bluuebunny/crossref_metadata_2025 huggingface dataset:
Autumn nitrogen for winter wheat
Authors: Widdowson F. V. , Penny A. , Williams R. J. B.
Published: March 2009

1. Fourteen experiments with winter wheat on heavy-land farms from 1958–60 compared autumn dressings of sulphate of ammonia with equivalent early (March) or late (May) spring top-dressings. Dressings applied on two or all three dates of application were also compared.

2. Consistent and significant gains in yield from low (0·5 or 0·6 cwt. N/acre) and high (1·0 or 1·2 cwt. N/acre) levels were obtained at most centres, which were on fields under arable rotation.

3. With the low level of N, gains in yield were greatest from a single May top-dressing. There was no gain from dividing the dressing.

4. With the high level of N, dressings divided between autumn-May or March-May were best. March-May was the most consistently satisfactory treatment and gave the highest mean increases in yield in 1959 and 1960, but in 1958 autumn-May was better. Single May dressings gave slightly lower yields. There was no advantage from dividing N between all three dates of application.

5. Single applications of N in autumn gave lower yields than single applications in spring; supplementing autumn N with a late spring top-dressing gave almost the same yield as giving all the N in spring. Dividing the dressing in this way may be convenient on many heavy-land farms.

6. The percentage of N in the grain was highest with a late top-dressing of fertilizer-N, lowest with autumn N and intermediate with March top-dressings.
Visual judgements of quality in meat III. Assessments of bacon qualities by naïve and experienced judges using photographic reference standards
Authors: Gatherum D. P. , Harrington G. , Pomeroy R. W.
Published: March 2009

1. Two panels of eight students, with no previous experience in scoring bacon sides for eye-muscle qualities or for fatness, co-operated in an experiment involving thirty-five photographs of back rashers of bacon presented to them in batches of twenty at a time. The members of the first panel made their assessments without any guide, whereas those of the second were provided with sets of photographic reference standards showing a graded sequence of rashers scoring from 0 to 10 for each of the two characteristics involved.

2. Those provided with the reference standards spread out their scores over the available range more than those who judged without them.

3. Judging discrimination between markedly different groups of rashers was improved when the reference standards were available. This was not true of discrimination between similar rashers since repeatability of scoring was to some extent decreased when the standards were used.

4. When the reference standards were not available, these inexperienced judges tended to adjust their level of scoring according to the quality of the batch of rashers being assessed. This adaptive effect was eliminated when reference standards were available although apparently random fluctuations of level of scoring from batch to batch still occurred.

5. Differences between judges due to their different uses of the available range of scores were less marked, although not entirely eliminated, when reference standards were used by the naive judges. Systematic differences between the scores awarded by various judges remained, as did a few differences of opinion on the relative quality of certain examples.
Analysis of honey farmers' records on queen rearing and queen introduction
Authors: Free J. B. , Spencer-Booth Yvette
Published: March 2009

1. Queen-rearing and queen-introduction records of two honey farmers have been analysed.

2. Cells with newly grafted larvae were sometimes more readily accepted by queenless and broodless colonies than by queenless colonies with brood, or queenright colonies, and sometimes more readily accepted and built by queenless colonies with brood than by queenright colonies. Giving larval food with the larvae made little difference to acceptance.

3. Sealed cells and virgin queens wero more readily accepted by colonies dequeened for 3 days or more than by more recently dequeened colonies, particularly when the former had queen cells. Queen cells were the least successfully introduced to colonies which had been dequeened 3 hr. or less. Younger cells were better accepted than older cells in recently dequeened colonies, but not in colonies dequeened 3 days or more. Cell protectors did not increase the percentage of mated laying queens produced.

4. Mated laying queens were less successfully introduced to colonies with virgin queens, cells, or laying queens and cells, than to colonies with laying queens only.

5. In June and July cells and virgins were more successfully introduced, and mated laying queens less successfully introduced, than in other months. The acceptance of grafted cells did not vary with the time of the year.

6. The success obtained with cell building, and cell and queen introduction differed greatly in different years.
The grazing behaviour and free-water intake of East African shorthorned zebu heifers at Serere, Uganda
Authors: Wilson P. N.
Published: March 2009

1. Results are presented which refer to the behaviour of twenty young East African shorthorned zebu heifers grazing a Chloris gayana ley at Serere Experiment Station in north-east Uganda. The heifers were studied for two trial periods, each of 72 hr. duration, one during the transitional season and one during the dry season.

2. Five of the heifers were recorded individually, and the results showed a fair degree of variation in behaviour between heifers. The difference in total ruminating time between two heifers was statistically significant, but all other differences were nonsignificant.

3. The day to day variation in behaviour was very small. There was no significant difference in the time spent engaged in any major activity between the 3 days of either trial.

4. During the transitional period of the year between the wet and dry seasons, young heifers spent 8·6 hr. grazing (22·5% at night; 77·5% by day) and 7·0 hr. ruminating out of a 24 hr. period. During the dry season, the heifers spent 7·8 hr. grazing (25·2% at night; 74·8% by day) and 6·5 hr. ruminating. There were no other important differences in behaviour time between the two seasons.

