S24 perennial ryegrass or Hungaropoly tetraploid red clover, at daily herbage allowances of 20 or 40 g OM/kg LW, in late August and September. The swards were similar in N content, but the weight of standing crop, and its digestibility, were higher on grass than on clover. Estimates of herbage intake were made in two successive periods of 19 days. Intake (g OM/kg LW) was lower at low than at high allowance (by 22% and 28% in periods I and II). and experienced grazers ate more than inexperienced animals (by 27% and 22%). Intakes on clover were 28% higher than on grass in Period I, but in Period II the difference was not significant.     

EFFECTS OF WHITE CLOVER ON THE BOTANICAL COMPOSITION OF SWARDS OF RYEGRASS, TIMOTHY AND MEADOW FESCUE AND MIXTURES OF THESE THREE

Results are presented to show the effect of white clover (Trifolium repens) and of applied N on the hotanical composition of swards sown with perennial ryegrass (Lolium perernne), timothy (Phleum pratense), meadow fescue (Festuca pratensis) and mixtures of two and three of these species. White clover had a more favourahle effect on the growth of perennial ryegrass than on either timothy or meadow fescue both in terms of yield and in terms of tiller numbers. Tiller numbers of rough-stalked meadow grass (Poa trivialis) were increased and tiller numbers of Agrostis species were reduced by application of N and by inclusion of clover. Possible reasons for these effects are considered.     

THE EFFECT OF THE GRAZING ANIMAL ON THE N STATUS OF GRASS SWARDS

Thirty-one sets of N yield data were considered, taken from seven experiments grazed by sheep. N yield could be explained in terms of fertilizer N rate, an estimate of soil N and an interaction between the two. Fertilizer N increased grass N yield more on grazed swards than on cut swards, and this effect was greatest on soils with high available soil-N. It is concluded that N recircula-tion can be substantial on heavily-stocked swards receiving high rates of fertilizer N, so increasing the efficiency of fertilizer as a source of N in these conditions.     

THE EFFECT OF COMPANION GRASSES ON TIMOTHY PRODUCTION IN SWARDS CUT FOR CONSERVATION

To assess the effect of companion grasses on timothy productivity, swards of timothy sown alone or with one of eight companion grasses were harvested as for silage four times per year for two years. The companion grasses were: diploid perennial ryegrasses S24 and S23; tetraploid perennial ryegrasses Reveille and Taptoe; meadow fescues S215 and S53 and cocksfoots Trifolium and S143. Averaged over the N application rates (226, 339 and 452 kg N/ha per year) the total herhage yields of timothy/companion-grass mixtures were all significantly superior to that from timothy alone in the first year. Only perennial ryegrass S24 and the cocksfoot mixtures significantly outyielded timothy alone in the second year. Winterkill hecame evident in April of the second year and pure timothy and timothy/meadow-fescue swards were least affected. Over all swards, timothy DM increased hy a mean of 19% from the first to the second year, compared with a fall of 20% in total herhage DM. The contrihution of timothy herhage to the mixtures was very low with companions other than meadow fescue. Late-heading varieties were more compatihie than early-heading varieties, and tetraploid ryegrasses were more compatihie than diploid ryegrasses. It is concluded that if the inherently valuahle characteristics of timothy are to he exploited, it should not he sovm with aggressive companion grasses.     

THE EFFECT OF URINE AND ITS COMPONENTS ON THE BOTANICAL COMPOSITION AND PRODUCTION OF A GRASS/CLOVER SWARD

A study was made of the effect of sheep urine and some of its components on herbage production. The return of urine to the sward increased production from the grass species; the clover content of the sward was reduced.
The application of nitrogen or potassium fertilizer equivalent to the normal return of nitrogen and potassium in urine increased production, but not as much as urine. The return of nitrogen and potassium fertilizer together increased production and altered botanical composition in much the same way as did urine.
On a grass-dominant urine-treated sward the application of nitrogen fertilizer increased the "efficiency" of urine.
The effect of urine on a grass/clover sward was almost entirely due to its nitrogen and potassium content. The water and indole acetic acid content of urine had no effect on pasture production or composition.     

THE EFFECT OF CUTTING HEIGHT AND CUTTING FREQUENCY ON THE PRODUCTIVITY OF AN ITALIAN RYEGRASS SWARD

Three cutting heights, 1, 3 and 5 in. (2.5, 7.6 and 12.7 cm), and three cutting frequencies, 3, 6 and 10 weeks, were imposed on a pure sward of Italian ryegrass (Lolium multiflorum) cv. Irish. Lowering the cutting height increased the yield of DM, digestible DM, crude protein and crude fibre. Increasing the interval between cuts increased the yield of DM, digestible DM and crude fibre. The results are discussed in relation to other research findings and to the management of short-term leys of Italian ryegrass.     

