bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies in the Inheritance of Disease Resistance. II
Authors: Biffen R. H.
Published: March 2009

The F2 generation of crosses between a number of varieties of wheat susceptible to the attacks of Yellow Rust (Puccinia glumarum) and “American Club.” which shows an extraordinary degree of resistance to the attacks of this parasite showed in the year 1906 obvious segregation into immune and susceptible forms. The immunity was further found to be independent of any recognizable morphological feature. An analysis of these F2 generations demonstrated the fact that the immune plants were present to the extent of 25 per cent., that is that the property of resisting the attacks of Yellow Rust behaves as a recessive character to the property of being susceptible. The plants which proved susceptible showed, however, very varied degrees of susceptibility. Many were as covered with rust pustules as Michigan Bronze, one of the extremely susceptible varieties used as a parent. Others on the other hand were relatively slightly attacked and between these extremes all degrees of susceptibility appeared to exist. Nilsson-Ehle who has also observed the segregation of this pair of characteristics has also noted the wide differences in susceptibility in plants of the F2 and succeeding generations.
Oxidation of Arsenites to Arsenates in Cattle-Dipping Tanks
Authors: Cooper W. F. , Freak G. A.
Published: March 2009

The gradual loss of efficiency of certain alkaline arsenite dipping baths has been traced by Brünnich to the oxidation of the arsenite to arsenate (Australian Association for the Advancement of Science, 1909). In this latter form, arsenic is not nearly so efficacious for the eradication of ticks, as in the reduced condition.
Studies on the Lime Requirements of Certain Soils
Authors: Hutchinson Henry Beougham , MacLennan Kenneth
Published: March 2009

The experimental results described in the two parts of the paper may be summarised thus:

Part I. Lime Requirements for Sterilisation Purposes.

(1) The capacity to produce partial sterilisation effects is a property belonging to calcium oxide (caustic lime), but not to calcium carbonate (chalk, limestone, marl, etc.).

(2) The amount of lime necessary to produce specific effects in different soils has been found to vary greatly and it is not possible to make any general recommendations.
Note on the Effect of Changes in the Viscosity of Water on the Results of Mechanical Analyses conducted at Varying Temperatures
Authors: Robinson G. W.
Published: March 2009

Some discordant results obtained in mechanical analysis during a spell of cold weather led the writer to enquire into the effect of temperature on the separation of the various fractions of a soil by mechanical analysis.
The Influence on Crop and Soil of Manures applied to Permanent Meadow
Authors: Crowther Charles , Ruston Arthur G.
Published: March 2009

The experiments reviewed in the preceding pages have been carried out on a light loam soil very poor in lime, in a district of medium rainfall (20–25 inches).

The chief conclusions drawn from the results are as follows:

1. Although the heaviest crops have been obtained with an annual application of dung, they are little heavier, and more costly to obtain, than the crops obtained with a biennial application of dung, especially if in the alternate year a light dressing of “artificials” including nitrate of soda be given.

2. A complete mixture of “artificials,” including nitrate of soda, has given good average crops, but not equal to those given by a biennial application of dung.

3. For the soil and other conditions of Garforth nitrate of soda is distinctly better for the hay crop than sulphate of ammonia. This is doubtless largely associated with the poverty of the soil in calcium carbonate.
The solubility of calcium phosphates in citric acid
Authors: Ramsay A. A.
Published: March 2009

The results of these investigations show

1. The substances sold as “Phosphate of lime” and “Calcium Phosphas B.P.” are not pure tricalcic phosphate but are mixtures of di- and tricalcic phosphates.

2. Sodium phosphate (Na2HPO4) added to ammoniacal calcium chloride and the resulting precipitate washed with water yields a mixture of di- and tricalcic phosphate and calcium hydrate.

3. Bone ash dissolved in hydrochloric acid and precipitated with ammonia, the precipitate being well washed, yields also a mixture of di- and tricalcium phosphate and calcium hydrate.

4. When three equivalents of lime (3CaO) are made to act on one equivalent of phosphoric acid (P2O5) and the resulting precipitate removed with little delay pure tricalcium phosphate is obtained.
The influence of soil conditions on the decomposition of organic matter in the soil
Authors: Russell E. J. , Appleyard A.
Published: March 2009

The biochemical decomposition of plant residues and other organic matter in the soil is of fundamental importance for soil fertility. It causes the breaking down of coarse plant fragments which otherwise might open up the soil too much: it leads to the production of colloidal complexes known as humus which exert many beneficial effects both chemical and physical, and it brings about the formation of nitrates, the most important of the nitrogenous plant nutrients.
Critical note on the method of correcting protein digestion coefficients
Authors: Woodman Herbert Ernest
Published: March 2009

The object of this note is to call into question the soundness of the generally accepted method by which the so-called apparent protein digestion coefficients of foodstuffs are corrected.