5. In the transitional season the grazing was divided into three distinct periods, two during the day and one at night. In the dry season the afternoon grazing period was divided by a short resting period into two parts, making four periods in every 24 hr. An average of 2 hr. were spent night-grazing in both seasons, and this night grazing was independent of moonlight.
The fleece of the Scottish Blackface sheep I. Seasonal changes in wool production and fleece structure
Authors: Doney J. M. , Smith W. F.
Published: March 2009

1. Seasonal changes in wool production per unit area of unstretched skin, number of fibres of each type per unit area, ratio of fibre types, mean fibre weights, lengths and diameters and degree of medullation are given. The production cycle shows a peak in August and September and a trough in February and March, the weight of wool produced in the latter period being only 16% of that in the former. Approximately 80% of the fleece is produced in the 6 months from June to November (lambing ewes). Other components show similar trends.

2. The production cycle does not entirely coincide with the nutritional cycle as estimated from bodyweight changes before late pregnancy. Whilst bodyweight increases from September to November wool production declines by about 25%.

3. The winter drop in wool production per unit area is caused partly by a decrease in the mean weight of each fibre type (in turn made up of a decrease in both length and diameter) and partly by a 50% reduction in the number of active fine fibre follicles and a 100% reduction in active kemp follicles. There is no apparent change in the number of active coarse fibre follicles. The degree of medullation of both coarse and fine fibres declines substantially between December and May.
The effect of sodium and potassium fertilizer on the mineral composition of sugar beet
Authors: Adams S. N.
Published: March 2009

Plants from salt and potash fertilizer trials at Bothamsted were harvested at intervals throughout the growing seasons of 1942 and 1943 and analysed for N, K, Na, Ca, Mg and Mn.

The uptake of nutrients is discussed with respect to field methods of fertilizer application.

Salt increased beet yield in both years, but it did not act by mobilizing soil potassium reserves and increasing the potassium status of the plant. Potash fertilizer, although increasing the potassium status of the plant, did not increase yield. Sodium and potassium were differently distributed in the plant. At harvest, only 6% of the plant's sodium content was in the root compared with 33% of the potassium. The potassium, but not the sodium content of the petiole, was higher than that of the lamina until the end of August. Sodium thus is a nutrient for beet and not a potassium substitute.
Studies of the effects of soil aggregate size on the emergence and growth of beet (Beta vulgaris L.) II. Leaf development
Authors: Hammerton John L.
Published: March 2009

Seedling beet plants grown on a fine soil separate produced more and larger leaves than those grown on coarser separates. This result has been ascribed to the greater quantity of available water, and the better root-soil water contact, in the fine separate compared with the others. Difficulties of root establishment in the coarser separates may retard the start of leaf development relative to that in the fine separates. Soil separates also affected leaf number, in some experiments, through their effect on seedling emergence, in that rapid emergence gave seedlings a slightly longer period for leaf production.

Fodder beet plants (variety Red Otofte) had a greater leaf number per plant at all counts than plants of any of the sugar-beet strains grown. Polyploid sugar-beet seedlings had larger leaves than diploid seedling.

Nitrogen applications to the seed-bed did not stimulate leaf production. In one instance, heavy fertilizerdressingsretardedleafproduction,probably by an osmotic effect.
The response of pastures in Northern Ireland to N, P and K fertilizers and to animal slurries: III. Effects in experiments continued for either two or three years
Authors: Adams S. N.
Published: March 2009

Three factorial experiments made in 1969 on Northern Ireland pastures to measure effects upon yield and mineral content of 0, 180 and 360 kg N, 0, 30 or 60 kg P and 0, 150 or 300 kg K/ha/year, both with and without 1380001 slurry/ha, were continued on the same sites with the same treatments in 1970 and two of them were continued again in 1971.

Responses to nitrogen in the second and third seasons were similar to those of the first season. There was no evidence that large nitrogen dressings plus slurry were causing nitrogen to accumulate in the soil.

Repeated cutting of herbage given neither fertilizer potassium nor slurry was beginning to reduce both yield and the potassium content of the herbage in the second and third years. Giving fertilizer potassium prevented these losses, but the potassium in the slurries was less effective because it did not maintain the potassium content of the herbage. Reasons for, and implications of this effect are discussed.

There was no evidence that soil phosphorus reserves were becoming depleted, when judged by the % P in herbage receiving neither fertilizer nor slurry even after the herbage had been cut and removed for two or three years. As there was no immediate need for fertilizer phosphorus, the P in the slurries, even though slower acting than that in mineral fertilizers, seemed suitable for maintaining the phosphorus status of these pasture soils.
Individuality and heritability of the blood composition of calves with particular reference to the selection of stock with improved growth potential
Authors: Rowlands G. J. , Payne J. M. , Dew Sally M. , Manston R.
Published: March 2009

Blood samples, taken from each of 231 calves on three occasions at 9,10 and 11 weeks of age, were analysed for packed cell volume, blood glucose and Hb; and serum albumin, urea nitrogen, total protein, Ca, inorganic phosphate, Mg, K, Na and Cu. Differences in the blood composition for individual calves were demonstrated for all blood constituents (P < 0·01) with variations among calves proportionally largest for albumin and smallest for sodium. Concentrations of glucose, Hb and K were inherited (heritability estimates > 0·4).

