bluuebunny/crossref_metadata_2025 huggingface dataset:
Simple carbon assimilation response functions from atmospheric CO2, and daily temperature and shortwave radiation
Authors: WILKS D.S. , WOLFE D.W. , RIHA S.J.
Published: April 2006

A global ‘CO2 fertilizer effect’ multiplier is often used in crop or ecosystem models because of its simplicity. However, this approach does not take into account the interaction between CO2, temperature and light on assimilation. This omission can lead to significant under‐ or overestimation of the magnitude of beneficial effects from elevated CO2, depending on environmental conditions. We use a mechanistic model of the biochemistry of photosynthesis to represent the response of net assimilation to different levels of CO2, temperature and radiation, on the daily time scale. Instantaneous assimilation rates for an idealized canopy model are integrated through diurnal cycles of environmental variables derived from historical climate data at three locations in North America. The calculated CO2 fertilizer effect is greatest at high light and warm temperatures. The results are summarized by assimilation response surfaces specified by the CO2 concentration, the canopy leaf area index, and by daily values of temperature and radiation available from climatic records. These summary functions are suitable for incorporation into crop or ecosystem models for predicting carbon assimilation or biomass production on a daily time step. An example application of the function reveals that for a relatively cool, high latitude location, the beneficial effects from a CO2 doubling would be negligible during the early spring, even assuming a + 4°C global warming scenario. In contrast, the beneficial effects from increasing CO2 at a relatively warm, lower latitude location are greatest in the spring, but decline in late summer because of excessively warm temperatures with a + 4°C global warming.
Species diversity and ecosystem response to carbon dioxide fertilization: conclusions from a temperate forest model
Authors: BOLKER B.M. , PACALA S.W. , BAZZAZ F.A. , CANHAM C D. , LEVIN S.A.
Published: April 2006

This paper explores how the response of a temperate forest ecosystem to climate change might depend on species diversity and community change. In particular, we look at the dynamics of a model of temperate forest growth under doubled CO2. We combine a detailed, field‐calibrated model of forest dynamics (Pacala et al 1993) with greenhouse data on the range of seedling biomass growth response to doubled CO2 concentrations (Bazzaz et al. 1990; Bazzaz & Miao 1993). Because total ecosystem response to climate change depends delicately on many environmental variables other than CO2, we isolate the effects of community change by comparing runs of the regular model, allowing dynamic community change, with runs of a reduced model that holds species composition static by using a single tree species with average parameters. Simulations that allowed community change instead of holding species composition constant showed a roughly 30% additional increase in total basal area over time scales of 50‐150 years. Although the model omits many possible feedbacks and mechanisms associated with climate change, it suggests the large potential effects that species differences and feedbacks can have in ecosystem models and reinforces the possible importance of diversity to ecosystem function (Naeem et ai 1994; Tilman & Downing 1994) over time scales within the planning horizon for global change policy.
Productivity and water use of wheat under free‐air CO2 enrichment
Authors: KIMBALL BRUCE A. , PINTER PAUL J. , GARCIA RICHARD L. , LaMORTE ROBERT L. , WALL GERARD W. , HUNSAKER DOUGLAS J. , WECHSUNG GABRIELE , WECHSUNG FRANK , KARTSCHALL§ THOMAS
Published: April 2006

A free‐air CO2 enrichment (FACE) experiment was conducted at Maricopa, Arizona, on wheat from December 1992 through May 1993. The FACE apparatus maintained the CO2 concentration, [CO2], at 550 μmol mol−1 across four replicate 25‐m‐diameter circular plots under natural conditions in an open field. Four matching Control plots at ambient [CO2] (about 370 μmol mol−1) were also installed in the field. In addition to the two levels of [CO2], there were ample (Wet) and limiting (Dry) levels of water supplied through a subsurface drip irrigation system in a strip, split‐plot design.

Measurements were made of net radiation, Rn; soil heat flux, Go; soil temperature; foliage or surface temperature; air dry and wet bulb temperatures; and wind speed. Sensible heat flux, H, was calculated from the wind and temperature measurements. Latent heat flux, λET, and evapotranspiration, ET, were determined as the residual in the energy balance. The FACE treatment reduced daily total Rn by an average 4%. Daily FACE sensible heat flux, H, was higher in the FACE plots. Daily latent heat flux, λET, and evapotranspiration, ET, were consistently lower in the FACE plots than in the Control plots for most of the growing season, about 8% on the average.

Net canopy photosynthesis was stimulated by an average 19 and 44% in the Wet and Dry plots, respectively, by elevated [CO2] for most of the growing season. No significant acclimation or down regulation was observed. There was little above‐ground growth response to elevated [CO2] early in the season when temperatures were cool. Then, as temperatures warmed into spring, the FACE plants grew about 20% more than the Control plants at ambient [CO2], as shown by above‐ground biomass accumulation. Root biomass accumulation was also stimulated about 20%. In May the FACE plants matured and senesced about a week earlier than the Controls in the Wet plots. The FACE plants averaged 0.6 °C warmer than the Controls from February through April in the well‐watered plots, and we speculate that this temperature rise contributed to the earlier maturity. Because of the acceleration of senescence, there was a shortening of the duration of grain filling, and consequently, there was a narrowing of the final biomass and yield differences. The 20% mid‐season growth advantage of FACE shrunk to about an 8% yield advantage in the Wet plots, while the yield differences between FACE and Control remained at about 20% in the Dry plots.
El Niño and tree growth near Jerusalem over the last 20 years
Authors: YAKIR DAN , LEV‐YADUN SIMCHA , ZANGVIL AVRAHAM
Published: April 2006

