bluuebunny/crossref_metadata_2025_split huggingface dataset:
The distribution of sulphur in the soils and herbage of North West Pembrokeshire
Authors: Williams Carolyn 
Published: March 2009

SUMMARYIn 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

SUMMARYDried 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

SUMMARYThe 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

SUMMARYAn 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

SUMMARYStudies 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

SUMMARYA 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

SummaryA 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.
Response of cotton to nitrogen and water in a tropical environment. III. Fibre quality
Authors: Hearn A. B. 
Published: March 2009

SummaryIn two experiments three dates for time of last irrigation were combined factorially with four rates of application of nitrogen fertilizer and two varieties of cotton. Early termination of watering (when the crop had set 70 bolls/m2) combined with heavy application of nitrogen (168and225 kg/ha) decreased fibre strength, micronaire and yarn strength, particularly in 1973. In two other experiments three frequencies of watering were combined factorially with several rates of application of nitrogen. Frequent watering (weekly) combined with heavy application of nitrogen (168 kg/ha) decreased uniformity of fibre length, micronaire and yarn strength and appearance. In both experiments application of nitrogen increased fibre length. The responses of both varieties were similar except for effect of nitrogen on micronaire. Application of nitrogen decreased the micronaire of Deltapine 16 more than that of Acala 1517 BRI.The response of the fibre properties to variation in crop nitrogen and water supplies are interpreted in terms of the effects of these factors on (i) the intrinsic fibre properties of bolls maturing at the same time, (ii) the change in the fibre properties of bolls maturing progressively later in the season, (iii) the proportion of total yield contributed by bolls maturing at different times and (iv) delay in harvest and consequent variation in exposure to weather prior to harvest. Yarn strength did not respond as much as fibre properties to the experimental treatments and in particular did not reflect the influence of weathering on fibre properties to the degree anticipated.
Net assimilation rate of cotton in relation to spacing
Authors: Bhatt J. G. , Shah R. C. , Sharma A. N. 
Published: March 2009

SummaryThe net assimilation rates (NAR) of three genotypes of cotton differing in their growth habit were studied under different spacings. The NARs of a very bushy type, G 67, and a comparatively less spreading type, IAN 560, were the same but that of a compact type, IAN 579, was twice as much when the leaf area index (LAI) was one. Though subsequently in G 67 and IAN 560 NAR under varying spacings either decreased less rapidly or remained steady, the decrease was nearly Hnear with increasing LAI. However, for IAN 579 dependence of NAR on LAI was generally positive indicating genotypic improvement. Under different spacings the leaf-density dependance of NAR appeared to have been decreased in IAN 560, but was nearly absent in IAN 579 with more efficiency towards increasing the yield of seed cotton.
The effect of herbage allowance on herbage intake and performance of lambs grazing perennial ryegrass and red clover swards
Authors: Gibb M. J. , Treacher T. T. 
Published: March 2009

SummaryThe effect of daily herbage allowance on herbage intakes and growth rates lambs grazing perennial ryegrass and red clover was investigated in two experiments. Herbage allowances defined as g herbage D.M./kg live weight (LW)/day were controlled by varying the areas of plots grazed for 2 days by groups of six lambs.In the first experiment five herbage allowances in the range 20–120 g D.M./kg LW/day were offered on two areas of a perennial ryegrass (cv. S. 23) sward that received nitrogen fertilizer applications of 39 or 78 kg N/ha/28 days. In the second experiment five herbage allowances in the range 30–160 g D.M./kg LW/day were offered on perennial ryegrass (cv. S. 23) and red clover (cv. Hungaropoly) swards.Asymptotic curves were fitted to describe the relationship between herbage allowance and daily intake of herbage. In Expt 1 nitrogen fertilizer rates did not affect the yield of herbage or animal performance. In Expt 2 intakes were higher on the clover sward than on the ryegrass sward at the higher herbage allowances.The asymptotic curves to describe the relationship between herbage allowance and growth rate of lambs differed widely between periods. Growth rate of the lambs increased linearly with increase in digestible organic matter intake. Live-weight gain per unit of digestible organic matter intake was higher on the red clover than on the ryegrass.The conclusion is drawn that if the herbage present to ground level is not more than three times the daily intake of the animals, intake of herbage of the animals may bo restricted.
The nutrition of the early weaned lamb. IV. Effects on growth rate, food utilization and body composition of changing from a low to a high protein diet
Authors: Ørskov E. R. , McDonald I. , Grubb D. A. , Pennie K. 
Published: March 2009

SummaryAbout sixty male lambs were fed ad libitum from 6 weeks of age on low- or highprotein diets based on barley or barley and fishmeal and containing respectively 120 and 200 g crude protein/kg dry matter. Some lambs were changed from one diet to the other when they reached 28 kg live weight. All were slaughtered as they attained a predetermined series of live weights ranging from 20 to 75 kg.Throughout the experiment, rates of live-weight gain were substantially higher with the high-protein (HP) than with the low-protein (LP) diet, but were highest after a change from low to high protein (LHP). The feed consumption of the LHP lambs did not exceed that of the HP lambs, but the former showed a substantial superiority in feed conversion ratio at the same live weight.At similar empty body weights, the LP lambs contained more fat and less water in the empty body than the HP lambs. Although the percentage differences decreased at higher weights, differences were still apparent at 70 kg live weight.The LHP lambs showed dramatic and rapid changes in body composition, particularly in water and fat content. By 40 kg live weight, their composition approached that of the HP lambs.The ratio of water to protein was consistently lower for the LP lambs. The ratio of protein to ash also differed between LP and HP lambs. It was initially highest for the HP lambs, at about 40 kg live weight it was the same, and at 70 kg live weight it was highest for the LP lambs.The ash content of the LHP lambs remained virtually constant during the period of rapid growth and rapid deposition of water, protein and fat which took place immediately after the change of diet, and only showed compensatory increases after 35 kg live weight. This finding was supported by the pattern of changes in weight and specific gravity of the femur and tibia + fibula.Use was made of separate relationships between live weight and body composition for the LP, HP and LHP lambs to estimate rates of accretion of crude protein, fat and water in the empty body. There was a particularly striking increase in the rate of accretion of water immediately following the change of diet. There was an increase in the water content of empty-body gain and a reduction in the ratio of gain in fat to gain in protein.Derived estimates of the ratio of metabolizable energy intake above maintenance to the energy content of empty-body gain gave some suggestion of an improvement in efficiency of utilization of metabolizable energy for gain following the change from low to high protein. It is concluded however that the improvement in food conversion ratio following the change is attributable mostly to difference in the composition of gain.