bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal variation in the reproductive capacity of the bull
Authors: Anderson J.
Published: March 2009

Seasonal variation in the reproductive capacity of the bull was studied during a 27-month experimental period at the Experimental Station. There are a total of 1049 ejaculates for this period. Supplementary data for other periods on the Experimental Station and for two other large farms practising artificial insemination are also included.

Highly significant individual and monthly differences were noted during the experimental period for the density and motility of the sperm, the pH of the semen and for the percentage of ejaculations performed. The seasonal variation in semen is marked, but there is considerable variation in different years between bulls and between farms in the periods of maximal and minimal types of semen and in seasonal trends.

The relationship between such variation and climatic and nutritional conditions is discussed. There appears to be a basic seasonal rhythm in bull semen associated with climatic factors, warmer conditions causing stimulation and vice versa. Nutritional factors may, however, modify this rhythm. The relationship between seasonal variations in semen quality and fertility is discussed.
Studies on the behaviour of cattle and sheep in relation to the utilization of grass
Authors: Hughes G. Pearson , Reid D.
Published: March 2009

The importance of conducting studies on the behaviour of grazing animals has been stressed by several authors. Stapledon & Jones (1927) indicated the need for such work; while more recently Stapledon (1948, 1949) has made further reference to this need.

Adequate reviews of the work conducted prior to 1939 are to be found elsewhere (Castle, Foot & Halley, 1950; Tribe, 1950), and only the more important aspects need be considered here. The main weakness on the part of many of these earlier studies was that they were based on few observation periods, and that few animals were observed during each period. Many workers (Cory, 1927; Hodgson, 1933; Sheppard, 1921) carried out their observations during the daytime only, on the assumption that little or no grazing occurred after dark. In spite of this and the fact that the methods of study adopted varied considerably, some correlation exists between the results reported by the different workers.
The carbonic anhydrase activity of the hen's oviduct
Authors: Common R. H.
Published: March 2009

1. Some preliminary observations on the carbonic anhydrase activity of the hen's oviduct are reported.

2. It is suggested that the carbonic anhydrase activity of the uterine epithelium is higher than that of the remaining oviducal tissues, and that this activity may play a part in shell secretion.
An investigation of nitrogen uptake in mixed crops not receiving nitrogenous manure
Authors: Nowotnówna Anna
Published: March 2009

1. The total yield of dry matter of rye-grass, grown in the presence of inoculated (a) peas, (b) red clover, (c) serradella, in sand with no added nitrogen, after 13 weeks' growth was increased by about three times in the peas-rye-grass series, twice in the clover-rye grass series, and nearly twice in the serradella series in comparison with the yield of rye-grass grown alone.

2. The nitrogen percentage and total nitrogen yield of rye-grass were greatly influenced by associated growth with peas, clover or serradella. Rye grass grown with peas after 13 weeks' growth contained nearly five times, grown with clover three times, grown with serradella about twice, as much total nitrogen, as grass of the same age similarly grown, but in the absence of leguminous plants.

3. Among the three leguminous species tested at Pulawy, peas were the best companions for rye-grass, giving the highest amount of assimilated nitrogen, while serradella gave the smallest.

4. In another experiment, when barley and (a) peas, (b) red clover, (c) lucerne were grown together in sand without added nitrogen, only peas exerted a beneficial influence upon the yield of dry matter and the nitrogen percentage and total nitrogen yield of barley.
Base exchange equilibria in soil profiles
Authors: Mitchell R. L.
Published: March 2009

1. The conditions governing base exchange equilibria in soil profiles are discussed.

2. Exchangeable cation contents of six profiles are reported, the results including figures for Ca, Sr, Mg, Na, K, H and exchange capacity, as well as clay content and pH value.

3. It is shown that cation displacement occurs as a result of the downward movement of hydrogen ions from the surface layers, and a layer of minimal basic cation content exists at about 30 cm. depth.

4. Below this depth the basic cation content increases once again, but the base exchange capacity follows the clay content fairly closely.

5. Calcium and strontium are displaced (and readsorbed) at similar rates, in accordance with their exchange constants, although there is about 400 times as much calcium as strontium present. The behaviour of the other cations also appears to be in accordance with theoretical demands.
The nutrition of the bacon pig: II. The influence of high-protein intake on protein and mineral metabolism
Authors: Woodman H. E. , Evans R. E. , Turpitt W. G.
Published: March 2009

An investigation has been made, by the method of balance trials, of the utilization of food protein, at different levels of protein intake, by bacon pigs throughout the period of growth from weaning to slaughter. Information has also been secured relating to the retention of lime, phosphoric acid and chlorine. The main conclusions are as follows:

(1) The young pigs after weaning were able to digest their food with as high an efficiency as was displayed in the later stages of growth. The extra protein in the high-protein rations had little or no effect on the extent to which the food was digested.