The digestion coefficient for the protein of a foodstuff as ordinarily determined by animal experiment does not afford a strictly accurate idea of the actual digestibility of that constituent. The figure represents a minimum value, and this arises from the well-known fact that the faeces do not consist solely of undigested food residues, but are to an appreciable extent contaminated by nitrogenous products which have been secreted into the alimentary tract and have escaped reabsorption. The nature of this so-termed metabolic material is twofold, being partly protein (mucus, epithelium, etc.) and partly non-protein (residues of digestive secretions, etc.). Before proceeding to a critical survey of the correction method, which is designed ostensibly to enable allowance to be made for the presence of such products in the faeces, it is of essential interest to consider briefly the true significance of the term “protein digestibility.”
The Influence of size and character of seed on the yield of potatoes
Authors: Salaman Redcliffe N.
Published: March 2009

The results of a preliminary investigation on this subject, in which single plots were used, which were published in 1921, tended to show that the following inferences, in respect to the relation of size and type of tuber-set to crop, might be drawn.

1. The size of the crop varied directly with the weight of the set up to a certain point, viz. 2 ozs., the crop then sinking slightly to a more or less constant level, whilst the weight of the set increased.
The water content of the seeds of peas, soya beans, linseed, grass, onion and carrot as a function of temperature and humidity of the atmosphere
Authors: Gane R.
Published: March 2009

Moisture content and temperature are of first importance in the storage of seeds. Seeds are usually stored in porous containers like sacks and paper bags, and their water content fluctuates with the humidity of the surrounding atmosphere. In sealed chambers, on the other hand, the humidity of the atmosphere will be determined by the water content of the seeds and, with different kinds of seeds in an enclosed space, an exchange of water will occur until equilibrium has been reached. This does not mean, however, that different kinds of seeds, or even different samples of the same kind will have exactly the same final water content, since the water content/humidity relations are affected by differences in structure, chemical composition and previous drying treatment; it is permissible, however, for practical purposes, to ignore the slight differences which occur between samples of the same kind of seed.
The fungicidal properties of certain spray-fluids. III
Authors: Horton E. , Salmon E. S.
Published: March 2009

The following solutions were tested with respect to their fungicidal properties towards the “powdery,” conidial stage of S. Humuli on young hop-leaves in the greenhouse:

(1) Disodium arsenate, containing 0·096 per cent. As2O5 proved fungicidal and killed also patches of leaf-cells underlying the mildewpatches, but did not otherwise injure the leaf. A solution containing 0·02 per cent. As2O5 was fungicidal without killing any leaf-cells.

(2) Trisodium arsenate containing 0·077 per cent. As2O5 proved fungicidal.

(3) Dicalcium arsenate. containing 0·048 per cent. As2O5 proved fungicidal; containing 0·024 per cent. As2O5 the solution was apparently just fungicidal, but with 0·01 per cent. As2O5 the solution was practically non-fungicidal.

(4) Tricalcium arsenate containing 0·076 per cent. As2O5 is fungicidal; containing 0·02 per cent. As2O5 it possesses some fungicidal value, but with 0·01 per cent. As2O5 it is practically non-fungicidal.

(5) The following constituents of lime-sulphur wash proved nonfungicidal: calcium sulphate, sulphite, thiosulphate, hydroxyhydrosulphide.

(6) Calcium polysulphide, at a strength of 0·11 per cent., proved fungicidal.
Investigations on yield in the cereals: II. A spacing experiment with wheat
Authors: Engledow F. L.
Published: March 2009

The agricultural conception, yield, piquantly clear to farmers, has evaded statistical analysis and confounded plant physiology. It may be defined for cereals as the average weight of grain produced per unit area. Grain is an end-product of the operation throughout the plant's life, of all its vital processes. Yield therefore, in some complex way, must reflect the working of these processes. An analysis of yield would simplify the testing of new plant forms and regularise the selection of parents in hybridising. Fundamentally this analysis should comprise the identification of the vital processes of the plant, the effects upon them of environmental factors, and their relationship to grain production. At present even to speculate upon the making of such an analysis would be mere pedantry. Nothing but an algebraic analysis is practicable.
A new method of testing cheeses
Authors: Geake Arthur
Published: March 2009

It has been shown that an important part of the ripening process of cheeses consists in the proteolysis of the cheese proteins, and it therefore seemed probable that by the estimation of the extent of this proteolysis a knowledge of the degree of ripeness of a cheese might be obtained. Although the ripeness of a cheese is a very important factor commercially, at present purely empirical methods of judgment are in use.
The digestibility of straw after treatment with soda
Authors: Godden William
Published: March 2009

The use of straw as fodder is beset by the double difficulty that on the one hand its bulky character seriously limits the extent to which it can be consumed by the animal, whilst on the other hand its tough and fibrous nature entails such a heavy expenditure of energy to secure the high degree of comminution and further preparation essential for effective action of the digestive agents that only a comparatively small surplus of energy remains over to serve productive nutritional ends. Thus it was found by Kellner and Köhler in the case of oat straw that of the total energy contained in the straw only 35·8 per cent, was usefully digested, whilst only 12·9 per cent, could be applied after digestion to productive purposes. For wheat straw the corresponding proportions were 31·1 per cent, and 5·5 per cent, respectively. These may be contrasted with the proportions of 49 per cent, and 20·7 per cent, respectively found by the same observers for meadow hay; and the proportions of 74·9 per cent, and 45·9 per cent, respectively found by Armsby and Fries for maize meal.
The feeding of raw and cooked potatoes and sugar beet to laying pullets
Authors: Temperton H. , Dudley F. J.
Published: March 2009

An account is given of experimental work on the feeding of uncooked and cooked potatoes and sugar beet to laying stock. The available literature on the use of these foods for poultry is reviewed and an explanation is offered for the poor results which have generally followed the use of raw potatoes.

