bluuebunny/crossref_metadata_2025_split huggingface dataset:
Climate implications of biomass burning since the 19th century in eastern North America
Authors: CLARK JAMES S. , STOCKS BRIAN J. , RICHARD PIERRE J.H. 
Published: April 2006

AbstractRecent predictions that tropospheric aerosols have counterbalanced greenhouse warming assume aerosol emissions were low beforead1850 and then increased dramatically with industrialization of the Northern Hemisphere and biomass burning in the Tropics. We assembled the lake sediment record of emissions across northeastern North America, where temperatures are predicted to have been substantially affected by industrial aerosols. Sediment evidence suggests a systematic shift in source and an overall decline in emissions since the 19th century. The geographical shift results from high presettlement emissions from wildfires in the Midwest that collapsed with tillage and fire suppression. Meanwhile, emissions were increasing in the North‐east with European settlement. These regional changes produced a shift from the continental interior to the North‐east. An overall decline results because decreases in the Midwest more than compensate for increases in the North‐east. Results suggest the Central Plains as an important source of emissions in the recent past, consistent with pioneer accounts of dense smoke clouds emanating from prairie in the 19th century. Contrary to recent models that suggest increased 20th century combustion emissions could have offset warming effects of rising greenhouse gases, our data suggest that aerosols could have actually decreased over this interval. Although we cannot directly quantify aerosols from our methods, the emissions of large particles suggest assumptions of 20th century aerosol declines should be reconsidered.
THE EFFECT OF TIME OF CUTTING ON EAR PRODUCTION AND SEED YIELD IN S.48 TIMOTHY
Authors: Langer R. H. M. 
Published: April 2006

After uniform defoliation in February, spaced plants of S.48 timothy were cut on one of 12 fortnightly dates, starting at the end of March.Analysis of the herbage removed at each cut showed an increase in plant and unit tiller weight throughout the season, but a decline in the number of tillers, especially before the beginning of shooting.The date of ear emergence was not affected by cutting up to 5 May and only slightly delayed in plants cut on 19 May. Plants treated subsequently flowered much later but after a fairly constant interval following defoliation.Cutting on and after 7 April depressed fertile tiller formation with increasing severity, until only vegetative tillers appeared in the recovery growth following treatment at the beginning of August.Seed yield per plant declined with the decrease in fertile tiller numbers, but after the early cuts some compensation by production of slightly more seed per ear was recorded.The results are discussed in terms of the physiological transition of the plant towards flowering.
GRASSLAND PRODUCTION FOR DAIRYING IN NEW ZEALAND*
Authors: Owens E. M. 
Published: April 2006

Comparison of results obtained on herbage samples freeze‐dried and hot‐air‐dried during tests of commercial green‐crop driers indicated apparent losses of crude protein and β‐carotene in freeze‐drying.Experiments on laboratory technique in drying, milling and analysing herbage samples showed a differential loss in conventional laboratory hammer mills biassed towards loss of high‐protein particles.The differential loss was particularly marked for freeze‐dried material, but was also shown to be significant for oven‐dried material.There is a need for development of a laboratory mill to disintegrate samples without loss of milled material and without undue temperature rise when used for milling samples at the same rate as existing laboratory hammer mills.
ARTIFICIAL REARING OF CALVES ON PASTURE*
Authors: Preston T. R. 
Published: April 2006

Two feeding trials are described in which indoor and outdoor methods of rearing calves are compared.In a small experiment in 1953 Ayrshire calves reared on pasture from birth made similar weight gains (approximately 1 lb. per day) to control animals reared conventionally indoors.In an experiment in 1954 the outside‐reared members of ten pairs of calves gained at a significantly slower rate (P<0.01) than their pair mates reared inside. The dry‐matter digestibility of the herbage on offer to the calves outside was high (<70%) throughout the experiment but, during August, in a period of particularly wet and cold weather, the amounts of T.D.N. consumed by the calves were less than their theoretical requirements. Concomitantly the worm burden of the calves increased to a critical level of 2,000 eggs per gram of faeces with associated symptoms of parasitic gastritis and loss of weight.The relation of environmental factors, particularly the interacting factors of climate, nutrition and worm parasites, to the growth of outside reared calves is discussed.
THE INFLUENCE OF VARIOUS GRAZING TREATMENTS UPON THE BOTANICAL COMPOSITION OF A DOWNLAND PERMANENT PASTURE
Authors: Norman M. J. T. 
Published: April 2006

