bluuebunny/crossref_metadata_2025 huggingface dataset:
The relative importance of some different sources of plant-weight variation in drilled and transplanted leeks
Authors: Benjamin L. R.
Published: March 2009

In six experiments the effects of various factors on plant-weight variation (sum of squares of deviation from the mean shoot weight) at harvest were examined. These factors were seed size, sowing depth, time of seedling emergence, size at different stages of development, within-row spacing, density and row position within a bed.

In a drilled experiment, up to 25% of the variation in mature leek size could be attributed to variation in time of seedling emergence. Similarly, in the experiments which used transplants, 15% of the variation in the mature crop could be associated with variation in size shortly after seedling emergence from peat blocks.

Variation in row position within a 4-row bed never accounted for more than 11% of the weight variation at harvest, and variation in within-row spacing never accounted for more than 4% of weight variation. However, the coefficient of variation (c.v.) of leeks growing at 22 plants/m2 was 44% whereas the c.v. of those growing at 50 plants/m2 was 61%.

Using large seeds or sowing deeply gave a quicker emergence and a higher percentage emergence than using small seeds or sowing shallowly. However, these factors each never accounted for more than 7% of the weight variation in mature leeks.

Most of the plant-weight variation could not be attributed to any of the measured factors in any of the experiments. The c.v. of leeks which had emerged on a specific day and had been grown in a uniform environment, was between 50 and 66%, which was similar to the c.v.s observed in the transplant and drilled experiments. However, selecting for large transplants reduced the c.v. to 28% in one experiment; this effect was only partly attributable to the greater mean plant size resulting from this treatment.
The influence of precipitation regime on the management of three-course crop rotations in northern Syria
Authors: Keatinge J. D. H. , Dennett M. D. , Rodgers J.
Published: March 2009

In the 350–600 mm seasonal rainfall ecological zone in northern Syria three-course rotations are commonly practised under rainfed conditions. The precipitation regimes at three sites in this ecological zone have been examined. These have been shown to exercise a powerful influence on crop management, and an enhanced understanding of the effect of precipitation on crop productivity would therefore assist in the development of improved strategies of agronomic and rotational management. Considerable variability has been demonstrated in characteristic elements of the precipitation regime at the selected sites and this has indicated the unsoundnesa of applying general management recommendations to the ecological zone as a whole.
The influence of winter nutritional depressions on the growth, reproduction and production of cattle
Authors: Joubert D. M.
Published: March 2009

1. During the period May 1948 to May 1952, a study was made of the influence of seasonal fluctuations in the nutritive value of the natural pastures in the Bankenveld region of the Transvaal, on the growth, reproduction and production of cattle. The paired method of investigation was adopted, each heifer maintained on grazing alone having a related counterpart of the same age which received supplementary feeding during the winter months. The former treatment was termed ‘Low plane’, and the latter referred to as the ‘High plane’. Four breeds were included in the investigation, viz. Friesians and Jerseys, and Shorthorns and Afrikaners, thus representative of both dairy and beef types. The latter breed also represented the stock indigenous to South Africa. Initially five pairs per breed were studied, but deaths and other causes depleted the numbers to twenty-eight head after 4 years of investigation.

2. Since the investigation formed part of a series of studies which have been in progress at the University of Pretoria and Agricultural Research Institute during the past two decades, the results of which hitherto remained unpublished, a review is provided in the early chapters. To furnish some indication of the natural conditions ruling in the Bankenveld region, the agro-ecological background is discussed, particular attention being paid to physical and nutritional factors. It is shown that for at least 6 months of the year the climate tends to be subtropical, whilst the results of digestion trials on pasture samples, indicated serious nutritional depressions in the natural grazing during winter.
Studies in selective weed control III. The control of annual weeds in leguminous crops with 2:4-dinitro-6-secondary-butyl-phenol
Authors: Roberts H. A. , Blackman G. E.
Published: March 2009

During 1947–9, field and pot experiments have been carried out first to assess the herbicidal properties of 2:4-dinitro-6-secondary-butyl-phenol, and secondly to determine its value for selective weed control in leguminous crops. In order to obtain precise estimates of the concentration required to produce a given percentage mortality of either weed or crops species, such experiments were so designed that the results are capable of probit analysis.

From the data of field experiments on thirteen species of annual weeds, it is evident that there are wide variations in the concentration required to produce a standard kill. Irrespective of the species, susceptibility is greatest in the young seedling stage and there is a rapid increase in resistance with age. For example, with Raphanus raphanistrum between the cotyledon and pre-flowering stage a sixfold increase in concentration is needed to give a 90% mortality.
Studies in grazing management I. A comparison of the production obtained from close-folding and rotational grazing of dairy cows
Authors: Holmes W. , Waite R. , Fergusson D. L. , Campbell Jean I.
Published: March 2009

1. An experiment was carried out from 3 May to 10 October 1949 to compare close-folding with rotational grazing of dairy cows. With close-folding the cows were moved daily to an area of fresh pasture which was calculated to supply the day's feed requirements; the rate of stocking ranged from 50 to 80 cows per acre. With rotational grazing the cows were stocked on pasture at the rate of 6–8 cows per acre and moved from one pasture to another at intervals of 5–14 days. Two uniform groups of Ayrshire cows were used, and each group spent a period on each system of grazing. Two pastures, a ryegrass-dominant old pasture and a cocksfoot-dominant ley, were used, and as far as possible the pasture grazed by both groups of cows was similar. Nitrogenous top dressings up to 104 Ib. nitrogen per acre in the season were applied uniformly to both the close-folding and rotational areas. No supplementary feeding was given to the cows.