There were significant correlations (P < 0·001) between the calves' growth rates from 1 to 12 weeks and the concentrations of each of the blood constituents, glucose Hb, K, Na, albumin and inorganic phosphate; in the cases of Na and albumin, comparison of the blood analysis at 9–11 weeks with body weights at 6 and 9 months showed that these correlations persisted, and that by 9 months differences in concentrations of Na and albumin among individuals were associated with anaveragedifference of as much as 55 kg in body weight.

The evidence that concentrations of certain blood constituents are both inherited and related to growth rate suggests that not only might calves be screened early in life for indications of rapid growth rate, but also that animals might be bred to have the blood characteristics indicative of this quality.
Distribution of red cell potassium and evidence of its genetic control in buffaloes
Authors: Sengupta B. P.
Published: March 2009

Distribution of red cell potassium in buffaloes and its possible genetic control was investigated. The mean values of red cell K+ varied between 37 and 41 m-equiv/l in LK type animals and between 87 and 91 m-equiv/l in the HK type. Red cell K+ concentration within individual animals of either LK or HK type was fairly stable over successive samplings, whereas the same values among animals within a type varied rather widely. The inheritance of red cell K+ type in buffaloes appeared to be controlled by a single pair of genes. HK animals were homozygous for the recessive allele while LK animals represented the heterozygotes and also the homozygotes for the other allele. In addition, there was indication that the gene responsible for LK phenotypes might not be completely dominant over the recessive allele. The three populations of buffaloes examined were found to be in genetic equilibrium in respect of red cell K+ polymorphism. HK animals predominated in both the breeds, the frequency of the recessive gene (h) being 0·78 and 0·74 for the Murrah and Bhadawari breeds respectively.
Effect of nitrogen source and time of application on wheat nitrogen uptake and grain yield
Authors: Ayoub Ali T.
Published: March 2009

Two field experiments were conducted in 1971–72 and 1972–73 on two similar sites of calcareous clay soils (vertisol) with paste pH 8·2, 0·024% and 0·22% organic carbon. Wheat (Triticum aestivum L. var. (LR N10) An3) was grown and the fertilizers ammonium sulphate, urea, nitrophoska 15% N, 15% P2O5, 6% K2O), calcium nitrate (Ca NO3)2·4H2O) and ammonium sulphate nitrate were each used at 70 kg N/ha at seeding, tillering, jointing or ear emergence and there was one treatment with no N fertilizer. The treatments were arranged in a randomized block design with four replications. Each plot was 6·0 x 7·0 m of which 4·0 x 5·0 m was harvested. N fertilizers were broadcast by hand and no basal potassium or phosphorus were added since they are known to have no effect on wheat yield on these soils. Seed a rate equivalent to 85 kg/ha was weighed separately for each plot and sown by hand in rows spaced 20 cm apart. Each experiment received 10 irrigations, each equivalent to a head of 10 cm of water, at 10-day intervals.
The effect of nitrogen source on the in vitro cellulose digestion of chemically treated oat straw and poplar wood
Authors: Adeleye I. O. A. , Kitts W. D.
Published: March 2009

The gross energy of forages can be classified into three fractions, namely the unavailable fraction, the digestible energy fraction and the potentially digestible energy (PDE) fraction. The PDE fraction can only be made available by appropriate treatment and supplementation (Pigden & Heaney, 1969). In young forages the PDE fraction is relatively insignificant, but as the plant matures, the PDE fraction increases very rapidly. By treating matured forages with delignifying agents, increased nutrient digestibilities have been demonstrated Chandra & Jackson, 1971; Wilson & Pigden, 1964), but no significant improvement on the voluntary intake was achieved unless the treated material was supplemented with a source of nitrogen (Donefer, Adeleye & Jones, 1969). While Zafren (1960) used ammonium hydroxide (NH40H) as the treatment alkali, with the claim that the ammonium acetate resulting from the neutralization of the excess alkali could serve as an extra source of nitrogen in the treated straw, other investigators (Donefer et al. 1969) have adopted the method of supplementing the treated straw with a source of nitrogen. Since the efficiency with which dietary nitrogen is converted to microbial nitrogen in the rumen has a considerable influence on the efficiency the animal as a whole, studies herein reported were carried out to test the effectiveness with which rumen micro-organisms utilize different nitrogen sources in degrading cellulose in vitro.
Growth and yield of highland maize in Mexico
Authors: Goldsworthy P. R. , Colegrove M.
Published: March 2009

The growth and yield of five highland varieties of tropical maize were studied. Grain yields were between 4·7 and 8·8 t/ha. Crop growth rates (C) increased to a maximum of between 25 and 35 g/m2/day at silking and then declined. Grain growth rates (maximum 21 g/m2/day) exceeded current C during most of the grain-filling period.