A strong correlation is observed between an El Niño index (anomalies in tropical Pacific sea surface temperature) and rainfall in the Judean foothills near Jerusalem over the past 20 years. These relationships clearly influenced the growth of local pine trees, as reflected in the width of their annual tree rings. The ability to predict El Niño events about a year in advance lend a special significance to relationships reported here for ecology, agriculture and water management in this climatic transition zone. To help explain the observed, long‐range teleconnection we propose a possible mechanism based on a newly identified direct cloud connection between equatorial Africa (more directly affected by El Niño) and the Southeastern Mediterranean shoreland. The penetration and contribution of the moisture current from equatorial Africa to this region may depend on a shift in the usual rain generating moisture currents to southwesterly trajectories (passing over north Africa). The occurrence of such shifts is supported by the observed decrease in the mean 18O content of the local precipitation during El Nino winters.
Elevated CO2 decreases seed germination in Arabidopsis thaliana
Authors: ANDALO CHRISTOPHE , GODELLE BERNARD , LEFRANC MADELEINE , MOUSSEAU MARIANNE , TILL‐BOTTRAUD IRÉNE
Published: April 2006

The impact of elevated [CO2] on seed germination was studied in different genotypes of Arabidopsis thaliana from natural populations. Two generations of seeds were studied: the maternal generation was produced in the greenhouse (present‐day conditions), the offspring generation was produced in two chambers where the CO2 concentration was either the present atmospheric concentration (about 350 ppm) or elevated (700 ppm). The seeds were tested for proportion of germinated seeds and mean germination time in both chambers to study the impact of elevated [CO2] during seed production and germination.

Elevated [CO2] during maturation of seeds on the mother‐plants decreased the proportion of germinated seeds, while elevated [CO2] during germination had no effect on the proportion of germinated seeds. However, when seeds were both produced and germinated under elevated [CO2] (situation expected by the end of next century), germination was slow and low.

Moreover, the effect of the [CO2] treatment differs among genotypes of Arabidopsis: there is a strong treatment × genotype interaction. This means that there is ample genetic variance for a selective response modiying the effects of high levels of [CO2] in natural populations of Arabidopsis thaliana. The outcome at the community level will depend on what seeds are available, when they germinate and the resulting competition following germination.
Appropriate controls in outdoor UV‐B supplementation experiments
Authors: NEWSHAM K.K. , McLEOD A.R. , GREENSLADE P.D. , EMMETT B.A.
Published: April 2006

Quercus robur L. saplings were exposed in an outdoor experiment to supplemental levels of UV‐8 (280–315 nm) radiation using treatment arrays of cellulose diacetate‐filtered fluorescent lamps that also produce UV‐A (315–400 nm) radiation. Saplings were also exposed to UV‐A radiation alone using control arrays of the same lamps filtered with polyester and to ambient levels of radiation, using arrays of unenergized lamps. The UV‐B treatment was modulated to maintain a 30% elevation above the ambient level of UV‐B radiation, measured by a broad‐band sensor weighted with an erythemal action spectrum. Saplings exposed to UV‐B radiation beneath treatment arrays developed thicker leaves than those beneath ambient and control arrays. Despite the fact that supplemental levels of UV‐A radiation were only a small percentage of ambient levels, apparent UV‐A effects were also recorded. Significant increases in sapling height, lammas shoot length and herbivory by chewing insects were observed under treatment and control arrays, relative to ambient, but there were no differences between the responses of saplings under treatment and control. These data imply that supplemental UV‐A radiation or other effects associated with energised lamps can significantly affect plant growth parameters and herbivory in outdoor studies. We conclude that the results from current outdoor UV‐B supplementation experiments that lack control exposures using polyester‐filtered lamps need to be interpreted with caution and that future supplementation experiments should include appropriate controls.
Carbon dioxide‐induced changes in beech foliage cause female beech weevil larvae to feed in a compensatory manner
Authors: DOCHERTY MAUREEN , HURST DEBRA K. , HOLOPAINEN JARMO K. , WHITTAKER JOHN B. , LEA PETER J. , WATT ALLAN D.
Published: April 2006

The phenology of Fagus sylvatica was unaffected by exposure to an atmosphere of elevated CO2 (600 μL L‐1) after two years of fumigation. Non‐significant changes in nitrogen and phenolic content of the leaves decreased the nutritional status of beech for female larvae in elevated CO2 such that they responded by eating in a compensatory manner; males were unaffected. Rates of development, mortality and adult biomass of Rhynchaenus fagi were no different from those in ambient CO2 concentrations (355 μL L ‐1). It is possible that, with the changes in leaf chemistry affecting the females, fecundity will be altered, with important consequences for populations of beech weevil.
DAY‐LENGTH AND HEAD FORMATION IN THE RYEGRASSES*
Authors: Cooper J. P.
Published: April 2006