2. The best methods of close-folding practised gave 215 and 201 cow-days of grazing per acre with 550 gal. milk per acre from the cocksfoot ley and 582 gal. from the permanent pasture. Rotational grazing on the same two pastures gave 181 and 138 cow-days and 450 and 351 gal. milk per acre respectively.
Studies in oil-seed crops I. Factors controlling seed production in linseed (Linum usitatissimum)
Authors: Blackman G. E. , Bunting E. S.
Published: March 2009

Between 1941 and 1946 some twenty-five field experiments were carried out at various centres in England to assess the factors which determine the yield level and seed composition of linseed (oil flax). The experiments were of multifactorial design, and the main variables studied were varietal differences, levels of mineral nutrient supply and plant population. Additions of nitrogen (35 lb./acre) over all experiments raised the yield of seed by 10%, whereas additional phosphorus (50 lb. P2O5/acre) or potassium (80 lb. K2O/acre) had small and inconsistent effects. A significant interaction between nitrogen and variety was recorded in one trial, but in twelve out of fourteen experiments the varieties reacted uniformly to a combined application of nitrogen, phosphorus and potassium, while in the remaining two experiments the interactions were contradictory.
Studies in soil cultivation: XI. The effect of inter-tillage on the sugar-beet crop
Authors: Russell E. W. , Keen B. A. , Mann H. H.
Published: March 2009

Experiments on the effect of inter-row cultivation of sugar beet, carried out in the three years 1939–41 on a sandy loam, led to the following results:

1. If the soil nutrients are in short supply hoeing or hand-weeding increases the yield of the beet, provided these operations are carried out before or shortly after singling.

2. Hoeing is more effective than hand-weeding, but it cannot yet be said with certainty whether this is due entirely to more efficient weed destruction, or whether there is some additional effect, such as mulching.

3. If adequate quantities of soil nutrients are present, inter-row cultivation has little effect on yield, and the crop can tolerate a considerable weed infestation without any effect on yield.

The results for sugar beet on the heavy clay-with-flints soil at Rothamsted show:

1. Additional hoeings after singling, above a modest minimum, have either no effect on yield or else depress it.

2. On the one occasion when pre-singling cultivations were given, the yield was increased.

3. In contrast with the Woburn results the effect of cultivation does not vary with, the level of manuring.
Gas and vapour movements in the soil: I. The diffusion of vapours through porous solids
Authors: Penman H. L.
Published: March 2009

The dependence of the coefficient of diffusion, D, upon the porosity, S, of a granular solid is investigated experimentally. For steady state conditions, using carbon disulphide and acetone vapours, it is shown that a curve connecting D/D0 and S can be drawn which is independent of the nature of the solid, its moisture content and, within limits, its texture. For a limited range of values of S (0·0 < S < 0·7) a good approximation is D/D0 = 0·66S and over this range the diffusion coefficients are larger than those found by Buckingham for carbon dioxide.

Investigation of the non-steady state shows that in soils the attainment of pressure equilibrium is retarded by adsorption, and it is suggested that Buckingham's low values for steady-state conditions can be attributed to premature observations of the diffusion rates; the steady state had probably not been attained when his measurements were made.
Wastage, length of productive life, replacement and depreciation of dairy cows
Authors: Pettit G. H. N.
Published: March 2009

1. In the Eastern Counties of England, annual wastage from milk recorded dairy herds amounts to 29·3 % of the number of cows at the beginning of the year.

2. Average length of productive herd life in milk recorded herds is 3·4 years.

3. Average length of total productive life in milk recorded herds is probably a little more than 4 years. Average length of total productive life in all herds is probably longer, and may be of the order of 5 years.

4. Deaths of cows are equivalent to 10·4% of the total wastage, and to a mortality rate of 3·0% of the number of cows at the beginning of the year.

5. During the three-year period 1934–5 to 1936–7, cows leaving the herd realized an average of £10. 10s. 6d. per head. The average market value placed upon heifers when they entered the milking herd was £20. 14s. per head, while cows for replacement purposes cost an average of £22. 5s. per head.

6. Of all replacements, 67·7 % are heifers, but not all of these are home-bred. In annual valuations, 49·0 % of cows are described as homebred, 50·6% as purchased and 0·4% as unknown.
Growth and development in the pig, with special reference to carcass quality characters: III. Effect of the plane of nutrition on the form and composition of the bacon pig
Authors: McMeekan C. P.
Published: March 2009

It is impracticable to give a detailed summary of the many findings of.this experiment; attention is confined, therefore, to the major aspects and the general principles emerging.