After silking, when C exceeded grain growth rate, dry matter accumulated in the stem and husk, resulting in an increase of from 200 to 600 g/m2. Later, as grain growth rate increased and exceeded current C, some of this accumulated material was incorporated into the grain, and stem weight decreased. A comparison of the dry weight changes after flowering in these varieties with those reported for a hybrid that yielded 12 t grain/ha indicates that the smaller yield of the Mexican varieties was associated with smaller grain growth rates and the incorporation into the grain of a smaller fraction of the dry weight produced after flowering. These results suggest that the capacity of the grain ‘sink’ to utilize assimilates limited yields in the tropical varieties.
Linear programming and the optimum carrying capacity of range under common use
Authors: Connolly J.
Published: March 2009

The common use of range by different types of animals may be more efficient than separate grazing by each type in that they may be complementary in their utilization of forage. Also, under certain pasture and range conditions the danger of permanent damage by over-grazing can be critical. This paper presents a method of assessing the optimum carrying capacity of range under single or common use subject to constraints on the level of utilization of forage plants. The joint optimum carrying capacity for the animal types may vary as the management objective varies between maximum profit, maximum animal gain or maximum utilization of forage, all subject to the same protection against over-grazing.
The constancy of the digested cell wall in grass
Authors: Moir K. W.
Published: March 2009

The quantity of in vitro digested cell wall was determined in the separated leaf and stem of Digitaria decumbens (pangola grass) fertilized at three different levels of nitrogen and cut after two different periods of regrowth. The treatment means ranged from 39·6 to 41·5 g digested cell wall per 100 g forage organic matter in leaf, and from 37·5 to 41·6 g in stem. For both leaf and stem the lowest mean amounts of digested cell wall were associated with the highest levels of fertilizer and the longer periods of regrowth. The results for nitrogen fertilizer were consistent with those from previous in vivo digestibility experiments, but when the effect of the total cell wall on digested cell wall was taken into account there were inconsistencies. The previous in vivo digestibility data were used in conjunction with the present results in support of a view that interpretation of digestibility data for grasses is best made by reference to a constant digested cell wall of 39·5 g/100 g forage organic matter.
Delayed nitrification and controlled recovery of aqueous ammonia injected under grass
Authors: Ashworth J. , Flint R. C.
Published: March 2009

Nitrification of aqueous ammonia, and its uptake by grass, are slower when the amount of NH3-N injected per unit length of slit is increased and as a result crop yield is spread more evenly over the growing season. Measurements of the amounts of NH4-, NO3- and NO2-N in the soil, made at intervals from February until October, and computed diagrams showing their distribution in soil under grass, are presented. We conclude that, at average current rates of application, most of the aqueous ammonia used for grass in England and Wales is probably not applied along the injection slit in sufficient quantity to allow it to persist throughout the summer.
Fat cell size in Pietrain and Large White pigs
Authors: Wood J. D. , Enser M. B. , Restall D. J.
Published: March 2009

In view of the dependence of fat metabolism on the size of fat cells and the lack of information describing the change in fat cell size which occurs during growth in pigs, an examination was made of the size of subcutaneous fat cells in Pietrain and Large White pigs of 30–95 kg live weight. A microscopic procedure was used and fat cell diameter was measured at two levels in the outer layer of shoulder fat and at two levels in the inner layer.

In both breeds the rate at which cell diameter increased in size with live weight was greater in the inner layer than the outer layer. At all levels this rate of increase was greater in Pietrains. At the two levels in the inner layer the cells from Pietrains increased in size by 41% and 54% between 30 and 95 kg live weight and the cells from Large Whites increased in size by 23% and 36%. The result was that at 95 kg live weight both breeds had cells of similar size in the inner layer.

Therefore in pigs of the same live weight, cell size varies, depending on the site at which the examination is made and the breed of pig. Even at constant cell size, however, the lipogenic capacity of the fat from different levels and different breeds must be different since the cells increase in size at different rates.
The transpiration of Mexipak wheat (Triticum aestiviumL.) in central Iraq
Authors: Al-Nakshabandi G. A. , Ismail H. N.
Published: March 2009

The actual transpiration of Mexipak wheat (Triticum aestiviumL.) was determined by the inflow-outflow method and by soil moisture determination by the use of a neutron probe and gravimetrically. Three irrigation treatments were used during the 1969 season, wet, medium and dry. Amounts of water given were 370, 310 and 255 mm for wet, medium and dry treatments respectively. One irrigation treatment was used during the 1971 and 1972 seasons in which 620 and 700 mm of water respectively was given. However, during the 1973 season, two wet irrigation treatments of 560 and 670 mm of water were used. Values ofEtmeasured by different methods were closely related. Seasonal averages ofEtwere 2·55, 1·99 and 1·62 mm/day for wet, medium and dry treatments respectively. The empirical coefficient (f = Et/Eo) under wet treatment, was found to be higher than that given by Penman (1956) for short grasses and higher than that obtained by Boumanset al.(1963) for wheat and barley in Iraq. The empirical coefficientKbin the Blaney-Criddle formula was less than the value given by Blaney & Criddle (1950) for an arid climate and less than the value obtained by Boumanset al.(1963) for wheat in Iraq. The water use efficiency for grain production was greater under dry than under wet treatment.
The relationship between productivity and some components of canopy structure in ryegrass (Lolium spp.): IV. Canopy characters and their relationship with sward yields in some intra population selections
Authors: Rhodes I.
Published: March 2009

Studies were carried out to measure the productivity of selections for extreme expression of the various components of canopy structure from within six Lolium populations of contrasting morphology.