A description is given of an experiment in which there were two control groups fed on mash, two groups on 3 oz. mash and 8 oz. potatoes daily, uncooked for one group and steamed for the other, and two groups on 3 oz. mash and 8 oz. sugar beet daily, uncooked in one case and steamed in the other.
Plant growth with nutrient solutions. IV. The influence of culture solutions of varying phosphate content on the growth of the turnip in fen and gravel soil.
Authors: Woodman Rowland Marcus , Johnson Delphine Ainslie
Published: March 2009

Statistical experiments were made to ascertain the effect of variations in applied soluble phosphate on the growth of Milan Strap-leaved Purple Top Turnips in a light gravel soil already containing sufficient available phosphate, and in a fen soil possessing an inadequate supply of available phosphate, as aggregates for growth.

No adverse effect on yield, calculated as fresh or dry matter of tops, roots, or whole plants, was suffered in either soil at any of the stages of growth considered at the highest concentrations of soluble phosphate, unlike the behaviour of this turnip when grown in a pure sand containing no clays or humates, where there was a narrow optimum range of phosphorus at a low concentration. The gravel soil occupied an intermediate position, however, between sand with its low optimum range of soluble phosphorus, and fen soil, where positive response to increasing concentrations of soluble phosphorus approached the ‘normal’, and thus there was a range of phosphorus at low concentration tending to a maximum yield followed generally by a greater numerical yield at the highest concentrations of phosphorus.

At the seedling stage in gravel soil variation in applied phosphate had absolutely no statistical effect on yield, moisture content of tops, roots and whole plants, and the ratios, for fresh or dry matter, Top/Root, Root/(Whole plant) and (Whole plant)/ Top.
The effect of time of application of inorganic nitrogen on the turnip
Authors: Woodman R. M. , Paver H.
Published: March 2009

An investigation has been made into the effect of time of application of nitrogen as sodium nitrate to the turnip. Experiments were arranged on a statistical basis, and were carried out in sand culture. The life of the turnip up to harvest was arbitrarily divided into three equal light periods, and the fourteen possible combinations of high and low nitrogen applied in these periods constituted the treatments. The absolute amount of growth was largely determined by the level of nitrogen, but the relative proportion of growth was independent of this level. Tops developed earlier than roots, and the effect of difference in nitrogen level was more marked with the roots than the tops. For a high yield of roots it seems desirable to apply nitrogen, early, but for a high yield of tops it would be preferable to apply the nitrogen as post-seedling dressings. The chief effect of level of nitrogen on moisture content was confined to the period in which the harvest took place. A comparison of top/ root ratios also showed that high nitrogen in the early stages of growth stimulated root development.

We thank Mr J. F. N. Leonard for his help during this experiment.
Studies on the fats of the bacon pig with reference to carcass quality. The effect of diet on the component fatty acids of the back fat
Authors: Shorland F. B. , De La Mare P. B. D.
Published: March 2009

The fatty acid composition of the back fats of pigs whose basic diets were buttermilk or skim milk have been determined by ester-fractionation, and the results are compared with those of previous workers. Pigs whose diets were supplemented with copra contained up to 13 mol. % of myristic acid, with smaller amounts of lauric acid.

Experimental evidence supports the view that dietary linoleic acid is assimilated to a greater extent by slow-growing than by fast-growing pigs. Dietary lauric and myristic acids, however, appear in greater proportions in the depots of fast-growing, as compared with slow-growing pigs.

The di-, and polyethenoid C18acids of the fat of unsupplemented milk-fed pigs appeared not to contain appreciable amounts of linoleic acid.
Seed disinfection. VIII. Radishes
Authors: Taylor R. Eric , Cronshey J. F. H. , Weston W. A. R. Dillon
Published: March 2009

1. The seeding rate of radish seed may be influenced by the mechanical effect of the material with which it is treated.

2. The seedling emergence of radishes may be improved by treating the seed with an organomercury seed disinfectant.

3. The beneficial effect is correlated with adverse weather conditions at the time of germination, and advantages are therefore usually confined to early sowings.
The Effects of Varied Dressings of Ground Limestone in the Field.
Authors: Nicholson H. H.
Published: March 2009

1. These field experiments show that equilibrium after applications of lime may be attained on arable land between one and two years later.