The importance of the time and extent of head production in the herbage grasses has been realized for a long time. In bay or silage making, or in grsiss drying, it deter‐mines tbe stage of maturity of the crop, and hence date of cutting, while in both hay and pasture tbe nutritive value of the herbage depends largely on the proportion of leaf and stem present. In seed production, the time of heading is of basic importance. It deter‐mines date of harvesting and so may affect yield of seed.
THE EFFECT OF EARLY DEFOLIATION ON LUCERNE SEEDLINGS§
Authors: Bignoli D. P.
Published: April 2006

Summary

Early defoliation in the seedling stage was found to have a profound influence on the vigour and the size of the seedlings. The effect of injury in the seedling stage on the establishment of lucerne leys is discussed.
THE RENOVATION OF DOWNLAND PERMANENT PASTURE II.
Authors: Norman M. J. T. , Green J. O.
Published: April 2006

An experiment, A, involving dates and methods of application of 2,4‐D (amine) as a preliminary treatment in the renovation of a poor downland permanent pasture, followed by surface cultivations and sowing of S.24 perennial ryegrass and S.100 white clover, was carried out at Hurley between 1953 and 1955.

In spite of initial differences in the establishment of S.24 and S.100, pre‐treatment with herbicide had no effect upon the cover of sown and unsown perennial ryegrass and white clover two years later. At this date, perennial ryegrass contributed one‐quarter and one‐eighth, and white clover one‐third and one‐quarter, to the total cover of renovated and unrenovated plots respectively.

The increase in dry‐matter yield resulting from renovation was approximately 10 per cent. This was considered small in relation to the estimated improvement in yield brought about by grazing management and manuring in the course of the trial.

In experiment B, plots receiving herbicide were given differential management and manurial treatments after spraying in an attempt to control the ingress of undesirable creeping grasses. The results indicated that this ingress could be checked by close grazing soon after spraying.
COMPARATIVE PRODUCTIVITY OF 27 STRAINS OF GRASS IN THE WEST OF SCOTLAND
Authors: Hunt I. V.
Published: April 2006

Seasonal productivity from plots of 27 strains of the principal grass species has been compared at Auchincruive over two seasons by a cutting technique. The following conclusions are reached:

Peak growth is limited to a short period before the first week in June. Extension at peak‐growth level into the summer gap is not possible by the use of any of these grass strains grown alone.

The provision of grass for one cow per acre is possible for up to 142 days by the combination of strains.

Extension into the autumn can be achieved by conserving second‐peak growth, which does not mature to the same extent as the first‐peak growth.

In combining strains with advantageous growth periods due regard must be paid to their growth at other periods, which may be particularly low.

Combination of many strains is not likely to achieve as good a result as the use of 2, or at most 3, well chosen strains.
RED CLOVER SEED STORAGE FOR 23 YEARS
Authors: Evans Gwilym
Published: April 2006

The moisture content of red clover seed proved to be the most important single factor governing its longevity. Life was conserved considerably better in a heated room, on account of its lower relative humidity, than in an unheated granary.

Low temperature (32°–41°F.) was shown to be very beneficial for maintaining viability when the moisture content was excessive (10.32 per cent). By replacing the air in the containers with dry CO2 longevity was increased.

A combination of low moisture content, cold storage and replacement of air by dry CO2 enabled red clover seed to germinate 71 per cent after 23 years’ storage and produce vigorous seedlings.

Purple and yellow colours may be retained in a considerable proportion of a red clover seed stock long after all the seeds are dead.
THE GROWTH OF LAMBS AT PASTURE
Authors: Large R. V. , Spedding C. R. W.
Published: April 2006

A preliminary experiment was carried out to investigate methods of maintaining short and long swards, and to measure the effect of height of sward on the growth of lambs. Differences in sward height did not occur until mid‐June: no marked differences in lamb growth, due to sward height, were observed. The effects of stocking rate and worm infection are discussed and conclusions are drawn concerning the design of experiments of this nature.
THE VIABILITY OVER A PERIOD OF FIFTEEN YEARS OF SEVERELY DRIED RYEGRASS SEED
Authors: Evans Gwilym
Published: April 2006

Perennial ryegrass seed was dried at temperatures from 50°C to 120°C, the increases of 10°C being made regularly at intervals of 3 hours. The figures for germination capacity obtained immediately after treatment indicated that a lethal zone had been reached with final temperatures above 100°C and moisture contents reduced to 0.09 and 0.00 per cent.

It was shown that heat drying to as low as 0.66 per cent moisture at a final temperature of 100°C for 3 hours does not injure the germination capacity over a period of seven years, but after 15 years a greater loss in viability appears than in seed treated less severely. Germination energy figures (6‐days’ test) rather than germination capacity are a more reliable guide to optimum temperatures, duration of heating, and moisture content in the drying of seed for long‐period storage.

The most favourable treatment in this series was found to be heating the seed gradually to a maximum temperature of 90°C for 3 hours with a reduction of moisture content to 1.62 per cent. Seed thus treated showed 81 per cent germination after 15 years; for the last eight years the bottles were stored in a cold room, after replacing the air in them with nitrogen.
STUDIES IN CALF MANAGEMENT
Authors: Alder F. E. , Chambers D. T.
Published: April 2006

Systems of calf grazing were compared in preliminary experiments during 1954 and 1955. Hereford colour‐marked beef calves in the post‐weaning stage were used, all calves having been reared on the nurse‐cow system in loose boxes.