Considerable variation existed for all canopy characters within each base population and this was reflected in the difference between the high and low selections.

In the first harvest year productivity was closely positively correlated with leaf length. Although some significant differences in yield occurred between selections for other characters, no general pattern was evident as with leaf length. Within the base populations differences in yield occurred between selections of similar leaf length, emphasizing the role of other physiological factors in controlling yield.

In general, dry-matter production was greater in the first harvest year than in the second harvest year. In the second year the long-leaved selections from L. multiflorum and L. multiflorum × L. perenne continued to produce greater yields than their respective short-leaved selections and base populations, but no such differences were evident in L. perenne S. 23 and S. 23 × Ba 6280. Whilst long-leaved selections from the former group were as persistent, or even more persistent than their base populations, the long-leaved selections from L. perenne S. 23 and S. 23 × Ba 6280 showed a lower persistency. Similarly, whilst erect tiller selections from L. multiflorum and L. multiflorum × L. perenne were as or more persistent than their base populations, the three L. perenne erect tiller selections exhibited reduced persistency.

The plant breeding implications of these results are discussed.
The utilization of maize silage for intensive beef production: I. The effect of level and source of supplementary nitrogen on the utilization of maize silage by cattle of different ages
Authors: Thomas C. , Wilkinson J. M. , Tayler J. C.
Published: March 2009

Fifty-four British Friesian castrated male calves, initially 3, 6 or 9 months of age (107, 180 and 249 kg initial live weight, respectively), were individually fed for 83 days on maize silage (27·9% dry matter (D.M.), 10·7% crude protein in D.M.), offeredad libitum. Silage was offered either alone or supplemented with cobs of dried lucerne (21% of total D.M. intake). Three levels of urea (0, 1 and 2% of silage D.M.) were added to the silage before feeding.

Total D.M. intakes averaged 23·0, 23·4 and 21·6 g/kg live weight (LW) for the 3-, 6- and 9-month-old animals, respectively. Addition of urea increased silage intake by 11% in the 6-month-old group but there was little effect in the 3- and 9-month-old groups. Lucerne supplementation reduced silage D.M. intake from 22·0 to 18·4 g/kg LW (P< 0·001) and increased total D.M. intake by 1·4 g/kg LW (P< 0·001).

Live-weight gain (LWG) of the cattle fed on silage alone increased (P< 0·001) with increasing age of animal. The main effect of urea was to elevate (P< 0·001) LWG from an average of 0·79 (no urea) to 0·94 kg/head/day (2% urea). However, it appeared that most of this effect was confined to the 6-month-old group. The effect of lucerne on LWG decreased with increasing age of animal (P< 0·001). Inclusion of lucerne in the diet significantly reduced the response to urea (P< 0·05).

Feed conversion efficiency (LWG/100 Mcal DE intake) decreased (P< 0·01) with increasing age of animal but increased with urea addition from an average of 4·7 (no urea) to 5·3 kg LWG/100 Meal DE intake (2% urea). The response to lucerne supplementation in terms of efficiency was greatest in the 3-month-old group and thereafter declined markedly with increasing age of animal.

The results of this experiment indicated that cattle older than 6 months of age (180 kg LW) could achieve a rate of growth of 1·0 kg/head/day on maize silage supplemented solely with urea, but that younger animals required supplementary lucerne to support a high rate of live-weight gain.
The feeding value of mixtures of alkali-treated straw and grass silage
Authors: Terry R. A. , Spooner M. C. , Osbourn D. F.
Published: March 2009

The digestibility and intake by sheep of a neutral mixture of alkali-treated straw and grass silage was compared with an all-silage diet, mixtures of treated straw and silage adjusted to pH of 4 and 10 and with mixtures of untreated straw and silage. Treatment of the straw with alkali increased the digestibility of the organic matter from 46% to 68%. The daily intake of dry matter and digestible organic matter of the neutral, treated-straw/silage mixture was 24·1 and 15·0 compared with 14·7 and 8·8 g/kg live weight for the untreated straw/silage mixture. The sheep when fed ad libitum ate more of the neutral mixture than they did of the mixtures made acid (pH 4·0) and alkaline (pH 10·0) or of the grass silage although the differences were not significant. Calves were fed similar diets of grass silage, a neutral mixture of treated straw and silage and treated straw and grass silage offered without premixing. The calves offered the neutral mixture ate 16·0% more dry matter and 14·5% more organic matter than did the calves offered either silage alone or the unmixed diet and gained live weight at the rate of 0·42 kg/head/day compared with 0·44 for the silage alone and 0·37 for the unmixed diet.
Methods of analysis of a competition diallel in Italian ryegrass with varying mixture proportions
Authors: Wright A. J.
Published: March 2009

Two methods of analysis of variance of experiments involving diallel arrangements of binary mixtures and monocultures where the former are each represented by a linear replacement series (de Wit, 1960) to detect mean quadratic and quartic patterns among the monocultures and different mixture types, and array differences with respect to linear, quadratic, cubic and quartic effects are given. These are applied to data from an experiment on Italian ryegrass where the four varieties 1145 and S. 22 (diploid), IG2 and Tetila (tetraploid) are mixed in the proportions 75:25, 50:50 and 25:75.