2. The quantitative correcting effects of a given dressing seem to be about equal on different soils.

3. Added calcium carbonate is quickly converted into exchangeable calcium base to an extent which depends on the individual soil.
A simple method for the determination of the pH values of turbid soil and other solutions
Authors: Gadd C. H.
Published: March 2009

In the course of investigations into the cause of an obscure pathological condition of the tea bush, it became necessary to make pH determinations of certain soils. Electrometric apparatus and a suitable centrifuge for clearing the solutions were not available. Considerable difficulty was experienced in making the determinations with accuracy by indicator methods owing to two causes. First, the turbidity of the soil solutions made comparison with standard buffer solutions somewhat difficult; secondly, the colours developed in the soil and buffer solutions with some indicators were different in hue, as distinct from shade or tint. This rendered exact matching quite impossible. The latter difficulties also arose when the drop ratio method was used instead of standard buffer solutions. The errors resulting from these causes were believed to be unduly large, and it was felt that greater accuracy would be attained if these difficulties could be overcome.
Yield and plant population in sugar beet
Authors: Engledow F. L. , Maher C. A. , Smith J. Hunter , Williams H. Rhys , Fail H. , Rayns F.
Published: March 2009

Three years of subsidised sugar-beet growing in England has made clear the chief agricultural features of the crop. Many of our soils suit it well; the climate is favourable; it fits satisfactorily into some of our typical rotations. With the 1928 crop will come into operation the first of the subsidy reductions. The consequential change in standard price per ton of beet—46s. instead of 54s. as in 1925–7—has aroused anxious interest in the likelihood that the crop will outlive the subsidy. What price the factories will be able to offer on termination of the subsidy is not yet known. It will, of course, be decided by world-prices of sugar. Values between 30s. and 35s. per ton have been tentatively suggested. It has been claimed, further, that any price which covers cost of production will make the crop an asset to English agriculture because of the benefit to following crops. Whatever the strength of this claim farmers are and will continue to be anxiously concerned about net monetary return per acre. Now this return is governed by three factors—cost of growing, yield per acre, and price per ton. Costs of growing are not likely to alter substantially. Price per ton is considerably influenced by sugar content. The factories have devoted much effort to routine sampling and testing of deliveries but have not convinced farmers that their ascertainments are reliable. It may well be doubted whether any workable factory testing can be devised to ensure accuracy to 1 per cent, of sugar content.
‘Single value’ soil properties: a study of the significance of certain soil constants: II. Studies on Natal soils
Authors: Coutts J. R. H.
Published: March 2009

In the first paper of this series (10)1, Keen and the present writer discussed work by earlier authors on the approximate specification of the nature of a soil by a single soil constant, in place of a detailed analysis, and described experimental work designed to show the significance of a number of simple physical measurements. The chief objects of the present paper are to describe the results obtained with such measurements as applied to a number of Natal soils, and to discuss the value of some other easily obtained physical data as a means of specifying the nature of a soil. Work of this type was discussed at the International Congress of Soil Science at Washington in 1927, and it was resolved that co-operative work on an international basis should be undertaken.
Plant growth with nutrient solutions: III. A comparison of sand and soil as the aggregate for plant growth, using an optimum nutrient solution with the sand, and incomplete supplies of nutrients with ‘once-used‘ soil
Authors: Woodman Rowland Marcus , Johnson Delphine Ainslie
Published: March 2009

Experiments are described in which the ‘once-used’ soils left over from previous culture experiments were employed as aggregates in the growth of vegetables. It was demonstrated that sand with full nutrients was superior to ‘once-used’ soil with water only, but that ‘once-used’ soil supplied with the full quota of soluble nitrogen was superior to the sand with full nutrients. The root of the cabbage in sand was an exception, and a possible explanation was that sand as aggregate favoured true root formation, while soil favoured the formation of tops. The ‘once-used’ soil in these experiments deteriorated in physical propertes owing to the conditions of the experiment, which included the use of nitrogen as sodium nitrate, possibly owing to the tendency to the formation of sodium clay; it is argued that a judicious choice of fertilizers and/or the use of flocculating electrolytes should overcome such tendencies.
The analysis of tomato plants. Part I.
Authors: Owen O.
Published: March 2009

In an attempt to determine the rôle of phosphates in tomato culture tomato plants have been analysed for potash, phosphoric acid and nitrogen.

In unmanured plants the fruit is of inferior quality but the weight as picked is 2·6 times that of the foliage and stems of the same plants. In manured plants this ratio is 1·6. The relative efficiency of the plants under the two sets of conditions is discussed.

