In 4 consecutive years, 1948 to 1952, combined varietal and manurial trials were carried out to obtain information on the yields of marrow-stem kale, thousand-head kale and cattle cabbage in the presence and absence of sulphate of ammonia applied as a top-dressing at the rate of 6 cwt./acre.

Yield and composition of all crops were apparently affected by differences in weather conditions. In most years, and particularly for cabbage, the yield declined with successive harvests.

Increased green crop, dry matter and crude protein yields resulted from the application of nitrogenous fertilizer in 3 years, but in the other year, a very dry season, the response to the top-dressing was negligible.

Marrow-stem kale both with and without the additional fertilizer, yielded more, in terms of fresh crop, dry matter and crude protein, than thousandhead kale with the same manurial treatment. Cabbage yields often approached those of marrowstem kale at the first harvest, but were nearer to those of thousand-head by the last harvest of each year.

The existence of a high degree of variability in all production traits of dairy cattle in tropical countries has been demonstrated. Evidence has been adduced to show that this is due largely to increased environmental variability than to any great inherent differences between animals. The conclusion is drawn that, despite minor differences, the genetics of milk production in tropical dairy cattle is fundamentally very similar to that in European stock.

1. It has been shown that under a given feeding régime the concentration of blood urea in the sheep is constant.

2. Changes in the diet lead to different levels of blood-urea concentration which can be correlated with different rumen-ammonia concentrations; the change in blood-urea concentration follows increases or decreases in rumen ammonia after a delay period of 4–8 hr.

3. Fluctuations in blood-urea concentration in the sheep are not primarily due to changes in the overall nitrogen intake.

4. It is suggested that these findings might form the basis of a supplementary test in assessing the value of the protein in a foodstuff for ruminants.

1. The reaction of spring and winter types of field beans and of Windsor broad beans to artificial vernalization treatments and to successional field sowing has been studied.

2. The broad bean type came into flower earlier and at a lower node on the stem than any of the field bean types, and this was not affected by either vernalization treatments or successional sowing.

3. The field bean types flowered at a low node when sown in winter, but in summer sowings the level of the first flowering node was much higher; the response of the winter types was more extreme than that of the spring types.

4. In the summer sowings vernalized plants came into flower earlier and at a lower node than unvernalized, but in the winter sowings both vernalized and unvernalized material flowered at an equally low node.

5. A convention for naming the different stems contributing to the yield was evolved, and using this it was shown that the date of sowing affected the stems produced.

6. The survival of plants in the field was not found to be affected by vernalization previous to sowing.

1. A study has been made over two growing seasons of the volatile fatty acid production from ley grass obtained from a single area of one field, under the action of rumen liquor in vitro.

2. The acida estimated were acetic, propionic, butyric, valeric and caproic. On only one occasion did the last named appear in measurable amount.

3. The main acid produced in early stages of the year is acetic acid, but as the season advances propionic acid becomes the acid of major production.

4. In parallel cellulose runs it was found that propionic acid was invariably produced in greater amount than any other acid.

5. An attempt has been made to eliminate, by using cellulose as a standard, the effects of using different rumen liquor samples.

6. The dried samples, corresponding to the fresh material, were invariably found to yield acetic acid in greater proportion than propionic acid. The average percentages of acids obtained from the dried grass were similar to those found by other workers. It is suggested that the variations between the fresh and dried grass results are due to changes in carbohydrate content resultant upon storage of the latter.

Statistical analysis of data from calcium and hosphorus balance experiments with laying hens has shown that, for regression equations relating shell calcium to calcium retention:

(a) Individual birds give different regression coefficients (b values).

(b) The equations obtained for each of twelve birds belong to one family which can be represented by a more general equation.

(c) Over the whole of an experiment the b value and the phosphorus balance for each bird is significantly correlated with the total shell calcium secreted by that bird.

The metabolic significance of these findings is discussed in relation to shell formation and bone mobilization, and it is suggested that potentially high secretors of shell calcium are those which have a greater ability to lay down calcium on the bone during periods of low production and a greater ability to remove it from the bones when in high production.

1. The effect of three factors (nitrogen level, time of nitrogen application and weed control) and their interactions on three different plant densities of winter wheat have been measured. Data concerning the growth, development and yield have been examined.

2. Plant populations of 104,000, 155,000 and 281,000 per acre produced on the average of all treatments 21·3, 22·4 and 23·2 cwt. grain per acre, respectively.

3. An increase in nitrogen fertilizer to the 2 cwt. sulphate of ammonia per acre level increased the grain yield of all populations. This response followed an increase in the number of tillers and an increase in the percentage of tillers producing ears. There was no significant interaction between nitrogen level and plant density. The nitrogen content of the grain increased with nitrogen level.