Significant mean quadratic effects for D.M. yield at certain harvests are due to higher yields from monocultures than mixtures, and a mean quartic effect at one harvest reflects a lower yield from 75:25 mixtures than 50:50 mixtures or monocultures. Array differences for linear and quadratic effects are largely a property of the ploidy contrast. Specific mixture effects were recognized for two varietal combinations, mixtures between the two tetraploid varieties showing some yield depression, and those between the two commercial varieties (RvP and Tetila) a considerable increase. No meaningful significant effects were detected for in vitro digestibility.

Further analysis of total D.M. yield by means of the regression of array covariance (Wr) on to array variance (Vr) show, as expected, a closer relationship of Wr and Vr with the non-recurrent component at a frequency of 75% than at 50% or 25%, but the significant departure of the slope from unity is interpreted as evidence that no reliable information as to the relative competitive abilities of the varieties can be obtained from these statistics. Examination of the de Wit replacement graphs strongly suggests a ranking of competitive ability which accords with the known morphology of the varieties.
The distribution of sulphur in the soils and herbage of North West Pembrokeshire
Authors: Williams Carolyn
Published: March 2009

In North West Pembrokeshire, sulphur was determined in soils sampled at 268 sites, and in pasture plants sampled at 172 sites. The sulphur contents of the topsoils ranged from 199 to 3392 mg/kg, with a mean of 710 mg/kg; and the S contents of the subsoils from 115 to 1344 mg/kg, with a mean of 356 mg/kg. Sulphur was concentrated in soils containing much organic matter. There was no clear relationship between plant and soil sulphur contents, though soil drainage influenced both. Poorly drained soils were richer in S than well-drained soils, whereas herbage on poorly drained soils accumulated less S than herbage growing on well-drained soils. Herbage S contents ranged from 0·180 to 0·560%, with a mean of 0·310%. If other factors, e.g. soil N, are not limiting, 14% of the herbage sampled in Pembrokeshire had less than the critical S level recommended by other workers for maximum dry matter yield.
Rapid methods of examining soils. I. Measurements of rolling Weights. (With three text-figures.)
Authors: Schofield R. K. , Blair G. W. Scott
Published: March 2009

1. A method for measuring the heaviness of a sample of soil is described which has the following advantages:

(i) The test can be completed in about 7 min; no initial drying, sieving or weighing is involved.

(ii) The apparatus is simple to construct and comparatively easy to work. The resultant figures are fundamental in nature, and not dependent on the dimensions of the apparatus used.
The present position of the theory of the coagulation of dilute clay suspensions A résumé.
Authors: Russell E. W.
Published: March 2009

In this paper the general theory of the coagulation of dilute clay suspensions is discussed. The more important of the points considered are summarised below.

1. Two separate mechanisms causing collisions between suspended particles are considered, namely their Brownian motion and the mass motion of one group of particles relative to another group. Following Wiegner, these two types of collision are called perikinetic and orthokinetic collisions respectively. The rate of coagulation of a suspension is then shown to depend on the rate of collisions between particles and on the probability of adhesion between them when they collide. If this probability is unity, that is if every collision between two particles results in their adhesion, the suspension is undergoing rapid coagulation. There is excellent agreement between theory and experiment for this type of coagulation whenever the mathematical equations involved can be solved. But if the probability of adhesion is less than unity, the suspension is undergoing slow coagulation, and there is as yet no theory capable of giving the rate of coagulation of such a system.
“Single value” soil constants: a study of the significance of certain soil constants VI. On the changes produced in a soil by exposure to high temperatures (With One text-figure.)
Authors: Coutts J. R. H.
Published: March 2009

1. Measurements on the loss of ignition of four soils of different physical type are not affected by changes in the temperature of furnace, provided that the temperature is above 600°. Errors in the determination of the loss on ignition are of the order of 1 per cent. of the true value.

2. The loss in weight of the soils can be ascribed in the main to loss of free and interstitial water up to about 100°; to destruction of organic colloids between 100° and 250°; and to destruction of inorganic colloids at higher temperatures.