Manured plants have a higher ash content than unmanured plants.
Note on the effect of sodium silicate in increasing the yield of barley:To the Editors of the Journal of Agricultural Science
Authors: Hall A. D.
Published: March 2009

The last issue of this Journal (p. 132) contains a paper by Dr R. A. Fisher on the effect of Silica upon the growth of Barley at Rothamsted, which begins by stating that his data “show conclusively that the view previously rejected that the silicate acts by making available to the plant the actual reserves of soil phosphates must be regarded as strongly established.” Twice elsewhere Dr Fisher states that this erroneous conclusion of previous investigators is due to the fact that they had considered only the proportion of phosphoric acid in the ash and had overlooked the increase in the total phosphoric acid in the crop. As Mr Morison and I were the previous investigators in question I turned to our twenty-three-year-old paper with some curiosity to ascertain the grounds for this magisterial dismissal of our conclusions, for my remembrance of the subject did not tally with the opinion Dr Fisher attributes to us. Still less do I agree now that I have re-examined our original paper.
Quality of potatoes in relation to soil and season I. The content of dry matter
Authors: Wager H. G.
Published: March 2009

The dry-matter content of about 260 samples of potatoes was determined. The samples were collected over three seasons and from many types of soil.

The average dry-matter content of a variety varied from season to season, but it always bore an approximately constant relationship to the average value of other varieties.

Wet seasons led to potatoes low in dry matter.

The variation in the content of dry matter of potatoes in different seasons and from different soil types is not a direct effect of the water balance of the tubers.

The average content of dry matter of potatoes depends on the soil in which they were grown; fen and blackland gave potatoes with the lowest dry matter, followed by skirt, silt and warp, then loam and medium loam, then clay, and the highest dry matter occurred in stocks grown in sands, gravels or light loams.

The difference between the soils is discussed, and it is tentatively concluded that the factor responsible for the variation in content of dry matter of the potatoes is the available water content of the soils.
Nitrate leaching from sheep-grazed grass/clover and fertilized grass pastures
Authors: Cuttle S. P. , Hallard M. , Daniel G. , Scurlock R. V.
Published: March 2009

Nitrate leaching from sheep-grazed pastures was measured over three winters between 1987 and 1990 at a lowland site in Wales. Losses from replicated plots of ryegrass/white clover (Lolium perenne/Trifoliwn repens) pasture that received no N fertilizer and from pure ryegrass pasture receiving 150–200 kg fertilizer-N/ha per year were determined using suction cup samplers. In Year 1, the average clover content of the grass/clover swards (April-September) was equivalent to 35% of total dry matter but declined during the course of the experiment and was only 4% in Year 3. Concentrations of nitrate and quantities of N leached from separate sampling positions exhibited a wide range of values and conformed to a log-normal distribution. In the first two winters, mean nitrate concentrations in soil water and quantities leached from grass/clover plots were greater than those from fertilized grass plots. In Year 3 the loss from the N-fertilized plots was higher and exceeded that from the grass/clover treatment. Total quantities of N leached during the three winters ranged from 6 to 33 kg N/ha from grass/clover plots and from 2 to 24 kg N/ha from fertilized grass plots. At no time did mean nitrate concentrations from either treatment exceed 11 mg N/litre. These values probably underestimate the true loss as the distribution of the main sets of water samplers did not provide adequate coverage of those areas of the plots where sheep congregated and which received high returns of excreta. These positions were characterized by particularly high leaching losses. Differences between losses from the two treatments and between years could only be partly explained by the decline in clover content and differences in stocking rates.
The Formation, Evolution, Reclamation, and the Absorbed Bases of Alkali Soils
Authors: Kelley W. P.
Published: March 2009

1. The formation of alkali soils is primarily a question of soluble salt accumulation. Those processes which bring about the accumulation of soluble salts in soils also tend to cause the accumulation of CaCO3. Under certain conditions simple calcium silicates may also be precipitated in alkali soils. Hilgard's researches were concerned chiefly with the soluble salts. On the other hand, more recent investigators have emphasised the base-exchange aspects of the subject. Sodium salts tend to react with the clay and humus constituents of the soil, converting them into Na-absorption compounds. These components produce extremely adverse conditions in the soil.

2. Under certain conditions alkali soils tend to pass through four evolutionary stages, namely, salinisation, alkalinisation, desalinisation, and degradation. As to whether or not an alkali soil will pass beyond the salinisation stage, depends on the composition of the soluble salts that accumulate in it. Where sodium salts predominate, more or less alkalinisation of the exchange complex has taken place. However, this is not true where soluble calcium is relatively abundant.

3. Desalinisation (by leaching, whether natural or artificial) of alkalinised soil is usually accompanied by the formation of Na2CO3and by pronounced deflocculation. If CaCO3be present, the formation of Na2CO3is accompanied by the replacement of absorbed sodium by calcium. Under these conditions the degradation stage will not be attained. If CaCO3be absent, base-unsaturated constituents arise under leaching conditions, and more or less of the inorganic-exchange complex becomes decomposed into simple oxides.
Nutritive Value of Pasture. X. The Utilisation of Young Grass by Swine
Authors: Woodman H. E. , Norman D. B.
Published: March 2009

In this communication are brought forward the results of digestion trials designed to discover the degree to which pigs are able to digest and utilise young grass. Three digestion trials have been carried out. In the first trial, the digestibility of a basal ration composed of equal parts of maize meal and coarse middlings was determined. In the following two periods, the amount of basal food was cut down to an appropriate level and definite weights of the grass to be tested were added. In period 2, very short, leafy grass, containing, on the basis of dry matter, 26·04 per cent, of crude protein and 16·73 per cent. of crude fibre, was used, whilst somewhat older grass, containing 16·76 and 19·42 per cent. crude protein and fibre respectively, was fed in the third period.