The results indicate that autumn‐ and winter‐bom calves can make good progress at pasture during their first summer, husk‐free ground being one of the most important requirements in the production of well‐grown calves.
THE INTERPRETATION OF DATA OF GRASSLAND EVALUATION IN RELATION TO THE VARYING POTENTIAL OUTPUTS OF GRASSLAND AND LIVESTOCK
Authors: Ivins J. D. , Dilnot Jean , Davison J.
Published: April 2006

When livestock are used to measure the output of pasture, the potential output of the animal is on occasions lower than that of the grassland so that this may determine the yields of animal products which are obtained, regardless of pasture type and treatment. The implications of this are discussed in relation to the interpretation of data of grassland evaluation, and also in relation to maximum utilisation of grass.
THE YIELDS OF PURE SOWN PLOTS OF EIGHT WHITE CLOVER STRAINS UNDER CUTTING
Authors: Davies W. Ellis
Published: April 2006

Eight strains of white clover were compared under a cutting treatment over a three‐year period. The medium‐leaved, persistent strains S.100, S.100 Nomark, Kersey, New Zealand CM. and P.P. generally gave the highest yield of clover, but this was counterbalanced by an increased yield of unsown species in the plots of wild white clovers S.184 and Kent.

The unsuitability of Ladino clover for British conditions was shown by its lack of persistency and poor yield. The new strain S.100 Nomark gave a similar total yield to S.100.
THE LOCAL INFLUENCE OF CATTLE DUNG AND URINE UPON THE YIELD AND BOTANICAL COMPOSITION OF PERMANENT PASTURE
Authors: Norman M. J. T. , Green J. O.
Published: April 2006

A study was made of the local effects on yield and botanical composition of the herbage of cattle dung and urine applied to permanent pasture as simulated defaecations and urinations.

A single application of urine had a negligible effect upon botanical composition. In the 2‐ft.‐diameter circle around dung patches there was an increase in cocksfoot, creeping bent, red fescue and white clover, and a decrease in herbs.

Urine patches were neglected by grazing stock for short periods only. Herbage around dung patches was neglected for a period varying from 13–18 months. The effect of this neglect was to restrict the spread of white clover around dung patches in comparison with similar plots kept short by cutting.

Yield response to urine in the area of deposition lasted for two cuts following application, response to dung for four cuts. An increase in crude‐protein content of the herbage was recorded only in samples taken one month after application of dung or urine, and not later.

Increases in crude‐protein yield following spring applications of dung or urine were greater than those following autumn applications. The inferiority of autumn applications may be attributed to winter leaching of nitrogen.
LUCERNE STRAIN TRIAL
Authors: Jekabsons V.
Published: April 2006

French, Canadian, U.S.A., German and New‐Zealand lucerne strains were compared in a trial under four different cutting treatments from 1951 to 1955 in north‐west Norfolk. The French strains W.268 and Du Puits produced the highest yields of dry matter and crude protein, followed by Ile de France, Provence, New Zealand's Marlborough and Germany's Old Franconian Blue and Old Franconian Motley. Rhizoma was the only Canadian strain which produced a high yield of crude protein. The rest of the Canadian and all the U.S.A. strains were inferior yielders compared with those from France. W.268 and Du Puits gave the best relative distribution of dry‐matter yield over the season. The highest yield of crude protein and the best distribution of dry‐matter and crude‐protein yields over the season was given when the first cut was taken at the bud stage and the second cut at 25% flower stage. Cutting treatments with the first cuts taken at the bud stage (early) depressed the growth of weeds more efficiently than cutting treatments with the first cuts taken at the 25% flower stage. Yearly fluctuations in yields over the period of four years were moderate; the majority of strains maintained a high yield into the fifth year.
A STUDY OF THE INFLUENCE OF NITROGEN ON THE ROOT WEIGHT AND NODULATION OF WHITE CLOVER IN A MIXED SWARD
Authors: Young Dorothy J. B.
Published: April 2006

Experiments are described in which a study was made of the top growth, root weight, nodule number, and type of nodules of white clover growing in a grass sward in the field. Soil cores were taken and the clover root‐system examined after removal of soil by washing.

The most important factor governing the total number of nodules and the number of large (2 mm. or more in length) nodules under the sward was the amount of clover root‐material present.

Nitrogenous fertilisers and the return of dung and urine by grazing sheep reduced the amount of clover root‐weight and consequently the number of nodules found under the pasture. 36 1b. of nitrogen applied in the early spring of 1956 had a beneficial effect on both clover top‐growth and nodulation. 80–100 1b. of nitrogen per acre had no effect on the number of nodules per gram of root. However, the application of 200 1b. of nitrogen per acre caused a significant decrease in the number of large nodules per gram of root.

The numbers of large nodules present reached a midsummer peak where nitrogen was not applied.