In spring 1952, a trial was laid down at Hurley to compare the botanical effects of five grazing treatments upon a low‐fertility downland permanent pasture. The treatments were: dose and lenient rotational cattle grazing, close rotational sheep grazing and continuous grazing by cattle and by sheep. The trial was concluded in autumn 1955.Continuous cattle grazing and close rotational cattle grazing resulted in a sward with a high proportion of forbs. With sheep under the same grazing systems, grasses predominated. An intermediate grass/forb balance was attained under lenient rotational cattle grazing. Legumes contributed more under rotational grazing than under continuous grazing.The grazing treatments most favourable to the major species were: For creeping bent—both sheep grazing treatments; for ribwort plantain—all cattle grazing treatments; for white clover—all rotational grazing treatments; for cocksfoot—lenient rotational cattle grazing; for ox‐eye daisy—close rotational cattle grazing; for red fescue—lenient rotational cattle grazing and continuous sheep grazing. Bulbous buttercup and rough‐stalked meadow grass showed no significant response to differential grazing treatments.The relative degree of consumption by stock of individual species was estimated by comparing the yields from matched pairs of groups of shoots harvested before and after each grazing spell (rotational treatments) or of areas protected from and exposed to grazing (continuous treatments). A close relationship was established between the intensity of grazing experienced by species and their final status in the swards. Accessibility appeared to be as important as palatability in determining the degree to which individual species were grazed.The resulting swards differed only slightly in agronomic quality. The lack of any clear advantage from rotational grazing was attributed to low levels of plant nutrients, since these probably limited the development of the more valuable grasses and of white clover.
VEGETATIVE PROLIFERATIONS IN HERBAGE GRASSES
Authors: Langer R. H. M. , Ryle G. J. A. 
Published: April 2006

S.48 timothy plants were induced to form proliferating inflorescences by exposure to 2–4 weeks of long days followed by a return to short days. Serial micro‐dissections showed that the lemma enlarges to resemble a leaf but that glumes, palea and all reproductive organs are also present and perfectly farmed. At a later stage a vegetative shoot bearing several foliage leaves, axillary buds and root initials is formed, presumably as a continuation of the rachilla.The production of proliferations by insufficient exposure to photoperiods favourable for flowering is discussed. Proliferations may occur spontaneously in many normally seed‐setting grasses, but in a number of species this form of growth is genetically fixed.
THE INFLUENCE OF DATE OF SOWING AND OF STRAIN ON HEAD PRODUCTION IN TIMOTHY
Authors: Cocks Betty 
Published: April 2006

Heading behaviour of eight strains of timothy was observed in the sowing and first harvest years, after sowing on a series of dates between March and August.All strains produced heads in the sowing year. Only a very few plants failed to head when sown between 18 March and 29 April. With subsequent sowing dates the proportion of heading plants progressively declined, most markedly in S.50 Phleum nodosum, least in the early‐heading P. pratense strains. No heading occurred in the sowing year after the mid‐August sowing.The environment to which the later sowings are exposed differs from that of the earlier sown lots in that (a) the initial temperatures and daylengths are higher and (b) the decline in daylength occurs earlier in their development. One or both of these factors must be responsible for failure of heading among plants of the later sowings.The sequence of heading dates among the strains in the sowing year differed considerably from that in the same plants after overwintering, suggesting the action of some factor other than photo‐period in determining heading date in the sowing year.Variability in heading date within the strains was much greater in the sowing year than after overwintering, and increased with lateness of sowing.
A COMPARISON BETWEEN TWO METHODS OF MEASURING SEASONAL GROWTH OF TWO STRAINS OF DACTYLIS GLOMERATA WHEN GROWN AS SPACED PLANTS AND IN SWARDS
Authors: Kelly A. F. 
Published: April 2006