1. By quantitative control of the plane of nutrition, twenty closely inbred pigs have been made to conform to four major variations in the shape of the growth curve from birth to 200 lb. live weight. A high rate throughout (High-High), a high followed by a low rate (High-Low), a low followed by a high rate (Low-High) and a low rate throughout the period (Low-Low) afforded comparison between animals of the same weight but different age and between animals of the same weight and age but with differently shaped growth curves. The relative effects of the treatments upon the development of body proportions and anatomical composition have been studied.
The teart pastures of Somerset: I. The cause and cure of teartness
Authors: Ferguson W. S. , Lewis A. H. , Watson S. J.
Published: March 2009

The scouring of cattle and sheep caused by the teart pastures of central Somerset is due to the presence of molybdenum in the herbage in amounts varying from about 20 to 100 parts per million in the dry matter.

The scouring can be prevented and cured by feeding or drenching with copper sulphate. A daily dose of 2 g. copper sulphate for cows and 1 g. for young stock, is sufficient to cure and prevent the scouring on very teart land. Less copper sulphate may be enough on mildly teart land.
Observations on the survival of stored spermatozoa in the genital tract of the mare
Authors: Laing J. A.
Published: March 2009

1. Twelve pony mares were inseminated at various intervals (18 days to within 24 hr.) before ovulation with spermatozoa which had been concentrated by centrifugation and stored for 24 hr.

2. Of fourteen inseminations, only two, both within 24 hr. of ovulation, produced pregnancies.

3. The survival time of the stored spermatozoa within the female tract was concluded to be somewhat less than 24 hr.

4. It is suggested that successful inseminations with stored spermatozoa could be made 24 hr. after the injection of prolan.

This work was carried out while holding the Miss Aleen Curt Memorial Veterinary Research Scholarship from the Royal College of Veterinary Surgeons.

My thanks are due to Dr J. Hammond and Dr A. Walton for their help and encouragement and to Mr F. T. Day for the loan of the ponies and for his help and instruction in the technique of examination.
Some observations on the need for copper in the diet of fattening pigs
Authors: Braude R.
Published: March 2009

1. The results of two trials involving twenty-four pigs did not provide a clue to the observed craving of pigs for metallic copper.

2. There seems to be no advantage in supplementing a normal diet for fattening pigs which contains about 5 p.p.m. of copper with copper given in form of a solution of copper sulphate. The addition of a mixture of copper sulphate, manganese sulphate and iron pyrophosphate to the same normal diet had also no effect on the rate of growth of the pigs and their food consumption.

3. The haemoglobin and copper contents of the blood appeared to be unaffected by the addition of copper to the diet. The copper content of the livers showed a tendency to be higher in the livers of the pigs receiving the copper supplements.
The behaviour of nitrogenous manures in the soil Part I. The loss of manurial nitrogen
Authors: Mann Harold H. , Barnes T. W.
Published: March 2009

An attempt was made to determine what becomes of the nitrogen added to a poor soil in moderate quantities of organic manures or of ammonium sulphate. Losses by drainage, in two successive barley crops, and by fixation in an unavailable form in the soil were determined, and it was found that with every material used (including tare residues containing 3½% nitrogen, mustard plant residues containing 1½–2¼ nitrogen and pure ammonium sulphate) and with intensive cropping and leaching, not more than 40–51% of the added nitrogen could be accounted for at the end of the experimental period. The balance, it is suggested, must have disappeared from the system, possibly as gaseous nitrogen.

Incidentally to the above, it would appear that after the first crop of barley the presence of the manurial additions of tare residues, and especially of ammonium sulphate, tends to hinder the formation of leachable nitrogen in the soil.
Ear distortion in barley and other cereals caused by spraying with MCPA and 2, 4-D
Authors: Large E. C. , Weston W. A. R. Dillon
Published: March 2009

1. Trials made near Cambridge in 1949 and 1950, under ‘mild’ and ‘hard’ spring weather conditions respectively, have confirmed that the findings of Aberg & Denward in Sweden, and of Pedersen, Andersen & Hermansen in Denmark, concerning distortions in barley caused by MCPA and 2,4-D, are also valid under English conditions.

2. Damage to barley caused by the application of MCPA and 2,4-D up to the 2-leaf and early 3-leaf stages may be recognized by the occurrence of many tubular leaves and bowed or trapped ears. As little as 2 lb./acre of 2,4-D, as the amine salt, applied at this stage may also cause severe stunting of theplants with distortion of the roots.

3. Damage to barley by the application of MCPA and 2,4-D at the 3–4-leaf stages may be recognized by the occurrence of tweaked ears. The application of as little as 2 lb./acre of MCPA, as the sodium salt, at these stages may cause tweaking in over 50% of the ears. 2,4-D (as amine) at the same dosage causes more distortion. Although the reduction in yield due to such tweaking may be slight, the grain sample is irregular in size, with a number of naked grains, and malting quality may be reduced.
Chemical composition and the feeding value of cotton-seed hulls
Authors: Hussain Anwar , Halim Abdul , Wahhab Abdul
Published: March 2009

With the installation of more factories for the decortication of cotton-seeds in Pakistan, the utilization of cotton-seed hulls as a feed is likely to assume great importance. During 1949–50, the writers made determinations of the chemical composition and the feeding value of Pakistan cottonseed hulls by conducting a digestibility trial on dry Sahiwal cows. They are found to contain 39.89–56.47% total digestible nutrients (mean value = 48.68%) and 0.0–0.38% digestible protein. It was observed during the trials that the cows could eat about 20 lb. of hulls per head per day without difficulty. The cows also ate hulls in preference to wheat straw.