4. Time of nitrogen application did not affect the grain yield, although it did cause considerable differences in the growth and development of the plants. There was no significant interaction betweentime of application and plant density. The late application of nitrogen produced a lower yield of straw and a higher nitrogen content in the grain.

5. Weed control increased the grain yield of all plant populations, this increase following an increase in the number of ears per plant. There was a significant interaction between weed control and plant density. Weed control raised the yield of the low plant population by 3·9 cwt. per acre compared with 0·9 and 2·0 cwt. for the medium and high populations. Weed control also increased the nitrogen content of the grain.

6. The only other interaction concerning grain yield which was significant was that of weed control with time of nitrogen application. Weed control increased the yield of the early and late applications but inexplicably reduced the yield of the intermediate date.

7. It is concluded (a) that the experiment provided no evidence that the yield of a thin stand of winter wheat can be increased further by altering normal nitrogen fertilizer application or by altering the time of application of the fertilizer; (b) that for good results weed control is essential where the plant population is low.

Between 1953 and 1955 a series of field experiments have been carried out in Great Britain to assess the effect of sowing date on the extent and the rate of emergence of a number of varieties of maize.

The range of sowing dates was from late March till May. Records were kept of the soil temperatures, these will be reported later, and in certain experiments the water content of the soil was maintained at field capacity. In all experiments a northern flint variety and a southern dent variety were sown, in the first year only flint × dent hybrids were also grown.

There was an increase in final emergence with the later sowing dates. The northern flint varieties were superior to the southern dent varieties, while the flint × dent hybrids occupied an intermediate position. The lower final emergence of the southern dent variety was most marked at the earlier sowing dates.

Differences between varieties in the speed of emergence, taken as the number of days from sowing until half of the surviving seedlings had emerged, was observed at several centres. The open-pollinated varieties usually emerged more slowly than the flint × dent hybrids. There was a very marked difference between early- and late-sowing dates in speed of emergence.

It was possible in the second year to compare seed of high quality with that of low quality as determined by the ‘cold test’ of germination capacity. The lowquality seed gave greatly reduced final emergence, the experiments stressing the need for the adoption of a standard ‘cold test’ for maize seed, especially of that intended for sowing in north-western Europe.

The high final emergence of the northern flint varieties suggest that a gene source for resistance to soil pathogen attack is readily available. The possibilities in north-western Europe for expansion of growing grain maize would be greatly strengthened by development of varieties capable of growth at low temperatures. The experiments suggest that until such varieties are available little advantage in time of emergence will be gained by sowing maize before late April in Britain.

1. When Cheviot ewes were fed a daily ration containing about 5 g. of calcium during pregnancy and lactation there was a loss of 6·5% of skeletal mineral by mid-lactation. Two months after the end of lactation this loss was fully replaced.

2. When the daily calcium allowance was about 2 g. the loss was 18·2% by mid-lactation and was not replaced by 2 months after the end of lactation. However, if the calcium intake was raised to about 5 g. at mid-lactation the skeleton was fully recovered by 2 months after the end of lactation.

3. Resorption was always more marked in certain bones than others, the cervical vertebrae, skull and mandible being more sensitive than the ends of the radius and metacarpal and these ends more sensitive than the shafts. This follows the pattern of resorption reported in Part I of this series.

4. In sheep on low calcium intakes the serum calcium levels rose in early lactation and then fell. If extra calcium was given from mid-lactation onwards serum calcium levels rose to normal. If extra calcium was not given the fall in serum calcium levels continued until the end of lactation, when they rose. Serum phosphate levels had a strong tendency to vary inversely with serum calcium levels.

5. The differences in the mineral status of the skeletons, provoked by differences in dietary provision of calcium of the order used in this experiment, were readily seen in radiographs of flesh-free bone. Differences of this magnitude could not be accurately identified in radiographs of live animals.

The effects of inbreeding of the sow and plane of nutrition after mating on litter size at 28 days were investigated.

Outbred Large White sows were mated at first heat after weaning to inbred boars, and inbred sows to outbred boars, so that both groups of sows carried the same type of embryo. The sows were then placed at random on either high or low planes of nutrition until slaughter 28 days later, when their corpora lutea and number of embryos were counted.

Litter size was significantly higher in outbred than in inbred sows by 2·52 ± 0·93 pigs. This resulted from 2·89 ± 0·94 more ova shed and 0·37 ± 0·93 more embryos dying. The general conclusion is that inbreeding of the sow reduces early litter size mainly by depressing ovulation rate.