A trial is described which was designed to test the hypothesis that measurements taken of the leaf‐plus‐shoot length of spaced plants may give a good indication of dry‐matter yield of strains of Dactylis glomerata, as determined by cutting and weighing the produce of sward plots.Two contrasting strains of Dactylis glomerata were used: the British S.143, and the German von Kamekes. The strains were established during 1955 both as spaced plants (10 plants per plot) and as pure swards, with six replications of each. The two methods of establishment formed the main treatments, occupying whole plots, and each plot was divided into four sub‐plots each of which carried one of the combinations of the two strains with the following two management treatments: Treatment 1, cut at monthly intervals from 27 April to 23 August; Treatment 2, cut on 12 April and subsequently at the mean date of emergence of the inflorescence for each strain, followed by cutting at monthly intervals until the end of August.Spaced plants were measured before cutting by thrusting a measuring rod into the crown of the plant and measuring the leaf‐plus‐shoot length of one of the longer shoots. Produce cut from sward plots was weighed and sampled for dry‐matter content.Results from the swards showed that von Kamekes produced more dry matter in early spring, but that subsequently the advantage passed to S.143.Significant positive correlations were obtained in early spring between the sward yields and leaf‐plus‐shoot measurements from spaced plants. Subsequently there was no agreement between the two methods, and some significant negative correlations were obtained.The data are discussed in relation to the physiological stages of development of the strains, which suggests that:

In the spring period the main factor contributing to yield was shoot elongation, with the majority of the tillers in the reproductive phase.
In summer the main factor was new tiller formation, with the majority of tillers in the vegetative phase.
In the early autumn neither factor was dominant and both contributed to yield.

Attention is drawn to the danger of comparing yields from spaced plants with yields from swards where the management may influence the results obtained, and to the difficulty of assessing hay yields by means of height measurements of spaced plants.
STUDIES ON THE EXTENSION OF THE GRAZING SEASON
Authors: Corbett J. L. , Gwynn P. E. , Walker D. , Aitken J. N. 
Published: April 2006

Foggage grazing trials with beef‐store cattle and in‐calf dairy heifers during four successive winters in Aberdeenshire are described. Many of the animals received only very small quantities of supplementary fodders, but their performance was satisfactory in all cases. During the last two winters, silage and oat straw contributed 40–50% of total food dry‐matter intake. It is suggested that this level of supplementary feeding would be satisfactory in practice.In a comparison of store‐feeding systems, four in‐wintered (housed) steers were 110 1b. per head heavier than their out‐wintered monozygous twins at the end of the winter‐feeding period. Live‐weight differences averaged 27 1b. per head one month later and were negligible at the end of summer. From the results of a metabolism trial it was concluded that the spring weight‐loss suffered by the housed cattle was due mainly to a reduction in the weight of gut contents.
WHITE CLOVER TRIAL
Authors: Aldrich D. T. A. , Davis A. G. , Cooper M. McG. 
Published: April 2006

Yields were recorded from a potato crop grown in the first year following a grazing trial comparing four strains of white clover, previously described in this journal (2 & 3). The Kent clover strain, which was the most persistent and which had produced the greatest live‐weight increase per acre, gave the highest yield of potatoes. The Dutch white clover, which had been the poorest in the grassland trial, gave the lowest yield of potatoes.A 2 × 2 × 2 N, P, K fertilizer design was superimposed in the form of split plots. Nitro‐chalk at 5 cwt. per acre and muriate of potash at 2 cwt. per acre both caused significant reductions in yield, and this was thought to be due to the exceptionally high soil fertility status of the field. The fertilizer × clover interactions were non‐significant, and contributed little towards an explanation of the fundamental basis of the soil fertility differences caused by these four clover strains.
INTERNATIONAL DEVELOPMENT OF GRAZING AND FODDER RESOURCES
Authors: Davies G. Maxwell 
Published: April 2006