THE EFFECT OF STAGE OF GROWTH AT DEFOLIATION ON WHITE CLOVER IN MIXED SWARDS

Four experiments are described in which various defoliation methods and frequencies were imposed on grass/white-clover swards. Clover was not reduced in any of these hy increasing the length of growth period or hy cutting at a late stage of growth, but intensive sheep grazing reduced clover compared nitb cutting and taking a silage cut in a grazing sequence improved clover yield. These results do not support the contention that cutting a mixed sward for hay or silage suppresses clover because of competition for light: with a ‘big white’ type of clover infrequent defoliation may cause no more shading than frequent. Alternatively, any additional shading may be compensated for by an increase in clover growth, stimulated hy the longer growth period. It is suggested that, in practice, competition for nutrients and moisture also contrihute towards clover suppression when swards are cut for hay or silage.     

THE EFFECT OF CUTTING HEIGHT AND NITROGEN LEVEL ON THE YIELD, IN VITRO DIGESTIBILITY AND CHEMICAL COMPOSITION OF ITALIAN RYEGRASS SWARDS

Three cutting heights, 2±5, 7±6 and 12±7 cm (1, 2±5 and 5 in.) and three levels of fertilizer N, 168, 280 and 392 kg N/ha (150, 250 and 350 Ib N/ac) were imposed on a sward of Italian ryegrass (Lolium multiflorum) cv. Irish. Lowering the cutting height and increasing the level of applied N increased the yield of herhage DM. Increasing the level of applied N had a greater effect on the chemical composition of the herbage than altering the cutting height     

SOME SELECTIVE EFFECTS OPERATING ON WHITE- AND RED-CLOVER IN SWARDS

Populations of white- and red-clover were examined after they had been grown for several years in grass/clover swards. The method of sowing, nitrogen application, management and season affected the ratio of very similar clover cultivars differing specifically in the leaf mark when sown in the same mixture. The companion grass also infiuenced the proportion of legume cultivars in the sward. In addition, the mean date of emergence of a single cultivar of broad-red clover was affected by management.     

THE EFFECTS OF WHITE CLOVER AND APPLIED NITROGEN ON THE NITROGEN CONTENT OF VARIOUS GRASS/CLOVER MIXTURES

Percentages and yields of N in various grasses and grass mixtures with clover and in associated clover grown at various levels of N application over 5 years are given. Grasses varied consistently in N content, percentages being highest in meadow fescue (cv. S53) and lowest in perennial ryegrass (cv. S24). N application did not significantly affect the N percentage in clover, but the associated grasses had a highly significant effect Percentages were highest in clover associated with meadow fescue and lowest in clover associated with ryegrass. The apparent transfer of N to grass per Ib N in associated clover was calculated for various treatments each year. Reasons for the changing levels of apparent transfer from year to year are considered.     

THE EFFECT OF LEAF NUMBER ON THE SENSITIVITY OF RED CLOVER SEEDLINGS TO PHOTOPERIODIC INDUCTION

The duration of the juvenile phase in early-flowering (Dorset Marl) and late-flowering (S123) red clover is described. Neither cultivar responded to inductive conditions at the first leaf stage but Dorset Marl attained maximum sensitivity by the 3-leaf stage. A comparable response was obtained with S123 only after the production of 12–13 leaves. The growth characteristics of the two types under continuous long or short days are described and possible explanations are advanced for the characteristic differences in tillering and stem internode number.     

THE EFFECT OF WHITE CLOVER AND NITROGENOUS FERTILIZER ON THE PRODUCTION OF A SWARD

Three-year leys of cocksfoot/white clover and cocksfoot alone were dressed with 0, 35, 105 and 210 lb. N per acre every year to provide information on the effect of clover and N on annual production.
White clover contributed 40% of the dry-matter yield but its presence was responsible for 77% of this yield where no N was used: it was responsible for less than 8%, and contributed 5%, where 210 lb. N per acre was applied annually, lt was estimated that grass alone receiving 160 lb. N per acre would yield as much dry matter as a mixed sward receiving none.
Clover had the indirect effect of raising yield of nitrogen in the companion grass by 60 lb. per acre per year. A maximum of l06 lb. was recorded in 1958.
The response of the tnixed sward averaged 10 lb. of dry matter per lb. N. Prevailing economic circumstances will determine if this level is satisfactory in practice.
The recovery of N by grass alone varied from 54% at the lowest level of N to 80% at the highest. On mixed swards apparent recovery was negative or low: N was to a large extent only replacing the effect of clover which was suppressed by its use.
Factors influencing response and the difference between that obtained under experimental and practical conditions are discussed.
The use of N to produce out-of-season grass may give good response, but may cause a reduction in clover contribution.     