Being low in calcium and phosphorus, cotton-seed hulls should not be used as a sole roughage for long periods, unless supplemented with calcium or phosphorus in mineral form, or preferably with silage, legume hay or green fodder of good quality.

Pakistan cotton-seed hulls appear to be equal, if not better, than wheat straw as a cattle feed. From the economic point of view, hulls should be used as a cattle feed only if they are purchasable at about the same price as wheat straw.
Biological aspects of soil fertility
Authors: Neilson-Jones W.
Published: March 2009

1. These researches were undertaken in order to analyse and define with precision the causes of infertility in a heath soil at Wareham Forest, Dorset.

2. The presence of substances actively inimical to growth has been confirmed and the origin of the resulting toxicity established.

3. A new technique for biological analysis, the nutrient-agar-film method, makes it possible to estimate the relative degree of toxicity in any given sample, thus facilitating development of methods of laboratory control for elimination and redistribution of the factor or factors responsible.

4. It has been proved that the toxic substances are of biological origin and that they operate directly by inhibiting fungal growth. The resulting biological inertia is exemplified by almost complete cessation of cellulose decomposition. Following upon this inertia are indirect effects of a secondary character on growth of the higher plants, in the case of trees restricting root growth, impeding mycorrhiza formation, and curtailing supply of nutritive requirements.

5. Justification for the use of organic composts for relieving the observed infertility under field conditions has been provided by laboratory experiments proving that removal of toxicity and profound alteration of the organic substrate and soil bionomics follow addition of compost. Changes so induced are self-propagating and the effects on growth persistent.

6. The bearing of these results on fertility in other natural soils and in cultivated soils is discussed.
Soil studies in relation to geology in an area in north-east Scotland: Part I. The mineralogy of the soil parent materials
Authors: Hart R.
Published: March 2009

1. An account is given of the distribution of four separate boulder clays, which form the parent materials of the soils of eastern Kincardineshire.

2. The mineral composition of the fine sand fractions of the boulder clays is given.

3. The boulder clays, notwithstanding colour similarities, have been shown by mineralogical examination to be distinct.

4. The middle boulder clay, largely influenced by rocks of Old Red Sandstone age, is shown to have a higher proportion of ferromagnesian silicate minerals than soils from glacial drifts similarly derived elsewhere in Scotland.
Marsh spot of peas: a manganese deficiency disease
Authors: Piper C. S.
Published: March 2009

By growing peas in water cultures with carefully regulated amounts of manganese, the effects of a deficiency of this element have been studied.

Complete absence of manganese produces a mottling of the younger leaves and death of the growing tip as previously reported. The plant does not reach the flowering stage.

Small amounts of manganese, insufficient for normal requirements, enable increased growth and seed formation. The seeds show marsh spot lesions, the severity of the lesions being greater at the lower manganese concentrations.

Normal growth and sound seed are produced when sufficient manganese is present in the nutrient solution.

Marsh spot results from a partial deficiency of manganese, the amount available to the plant being sufficient for its normal vegetative requirements but not for healthy seed production.
The effect of plant spacing, nitrogen fertilizer and irrigation on the appearance of symptoms and spread of virus yellows in sugar-beet crops
Authors: Heathcote G. D.
Published: March 2009

Satisfactory comparisons of the incidence of virus yellows in sugar-beet fields or experimental plots with different amounts of N fertilizer can be made from visual symptoms early in the growing season, but not later because dressings of N fertilizer may then mask or delay the appearance of symptoms. Sugar-beet plants in the field infected with beet mild yellowing virus (BMYV) are less likely to show symptoms than those with beet yellows virus (BYV), and plants with BMYV in the glasshouse often fail to show clear symptoms.

Crop yield will be affected by the spread of viruses and colonization of plants by aphids, which in turn are affected by such factors as plant density, nitrogen supply and irrigation. The presence or absence of virus diseases and of aphids should therefore be considered during studies on the effects of these agronomic factors on the growth and yield of sugar beet. Where ample rather than little N fertilizer is used a small increase in the percentage of plants infected with yellows can be expected, and aphids will be more numerous, if plants are not treated with insecticide. Irrigation may also increase yellows incidence (e.g. from 16% to 20% of plants at Broom's Barn in 1967), but any loss of potential yield from increased virus incidence will be small compared with that gained from the use of fertilizer or irrigation. However, plant density can appreciably affect yellows incidence. For example, at Broom's Barn in 1972, 51% of plants in crops with 17500 plants/ha contracted BMYV but only 15 % of plants in crops with 126500 plants/ha. The less dense crop lost 3–4% more of its potential yield due to yellows than the dense crop; this represents a difference due to virus of about 0·25 t sugar/ha.
An empirical law describing heterogeneity in the yields of agricultural crops
Authors: Smith H. Fairfield
Published: March 2009

Using data from a blank experiment with wheat it was found that the regression of the logarithms of the variances for plots of different areas on the logarithms of their areas was approximately linear. A graphical review of variances, etc., reported in the literature for thirty-nine other blank experiments indicates that the results of most such experiments conform to the same law.