It was found that the Large White hogs, which averaged about 195 lb. live-weight during the carrying out of the grass periods of feeding, were unable, with the exception of the fibrous component, to digest the constituents of even young grass with anything like the same degree of efficiency as they displayed in the digestion of the basal ration of middlings and maize meal. The constituents of the older grass, with the exception of the crude protein, were not markedly less digestible than those of the very young grass. The relative values of the pasturage and mixed meal are best brought out by the data for the digestion coefficients of the total organic matter; the pigs were able to digest about 85 per cent. of the organic matter of the meal, and only 60–62 per cent. of that contained in the grass.
Some factors affecting the pH change in bull semen
Authors: Anderson James
Published: March 2009

The extent of the change in pH on incubation, when bull sperm were suspended in various fluids of different composition, was affected by the buffer capacity, the pH, and the glucose content. In one such fluid, used to replace seminal fluid, there was a highly significant positive correlation between the pH. change and the number and motility of the sperm, and between the pH change in this fluid and in undiluted semen. The various conditions which appear to affect the increase in acidity are discussed, and it is concluded that there is no practical object in determining the change in pH on incubation in an artificial fluid of uniform and constant composition, instead of in semen.
Woburn irrigation, 1951–59 II. Results for grass
Authors: Penman H. L.
Published: March 2009

A grass/clover ley (mainly S26 cocksfoot and S 100 white clover 3 years, 1951–53) and a pure grass stand (S 37 cocksfoot 6 years, 1954–59) on the same site had threefold replication of four irrigation treatments: O, unwatered control; C, kept near field capacity throughout; A and B, intermediate between O and C. All plots received the same basic P and K dressing, and half-plots got N dressings either as N1 and N2, or as N2 and N4, the nitrogen being applied in the spring and after every cut except the last at rates: N1 0·15; N2, 0·30; N4, 0·60 cwt. N/acre. Cuts were taken at about 3 or 4 week intervals in the summer, and yields expressed as dry matter.
Woburn irrigation, 1951–59 III. Results for rotation crops
Authors: Penman H. L.
Published: March 2009

Potatoes

1951–53, Ulster Chieftain; 1954–56, Majestic, came after spring barley, with threefold replication of four irrigation treatments. All plots received the same basic P and K dressing, and half-plots got N dressings at N1= 0·5, N2 = 1·0 cwt. nitrogen/acre. Under main crop all plots received farmyard at 15 tons/acre, in addition. The ‘early’ potatoes were lifted about mid-July: the main crop at the beginning of October, a few weeks after killing of the haulms by a spray.
A study in sampling technique: the effect of artificial fortilisers on the yield of potatoes
Authors: Wishart J. , Clapham A. R.
Published: March 2009

(1) The desiderata of a sampling-method are outlined, and the particular case of sampling a large number of potato plots discussed.

(2) An analysis is made of the yields of 54 sub-plots of the Rothamsted Potato Experiment of 1928, both as estimated by a sampling-method and as determined by large-scale lifting.

(3) It is shown that most of the significant results of the experiment are obtained from the sample-yields, but that the higher standard error per plot obscures the effect of superphosphate.

(4) It is concluded that at Rothamsted 102, and at Woburn 56, plants would have to be lifted to give a sampling-error as small as 4 per cent. It would then be profitable only to sample experimental plots of 1/20th acre or more in area.

Finally it is a pleasure to record our indebtedness to Dr R. A. Fisher for much valuable advice and criticism: and to Mr H. J. G. Hines for assistance with the field work.
Plastometric studies of soil and clay pastes
Authors: Keen B. A. , Blair G. W. Scott
Published: March 2009

The laboratory study of the physical properties of soil and clays can conveniently be divided into three stages:

(a) Moisture content comparable to that under field conditions.

(b) Thick pastes.

(c) Weak suspensions.

The use of the plastometer for experimental work on intermediate stage is described and recent developments of the theory of the flow for thick pastes under stress are outlined. It is shown that certain constants defining the material can be obtained from the experimental data. The two to which special attention is given are the pseudo-viscosity (a quantity analogous to the viscosity of true fluids) and the static rigidity (which represents the energy required just to cause the paste to flow and a measure of the solid cohesive properties of the system). The latter quantity is related to other physical measurements made under very different experimental conditions,e.g.the resistance of the soil to the passage of cultivation implements; the effect of chalk, etc., on the soil resistance; the moisture content at which a well-kneaded mass of soil is about to become sticky.
Nitrification in Sudan Gezira soil
Authors: Jewitt T. N.
Published: March 2009

A laboratory study has been made of nitrification rates of the soil's own nitrogen, ammonium sulphate and certain organic nitrogen compounds. It is shown that nitrification in this soil is substantially normal, with no striking differences from that in soils of other arid regions.