THE EFFECTS OF CUTTING AND GRAZING SYSTEMS ON HERBAGE PRODUCTION FROM GRASS SWARDS

Studies were made on two perennial ryegrass–dominant swards of the effects of cutting and grazing systems of herbage production. A motor scythe was used for cutting and sheep in small enclosures for grazing. In both systems, herbage production was measured by a ground-level sampling technique, using sheep shears, and the difference between pre-treatment and post-treatment herbage was expressed as ‘utilized yield’. Correction for soil contamination is ensured by quoting all results on an organic-matter basis. Grazing treatments averaged 14–16% more organic matter and 36–45% more crude protein than cutting treatments in both experiments. These differences were ascribed to recycling of N under grazing. Infrequent defoliation gave higher yields than frequent, and severe defoliation higher yields than lenient under both cutting and grazing systems. The trends shown by cutting and grazing intensities are comparable and can be quantified. There is need to examine closely the relationships between the effects of cutting and grazing techniques on herbage production, since such knowledge would allow a more accurate prediction of the relevance to the grazing situation of results obtained under cutting.     

THE EFFECT OF DRILL WIDTH ON THE SEED PRODUCTIVITY OF LEAFY VARIFTIES OF THREE GRASS SPECIES

Three leafy grass varieties, S215 meadow fescue, S37 cocksfoot and S51 timothy. were subjected to four dril spacings of 6, 15, 24 and 36 in. under two levels of nitrogen application. Over three harvest years, meadow fescue gave better seed yields with 6- and 15-in, drill spacings. Cocksfoot gave very similar yields from 1.5, 24- and 36-in, drills but a signincantly reduced yield from 6-in, spaced drills. Timothy produced significantly higher yields at the 24 in spacing.
The three varieties showed a significant response to nitrogen application.
Aphids seriously affected the vegetative growth of meadow fescue and timothy at the wider spacings, but the 6-in. drills m boths species remained relatively free of aphid attack, as also did the cocksfoot block.     

THE EFFECT OF WHITE CLOVER AND NITROGENOUS FERTILIZER ON THE PRODUCTION OF A SWARD

Data from an experiment already reported (2) are used to examine a statistical method proposed by Walker et al . (8) for apportioning the nitrogen harvested in grass in a grass/ legume sward to legume, fertilizer and soil. Multiple regressions of the yield of N in the grass (G_n) upon N harvested in the associated legume (C_n) and N applied in fertilizer (F_n) were highly significant; but they were very variable, mainly because of the strong (negative) correlation between C_n and F_n. In some cases the coefficient for clover N was negative, in some cases the coefficient for fertilizer N exceeded unity; and the residual constant varied widely among 4 sets of plots on the same soil. The interpretation of such equations in physical terms is criticized on these grounds. The use of pure grass swards in conjunction with mixed swards gave estimates of the recovery of fertilizer N, and of the transfer of N from clover to grass, which agreed better with other published data than did the coefficients in a multiple regression. A simple regression of the estimate of transferred N in the grass upon the N harvested in the clover yielded a second constant. This constant, which varied considerably from one series of plots to another, is thought to indicate interactions between the various sources of N, which would be attributed to a direct effect of soil N if the multiple regressions were interpreted as Walker et al . suggest.     

THE EFFECT OF WHITE CLOVER AND NITROGENOUS FERTILIZER ON THE PRODUCTION OF A SWARD

Three-year leys of cocksfoot/white clover and cocksfoot alone were dressed with 0, 35, 105 and 210 lb N per acre every year to provide information on the effect of clover and N on production.
Data from the grass-alone swards allowed an estimate to be made of the effect of N on production at different cutting dates. This was compared with the effect of clover.
The effect of N was greater than that of clover in the mid- and late-season cuts. Clover made its greatest contribution, both directly and indirectly, at the first cut, taken in May.
Under very dry conditions (1959), N was more effective than clover in maintaining production and the proportional response was large in relation to that produced under moist conditions.
The results are discussed with reference to the present seasonal use of N on grassland and an argument is advanced for increasing its use in mid-season.     

SOME ASPECTS OF THE NITROGEN: WATER INTERACTION ON GRASS SWARDS

Experiments were conducted on ryegrass swards using different amounts of N fertilizer applied as a single early dressing (S) or in repeated applications during the season (R). Over three years, the yield from R was generally higher, but under dry conditions (using plot covers) S gave the greater yield. The latter result is ascribed to the bigb yield obtained from S at the first cut, at which time N uptake was not limited by a lack of soil water. Irrigation at less than the full requirement resulted in lower total yields but it increased water-use efficiency by up to 70% (R) and 94% (S).