(2) No evidence was secured at any stage of the trials suggesting the presence of protein in the urine of the pigs subsisting on the high-protein diet.

(3) The gilts showed a consistently higher rate of nitrogen retention than their brother-hogs. This behaviour was manifested even when the protein supply in the gilt's ration was lower than that in the ration of the hog with which it was compared. This more efficient utilization of food protein by the gilts is held to explain the tendency of gilts to give somewhat leaner carcasses than hogs.

(4) Nitrogen retention from the high-protein diet was no higher than from the normal-protein diet, a rinding suggesting that the amount of protein in the normal rations is sufficient to meet the demands for the quick growth required by modern standards of bacon production.
Fertility, morality, and growth rate in pigs
Authors: Menzies-Kitchin A. W.
Published: March 2009

1. Large White sows are more prolific than Large Black sows, but mortality up to 6 weeks is higher in the former breed. At 6 weeks, litters from both breeds contain practically the same number of pigs. At that age, however, pure-bred Large White pigs appear to be slightly heavier than those of the Large White/Large Black cross.

2. Sows show no significant deterioration in litter size or in litter weight at 6 weeks up to the tenth litter, but percentage death-rate tends to increase with farrow number.

3. There appears to be little advantage in producing litters with more than 12 pigs at birth. In litters containing more than 12 pigs the addition in number is more than off-set by an increase in death-rate.

4. There is no significant difference at 6 weeks between the average weights of pigs from litters of different size at birth. There is, however, a difference in average weight according to the number of pigs surviving at 6 weeks; the larger the number the lighter the pigs.

5. The season in which the sow farrows appears to exercise a considerable influence on survival rate at 6 weeks; approximately one pig more per litter surviving in the summer than in the winter months.

6. There is a definite negative correlation between the weight of the pigs at 6 weeks and the age at which they reach bacon weight. But the rate of post-weaning growth of the heavy pig is not necessarily greater than that of the light pig.

7. Post-weaning mortality appears to increase with increase in litter variation.

8. Litters which are fattened during winter months take longer to reach bacon weight than those fattened during summer.

9. Rapid growth rate and high grading results are not incompatible when the conditions of suitable rations, good stock, and proper management are observed.

10. The third and fourth week of age appears to be a critical stage in the life of the suckling pig, and especial care must be exercised in its treatment at that period.
The mechanism of cellulose digestion in the ruminant organism: IV. Further observations fromin vitrostudies of the behaviour of rumen bacteria and their bearing on the problem of the nutritive value of cellulose
Authors: Woodman H. E. , Evans R. E.
Published: March 2009

Further studies of the behaviour of cellulose-splitting bacteria in artificial media have been made in an attempt to account for the manner in which cellulose is utilized for fat production in the ruminant. The behaviour of thermophilic bacteria, with an optimum temperature of fermentation in the neighbourhood of 65°C, has been compared with that of the micro-organisms capable of fermenting at 37°C. In both cases the cultures were obtained from the rumen contents of sheep.

By the addition of toluene at the “head” stage of fermentation, it was possible to demonstrate, both at 37 and 65°C., the production of small amounts of glucose during subsequent incubation. Glucose is clearly a primary breakdown product in the bacterial fermentation of cellulose.

An investigation has been made of the nature of the volatile fatty acids produced by bacterial decomposition of shredded filter paper. No consistent differences from this standpoint were noted between the reactions as carried out at 37 and 65°C., but the nature and proportions of the acids varied considerably from culture to culture. In some cases acetic acid was produced almost exclusively, whilst in others the fatty acids consisted of butyric and formic acids, with but traces of acetic acid. The findings in this regard apparently afford no clue to the manner in which cellulose is used for fat production, since propionic acid, the only recognized fat-former among the lower normal fatty acids, was not detected.
Observations on the proteins of pasturage. Phosphorus and protoplasm
Authors: Foreman F. W.
Published: March 2009

1. Studies lead to the conclusion that Chibnall-preparations of pasturage proteins, in spite of their small amounts of carbohydrate impurity, may yet yield, on hydrolysis by mineral acids, practically the right amounts even of most of those amino-acids which are adversely affected by carbohydrates to some extent when tested singly under the conditions.

2. Preparations made in another way after treating the pasturage with ether as in the original Chibnall-method showed features of interest in the problem of attaining very pure proteins now much needed for purposes of comparison.

3. A new method is introduced by which it is possible to compare what may be extracted from the protoplasm of fresh unpulverized pasturages with the composition of the natural saps on a unit weight basis.