Following a report by Oram on “The Use of Pastures and Fodder Crops in Rotations in Mediterranean Agriculture”, which was presented to the Fourth Meeting of the F.A.O. Working Party on Mediterranean Pasture and Fodder Development at Lisbon in 1955, a further study was carried out by the writer on the integration of livestock husbandry with the grazing and fodder resources in the region, and with crop husbandry in general. This study was based on a three‐month survey carried out at the end of 1955 as an F.A.O. assignment, and visits were made to Libya, Cyprus, Israel, Greece, Turkey, Spain, Portugal, Morocco, Algeria and parts of Southern Italy.The survey dealt with prevailing conditions in these countries, with particular reference to existing research and extension programmes in both agronomy and animal husbandry. Following this, a report (5) was prepared for the Fifth Meeting of the Working Party held at Tel Aviv in May, 1957. The report covers the general principles of animal husbandry, with special reference to the Mediterranean environment, and stress is laid on the need for increased efficiency in both the production and use of pasture and fodder crops, especially in view of the fact that an increasing livestock population will in future probably have to be maintained on a steadily diminishing area, owing to the progressive encroachment of food‐ and cash‐crop production on land previously used for grazing. As far as practicable, grazing pressure must be transferred from “natural” pastures and upland grazings to the cultivated land, on which improved systems of rotational cropping will be necessary. Wherever possible these should incorporate both supplementary fodder crops and sown pastures. This should benefit both the livestock and the over‐cropped cultivated soils. In turn, any reduction in stocking rates on the natural pastures and on the upland and forest grazings should facilitate their improvement and the introduction of erosion control. Any improvement scheme designed to achieve these ends will require much closer co‐operation between cultivators and pastoralists and more effective integration of research and extension work in both agronomy and animal husbandry.This article describes some of the many difficulties confronting workers in both these fields in a Mediterranean environment, and suggestions are made as to how some of these problems may possibly be overcome.
THE EFFECT OF SHEEP EXCRETA AND NITROGENOUS FERTILIZER ON THE BOTANICAL COMPOSITION AND PRODUCTION OF A LEY
Authors: Wheeler J. L. 
Published: April 2006

Results are presented for the final two years of a previously described experiment.The return of dung and urine by sheep to a ryegrass/white‐clover ley was controlled by suitable harnesses to give four treatments (no dung or urine, dung, urine, dung and urine) which were combined in a replicated factorial design with four levels of nitrogenous fertilizer application (0, 52, 182, 312 1b. N per acre).Applied nitrogen and urine were the dominant factors affecting botanical composition. The percentage of ryegrass increased and that of clover decreased with the progressive increases in nitrogen application. Volunteer species (mainly Poa spp.) contributed up to 20 per cent by the final year, the maximum occurring under the medium‐high nitrogen treatment.Urine restricted the incursion of weed grasses.Combined with urine or the full return of excreta, high levels of applied nitrogen increased herbage production by up to 120 per cent. There was little response to dung except at the highest nitrogen level.The yield response to applied nitrogen was almost linear. In the absence of animal returns response was poor, partly due to shortage of potash. When both excreta were withheld the light nitrogen dressing depressed the annual production compared with the control; where both excreta were returned together with this dressing no reduction occurred in annual yield and the spring yield was improved (p <0.05).
THE INFLUENCE ON THE FOLLOWING ARABLE CROP OF SHEEP EXCRETA AND FERTILIZER TREATMENTS APPLIED TO A LEY
Authors: Wheeler J. L. 
Published: April 2006

The differences in soil fertility in a ley as a result of treatments applied for four years in a sheep‐grazing trial were measured by growing crops of wheat and kale. The pasture treatments had been: control, dung, urine and dung plus urine, each combined with four levels of fertilizer nitrogen.Yields of winter wheat harvested in 1956 ranged from 27.1 to 38.6 cwt. per acre. Plots to which faeces had been allowed to return during the pasture phase outyielded (p <0.001) those from which it was withheld. Urine was relatively ineffective except in combination with nitrogen. In the absence of animal returns, nitrogenous fertilizer depressed grain and straw yields. A top‐dressing of K applied to the wheat in spring as a sub‐treatment had no significant effect. The percentages of N and K in the grain were unaffected by the former pasture treatments, or by the K top‐dressing.A subsidiary small‐plot experiment in which the above pasture treatments had been combined with P and K, each at two levels, was cropped with marrow‐stem kale. In general, N applied to the pasture increased kale yields except where dung and urine had been withheld. Neither P nor K had a significant effect, except when combined. The leaf/stem ratio of the kale was reduced by applied N and by P (both p <0.05).The pasture/arable‐crop relationship is considered.
SIDEWAYS CREEP GRAZING FOR INTENSIVE LAMB PRODUCTION*
Authors: SPEDDING C. R. W. , LARGE R. V. 
Published: April 2006