During the autumn many nodules showed part green and part pink colouration or were completely green or brown, an indication of a decline in nitrogen‐fixing ability. Decaying nodules increased considerably in number when the legume was being suppressed by nitrogen application and top growth was poor. The practical application of these results is discussed and methods of maximising the benefit from clover and fertiliser nitrogen are suggested.
AN EXPERIMENTAL SILO UNIT FOR THE CONTINUOUS MEASUREMENT OF LOSSES OCCURRING DURING ENSILAGE
Authors: McDonald P. , Attwood P. R.
Published: April 2006

An experimental silo unit consisting of four silos, each capable of holding 1000 kg. fresh grass, is described. The silos are suspended from a weighing apparatus enabling weight recordings to be taken at all stages during ensilage. The weighing apparatus is sufficiently sensitive to record a change in weight in the silo and contents of 100 grams.
THE EFFECT OF WEEDS, AND THEIR CONTROL BY MCPA SPRAYING, ON THE ESTABLISHMENT OF PERENNIAL RYEGRASS AND COCKSFOOT IN THE KENYA HIGHLANDS
Authors: Birch W. R.
Published: April 2006

The vigour of perennial ryegrass and cocksfoot after spraying with the sodium salt of MCPA during establishment was estimated from their yields in small‐plot cutting experiments on weedy land. Where the weed yields of control plots was of the order of a ton of air‐dry matter an acre (mostly Spergula arvensis L.), spraying at up to 1·2 1b. acid equivalent an acre caused twofold to threefold increases in grass yields. The optimum time to spray perennial ryegrass was at the three‐ to four‐leaf stage or 26 days after sowing; for cocksfoot, which appeared more susceptible to the herbicide, spraying at the tillering stage, or about 40 days after sowing, was best. Increasing the seed rates of ryegrass produced transitory increases in yields while decreasing weed yields. Increasing phosphate or nitrogen caused decreases in weed yields. Although the former gave a large increase in weed yield in the first cut this was offset by a large decrease in the second cut. There was an indication that the level of nitrogenous manuring affected the toxicity of the herbicide to the grasses.
GRASSLAND RESEARCH AND THE FUTURE*
Authors: Duckham A. N.
Published: April 2006

It seems to me that during the next 20 years:

grass as a feed will increasingly over‐shadow grass as a break in tillage cropping or as a fertility builder

the current rapid progress in biochemistry, plant physiology, radiation biology and the physical sciences may revolutionise our knowledge of applied ecology and genetics

as a result of such research, scientific principles will replace much of the present patchwork of empirical husbandry knowledge

these developments, plus forthcoming changes in labour costs and in grazing, harvesting and conservation techniques will call for a drastic re‐appraisal of much of our current thinking and practice in sward establishment and management; this will involve more applied ecological research

the scientist's laboratory and the engineer's workshop will become more important in grassland research whilst husbandry experiments will increasingly depend on scientific instrumentation.
GRASSES IN WINTER
Authors: Beddows A. R. , Jones Ll.I orwerth
Published: April 2006

The Aberystwyth district experienced exceptionally cold winter weather in 1954, 1955 and 1956, especially during the period from the end of January to early March. Its effect on the grasses, both in the single‐plant nurseries and in the agronomic experimental areas, is briefly described.

It was observed that plants which entered the winter carrying a bulk of herbage in a winter‐proud condition were at a disadvantage compared with those which had been reasonably grazed or cut back during the autumn. The younger plants were found to be better able than the older ones to withstand extreme conditions.

Suggestions are made as to how some simple‐mixture swards can be managed so as to be reasonably likely to provide keep in situ during the difficult months December to April. The species under consideration are cocksfoot (Dactylis glomerata), timothy (Phleum pratense and P. nodosum), tall fescue (Festuca arundinacea), perennial ryegrass (Lolium perernne) and Italian ryegrass (L. italicum).
IRRIGATION OF GRASSLAND
Authors: Munro I. A.
Published: April 2006

An experiment to measure the effects of three soil‐moisture deficits and four nitrogen treatments on the yield, utilisation and botanical composition of a four‐years‐old riverside meadow at the University Farm, Sonning, Berkshire, during the grazing seasons of 1955 and 1956 is described.

In both years the yield increased with increasing applications of nitrogen and decreased with increasing soil‐moisture deficit. The utilisation of the herbage, by young stock (15 to 18 months old), was significantly better with irrigation. Irrigation improved the botanical composition of the sward: the clover percentage increased on the irrigated plots but nitrogen produced some depression, the depression increasing with increasing soil moisture deficit; meadow fescue increased and the Poa spp. decreased with progressively greater applications of nitrogen, while on the non‐irrigated plots the sward deteriorated still further, with an ingression of Agrostis and Holcus spp.
A DISCUSSION ON THE INFLUENCE OF RELATIVE MOISTURE AVAILABILITY ON THE SWARDS RESULTING FROM STANDARD GRASS SEEDS MIXTURES
Authors: Greenaway Thomas E. , Budden M.
Published: April 2006

Results are given of analyses made over a three‐year period, 1955–57, on swards produced from a standard seeds mixture sown under a wide range of ecological conditions. The results are related lo available moisture on the different soils in the areas examined.
AN INVESTIGATION INTO UTILISED GRASSLAND PRODUCTION ON TEN FARMS IN NORTH COUNTY DUBLIN
Authors: Deeny M. C.
Published: April 2006

Utilised grass production on ten small farms in North County Dublin has been estimated using (A) the method adopted by the British Grassland Society Sub‐Committee on the assessment and recording of the utilised output of grassland, and (B) a live‐weight increase method using Woodman's figures.

At the beginning of the grazing season all the grazing animals on each farm were weighed. At the same time the records for method A were begun. Altogether 169 animals and 12 sheep were weighed during March‐April. Animals sold during the period of investigation were weighed, where possible.

The results obtained using the two methods have been compared. Average percentage difference on ten observations was 11.3%, with a variation of ± 3.7%. On farms 1–5, where only mature stock were kept, the percentage difference was 9.9%± 2.2%. On farms 6–10, where animals of all categories were grazed, the percentage difference averaged 12.8%± 2.2%. In all cases the live‐weight‐increase method gave the higher estimated yield.