4. Production and breakdown of protoplasmic protein in perennial rye-grass during growth consistently appeared related to variations in the content of “nitrogen” and phosphates in the saps and the supplies of “nitrogen” and phosphates from the soil.
The effect of nitrogenous fertilizers on the calcium status of soil
Authors: Lewis A. H.
Published: March 2009

The results of an experiment, conducted over one cycle of a four-course rotation to study the effects of nine nitrogenous fertilizers on crops and soil, are described.

All the crops gave fairly good responses to nitrogen but in no case was there a significant difference between the effects of the various nitrogenous fertilizers. The “recovery” of added nitrogen was about 40–50 % with all the fertilizers.

Figures are given for the changes in exchangeable CaO content of the soil. The results confirm Crowther and Basu's deduction that “the loss of calcium exceeds that for equivalent nitrogen added as nitrate by an amount equivalent to the excess of anions over the cations in the added fertilizer, all added nitrogen being regarded as nitrate and all carbon and phosphates being ignored”.

The fact that phosphate should be ignored is shown by results for mono- and diammonium phosphates. Precipitation of phosphates in the soil almost certainly involves removal of calcium from the exchange complex but the calcium in such precipitated phosphates is exchangeable.

Since phosphate has no effect on calcium status, it is clear that fertilizers based on ammonium phosphates remove less calcium from the soil than do mixtures based on ammonium sulphate and superphosphate.
An attempted fractionation of the soil phosphorus
Authors: Dean L. A.
Published: March 2009

1. Extractions of soils with sodium hydroxide, followed by an acid, have been used in an attempt to fractionate the soil phosphorus.

2. Colorimetric methods for the estimation of the organic and inorganic phosphorus in alkali soil extracts have been suggested.

3. The amount of soil phosphorus soluble in sodium hydroxide is affected by the active soil calcium. It is suggested that sodium-saturated soils be used when studying the alkali-soluble phosphorus.

4. The acid-soluble phosphorus remaining in soil after extraction with sodium hydroxide was determined. This fraction appears by analogy to be similar to the apatites.

5. The largest fraction of the total soil phosphorus was not dissolved by the sodium hydroxide and acid extractions. This fraction was not increased by the long-continued use of phosphatic fertilizers at Rothamsted and Woburn.

6. Relatively large amounts of organic phosphorus were found in soils and the amounts were closely related to the carbon contents.
Excretion of nitrogen by leguminous plants
Authors: Wilson P. W. , Burton J. C.
Published: March 2009

The literature which deals with the question of excretion of nitrogen by leguminous plants is reviewed especially with reference to accounts of experiments in which no excretion was obtained.

Experiments made at the Wisconsin experiment station prior to 1936, primarily concerned with the associated growth of pea and oat mixtures, were uniformly negative with respect to benefit to the oat plants through the association.

Experiments carried out at the Biochemical Institute in Helsinki, Finland, with a pea and barley mixture were in general positive, although poor development of the plants because of unfavourable weather were accompanied by little or no excretion.

On duplicating the Helsinki experiments at Wisconsin, once more both positive and negative results were obtained, although the development of the plants was excellent.

The occurrence of excretion appears to depend on many complicated circumstances some of which have been defined, while others are at present unknown. Factors which insure a uniform development of the plant cultures and especially a not too rapid growth of the leguminous plant appear to be important; as yet no universally successful method of achieving this type of development has been determined. It is concluded that although there can be no doubt with, regard to the existence of excretion, knowledge of the factors concerned is still insufficient to allow duplication of the results consistently at all experiment stations. Until such knowledge becomes available, application to practical agriculture can remain only an attractive possibility and not an established fact.
Some observations on the normal variations in composition of Light Sussex cockerels
Authors: Halnan E. T.
Published: March 2009

Individual analyses of forty Light Sussex cockerels of twenty-two weeks of age yielded the following results:

1. There is a highly negative correlation between the fat percentage of the carcass and the moisture percentage.

2. Owing to the large variability in the fat content of individuals, live-weight increases are unreliable as a measure of energy storage.

3. Comparison of the fat content of the bones with that of the flesh and offal leads to the conclusion that the bones as well as the flesh and offal play a significant role in the general fat metabolism of the body.

4. There exists a strongly positive correlation between the ash content of the bones and that of the flesh and offal.

5. The protein ash ratio of both the Light Sussex breed and the White Leghorn breed is practically constant for all individuals after the age of seven weeks, indicating that the growth of the skeletal and the muscular tissues are closely correlated and controlled by the same growth impulse.

6. The individual variation in energy content is shown to be ± 11.42% of the total energy content.
Relation of ear survival to the nitrogen content of certain varieties of barley: With a statistical study
Authors: Hunter H. , Hartley H. O.
Published: March 2009

1. The high grain-yielding capacity and low total nitrogen content of predominant British varieties of barley, in conjunction with high ear survival at harvest, are discussed.

2. The results of a series of quantitative comparisons in which increased tillering was promoted by the application of nitrate of soda at various phases of plant development, and similarly when tillers were removed at various stages, were examined.