It is shown that the above law can be generalized (so as to be applicable to any size of field) by applying a certain adjustment to the regression coefficient b', so as to give a modified coefficient b applicable to an “infinite” field.

From this generalized relationship there has been deduced an expression ((4), p. 16) to indicate average relative efficiencies to be expected for randomized block experiments with varying numbers of plots per block in a field for which the coefficient b is known.

A formulae (5), which may be used to estimate the most efficient size of plot for any given experiment, has also been deduced. The cost of using plots of other than the most efficient size is indicated graphically in Fig. 7.
Changes in the composition of guano during storage
Authors: Copeman P. R. v. d. R. , Dillman F. J.
Published: March 2009

The term “guano” is applied almost wholly to the excrement of sea-birds and, since it contains a high proportion of nitrogen and phosphorus, guano forms a very valuable fertilizing material. The Union of South Africa has a large number of small islands scattered round the coast which are used as breeding grounds by various sea-birds. The deposits of guano from different islands vary considerably and are therefore systematically mixed to obtain an approximately uniform grade of material. The average analytical results for the years 1921–8 were: 10·0 per cent nitrogen, 11·2 per cent phosphoric oxide, 2·0 per cent potash.
Sheep nutrition: II. Determinations of the amounts of grass consumed by sheep on pasturage of varying quality
Authors: Woodman H. E. , Evans R. E. , Eden A.
Published: March 2009

A technique for measuring the appetites of sheep on pasture is described.

Results are given to show that sheep consume a bigger ration, in terms of lb. dry matter, when on pasture than when subsisting out-of-doors on the winter type of diet composed of hay, swedes (or kale) and concentrates. This difference was noted even on grass that had deteriorated in quality, in one case as a result of hot, dry weather in early summer, and in a second case as a consequence of cold, dry weather in spring. With young, leafy pasturage at its best, however, the distinction is most marked.

In the March of 1934, to quote but one example, four pure-bred Suffolk wethers, of live-weight varying from 120 to 181 lb., were shown to consume, on a diet of concentrates (350 g. daily), swedes (ad lib.) and chaffed hay (ad lib.), only 80–88 per cent of the amounts of dry matter predicted on the basis of Wood's feeding standards. During the following May, when grazing leafy pasturage of very good quality (digestion coefficient of organic matter = 81·l per cent), the appetites of the same sheep (range of live-weight now from 137 to 201 lb.) were found to have undergone a striking stimulation, the mean daily consumption of dry matter now being from 104 to 117 per cent of the amounts predicted from the standards. This implied that the sheep were consuming 1·13, 1·37, 1·13 and T53 lb. respectively more dry matter per day than they would have eaten had the diet consisted of hay, concentrates and swedes. The increased appetite is to be attributed to the superior palatability of the young grass.
Population studies with wheat: I. Sampling
Authors: Hudson H. G.
Published: March 2009

The design and field technique of two large scale experiments, laid down to investigate the problems of sampling and “propinquity”, are described in detail. These experiments were designed so that the plant number, stem number, ear number, straw weight and grain weight for 7200 lengths of 6 in. of drill row, together with the position of each observation, might be obtained.

The lowest sampling error, expressed as a percentage of the mean, is obtained by using the smallest sampling unit, but the large number of sampling units of this size that would have to be taken make it impracticable. The optimum sampling unit consists of 6 ft. of drill row, taken as 3 ft. of two adjacent rows. The size of the sampling unit is of greater importance than the shape in determining its accuracy, and little s lost by using sampling units of 18 in. of five adjacent rows.

The nature of the observation affects the degree of sampling. In the experiments examined the plant number, stem number and ear number require very similar sampling, but grain weight requires a sample which is about twice as large as that required by the other observations.

The percentage of the plot that must be taken as a sample (the sampling percentage) to obtain any given accuracy is related to the size of plot: the larger the plot, the lower the sampling percentage necessary. To obtain an error of 5% of the mean the sampling percentage for grain weight is approximately 5% in 1/20 acre plots, 15% in 1/100 acre plots and 43% in 1/600 acre plots if the plots are not subdivided. These percentages are similar to those calculated from various randomized block experiments in Cambridge.
Studies in the nutrition of vegetables: Phosphate deficiency and yield tests on sand cultures of May King lettuce
Authors: Woodman R. M.
Published: March 2009

Media from which phosphate was absent finally caused bronzing of the leaves of the resulting stunted plants of May King lettuce grown in sand culture, and red or crimson stalks. Phosphate alone produced characteristic purple (and/or bronze) and apple-green, flat, stunted rosettes with broad, non-crinkly leaves, and red stalks. Water alone caused stunted, straggly, purple plants, with relatively long, crimson stalks.

Where some phosphate was supplied in addition to the other essential elements, a plant of normal colour resulted at first. Later, purple blotches appeared on the plants receiving inadequate supplies; the intensity of this purple became greater as the amount of phosphate in the medium diminished, and it could be controlled by varying the concentration of phosphate in the medium or the frequency of application. Another deficiency symptom was the tougher leaf resulting from a lack of phosphate. A sufficiency of phosphate caused earlier maturity.