I am indebted to H. Greene and E. M. Crowther for access to their earlier unpublished work on nitrification in Gezira soil, and to O. W. Snow of this Service for advice during the course of this work.
A census of an acre of corn (by sampling)
Authors: Engledow F. L.
Published: March 2009

In human society, density of population is marked by striking variations. With these are associated geographic, social, and economic differences. Among the plant populations of our fields occur gradations of spacing or density which, by broad analogy, suggest problems akin to those arising from density differences in human populations. It is necessary to do no more than walk the length of one of the drill rows in a field of young corn to appreciate the general situation. The facts are patent some five weeks after sowing when the emergence of the seedlings is almost completed. Side by side with a foot length of drill in which are thirty plants may be another foot with only three. Complete gaps of 2 feet or more are to be found in places: in others the plants are almost too numerous to count. In every field of corn, even at this early stage, the density or closeness of the plants in the drills is extremely irregular. As the season advances various influences induce irregular reductions in the number of plants. Vermin and disease take sporadic toll. Competition between plant and plant with death or effective disablement of the weaker has some effect. Its intensity at any point is mainly determined by the density or closeness of the plants. By May, for winter corn, a static condition has generally been reached. Plants living then are likely to contribute grain and straw to the harvest. Among these survivors are great differences in spacing. This may be readily appreciated by uplifting and counting the roots in sample 1-foot lengths of drill on a stubble field.
Biochemistry of water-logged soils: Part I. The effect of water-logging on the different forms of nitrogen, on the reaction, on the gaseous relationships, and on the bacterial flora
Authors: Subrahmanyan V.
Published: March 2009

Rothamsted and Indian soils were water-logged in the absence of freshly decomposing organic matter.

Nitrogen changes: Water-logging resulted in:

(1) A distinct increase in the free and saline ammonia content.

(2) A significant though only slight diminution in the nitric nitrogen.

(3) No marked loss of ammonia by volatilisation or otherwise in the gaseous form: nor considerable variation in the nitrites: nor any observable diminution in the total nitrogen.

Reaction: Water-logging resulted in an increase in alkalinity; the increase in pH value was closely correlated with the corresponding increase in ammonia.

Gaseous relations: Water-logging resulted in:

(1) No release of any soluble reducing matter capable of absorbing dissolved oxygen.

(2) No appreciable carbon dioxide production.

(3) An absorption of dissolved oxygen from the surface water. An equation has been worked out expressing the concentration gradient of dissolved oxygen with depth.

Bacterial numbers:

From bacterial counts on water-logged soils it was found that:

(1) There was significant though slight decrease in bacterial numbers on Thornton's Agar.

(2) Very few colonies were obtained by plating aerobically (and fewer still anaerobically) on Giltay's Agar. None of the organisms appearing on the plates brought about any nitrate reduction in soils.

(3) The total counts on gelatine plates also showed some decrease. The numbers of gelatine-liquefiers on the other hand did not vary. There was no evidence to suggest that the increased production of ammonia was due to the activity of the gelatine-liquefiers.

Agency responsible for ammonia formation:

The results indicate that the formation of ammonia in water-logged soils is not due to biological action. It is suggested that the action is due to an enzyme.
The determination of exchangeable calcium in carbonate-free soils
Authors: Williams Rice
Published: March 2009

(1) The possibility of using acetic acid as a reagent for extracting exchangeable calcium from carbonate-free soils is discussed, and experimental results are given showing that calcium is quantitatively precipitated from an acetic acid medium.

(2) A method for determining exchangeable calcium using 0·5 N acetic acid is described, and figures are given comparing this proposed method with the Hissink method.

(3) A modification of the proposed method is suggested in the case of heavy clay soils owing to the impervious nature of these soils which probably does not allow the acid to penetrate through the whole mass of the soil when leached on the filter paper.
The Differentiation of Grain Samples of Closely Related Varieties of Wheat by Means of a Simple Mechanical Test for Grain Quality
Authors: Frankel O. H.
Published: March 2009

1. A reliable identification of grain samples of related wheat varieties of different grain values is of economic importance.

2. The distensometer test distinguishes with a high degree of reliability between Tuscan and Cross 7 grain, whereas eye inspection, baking and fermentation tests cannot be relied upon for differentiation between the two varieties.

3. A testing service for the use of farmers, grain merchants and millers would involve no technical difficulties.
Digestibility trials with poultry. X. The effect of war-time changes in milling practice on the composition and nutritive value of fine and coarse wheat bran
Authors: Halnan E. T.
Published: March 2009

Digestibility tests with poultry, and one with rabbits, on brans produced under war-time conditions led to the following conclusions:

1. Changes in war-time milling practice, brought about by the implementation of Government policy directed towards maximum production of flour for human use, at first led to the production of a fine bran, somewhat better in food value than prewar bran, and a coarse bran, of poorer quality than pre-war bran. Later, owing to dilution of the grist with barley, the quality of the fine bran deteriorated and became worse than that of prewar bran.