3. It was shown that the effect of nitrogen on the yield and quality of the grain depends upon the time in relation to the stage of plant development at which it was applied; the early applications enhanced the yield without detriment to the quality of the grain, whilst the later applications did not increase the yield but increased the total nitrogen content, and consequently reduced the malting quality of the grain.

4. The increase in yield was obtained primarily by an increase in the number of surviving tillers and to a less extent by an increase in yield of grain per ear; the latter was in some cases accompanied by an increase in 1000-grain weight. High ear survival in varieties such as those under examination may consequently be regarded as an index of high yield of grain and of low total nitrogen content.

5. The removal of tillers resulted in increased total nitrogen content and increased 1000-grain weight in the grain of the main stem; the former was not affected by the stage of development of the plant at which abscission was made, but the highest value of the latter was obtained when the abscission was made before flowering.

6. The relation of 1000-grain weight and nitrogen content was discussed, and it was shown that high 1000-grain weight may exist with both high and low total nitrogen. Although the 1000-grain weight is an hereditary attribute it is subject to considerable fluctuation and cannot by itself be usefully employed as an index of nitrogen content, and consequently of malting quality, in either an inter- or intra-varietal sense.
The indirect determination of the “wilting coefficient” by the freezing-point method, and the influence of the salts upon the pF at that critical moisture content
Authors: da Costa J. V. Botelho
Published: March 2009

The results obtained in the preliminary investigation were entirely confirmed, the pF at the “wilting coefficient”, as measured by the modified freezing-point method, varied from 4·0 to 4·4 (round figures), with an average of 4·2.

The variation observed bears no relation to the soil texture, neither can it be explained by uncertainties in the freezing-point determinations which have proved to be accurately reproducible. Freezing-point measurements after leaching, conductivity measurements and freezing-point determinations in saturated soil and at the moisture equivalent proved that part of the variation is due to the presence of soluble salts, the more saline soils having a higher pF at the “wilting coefficient”. When the salt content does not exceed about 500 p.p.m. the influence of the salts is hardly detectable, and the pF at the “wilting coefficient” lies between 4·0 and 4·3. Besides unavoidable errors in the wilting experiments several other factors may account for this variation. They are all the factors that have any role in the “history” of the soil. In view of these uncontrollable sources of error a variation of 0·3 pF units can be considered very small.

It can therefore be confidently concluded that in ordinary agricultural soils with a salt content of less than about 500 p.p.m. permanent wilting occurs when a critical pF value (lying between 4·0 and 4·3) is reached.
A note on the estimation of the sulphur content of fodder and excreta
Authors: Marston Hedley R.
Published: March 2009

Critical estimations of the recovery of sulphur, when materials such as fodder and excreta were subjected to a number of analytical procedures. The only method in this series which resulted in consistently good estimations was one involving oxidation in compressed oxygen confined in an Emerson Calorimeter Bomb.
The effect of the addition of various materials and bacterial cultures to grass silage at the time of making on the subsequent bacterial and chemical changes
Authors: Allen L. A. , Watson S. J. , Ferguson W. S.
Published: March 2009

The investigations previously described (1) have demonstrated that the changes occurring in the early stages of silage fermentation result in simultaneous development of acidity and degradation of proteins. There seems little reason to doubt that the lactobacilli play an effective part in the former by virtue of their formation of lactic acid. Contributions to proteolysis are undoubtedly made by various groups of bacteria, and in the later stages of ripening the spore-forming anaerobes, if numerous, will cause extensive protein breakdown and formation of volatile acids, especially butyric acid. The growth of the latter group of bacteria is greatly affected by thepH of the silage, for at values below about 4·0 the only group capable of anything like active multiplication is the lactobacilli. In fact the A.I.V. method of making silage consists in the addition of mineral acids at the commencement in quantities sufficient to reduce thepH to approximately 3·5. The production of good silage with a minimum loss of feeding value, low proteolysis and the presence of only small quantities of butyric acid may therefore be regarded as depending on the formation of sufficient acid in the earlier stages to retard the activities of the obligate anaerobes and proteolytic bacteria in the later stages.
Experiments on the spacing of sugar beet: II. Results based on weights of individual plants
Authors: Garner F. H. , Sanders H. G.
Published: March 2009

1. Yields of plots estimated from the known weights of “perfect” beet (i.e. plants with no gaps in the ring immediately surrounding them) showed 18 × 9 in. to be the optimum spacing.

2. Sugar analyses performed on individual “perfect” beet showed that very diminutive roots were low in sugar, but that in general sugar percentage decreased with increasing weight of root; the decrease was, however, slight and only amounted to unity for an increase of 1000 g. in weight of root.