Thanks are due to Miss T. Alper, M.A. (Cape Town) for assistance in making some of the preliminary measurements.
Retention by sheep of copper from aerobic digests of pig faecal slurry
Authors: Dalgarno A. C. , Mills C. F.
Published: March 2009

Dried grass originating from a farm on which herbage had been repeatedly dressed with faecal slurry from pigs given diets containing 250 mg copper/kg had a very variable, but frequently high content of copper. A maximum content of 70 mg Cu/kg dry matter was found. The mean copper content of growing herbage sampled subsequent to this finding was 10·5 mg/kg, while residues of slurry on the soil surface contained 805 mg Cu/kg.

In an experiment involving three groups of eight sheep the utilization and hepatic retention of copper from the solid residues of an aerobic digest of high-copper faecal slurry from pigs was investigated. When these residues constituted 1 or 2% of the dietary dry-matter intake of copper-deficient sheep, rapid increases in plasma copper content, in plasma ferroxidase I activity and in hepatic copper content occurred. Thus copper from this source was readily utilized and retained.

The utilization of copper added to the diet as cupric sulphate was compared with that of copper from dried slurry solids in an experiment with two groups of four sheep. Although the rate of recovery of plasma copper and ferroxidase I activity tended to be slower in sheep given slurry solids this difference was not statistically significant. A significantly slower rate of increase in hepatic copper content resulted from the ingestion of slurry solids.

The significance of these findings is discussed with particular respect to the inadvertent ingestion of residues from the soil surface of pastures dressed with slurry and from the variable inclusion of such residues in herbage uplifted during forage harvesting.
Effect of different diets on the diurnal concentrations of ciliate protozoa in the rumen of water buffalo
Authors: Michalowski T.
Published: March 2009

The relation between composition of food and numbers of rumen ciliates was examined in three buffaloes fed once a day. Depending on the diet and time after feeding, the total protozoa varied from 0·97 x 105to 9·11 x 105/ml rumen fluid. Entodinia formed from 87·0 to 97·1%, Diplodinia from 1·9 to 11·4%, and Holotricha from 1·0 to 1·7%. The numbers ofEntodinium, Polyplastron multivesiculatumand Holotricha were least in animals fed on hay only, while the smallest number ofAnoplodinium denticulatumandEudiplodinium maggiiwas found in buffaloes given a mixed diet containing 13·3% of concentrates. The highest number of protozoa was found in animals fed a mixed diet containing 26·9% of concentrates. No correlation was found between level of protein, crude fibre or nitrogen extracts in food and numbers ofEntodinium, Polyplasstronand Holotricha in the rumen, but numbers ofAnoplodinium denticulatumandEudiplodinium maggiiincreased as protein content increased.
Response of grass swards to fertilizer N under cutting or grazing
Authors: Jackson M. V. , Williams T. E.
Published: March 2009

An experiment was conducted at six widely separated centres in England and Wales for 4 years to compare the response of a perennial ryegrass (cv. S. 23) sward to fertilizer N at input rates of 200, 400 and 600 kg N/ha under cutting-only or grazing-only management systems. Under both managements the yield response to N varied substantially and was always greater under cutting than grazing and the response was greater in the first than in subsequent years. Under cutting, significant responses were obtained from 200 to 400 kg N/ha at all sites and in all years but very few sites responded significantly from 400 to 600 kg N/ha after the first year. Under grazing there was on average of all sites (but not at every site) a significant response from 200 to 400 kg N/ha only in the first year. In subsequent years no single site gave a worthwhile response in each year. Under grazing no site showed a significant response from 400 to 600 kg N/ha.

At the lowest application of nitrogen, 200 kg N/ha, dry-matter yields under grazing were greater than those under cutting on eight of the possible 24 centre-year occasions. At the two higher rates of applied nitrogen dry-matter yields under cutting were consistently greater than those under grazing.

With smaller responses to applied nitrogen on grazed than on cut swards maximum yields were achieved under grazing with an input of about 200 kg N/ha less than under cutting management. The results suggest that cutting experiments cannot be used to predict herbage yields and responses to fertilizer nitrogen under grazing conditions.
Effect of seed immersion in organic solvents on germinability
Authors: Lewis J. A. , Papavizas G. C. , O'Neill Nichole R.
Published: March 2009

Studies on the effects of solvents on germinability of seeds of various crops established the optimum conditions for immersing seeds in several solvents. Reduction in germinability,in vitroand in soil, of seeds of cotton, bean, pea, soya bean, and sugar beet after immersion in acetone, dichloromethane, or ethanol for various periods up to 24 h depended upon the length of immersion and the seed type and solvent used. Soya-bean and sugar-beet seeds were the least sensitive to the solvents whereas bean and cotton seeds were the most sensitive. Various cultivars of the same crop behaved similarly. The amount of seed germinationin vitrowas similar to that in soil. Solvent combinations consisting of acetone with dimethylsulphoxide, dichloroethane. polyethylene glycol, or triethanolamine did not affect cotton-seed germination in soil whereas soya-bean seeds were adversely affected by some materials. The amount of solvent taken up by the seeds and the amount of oxidizable matter extracted by the solvent depended upon the solvent and the crop. Maximum absorption of solvent occurred within 1 h. The amount of oxidizable material diffusing from seeds immersed in solvents was not correlated with the amount of solvent uptake or extent of seed germination.
The effects of subsoiling and deep incorporation of P and K fertilizers on the yield and nutrient uptake of barley, potatoes, wheat and sugar beet grown in rotation
Authors: McEwen J. , Johnston A. E.
Published: March 2009

A small-plot experiment on sandy loam soil at Woburn tested the effects of subsoiling by hand and of incorporating a large dressing of P and K fertilizer into the subsoil.