The techniques used in the estimation of utilised grassland production are discussed. Total output varied between 26.5 cwt. and 9.0 cwt. of utilised S.E. per acre. The significance of the findings is discussed and the value of the methods used is considered.
THE EFFECT OF DEFOLIATION ON THE SEED‐PRODUCING CAPACITY OF BRED STRAINS OF GRASSES
Authors: Roberts Humphrey M.
Published: April 2006

A leafy strain of timothy and of perennial ryegrass showed no significant reductions in seed yields following grazing at different dates from October to January, when extra nitrogen was applied.

Spring and winter + spring grazing, together with extra nitrogen, significantly reduced the seed yield of S50 timothy for three successive harvest years.

Perennial ryegrass S101 showed no reduction after spring or winter + spring grazing when defoliation was made not later than mid‐April, but when grazing was delayed until May and drought occurred there was a significant reduction in seed yield.
GRASSLAND MANAGEMENT ON A PEDIGREE STOCK FARM IN AYRSHIRE
Authors: Hunt I. V. , Montgomery A. W.
Published: April 2006

Messrs. A. W. Montgomerie and Sons of Lessnessock, Ayrshire, manage their grassland so as to encourage full development of white clover. The method is an adaptation of the system followed in New Zealand. The results are that production in terms of stock output is high, reaching a utilised starch equivalent of 23 cwt. per acre.
THE POTENTIAL NUTRITIVE VALUE OF SOME WEEDS COMMON TO NORTH‐EASTERN ENGLAND
Authors: Fairbairn C. B. , Thomas Brynmor
Published: April 2006

The proximate and ash constituents of twenty weed species have been determined. These weeds are all common to north‐eastern England. Some are characteristic of hedgerow and roadside and a few species of arable land; the majority, however, usually occur in pasture and meadowland, or in other sites where they are freely accessible to stock. Exact locality, approximate stage of growth and date of harvesting are recorded.

A comprehensive examination of their ash has been made and four trace elements of recognized importance, viz. iron, manganese, copper and cobalt, were determined.

The weeds have been classified on the basis of a marking system, and it was found possible to place them in one or other of three fairly well‐defined groups, viz. high, medium or low apparent value.

Reference has been made to earlier assessments of these weeds and probable values, as reflected by chemical analysis, have been discussed. Most of the weeds listed as being of high apparent value are known or could justifiably be assumed to be of good nutritive status; examples of such are dandelion, nettle, creeping thistle and broad‐leaved plantain. Ragwort, although ranked highly on the marking system used, is well‐known to be toxic to animals. Not all members of the group of medium apparent value are likely to be eaten to any appreciable extent and at least two are of doubtful wholesomeness. Among weeds of low apparent value, only bird's‐foot trefoil would appear to have much potential usefulness.
THE EFFECT OF SHEEP URINE ON THE GERIMINATION AND EARLY ESTABLISHMENT OF A COMMON WEED GRASS
Authors: Wheeler J. L.
Published: April 2006

Sowings of annual meadow grass (Poa annua) were made in pots of soil which had been treated with sheep urine, with urine diluted × 50, or with water as a control. The treatments were applied before, at, and after sowing.

Urine, whether applied at sowing time, or eleven days before or after, significantly reduced the germination or establishment of the weed grass.

Diluted urine tended to reduce the number of established seedlings when applied at or shortly after sowing.

In a subsidiary experiment the number of viable seeds in soil taken from pastures which had received no urine for four years were compared with those from soil under pastures receiving urine. The difference was not significant.
THE OUTDOOR REARING OF AYRSHIRE CALVES ON PASTURE WITH AND WITHOUT SUPPLEMENTARY FEEDING
Authors: Castle M. E. , Walker R. F. R.
Published: April 2006

An experiment conducted in south‐west Scotland during 1956 and 1957 to investigate an outdoor method of rearing calves on pasture, with and without supplementary food, is described.

Twenty‐four Ayrshire bull calves were put on pasture at 2 weeks of age and received an average of 37 gallons of whole milk up to the time they were weaned at 8 weeks old. Twelve of the calves received no supplementary feeding, but the other twelve each ate 257 lb. of a meal containing oats, linseed cake, flaked maize and fish meal from their 3rd to their 20th week.

The calves were moved around a series of plots (0.4 acre) which yielded an average of 1400 lb. of dry matter per acre at each grazing. The mean crude protein of the herbage dry matter was 17.4% in 1956 and 14.1% in 1957.

The mean daily liveweight‐gains of the calves from birth to 20 weeks of age were 1.05 lb. for the unsupplemented calves and 1.14 lb. for the supplemented ones—a non‐significant difference, as was also the difference between the mean increases in belly‐girth measurements of the two groups.

Parasitic infestation of the two groups was extremely low and 83% of all faeces samples examined contained no worm eggs.

The latest‐born calves made the poorest liveweight gains.

The outdoor rearing of calves is discussed.
STUDIES ON THE ROOT DEVELOPMENT OF HERBAGE PLANTS
Authors: Baker H. K. , Garwood E. A.
Published: April 2006

Herbage, stubble and root weights were recorded for thirteen months on various leys subjected to two treatments differing in frequency of cutting.