3. In a dry year the roots immediately surrounding a gap compensated to the extent of 80–89% for the missing plant: the allocation to the individual neighbours was approximately inversely proportional to the square of their distance from the site of the gap. In a wet year compensation was less complete, amounting to from 41 to 84% under various spacing treatments. In both years compensation was less complete in the case of tops than in the case of roots.

4. Within classes of beet similar in regard to spacing treatment and gappiness there still remained considerable variation due to soil and to genetic heterogeneity.

5. The genetic variability of commercial seed appears to be large, so that in sugar beet experiments it is very desirable that each plot should carry a considerable number of plants: in these experiments, assuming that all variations within ultimate classes were of genetic origin, 400 plants would have been necessary to reduce the plot error due to genetic variability to 2% of the mean.
The estimation of leaf area in field crops
Authors: Watson D. J.
Published: March 2009

1. It is shown that the leaf area: leaf weight ratio decreases with increasing leaf weight.

2. The relation between the leaf area: leaf weight ratio and leaf weight is well fitted by a linear regression equation.

3. A method of estimating the mean leaf area per leaf or per plant of a field crop by means of this regression is described. The mean weight per leaf is determined by a large sampling, and the leaf area: leaf weight ratio and its regression on leaf weight are estimated on a small subsidiary sample.

4. Alternative methods of estimation from the mean leaf weight and either the unweighted or the weighted mean leaf area: leaf weight ratio are shown to give positively biased estimates of mean leaf area.

5. It is emphasized that the small sample, from which the leaf area: leaf weight ratio and its regression on leaf weight are determined, must be a strictly random selection from the whole population.
Analytical yield investigations on New Zealand wheat: IV. Blending varieties of wheat
Authors: Frankel O. H.
Published: March 2009

1. An endeavour was made to obtain a blend of Tuscan wheat with a high quality line which would yield as much as Tuscan, at the same time possessing a superior baking quality. Of the eleven lines which were blended with Tuscan, nine blends returned yields corresponding to the expectation calculated from the pure varieties, and two blends yielded more than the expectation; these increases were not statistically significant.

2. Tuscan, three lines and their blends were submitted to yield analytical treatment. The yield characters of the components of blends were compared with their yield characters when grown by themselves. Whilst the yields per plot of the blends corresponded to the expectation, the yield analyses revealed that the component varieties exerted a modifying influence on each other, which was different in each of the three trials. Tuscan demonstrated its aggressiveness by depressing in every case the yield characters of the lines with which it was blended.
Genetic variability and inter-relationship of some quantitative characters in safflower
Authors: Khidir M. O.
Published: March 2009

Eighteen varieties of safflower were studied in a randomized block design with five replications. Data on fourteen quantitative characters were recorded. Appreciable variability was displayed by all characters, especially yield and number of heads/plant. The heritability estimates ranged between 65 and 98%.

Seed (achene) yield gave a significant positive genotypic correlation with number of seeds/head, head width, bract width and oil content. The 100-seed weight was significantly negatively correlated with the number of seeds/head and plant height at maturity. The genotypic correlations between yield/plant and four other traits were partitioned into direct and indirect effects. The highest direct positive contribution to yield was given by plant height, which had also a positive indirect effect via number of heads. The direct effect of the number of heads/plant was negative and the indirect effect via head width was positive.
Photosynthesis in the ear of barley, and the movement of nitrogen into the ear
Authors: Watson D. J. , Norman A. G.
Published: March 2009

Experiments were made in 1936 and 1937 on barley plants grown in pot culture, to determine the effect of shading the ear or the shoot after ear emergence on dry weight and nitrogen content.

It was found that after ear emergence the ear and the shoot (leaves and stem) make approximately equal contributions to the assimilation of the whole plant. In the 1936 experiment 28% of the final dry weight of the ear was accounted for by assimilation in the ear itself, and in the 1937 experiment, 19%. These are minimum estimates, for assimilation must have been proceeding in the ears during emergence, before the shading treatments were applied. The results agree well with similar estimates of the extent of assimilation in the ear made on wheat by other workers.

The effects of shading on the amount of nitrogen present in the plant at harvest were somewhat variable, but they were always small compared with the effects on dry weight. Shading tended to reduce the amount of nitrogen in the ear, but as the dry weight of the ear was reduced to a much greater extent, - nitrogen as percentage of dry matter in the ear was increased. It is concluded from this result that translocation of nitrogen compounds to the ear is not closely dependent on the amount of the concurrent increase in dry weight of the ear. It appears that the approximate constancy of nitrogen percentage in the ear and the grain throughout development is a consequence of the particular conditions prevailing during normal growth in the field.

The experiments showed that 20–30 % of the dry weight of the whole plant was added after ear emergence, suggesting that climatic conditions during this late stage of growth is of considerable importance in determining the final yield.