Ths treatments were applied once in 1973 and their effects were assessed from 1974 to 1977 on the yields of, and N, P, K uptakes by, barley, potatoes, wheat and sugar beet grown in rotation. All crops were present each year and all plots received annual seedbed dressings of N, P and K appropriate to the crop. Dolomitic limestone was applied once in the rotation. The effects of the treatments on P soluble in 0·5 M-NaHCO3 and exchangeable K in surface and subsoils were measured.

Subsoiling alone increased the 4-year mean yield of wheat by 21%, of barley by 24% and of sugar from sugar beet by 11%. Mean yield of potatoes was unaffected.

Incorporating P and K into the subsoil increased the mean yield of potatoes by 16% and further increased mean yield, in addition to the effect of subsoiling, of barley by 20% and of sugar by 4%. Mean yield of wheat was not further affected.
The Progeny Test as a Method of Evaluating the Dairy Sire.
Authors: Edwards Joseph
Published: March 2009

A survey of some environmental and physiological factors influencing milk yield and an analysis of theories of and experiments on milk and butterfat inheritance have been made.

Further evidence is given of the fact that the proved dairy sire is the outstanding medium through which improvement in dairy cattle breeding may be effected. The need of (1) prolonging the breeding life of such an animal and (2) evolving a scheme for the regular progeny-recording of all dairy sires is emphasised.

The minimum number of unselected daughters necessary to give a reasonably accurate indication of their sire's transmitting ability is six.
Nutritive Value of Pasture. IX. The Influence of the Intensity of Grazing on the Yield, Composition and Nutritive Value of Pasture Herbage.
Authors: Woodman H. E. , Norman D. B.
Published: March 2009

The main conclusions from the present investigation, which was undertaken in order to obtain an insight into the consequences of the adoption of a 5-weekly rotational close-grazing system, may be summarized as follows:

The lengthening of the interval between successive cuts from a month to 5 weeks leads to a definite, though not very serious, reduction in the digestibility of the herbage. This reduction is most noticeable during the flush period of growth, and the constituent most affected is the crude protein. During the fore-flush and post-flush periods, it appears to be immaterial, from the standpoint of digestibility, whether a system of monthly or 5-weekly cutting is adopted. The falling off in digestibility is not connected with the onset of lignification in the herbage, since the digestion coefficient of the fibrous constituent remains high throughout the season, and it may be concluded that, during a season of favourable rainfall, it is possible by cutting (or close-grazing) at intervals of 5 weeks, to prevent the herbage from becoming lignified and of greatly reduced digestibility. The possibility, however, during seasons of a droughty character, of a premature onset of lignification under a system of cutting (or close-grazing) at 5-weekly intervals is discussed.
The Relation of Calcium and Phosphorus to Growth and Rachitic Leg Weakness in Chickens
Authors: Parkhurst Raymond T. , McMurray Mary R.
Published: March 2009

Retarded growth and poor bone development resulted from feeding both a ration containing only 0·26 per cent. calcium and with a Ca:P ratio of 0·44:1 and from a ration in which 5 per cent, of maize meal had been replaced by 5 per cent, of ground limestone to give a calcium content of 3 per cent. and a Ca:P ratio of 4:1. The basal or No Limestone group confirms previous results indicating that ground limestone may have a depressing effect on growth.

The authors wish to acknowledge the assistance of Mr G. H. Botham, B.Sc, A.L.S., who did the chemical analysis of the food and bones, Mr J. Lavelle, who made and interpreted the skiagrams, and Mr F. J. Dudley, who statistically analysed the results.
A dynamic model for the effects of potassium and nitrogen fertilizers on the growth and nutrient uptake of crops
Authors: Barnes A. , Greenwood D. J. , Cleaver T. J.
Published: March 2009

A dynamic model has been derived to predict the day-to-day changes in the growth and nutrient composition of crops grown in the field with different levels of nitrogen and potassium fertilizer. Equations are included in the model to represent processes such as re-distribution of nutrients down the soil profile after rain or evapotranspiration, transformations between the various forms of potassium, transport of potassium ions through the soil to the roots and the dependence of growth and nutrient uptake on incoming radiation, plant composition, and soil water stress.

The model was tested by using it to forecast the responses of a test crop, cabbage, to fertilizers in four separate field experiments at WeUesbourne. From data describing the initial soil conditions and weights of the plant, the soil and crop characteristics and the daily weather conditions, the model correctly predicted the pattern of responses in each experiment, although, in some instances the absolute values of the theoretical and experimental yields differed somewhat. Of special significance was the ability of the model to forecast the effects of different weather conditions on crop response and the interactions between the effects of N and K fertilizers on the growth and chemical composition of plants.