The different planes of nutrition produced negligible differences in within-litter mortality and, therefore, on litter size, but resulted in a marked difference in conception rate. All animals on the high plane were pregnant, whereas on the low plane 25% were empty, this difference being highly significant.

Age of the sow, but not her weight, was found to be significantly correlated with number of corpora lutea (r = 0·39). The latter had a correlation with litter size of 0·55 and with mortality of 0·45. The correlation between litter size and mortality was −0·50.

Parity increased and inbreeding reduced the length of the uterus which was not, however, significantly correlated with litter size.

Often the ultimate measure of performance in a field experiment is the product of a gross weight and a factor relating to quality, as when yield of dry matter is determined from gross yield and percentage dry matter. Since the factor is usually much less variable than the gross yield, yet relatively troublesome and expensive to determine, the practice of making independent estimates of it in every experiment involves diversion of an appreciable part of the total expenditure to a measurement whose inaccuracy will affect only slightly the final experimental error.

Proposals are made for determining the quality factor on only a fraction of all the experiments of one series and applying the averages to the gross yields of others in the same series; formulae and tables relating to the most economic ratio of incompletely to completely recorded experiments are presented.

In a co-ordinated experiment involving twenty centres and 558 pigs it was found that the growth rate, efficiency of food conversion and carcass quality of the pigs were not affected when one after-noon meal was omitted each week throughout the fattening period, provided the amount of meal thus saved was distributed between the remaining feeds during each week.

Limited evidence is presented to show that similar results may be obtained when two afternoon feeds are omitted each week.

A field experiment to test effects of cultural treatments on eyespot (Cercosporella herpotrichoides Fron.), lodging and yield of winter wheat, begun in 1952 (Salt, 1955), was continued on the same site in 1953. In 1952 only eyespot and lodging were severe, but in 1953 take-all (Ophiobolus graminis Sacc.) and weeds were severe also.

Squareheads Master 13/4 and Cappelle, each sown at 1½ and 3 bushels/acre, were top-dressed at four different dates with ammonium sulphate at 0, 2 and 4 cwt./acre. Sulphuric acid (12½% b.o.v. at 100 gal./ acre) was sprayed on four of the eight blocks of ten plots in March to control eyespot.

Halving the seed rate decreased the percentage of severe eyespot from 63 to 52%, decreased the area stunted by take-all from 36 to 14% and increased yield by amounts ranging from 8·3 cwt. in nitrogendeficient plots to 2·6 cwt./acre in plots well supplied with ammonium sulphate. The fertilizer applied to Squareheads Master at 0, 2 and 4 cwt./acre had little effect on the incidence of eyespot lesions at harvest, but increased the area lodged from 23 to 53 and 60% respectively; it decreased the area stunted by takeall from 47 to 19 and 10% respectively, and increased yield from 13 to 17 and 18 cwt./acre. Cappelle did not lodge and the fertilizer decreased take-all patches from 51 to 28 and 18% respectively, and increased grain from 15 to 20 and 21 cwt./acre. The time when nitrogen was applied to either variety had no important effect on disease incidence or yield.

Sulphuric acid sprayed in 1953 on blocks unsprayed in 1952 and so having a higher initial infection of eyespot and weeds, decreased the area lodged and the area covered by weeds, but did not decrease the percentage of straws with eyespot below that in unsprayed plots.

The paper describes the results of over 300 factorial experiments carried out in each factory area in the years 1934–49 for the Sugar Beet Research and Education Committee of the Ministry of Agriculture as a result of co-operation between Rothamsted workers and the agriculturists and fieldmen attached to the beet factories. All the experiments tested the effects of levels of nitrogen, phosphate and potash, and rather more than half tested the effect of salt also.

Except on fen soils, nitrogen gave substantial responses in all factory areas, especially in the presence of high levels of potash or salt. Large variations in response from season to season were closely associated with the rainfall of the preceding winter months, responses being greater after wet winters than dry ones.

In spite of some selection of sites in favour of greater responses, the average net returns from phosphate were relatively small.

The effect of potash was closely linked with the amount of nitrogen applied; in the presence of nitrogen, dressings well above the level of 1·2 cwt. K2O per acre tested in the experiments are likely to give a useful net return. Soils derived from the Chalky Boulder Clay seem to be exceptional in showing no response. Apart from this, there were only small variations in responses to nitrogen and potash between factory areas. The application of 5 cwt. salt gave substantial responses in almost all parts of the country, whether or not potash was also applied; on the other hand, responses to potash were usually small when salt was also applied.

Whilst there was a general relationship between soil analysis for phosphate and potash (citric acid method) and crop response, adjustments to the optimal dressings according to soil analysis were not of sufficient reliability to be of much practical value.