The authors wish to thank Miss J. Hellyer for carrying out many of the determinations of nitrogen content, and Mr S. A. W. French for assistance with the statistical computation.
Field experiments on the effect of applying a nitrogenous fertilizer to wheat at different stages of growth
Authors: Watson D. J.
Published: March 2009

An account is given of the results of two series of field experiments carried out at Rothamsted and Woburn in the years 1926 to 1936 on the effect of nitrogenous fertilizers on wheat. In the first series a comparison was made of the effects of early (March) and late (May) top-dressings, and in the second series a range of times of application from sowing to the end of May were tested.

At Rothamsted, the increases of yield of grain produced by the nitrogenous fertilizer were small and rarely significant, but they were greater at Woburn. On the average of all experiments, the effect of the fertilizer on yield of grain was independent of the time of application. In individual years, variation in effectiveness between times of application was found, and this was correlated with the amount of rain falling in a short period after the time of application. At Woburn, the effectiveness of the fertilizer decreased with increase in the amount of rain falling immediately after the application of the fertilizer, but at Rothamsted the effects were less clear and appeared to be in the opposite direction.

The effects on straw yield were relatively greater, and more consistent, than those on grain yield. A greater increase of straw yield was produced by early top-dressing (January–March) than by application at the time of sowing, and the increase declined steadily the later the time of topdressing. Shoot height was increased by the nitrogenous fertilizer, and varied with time of application in a similar manner to straw yield.
Experimental methods with cotton: II. A study of the effects of seed rate and time of thinning on the development and yield of cotton plants in hand-planted cotton trials
Authors: MacDonald D. , Fielding W. L. , Ruston D. F.
Published: March 2009

The object of this experiment was, in the first place, to see whether, with cotton experiments, there was an advantage in planting a larger number of seeds per hill than the customary number of three; and, in the second place, to see the effect of the interaction of time of thinning with varying numbers of seeds per hill.

In cotton breeding work, where trials of new strains have to be carried out as soon as sufficient seed is available, it is important to conserve seed in all possible ways. At the same time it is necessary to plant sufficient seed to give a full and even stand for all strains.

In experiments carried out in 1936–7 and 1937–8 stand counts, made soon after germination, showed the advantage of the higher seed rates in obtaining a quick and full stand. Later counts and final counts at harvest showed a considerable evening up, although the two-seed treatment proved unreliable, giving the lowest stand in both seasons.

Plant height and weight records, made during both seasons, showed that plants from the larger hills were drawn up much more rapidly than plants from the smaller hills. This rapid elongation in stem height proved, from weight figures, to be at the expense of lateral development, weak and leggy plants being produced in these hills. The ten-seed treatment showed up particularly badly in this respect, the yield figures showing that the plants never recovered from this early deleterious effect.

The six-seed treatment, whilst giving a quick and excellent stand suffered to a certain extent from the same defects as the ten-seed treatment. If thinned early they tended to fill out and become more comparable with plants from the three-seed treatment, but when thinning was delayed they never caught up and final yield suffered adversely.
Field crops and variety comparison between Imperial Valley, California and Kufra Oasis, Libya
Authors: Worker G. F.
Published: March 2009

A study was conducted to compare field crops and varieties grown at the Kufra Agricultural Project, Libya, and the Imperial Valley Field Station, El Centro, California. Lucerne (Medicago sativa L.), barley (Hordeum vulgare L.), wheat (Triticum octivum L.), sudangrass (Sorghum bicolor Moench) were grown at both locations in 1969–70.

Yield studies at Kufra, Libya, and the Imperial Valley Field Station indicated that the crop performances were equally well adapted at both locations. Lucerne yields were higher at Kufra, which may have been due to more moderate temperatures and less salt in soil and water at Kufra. Low yields in some of the other crops at Kufra such as wheat may be due to inexperience and inadequate fertilizers. Newly developed varieties for Imperial Valley should be adapted to the Kufra area.
Effect of temperature and scarification on germination and emergence of wild safflower, Carthamus oxyacantha Bieb.
Authors: Bassiri A. , Rouhani I. , Ghorashy S. R.
Published: March 2009

Seeds of wild safflower, Carthamus oxyacantha Bieb., collected from the Bajgah area, Iran, were subjected to chilling and/or scarification and their germination and emergence characteristics and seedling growth were studied in two laboratory experiments. Seeds of Arak 2811 variety of cultivated safflower, C. tinctorius L., harvested from the same area at the same time was used for comparison.

In the first experiment, the untreated, scarified, chilled at 0 °C for 1 month, and chilled and scarified wild seed and seed of the variety Arak 2811 were incubated at six different temperatures (5, 10, 15, 20, 25 and 30 °C) and their germination percentage and seedling lengths were recorded. In the second experiment, the seeds of the above five treatments were planted in a silty clay loam at room temperature (23 ± 2 °C) and their emergence and seedling heights were noted.