An experiment is described in which folding and sideways creep‐grazing was compared with a rotational grazing management for lamb production at pasture.The experiment was carried out in two years (1957 and 1958) using a stocking‐rate of 7 ewes and 12 lambs per acre from the birth of the lambs until they had all been sent for slaughter.The folding management produced more liveweight gain per acre (955 and 983 Ib.) than the rotational management (870 and 926 Ib.) and the mean carcass‐weights were higher.The biggest differences, in favour of the sideways creep‐grazing system, were in tbe quality of the carcass produced. Folding produced 74% and 77% grade A carcasses and the rotational management 43% and 53%, respectively, in 1957 and 1958.Worm‐infestation was considerably less under the folding management and parasite control appeared to be more efFective where the area reserved for lambs only was not expanded to include ewe‐grazed pasture as the season progressed.
STUDIES IN THE DIGESTIBILITY OF HERBAGE
Authors: Raymond W. F. , Minson D. J. , Harris C. E. 
Published: April 2006

Results are reported from six digestibility experiments in which frozen herbage was fed to groups of sheep at HIGH and Low levels of intake. The sheep on the HIGH level of intake digested the dry matter, organic matter, nitrogen and normal‐acid fibre in the herbage less efficiently than those on the LOW level, confirming earlier results reported in Part VI of this series. Evidence suggests that this difference results from the higher rate of passage of food through the digestive tract at the HIGH level of intake.These results are discussed with reference to the errors introduced into the faecal‐index method for estimating the digestibility of grazed herbage.
THE MACHAIR GRASSLANDS OF THE HEBRIDES
Authors: Roberts H. W. , Kerr D. H. , Seaton D. 
Published: April 2006

The utilization of Scottish hill‐land potential is severely limited by inadequate wintering facilities resulting from a low proportion of inbye land to hill‐land. The machair lands of the Uists, in the Outer Hebrides, however, provide a more suitable ratio, which is not commonly found in the Highlands of Scotland.Investigations into the grassland problems of the Hebrides were intensified in 1955; and some of the data obtained from trials are given here, as are suggestions for improving the production and utilization of grass in these areas. The climate, soil, and agricultural system all interact to provide conditions which are rarely seen elsewhere.
ECOLOGICAL STUDIES ON POA ANNUA IN TURFGRASSES
Authors: Youngner Victor B. 
Published: April 2006

Ecological studies of Poa annua populations in turf using the core sampling method conducted over a period of several years showed that Poa annua was able to produce seed under frequent mowing at 1/2 to 3/4 of an inch. The population the second winter after seeding into Bermuda Grass turf was as high as that of the first.High soil moisture maintained by frequent light irrigations favoured its persistence in Bermuda Grass turf during the summer months.Matted Bermuda Grass turf which was lightly renovated in November contained a higher winter population of Poa annua than the non‐renovated. Significantly denser populations were found in turf mowed at 1/2 to 3/4 of an inch than in turf mowed at 3 inches.Perennial prostrate growing strains were selected which could be readily propagated vegetatively and persisted in field plots for two to three years when clipped at 1/4 inch.
Lucerne Variety Trial
Authors: Jekabsons V. 
Published: April 2006

SUMMARYThe object of the trial was to obtain information on productivity and persistence of 10 selected lucerne varieties subjected to a regular cutting treatment at an early and a very early stage of growth.The trial was established on the Company's land at Walsingham, Norfolk. The soil of the trial plots consisted of sand‐loam topsoil (pH 6.9) and coarse sand subsoil (pH 7.5).