The root‐weight per unit area of a ryegrass/white‐clover ley was not affected by the frequency of cutting, but the less frequently cut plots had fewer tillers per unit area; the root‐ and stubble‐weight per tiller was, therefore, higher on the less frequently cut plots, On a cocksfoot ley the root‐weight was not affected by the cutting treatment, but in late summer and early autumn the stubble‐weight was considerably higher on the less frequently cut plots.

When cocksfoot was grown in rows 2 feet apart, the more frequent cutting decreased both the root‐ and stubble‐weight.

On grass leys root‐weights were heaviest in the summer and thereafter decreased until the following spring.

The root‐weight of lucerne decreased from May to July, increased to a maximum in December and then decreased in weight. The changes in root‐weight under lucerne leys were mainly due to changes in the weight of the tap‐roots.

The vertical distribution of roots was recorded, and, in the case of the cocksfoot in rows, the lateral distribution of roots is also given.
AN INEXPENSIVE SEED CLEANER FOR USE WITH SINGLE HEADS OF TIMOTHY
Authors: Stoddart J. L. , Evans Gareth M.
Published: April 2006

Constructional details are given of an inexpensive seed cleaner capable of handling material from single heads of timothy, yielding cleaned seed of over 98% purity by weight. The conditions within the cleaner are reproducible and running costs negligible.
PARTIAL WILTING OF GRASS CROPS FOR SILAGE
Authors: Nash M. J.
Published: April 2006

The aim of this part of the investigation was to test in practice, on a small scale, the partial‐wilting method of making silage and to obtain data on quality, losses and digestibility of the wilted and un‐wilted products. Wilting of grass/clover herbage was carried out for periods of up to about 24 hours and, on average, the moisture content was lowered by 6–4%, from 80–4 to 74.0%. All silages were well preserved, there was no overheating, the wilted products showed considerably lower nutrient losses than the unwilted silages and were not lower in digestibility. Mould formation was much more extensive in the top layers of the wilted silages, except when the wilted material had been bruised.
A GRASSLAND MANAGEMENT METHOD OF CONTROLLING NEMATODIRUS INFESTATION
Authors: Black W. J. M.
Published: April 2006

The parasite‐control value of keeping Nematodirus‐infested pasture free from susceptible lambs for a complete year was examined in a controlled experiment. The practice was shown to be successful and confirmed previous recommendations, based on a knowledge of the parasite's life cycle

The detrimental quality of Nematodirus infestation was measurable by mortalities, depression of weight gains and the quality of the lambs. In the conditions of the experiment, the effects of Nematodiriasis approximately halved the liveweight production of affected animals.
A STUDY OF SEED DEVELOPMENT AND YIELD IN TIMOTHY AS RELATED TO DATE OF HARVEST
Authors: Stoddart J. L.
Published: April 2006

Studies of seed development and yield were conducted on three Aberystwyth varieties of timothy. The stages of seed development are described, as are their correlation with the external appearance of the head. Evidence is presented to support the suggestion that the latitude in the dale of harvest is greater than has hitherto been accepted. Population studies of seed crops have revealed that the abundant small heads (less than 4 cms. in length) contribute very little to the yield. The partition of the yield amongst the different inflorescence age‐groups is given for each variety and methods of judging crop ripeness are discussed.
SEASONAL YIELD AND COMPOSITION OF LUCERNE IN RELATION TO THE TIME OF CUTTING OF FIRST AND SECOND GROWTH
Authors: Dent J. W.
Published: April 2006

Cutting experiments on the spring growth of a stand of Provence lucerne, the first year of which were described in a previous paper (1), were continued For a second and third season.

The value of taking the first cut at the early bud stage, particularly in an unfavourable season, was confirmed.

No adverse effects were observed in the crop after three seasons of this treatment and yields were satisfactory in the third year.

Similar cutting experiments were made on the second growth of an area of Du Puits lucerne after the spring growth had been cut uniformly at the early bud stage.

The curves for protein and fibre production were similar to those for the first growth but the crop matured more quickly and yields were lower.

No further advantage was observed in cutting the second growth before the flower stage although earlier cutting produced no apparent ill‐effect on the plant or upon subsequent yield.
THE NORMAL‐ACID FIBRE CONTENT OF SPFCIES AND VARIETIES OF HERBAGE GRASSES
Authors: Griffith G. ap , Cooper J. P.
Published: April 2006

Normal‐acid fibre content has been suggested as a useful indication of the digestibility of herbage. The changes in fibre content were therefore recorded during the spring and early summer of 1957 and 1958 to see whether regular differences occurred between species and varieties of herbage grasses.

All species showed an increase in fibre content during spring and early summer, but considerable year‐to‐year fluctuations occurred: fibre content was also influenced by manuring and spacing. Regular differences between species and varieties have been detecled and, in perennial ryegrass, differences between individual genotypes. It should be possible to select breeding material for high or low fibre content if required.
TECHNIQUE AND METHODS OF LUCERNE SEED PRODUCTION
Authors: Zaleski A.
Published: April 2006

During 1955–8 the technique of lucerne seed production was examined to compare the yield of seed and fodder under identical treatments on light and heavy soil. In addition, direct combine harvesting was compared with the tripod method.

With the exception of the first year, which suggested certain advantages in seed production on light soil, the results obtained were not conclusive because of damage to the seed crop on light soil. The previous finding, that the best yield and quality of seed are secured from the first growth, were confirmed. It was shown that the aftermath could be cut in the autumn without a significant effect on the yield of seed, or persistency of the stand in subsequent years, and that the total yield of fodder was higher on heavy than on light soil.