2. The changes noted were largely caused by the extremely efficient removal of the starch by the millers, and reflect the ability shown by the milling industry in diverting to human food supplies the maximum possible edible food material present in the wheat berry.

3. The superior efficiency of the rabbit's digestive system for dealing with fibrous foods, as compared with the fowl's, is emphasized by the differences in the amounts of digestible nutrients extracted from a given sample of coarse bran by these two classes of animals. 1 kg. of coarse bran yielded 2522 kg. cal. of metabolizable energy in the rabbit as compared with 1637 kg. cal. in the fowl.
Adaptation of the ovine ruminal flora to biuret
Authors: Schröder H. H. E. , Gilchrist F. M. C.
Published: March 2009

The adaptation of the ruminal flora of sheep to the hydrolysis of biuret has been successfully demonstrated. Bi-weekly measurements of biuretolytic activity of ruminal ingesta were made before, during and after the supplementation of biuret to poor, medium and high-quality rations. Generally no activity was found prior to biuret feeding, but an almost immediate response to biuret feeding occurred which increased progressively with the number of days the animals were fed biuret. The time required to reach maximum activity on very low, medium and somewhat higher protein diets were found to be 15, 30 and 70 days approximately. The supplementation with starch in addition to biuret was found to increase biuretolytic activity. Since neither protein nor starch was found to have any direct effect on biuretolytic activity in vitro, a change in numbers of biuretolytic organisms in the ingesta is discussed as a likely mechanism for the adaptation and de-adaptation of the ruminal flora. A stoichiometric conversion of biuret-N to NH3-N by active ingesta was demonstrated in vitro but was not reflected by the nitrogen levels in vivo. The activity of the ingesta was greatly reduced by straining.
Studies on the relation between cultivation implements, soil structure and the crop I. Some preliminary observations on the measurement of soil structure, with a description of an instrument for the measurement of soil resistance
Authors: Culpin Claude
Published: March 2009

The need for physical measurements of soil structure to assist in studies of the relation between cultivation implements and plant growth is pressing.

The nature and measurement of soil compactness and consolidation are briefly discussed. Measurements of soil resistance give an indication of consolidation rather than of compactness.

An instrument used for the measurement of soil resistance is described, with some notes upon its performance.

A brief outline is given of studies on soil structure in relation to gyrotilling. It is shown that the soil-resistance apparatus described gives results similar to those obtained by the use of the drawbar dynamometer in ploughing. A relation between soil resistance and plant growth is demonstrated.
Physiological studies of competition in Zea mays L: I. Vegetative growth and ear development in maize
Authors: Eddowes Maurice
Published: March 2009

Preliminary field studies were carried out to obtain an understanding of the progress of dry-matter accumulation in maize and its end-point at harvest. Dry-matter accumulation and its partition between morphological parts was affected, at various stages of growth, by competition. For maximum total yield per unit area of land, early and rapid development of leaf area was needed to exploit the relatively high net assimilation rate early in the season. This leaf area should persist as long as possibleto maximize leaf area duration. A high total plant yield, and high yield of the important ear component, by the individual plant, was obtained at a plant population of about 40000 per acre. The photosynthetic area of the ear made no significant contribution to cob weight.
Seasonal production of Andropogon gayanus
Authors: Haggar R. J. , Ahmed M. B.
Published: March 2009

The crude protein content and in vitro dry-matter digestibility (I.V.D.) of leaves and stems of Andropogon gayanus, grouped into four different age categories, were measured at weekly intervals during the secondhalf of the 1968 wet season. The crude protein content of all categories of leaf and stem rose to a maximumat ear emergence; significant reductions occurred thereafter, especiallyin the younger categories of leaf and stem. At any point in time the younger leaves and stems contained significantly more crude protein than the older leaves and stems.

Although the mean crude protein content of each stem category was significantly lower than the corresponding leaf category, the young, elongating stems had a significantly higher crude protein content than the older, mature leaves at the time of ear emergence.

The mean I.V.D. of all leaf and stem categories was highest at the start of the recording period. At ear emergence the I.V.D. of the young elongating stems was at least as high as the mature leaves. After ear emergence the I.V.D. of the stems fell more rapidly than the leaves.

The results support the principle of cutting at ear emergence to achieve maximum yields of digestible nutrients.
Effects of high levels of fertilizer on yield of potatoes grown for ware
Authors: Rodger J. B. A. , Robertson G. M.
Published: March 2009

Nine experiments in the East of Scotland were completed in the years 1966, 1967 and 1968 to test the response of potatoes grown for ware to five levels of a 15½–15½–21 fertilizer applied at rates of 0, 4, 8, 12, 16 and 20 cwt per acre.

1. Mean yield of ware tubers increased up to the highest fertilizer level.

2. Mean yield of small tubers increased only up to the 8 cwt per acre level and then declined.

3. Dry matter content of ware tubers decreased with increasing levels of fertilizer.

4. Increasing fertilizer levels lowered soil pH. At one site this was associated with a significant reduction of common scab on the tubers.