The media which contained the two greatest concentrations of phosphate were the best of those used because they gave the best growth, lettuces of the best colour without purple blotches, earlier maturity, and tenderer leaves.

The final yields of heads were statistically the same with the two heaviest phosphate treatments, and both were greater by about 40% of the lesser yields than the two statistically equal yields with the lower amounts of phosphate. All the phosphate treatments gave yields superior by about 40,000–60,000% to the non-phosphate and phosphatealone yields, but this second difference had no commercial significance. Similar results were obtained for the roots, and for the dry weights of the tops and roots.
Factors influencing the percentage of nitrogen in the barley grain of Hoosfield
Authors: Yates F. , Watson D. J.
Published: March 2009

The effect of rainfall, sowing date and yield on the percentage of nitrogen in the barley grain of certain representative plots on Hoosfield is studied.

All these factors are shown to have marked effects. The farmyard manure plot differs from the others, both in mean percentage and in the effects of rainfall and yield.

Changes in variety appear to have had little apparent influence, but there is a progressive decrease in the percentage of nitrogen which cannot be accounted for by changes in any of the above factors, and which may well be due to varietal improvement

Comparison is made with the results of the similar study on the permanent barley plots at Woburn.
The identification of minerals in soil colloids
Authors: Nagelschmidt G.
Published: March 2009

X-ray, optical, dehydration and chemical methods in use for the identification of minerals in soil colloids are discussed with special regard to their limitations. These are mainly due to uncertainties about the variation of physical properties of standard minerals with decreasing grain size and the possible existence and importance of amorphous material. The aggregate method in X-ray analysis, which is specially important for soil colloids, is described. Various techniques for dehydration and optical analysis are discussed, and it is concluded that they are useful only when used in combination with X-ray data. The advantages of combining various chemical methods with X-ray analysis are pointed out.

Standard data are given for a number of minerals, and the evidence for their occurrence in soil colloids is reviewed. These minerals are quartz, cristobalite, oxides and hydroxides of iron and aluminium, minerals of the kaolinite, montmorillonite and mica groups.
The use of carcass measurements to predict the yield of ‘high-priced cuts’ in carcass of Holstein calves
Authors: Butterworth M. H. , Diaz J. A. , Hoystad E.
Published: March 2009

Measurements were made on 104 carcasses of Holstein or Holstein cross-bred calves in a commercial slaughterhouse and retail butchers in Monterrey, NL. Measurements were: chilled carcass weight, circumference of side, maximum depth of forequarter (three measurements), length of leg, length of side, and length of forearm. Carcasses were cut and the sum of the weights of round, rump, short loin and rib (all bone in) defined as ‘high-priced cuts’. Multiple regressions were computed for linear, semi-allometric and allometric equations using a CDC 3300 computer.

The linear form of the equation accounted for more of the total variance than either the semi-allometric or allometric forms. In all equations cold carcass weight accounted for the greater part of total variance (98·9, 97·1 and 98·2% respectively for the three equations in the order as mentioned above). The incorporation of circumference of side slightly improved the goodness of fit in all cases as did the inclusion of length of side and length of leg in the semi-allometric form. The particularly high proportion of the total variation attributable to cold carcass weight in the present study was probably due to the sparse fat cover of the calves.
Factors modifying egg production with special reference to seasonal changes
Authors: Whetham Elizabeth O.
Published: March 2009

1. Sexual periodicity in many animals is largely conditioned by variations in the daily light period. That egg production in hens may be controlled by the use of artificial lights has long been known.

2. The action of light is probably connected with the activity of the anterior lobe of the pituitary.

3. The natural variation in daily light period at different latitudes has been used to study the effect of light on egg production throughout the world. Curves have been constructed of egg production grouped in 5° of latitude and the correlation with the hours of daylight at those latitudes studied.
Investigations into the Intensive System of Grassland Management. By the Agricultural Research Staff of Imperial Chemical Industries, Limited. VIII. The Comparative Digestibility and Feeding Value of Fresh and Artificially Dried Grass
Authors: Watson S. J. , Ferguson W. S.
Published: March 2009

Two series of trials have been carried out to compare the digestibility of fresh grass with the material obtained by drying grass, from the same source and cut at the same time, in a band drier by heated air at an inlet temperature of 200° C.

This process has not affected the digestibility of the various constituents with the possible exception of the crude protein which is slightly depressed.

In the second series of trials a drier operating with air at an inlet temperature of 600° C. was also used. In this drier a depression of the digestibility of the constituents of the grass was noted. This was particularly so in the case of the protein which was depressed to a very marked degree.

It would therefore appear that although the use of the higher temperature increases the output of the drier, it adversely affects the digestibility of the final product.
Nitrogen requirements of sugar beet in relation to harvesting date
Authors: Holmes M. R. J. , Devine J. R. , Dunnett F. W.
Published: March 2009

Seven field experiments were made on the effect of two harvesting dates on the nitrogen requirements of sugar beet. All were on Rauceby series soils overlying oolitic limestone in Lincolnshire.