In all cases, the cultivated variety, Arak 2811, had higher germination and emergence percentages and seedling heights than the wild type. Germination of both strains was greatly reduced at the two extreme temperatures (5 and 30 °C). The optimum temperatures for germination of the wild and the cultivated strains were between 15 and 20 °C.

Scarification of the wild seed did not improve the germination or emergence percentages and chilling of the seed for a month at 0 °C reduced the emergence of the wild seed. Temperature of germination, however, seemed to be an important factor affecting germination and seedling growth of wild safflower.
Potassium in soils under different cropping systems: 3. Non-exchangeable potassium in soils from long-term experiments at Rothamsted and Woburn
Authors: Addiscott T. M. , Johnston A. E.
Published: March 2009

Soils from long-term experiments at Rothamsted and Woburn were cropped for very long periods (up to 5½ years) with ryegrass in pots. Measurements of the potassium taken up by the ryegrass that was not exchangeable to ammonium acetate and the kinetics of its release both suggested two categories of non-exchangeable K. Of these, the first to be released was closely related to the initial exchangeable K, whilst the second, though partly related to the initial exchangeable K was also influenced by the clay percentage. Release of both categories may have been controlled by diffusion, because both showed good relationships between the quantity released and time. It is suggested that the first category may be K ‘trapped’ when K fertilizer added in the field decreased the interlamellar spaces of vermiculite layers in clay particles, whilst the second may simply be the ‘native’ K (described by others) present in clay and other minerals in the soil.

Resowing the soils (without drying them) during the later stages of K. uptake suggested that the ability of the old ryegrass to absorb K was not a factor limiting K uptake even after long growth.

When the ryegrass ceased to grow, the mean K potentials in the exhausted soils were close to the ‘uptake potential’ for ryegrass derived earlier by considering K uptakes from soils in relation to the quantity/potential relationships of the soils. Drying and rewetting the exhausted soils released K; the amount was influenced in one group of soils by the exchangeable K in the moist exhausted soil and in another group by the clay percentage.
Rapid methods of examining soils. III. The use of dihydrogen potassium phosphate in studying base exchange capacity
Authors: Schofield R. K.
Published: March 2009

The reduction in the electrical conductivity of a mixed solution of K2HPO4 and KH2PO4 caused by the addition of soil is a measure of the potassium uptake, and is therefore an indication of the “;base exchange capacity” of the soil at pH. 7. Two disturbing factors are noted, and it is concluded that the method is likely to be most useful where a rapid comparison of soils of a similar nature and pH is required.
Factors in the development of deforming leg weakness in chickens (With plate I.)
Authors: Parkhurst Raymond T. , McMurray Mary R.
Published: March 2009

Abnormal leg trouble or perosis occurred in chickens getting an excessive amount of meat and bone meal in their ration, and rarely occurred when the bone meal content was low or nil.

The use of the battery brooder was found to intensify bone deformities, when the ration was unsatisfactory in mineral balance.

The floor space allowed was not found to be a factor in perosis.

Under the conditions of the experiment, slipped tendons were not produced by feeding calcium carbonate (ground limestone) in the ration.

The protein content of the ration and the rate of growth did not materially affect the occurrence of perosis.
The relative importance of the total cell wall and quantity of digested cell wall in the regulation of the voluntary intake of grass hays by sheep
Authors: Moir K. W. , Laws L. , Blight G.
Published: March 2009

In 18 digestibility experiments with sheep, 9 diets consisting of single-grass hays and 9 diets each consisting of equal quantities of a good and poor quality hay were fed. Correlations between the voluntary intake of organic matter, digested organic matter, total cell wall and digested cell wall in all possible combinations were investigated. There were no significant differences among the simple correlation coefficients for hays fed singly or as mixtures, even though they were eaten in very different amounts. The simple pooled correlationswere significant (P < 0·01) among voluntary intake, digested organic matter and cell wall. The cell wall was significantly correlated with digested cell wall, but there was no simple correlation between voluntary intake and digested cell wall. However, when considered together in a multiple linear model they explained 58% of the variation in voluntary intake compared with 43% explained by the total cell wall alone. The additional variation accounted for by the digested cell wall was significant (P < 0·05).

The relative importance of the total cell wall and digested cell wall is discussed in relation to selection in grass breeding.
The appraisal of fineness in greasy wool sale lots
Authors: Whiteley K. J. , Charlton D.
Published: March 2009

Relationships among quality number, crimp frequency and. fibre diameter of sale lots are reported for a wide range of Australian wools, the quality number appraisals being those of the selling broker and the successful bidder at auction.