Direct combine harvesting of a seed crop after pre‐harvest desiccation (4.8 lb. of D.N.O.C. in 30 gal. of water per acre), proved to be a satisfactory harvesting method when facilities for drying the seed were available.

Observations on pollinating insects suggested that honey bees were mainly responsible for the amount of seed set.
THE GROWTH OF VARIETIES OF PERENNIAL RYEGRASS IN THE SEEDING YEAR
Authors: Davies Alison
Published: April 2006

These studies showed that in the first autumn the capacity for soil establishment of different varieties of perennial ryegrass was connected with seed size. On one of two experimental fields, shoot production in the early stages was found to be positively correlated with seed size. The rate of tillering was initially similar for all varieties, but by January or February, the pasture varieties had the highest tiller numbers. However, shoot weights at this time differed very little from variety to variety. Tillering virtually ceased during December and January and started again in February.

The yields obtained from the five varieties in spring, when cut with an autoscythe. differed greatly despite the similar shoot weights of individual plants. It is suggested that the spring growth in pasture varieties is largely below cutting level.
THE RECOVERY OF FERTILIZER NITROGEN FROM VARIOUS DEPTHS BELOW SWARDS
Authors: Kernick M. D.
Published: April 2006

A microplot technique for the placement of nitrogen at depth under an established grass sward is described. The effect of nitrogen placement at various depths on the dry matter yields, root yields and nitrogen uptake of two grass species is recorded. The results for cocksfoot and red fescue indicate that there is little fall‐off in uptake of nitrogen from placement at depths down to 12 inches, and that cocksfoot also recovers substantial amounts of nitrogen from 18 inches and 2 feet. Recovery by red fescue at these depths was not investigated.

Althotigh there is little difference between the two grasses in their relative ability to absorb nitrogen at the various depths, there is an indication that, weight for weight, cocksfoot roots are probably more efficient absorbers of nitrogen than those of red fescue.

The significance of the findings is discussed in the light of present‐day methods of fertilizer application.
FURTHER STUDIES ON THE RELATIONSHIP BETWEEN SHOOT AND ROOT SYSTEMS OF GRASSES
Authors: Troughton Arthur
Published: April 2006

In young grass plants it is possible to relate the weight of the root to that of the shoot through the allometric formula y=bxk. Using this formula it was found that flower formation was associated with an increase in shoot growth relative to that of the root. Within varieties of Lolium, the greater the intensity of heading the more was the growth of the shoot relative to that of the root. Perenniality was associated with a high rate of root growth relative to that of the shoot. A decrease in the light intensity or soil water reduced the growth of the plant as a whole, but light decreased root growth more than that of the shoot while water supply had the opposite effect.
THE EFFECT OF MECHANICAL TREATMENT ON THE RATE OF DRYING AND LOSS OF NUTRIENTS IN HAY
Authors: Murdoch J. C. , Bare D. I.
Published: April 2006

Trials are described in which various mechanical treatments of hay in the field were compared. Cutting the crop with a forage harvester resulted in very rapid drying of the hay, but this was accompanied by very high nutrient losses. When the crop was tedded with the harvester the hay dried more quickly than with conventional ledding, the nutrient loss being similar for these two treatments. Tedding with either a harvester or a conventional machine appeared to increase the loss of nutrients compared with less severe treatment, but this loss appears to be acceptable as tedding considerably reduces the risk of the hay being weathered.
A STUDY IN METHODS OF GRASS VARIETY TESTING
Authors: Green J. O. , Eyles Jean C.
Published: April 2006

Methods for the appraisal of varieties in forage grasses are examined in the light of results from an experiment. Five varieties of perennial ryegrass were grown as spaced plants, broadcast swards and swards with white clover, and all were subjected to five cutting treatments during the first and second harvest year.

Spaced plants and swards gave equally good information on the order in which varieties attained maximum rate of growth in spring each year; but in respect of actual yield, the order in which varieties were placed in spaced‐plant culture was reversed in broadcast swards. It is suggested that the disparity may have arisen because all varieties were sown at a common seed rate; and that spaced‐plant cultures give a better indication of relative potentialities than do the majority of sward trials.

Late‐maturing varieties compared better with early varieties when each variety was cut with reference to date of ear emergence than when all varieties were cut simultaneously (that is, in respect of dry matter production: at a given stage of development the early varieties had a slightly higher nitrogen content than the late). The shortcomings of both systems of cutting, and the need for comprehensive tests, are discussed.

There was little interaction between method of culture and cutting treatment in this experiment.
STUDIES OF ROOT DEVELOPMENT IN A GRASS SWARD GROWING ON DEEP PEAT USING RADIOACTIVE TRACERS
Authors: Boggie R. , Knight A. H.
Published: April 2006

The experiment was designed to investigate the root activity of plants growing in deep peat. This was measured by the absorption of radioactive phosphate placed at different depths in the peat, and the method is described.

The roots in the grass/clover sward were apparently confined to the surface 6 in. of the peat and no differences were detected between those growing next to the ditch, where the water table was at its lowest, and those in the middle of the plot.

These points are discussed in relation to seasonal differences in the height of the water table, depth of cultivation and application of lime and fertilizer.