Nitrogen fertilizer increased sugar yield in all experiments, and yield was considerably higher at the mid-December harvest than in early October. On average, the sugar-yield response to nitrogen was greater at the late harvest, and the requirement for nitrogen was about 45 kg/ha higher then than at the early harvest. Sugar content was depressed less at the late harvest than at the early by increasing nitrogen rate.

These results suggest that farmers should apply more nitrogen to fields that they plan to harvest late than to early-harvested fields; they also have implications for the conduct and interpretation of nitrogen response experiments on sugar beet.
Spring top-dressings of ‘Nitro-Chalk’ and late sprays of a liquid N-fertilizer and a broad spectrum fungicide for consecutive crops of winter wheat at Saxmundham, Suffolk
Authors: Penny A. , Widdowson F. V. , Jenkyn J. F.
Published: March 2009

An experiment at Saxmundham, Suffolk, during 1974–6, tested late sprays of a liquid N-fertilizer (ammonium nitrate/urea) supplying 50 kg N/ha, and a broad spectrum fungicide (benomyl and maneb with mancozeb) on winter wheat given, 0, 50, 100 or 150 kg N/ha as ‘Nitro-Chalk’ (ammonium nitrate/calcium carbonate) in spring

Mildew (Erysiphe graminisf. sp. tritici) was most severe in 1974. It was increased by N and decreased by the fungicide in both 1974 and 1975, but was negligible in 1976. Septoria (S. nodorum) was very slight in 1974 and none was observed in 1976. It was much more severe in 1975, but was unaffected by the fungicide perhaps because this was applied too late.

Yield and N content, number of ears and leaf area index were determined during summer on samples taken from all plots given 100 or 150 kg N/ha in spring; each was larger with 150 than with 100 kg N/ha. The effects of the liquid N-fertilizer on yield and N content varied, but leaf area index was consistently increased. None was affected consistently by the fungicide.

Yields, percentages of N in, and amounts of N removed by grain and straw were greatly and consistently increased by each increment of ‘Nitro-Chalk’. Yields of grain were increased (average, 9%) by the liquid fertilizer in 1974 and 1975, and most where most ‘Nitro-Chalk’ had been given, but not in 1976 when the wheat ripened in July; however, both the percentage of N in and the amount of N removed by the grain were increased by the liquid fertilizer each year. The fungicide increased the response to the liquid N-fertilizer in 1974, but not in 1975 when Septoria was not controlled, nor in 1976 when leaf diseases were virtually absent.

The weight of 1000 grains was increased by each increment of ‘Nitro-Chalk’ in 1975 but only by the first one (50 kg N/ha) in 1974 and 1976; it was very slightly increased by the liquid fertilizer and by fungicide each year.
A note on the construction of phase-confounded designs
Authors: El Z. A.
Published: March 2009

In experiments comparing the effects of different crop rotations it sometimes happens that blocks of reasonably small size can only be achieved by not letting all sequences of each rotation occur in each block. If one of the rotations carries the test crop more than once such a restriction usually leads to the confounding of some phase contrasts. Stevens (1956) and Patterson (1964) provided two classes of phase-confounded designs. The two designs, however, lack the desirable property that if, in a particular block, some of the rotations carry the test crop in a given year, other rotations also do. Furthermore, the designs do not involve equal block sizes in the sense that, in any year, in any block, the number of plots carrying the test crop is the same.
Seasonal variation in the potential herbage production and response to nitrogen by kikuyu grass (Pennisetum clandestinum)
Authors: Colman R. L. , O'Neill G. H.
Published: March 2009

The herbage production and response to nitrogen fertilizer by kikuyu grass were measured in a field experiment conducted over a 12-month period. The experiment was designed to measure the growth of kikuyu grass at different rates of application of nitrogen fertilizer but without limitation due to mineral nutrient supply other than nitrogen, soil pH effects of nitrogen fertilizer, defoliation and pests and diseases.

Growth rate and response to nitrogen were closely related to mean temperature and moisture supply. Relations were established between growth rate, nitrogen response and apparent nitrogen recovery and the climatic variables, mean temperature and mean available soil moisture in 14-day periods. With nitrogen applications of 224 kg N/ha the predicted growth rate at 13 and 23 °C mean temperature were 38 and 196 kg D.M./ha/day, respectively; with 112 kg N/ha growth rate at the higher temperature was 106 kg D.M./ha/day. Growth and response to nitrogen ceased at mean temperatures around 10 °C.

Apparent recovery of nitrogen in harvested herbage over a 16-week growth period after nitrogen application was 51%; recovery in the first 4 weeks of growth varied from 1 to 56 % depending on temperature and moisture supply.

Relations between growth rate and mean temperature were used to predict the seasonal growth pattern for a range of environments in which yield data for the species are available. The results indicate the potential for high annual dry-matter production from kikuyu grass when adequately supplied with nitrogen and moisture is nonlimiting. The grass is also adapted for growth and survival in areas ranging from moist sub-tropical to cool-temperate.
The relationship between productivity and some components of canopy structure in ryegrass (Lolium spp.)
Authors: Rhodes I.
Published: March 2009

Experiments were carried out to measure the components of canopy structure (on young spaced seedlings), their heritabilities and relationship to sward yield in the F1 generation of a diallel cross between six ryegrass populations.