Results show that sale lots classified as having the same quality number exhibit a 95% confidence interval of ± 2·5 μm about the mean value. This variation is attributed first to the dependence of quality number on staple crimp frequency and secondly to the strength of the relationship between crimp frequency and fibre diameter.
A quantitative comparison of the growth, development and yield of different varieties of oilseed rape
Authors: Allen E. J. , Morgan D. G.
Published: March 2009

A field experiment to compare the growth, development and yields of four varieties of oilseed rape, Cresus, Guile, Rigo and Nilla, is described and the results discussed. Cressus was the highest-yielding variety largely because it produced more pods and more seeds per pod. The numbers of pods and seeds per pod were positively correlated with the leaf area index at the onset of flowering. This suggests that the rate of supply of carbon assimilates to the inflorescences around the time of anthesis is an important yield-determining character. The mean weight of the individual seeds was greater in Cresus than Guile and this difference, which developed late on in pod growth, also contributed to the higher yields in Cresus.
Survey of the presence and methods of control of wild oat, black grass and couch grass in cereal crops in the United Kingdom during 1977
Authors: Elliott J. G. , Church B. M. , Harvey J. J. , Holroyd J. , Hulls R. H. , Waterson H. A.
Published: March 2009

In summer 1977 a random survey was made of 2250 fields on 1153 farms selected throughout the United Kingdom. Wild oat, Avena spp., was surveyed in all countries; black grass, Alopecurus myosuroides, was surveyed in England and Wales; and couch grass, including Agropyron repens and other perennial grasses, in Scotland and N. Ireland.

Wild oat was reported by farmers on 95% of farms in England, 34% in Wales, 65% in Scotland and 30% in N. Ireland; the areas of infestation in the different countries were 67, 13, 37 and 16% respectively. The majority of wild oat was A.fatua. Only 6% of the cereal area of U.K., including sprayed and unsprayed fields, contained more than one wild oat seed head/m2 (10000/ha), the majority had less than one/20 m2. Black grass was reported on 50% of farms in England (22% of cereal area) mainly in East and South, and on 2% of farms in Wales. Couch grass occurred on 92% of farms in Scotland and 68% in N. Ireland: areas of infestation were 88 and 67% respectively. Most of the infestations of all three weeds had been present for longer than 5 years.

Most farmers intended to eliminate or reduce wild oat and few proposed to hold the weed at its present level or do nothing. Herbicides were used against wild oat on approximately half of the infested area in England and Wales, with proportionately more use in Wales and much less in Scotland and N. Ireland. A third of the black grass infested area of England was treated with a herbicide. There was little spraying against couch grass in Scotland and N. Ireland. Details of dose, time of application and mixing of chemicals were obtained. Wild oat was subsequently found on most of the area treated against this weed, similar observations were made of black grass and couch grass. Most farmers considered herbicide performance good or excellent and those in East and South England believed wild oat to be decreasing as a problem; farmers elsewhere thought the problem to be increasing.

Hand pulling of wild oat (roguing) had occurred on only one tenth of the infested area but a greater area was intended to be rogued after the survey visit. Much of the land that had been rogued was found subsequently to contain few wild oats.

The survey provided information on associations between weed presence, soil type and cropping system, the types of herbicide used and farmers’ impressions of their performance. Comparisons are made with previous surveys in 1972, and information on the disposal of the 1976 crop of straw and on types of cultivation used in different regions is provided. The implications of the results are discussed.
The effect of level and frequency of concentrate feeding on the performance of dairy cows of different yield potential
Authors: Johnson C. L.
Published: March 2009

An experiment has been made using adult lactating cows in a randomized block design to study the effectiveness of basing feeding during the first 20 weeks of lactation on yield predicted from that obtained during the 8–12th days of lactation. Cows were classified as high yielding (HY) or low yielding (LY). The levels of feeding were identical within each yield group during the first 8 weeks of lactation but during the 9th to the 20th week two different levels of concentrate feed (HP and LP) were used. Over the 20-week period concentrates were offered in two or five daily feeds. Thus the effect of two levels and two frequencies of feeding on feed intake, milk yield and composition, and on live-weight change were studied.

Cows in the HY group achieved a mean daily peak yield 2·6 kg higher than predicted while those in the LY group achieved the predicted mean peak daily yield. There was no significant effect of level of feeding on the 20-week milk yield but there was a significant effect on the yield of the LYLP class in weeks 9–20. Frequency of feeding had no significant effect on yield in either high-low-yielding cows. There was no significant effect of level of feeding on milk composition but low-yielding cows gave milk with a higher fat percentage than high-yielding cows. Five-times-a-day feeding also produced milk with a higher fat percentage than twice-a-day feeding.

Live-weight changes were small and the largest variation was recorded in highyielding cows.

The number of days from calving to first service was not significantly different for the two yield groups but there was a significant effect of level of feeding.