1. The results of a survey of the methods of milk production on a random sample of farms in four counties of England and Wales were used in conjunction with bacteriological and keeping quality tests of the milk produced, to estimate the influence on milk quality of factors in equipment and technique.

2. Of the many factors in technique investigated, only the sterilization of utensils and the cooling of the milk appeared to affect milk quality. The effects of these two factors differed in some degree with the four tests used.

3. Milk samples from machine-milked herds had significantly greater thermoduric colony counts than samples from hand-milked herds. No other factor of equipment showed appreciable association with milk-quality tests.

4. Brief recommendations are made about the conduct of any future field survey of factors affecting bacteriological and keeping quality of milk.

1. Three contrasting varieties of spring oats were grown at six centres in England and Wales for three seasons, at two levels of manuring. They were harvested at two stages of ripeness, and both straw and grain were analysed for all treatments.

2. Varietal differences in composition between samples of straw grown under similar conditions and harvested at comparable stages of ripeness were negligible. In this respect there was no relationship between quality of straw and that of grain.

3. Differences in composition attributable to environment were very large. Crude protein content ranged from 1·9 to 7·6%, and crops grown under cool and wet conditions always yielded a better quality straw than those grown under the warmer and drier conditions in the south of England.

4. The chemical composition of oat straw changed very little between the early ‘binder-ripe’ stage and the fully ripe ‘combine’ stage, although physically it tended to become more brittle and less attractive in appearance. The grain also showed little change in composition between the two times of harvesting.

5. A spring dressing of 2 cwt. per acre of nitrochalk increased the protein content of the straw very considerably, but the response varied widely with conditions. The average increase at all centres over three years was 20%.

6. Under cool and moist conditions the composition of oat straw was comparable with that of meadow hay.

1. Methods of estimating water retention in the body of cattle are discussed, and it is shown that methods based on determinations of the initial and final body-water content are of low accuracy and are not suitable for the indirect estimation of fat balance over a period of 24 days.

2. Analyses of tissues from young and adult cattle showed that with the exception of serum, brain, skin and bone, water content of the tissues may be predicted from the following equation:

Water(g./100g.) = 0·292 Na(mg./100g.) + 0·147 K(mg./100g.).

This equation shows that 1 m.equiv. of the Na of tissues is associated with more water than is 1 m.equiv. of the K.

3. No differences between cattle aged from less than 1 week to more than 5 years were observed in the relationship between water and Na and K content.

4. The equation applied also to the contents of the digestive tract, other than those of the abomasum which gave low results, ascribed to the presence of a high concentration of H+ ions.

5. Analyses of whole foetuses for Na, K and H2O showed that their water content could be predicted accurately. The same was true of amniotic fluid, but the water content of allantoic fluid was underestimated by 50%.

6. It was shown that despite the anomalous behaviour of brain, serum, skin and bone, accurate predictions of the water content of the animal could be made from simultaneous determinations of Na and K retentions, providing a correction was made for the storage of bound Na in bone.

7. Data are presented which indicate that the equations apply equally well to the tissues of the sheep.

Information on how growers actually manure their crops is available from the Survey of Fertilizer Practice, carried out by the Provincial Soil Chemists of the N.A.A.S., in collaboration with Rothamsted. These data indicate that, taking into account the nutrients in farmyard manure, the average amounts of nitrogen and potash applied are not far from the optimal amounts suggested by experiment, whilst phosphate dressings are on the average at least double requirements. This may be due in part to the fact that few compounds are available with a low ratio of phosphate to other nutrients.

Except in one or two factory areas the use of salt on sugar beet is still very limited.

1. Sixty Large White pigs in ten blocks of six litter-mates were individually fed on six different planes of feeding. Three groups were fed according to live weight and according to three different scales, and in the other three groups the pigs were given as much food as they would eat in 30 min. at two feeds daily up to a maximum of 7·0, 6·5 and 6·0 lb./day respectively. All pigs received the same meal mixtures.

2. Although the groups being fed according to the various scales took slightly longer to reach bacon weight, they utilized their food more efficiently than the groups fed on the ‘to appetite’ systems. Thus the pigs fed according to the scale shown in Table 1, but up to a daily maximum of 6½ lb. meal/pig, required about 35 lb. less meal to reach bacon weight than those pigs fed ‘to appetite’ up to a maximum of 7 lb. meal/day. The saving in food costs at present-day prices was approximately 10s. per pig.

3. The percentages of grade A carcasses were very high in all groups, but there was a marked tendency for the ‘to appetite’ fed groups to have thicker midback and loin fats, the latter being reflected in the poorer commercial grading results.

4. The importance of interpreting the results in the light of the influence of the strain of pig, environment and type of diet fed on the question of plane of feeding, was emphasised.