Considerable differences existed between parent populations in both leaf length and tiller angle, but little difference existed in leaf angle. All the components of canopy structure were highly heritable, tiller angle, leaf length and leaf rigidity showing narrow sense heritabilities greater than 0·75.

There were large differences in yield between F1 families, moreover, when (a) Lolium perenne families, (6) L. multiflorum families and (c) L. perenne x L. mvltiflorum families were considered separately, leaf length and a composite character derived from leaf length and tiller angle (all measured on young spaced seedlings) were closely related to yield under sward conditions.

The plant breeding implications of these results are discussed.
Observations on mammary development in calves and lambs
Authors: Wallace C.
Published: March 2009

The normal course of mammary development has been briefly described, in sheep from 2 months of foetal age to 4 months after birth; and in dairy cattle from the 3-month foetus to calves 6 months old. Observations were also made on a series of udders from ewes during their first pregnancy. A small group of beef calves and a number of freemartins of various ages were also examined.

Development was found to be closely similar in the two species, and in both, sex differences were marked.

Experimentally it was found that in males of either species castration at birth had little effect on mammary growth, while prolonged treatment with oestrogen gave rise to enlarged teats, dilated cisterns and ducts, and to a certain amount of secretion. Little gland tissue was formed in oestrogen-treated males, and there was no increase in the spreading of mammary tissue from the neighbourhood of the teat.

Females of the two species showed a striking difference in their response to experimental treatment. In sheep, removal of the ovaries at birth had no apparent effect on mammary development up to 4 months, while treatment with oestrogen stimulated gland formation in both spayed and intact lambs and also restricted the normal spread of mammary tissue into the udder. In cattle, on the other hand, heifers spayed at birth showed almost complete cessation of mammary development, while implants of oestrogen, in addition to inducing gland formation, promoted the spreading of tissue into the udder pad of the spayed animal.

Udder development of freemartins appeared to be similar to that of normal heifers from 5 months foetal age to about a month after birth, but thereafter was more like that of a spayed animal. Removal of the abnormal gonads shortly after birth had no effect, while oestrogen treatment induced development of teats, ducts and glands exactly as in a normal heifer.

Comparing small numbers of calves of the two types, it was found that heifers of the beef breed in general showed slightly poorer mammary development than dairy heifers that had been treated in the same way, with more connective tissue and numerous leucocytes in the mammary zone.
Some chemical changes in the nitrogenous constituents of urine when voided on pasture
Authors: Doak B. W.
Published: March 2009

1. The chemical changes which take place in a urine patch have been studied using urine from wethers and to a small extent from cows.

2. The sizes of individual urine patches vary considerably, depending mainly on the volume of the urination. The average from wethers is about 45 sq.in.

3. The volume of urine per wether per day averages 2880 ml. with a nitrogen content of 0·92%, of which about 75% was in the form of urea; 4·1% as allantoin; 2·6% as hippuric acid; 1·5% as creatine-creatinine; and 12·4% as amino-nitrogen.

4. Improved herbage growth results in twice the area actually wetted with urine. The total area affected averaged 100 sq.in.

5. The probable area wetted with urine from cow urinations was about 650 sq.in. with a further 200 sq.in. affected indirectly.

6. With wethers the average rate of nitrogen application on a urine patch amounts to 432 lb. of nitrogen per acre.

7. The rate of hydrolysis of urea in laboratory experiments is affected by temperature and is increased by small amounts of hippuric acid but not by the other urinary constituents tried. The hydrolysis rate is greater at soil moisture content of 24% than at higher moisture levels.

8. Urea hydrolysis in soil (both in laboratory and in the field) is accompanied by pronounced increase in pH (up to pH 9·2 with urea equivalent to that applied to a urine patch).

9. The rate of nitrification is greatly affected by the pH changes. At pH values in excess of 8 nitrites accumulate and nitrate formation is retarded.

10. Heteroauxin and allantoin were both found to stimulate nitrification in laboratory experiments when used at levels found in urine. Other urinary constituents were without effect.

11. The hold up of urine on leaf surfaces of pastures was shown to amount to as much as 12·5% of the green weight of herbage.

12. Ammonia in considerable amounts may be lost to the air both from herbage and from soil.

13. Field experiments are in complete agreement with laboratory experiments and no essential difference of wether and cow urine was noticed.

14. The fate of the nitrogenous constituents is briefly considered and shown schematically.
The effect of treatment by prostaglandin analogue (ICI–80, 996) or progestagen (SC-9880) on ovulation and fertilization in cyclic ewes
Authors: Boland M. P. , Gordon I. , Kelleher D. L.
Published: March 2009

Mature cyclic ewes were treated intravaginally with sponges impregnated with 30 mg SC-9880 (G. D. Searle) or intramuscularly with 100 μg Cloprostenol (I.C.I. 80, 996) and examined subsequently for oestrus, ovulation and fertilization. At 70 h after the end of treatment, 90% of ewes treated with SC-9880 and 45% of those treated with Cloprostenol had ovulated. Of ewes yielding eggs at 100 h a significantly higher proportion of SC-9880 treated sheep showed evidence of fertilization (69% v. 7%).