An account is given of methods which have been employed in laboratory and field studies of the actions of rolls on the soil. These studies have revealed little that is remarkable or unexpected concerning the actions of rolls on the soil, but they have clearly demonstrated that the exact actions of rolls differ widely according to the circumstances in which they are employed. When rolling is carried out in field experiments, it is necessary to perform tests to measure the exact effects produced on the soil. In this way it should gradually become more apparent when and how rolling is likely to be beneficial.

Of the methods which have been described, the last two, viz. tests of the consolidation, moisture content and tilth by means of a sampling tube, and of the mechanical resistance to the penetration of a probe with the automatic “resistance” recorder, are well adapted to use in field experiments. These methods are being used in many field experiments involving cultivations, and it is hoped that it may at some time in the future be possible by such methods to relate cultivations and crop yields through a knowledge of the soil structure.

In the accompanying article attention is drawn to a source of error which arises in grading coarse and fine sand subsequent to dispersion. The method of mechanical analysis in which the error arises, and to which the writer refers, is the revised official method adopted several years ago by the Agricultural Education Association(1). The usual procedure is to wash the dispersed soil on to a No. 70 I.M.M. sieve with a jet of hot water, and to rub it gently with a rubber pestle or the finger until no more will pass through. Robinson(2) states that this rubbing is generally unnecessary. The writer has found, however, that even prolonged washing and rubbing with a rubber pestle are ineffective in removing all the fine sand. In the wet mixture the sands are held together closely by surface tension. In order to overcome this, it would seem reasonable first to dry the sieve and its contents at 105° C. and give a further light sieving. This has been done with a large variety of soils, and it has been found that an extremely high proportion of fine sand is withheld when working with certain soils. The amount of fine sand sieved out of the dried mixture increases or decreases in proportion to the amount of total sands present. This is illustrated in the accompanying graph (Fig. 1), where it is to be noticed that, in soils increasing in total sands from 50 per cent (or thereabouts) upwards, the error begins to assume serious proportions.

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.

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

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

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

Experiments have been conducted on heavy gault clay and on a gravelly loam to determine the effects of rolling and harrowing autumn-sown wheat in spring. It is concluded that rolling has no effect on yield on such soil types. In general, harrowing also had little effect on yield, although on three occasions it significantly increased the weight of grain per ear in excess of the increment to be expected from its effect on ear number.

1. Digestibility determinations of broad bran, straight-run middlings and fine middlings are here reported.

2. On the basis of these determinations bran would appear to be a relatively dear feeding stuff for use with poultry, as compared with the finer grades of milling offals.

3. In the case of chick feeding mixtures, the finer milling offals suffer from the disadvantage of causing pasting in the mouth, this disadvantage militating against their too extensive inclusion in chick feeding mixtures. From the evidence obtained in these experiments it would appear that this disadvantage would come into play when more than 40 per cent of the total mixture consists of the finer offals.

4. From the point of view of economy and efficiency of utilization, a mixture of bran and middlings would appear to be of more value than either of these foods fed separately.

5. The inclusion of bran in chick feeding mixtures would appear to be justified on dietetic grounds, in spite of its relatively poor value measured by digestibility trials.

6. From a biological standpoint, bran and bran-weatings mixtures appear to be definitely superior to wheat itself when used exclusively as a source of food and supplemented with 1·5 per cent cod-liver oil and 2 per cent oyster shell.

The associated growth of peas and different non-legumes (barley, oats, wheat, and potato) was investigated both under sterile conditions and in ordinary pot cultures. In the former case the medium consisted of quartz sand, and in the latter of clay or sandy loam soil, poor in soluble nitrogen. It is shown that nitrogen was transferred from the pea nodules to the non-legumes.

In sterile cultures, where the excreted amino-acids cannot undergo decomposition, oats, wheat and barley utilized only a part of the excreted nitrogen, generally less than 50 per cent. In some instances, however, the barley took up considerably over 50 per cent of the excreted nitrogen. There was an apparent accumulation of aspartic acid in the medium of the associated cultures. In pot cultures, where the amino-acids may have been broken down by contaminating micro-organisms, the transfer of the excreted nitrogen to the potato exceeded 90 per cent.

All experiments show that with increasing ratio of non-legumes to legumes the growth of the peas suffers, obviously from lack of nitrogen. Under these conditions, the excretion from the nodules increases to such an extent that the peas receive only a small fraction of the nitrogen fixed by the nodules. The major part of the carbohydrate material furnished by the pea for the amino-acid synthesis in the nodules is excreted into the medium. This naturally causes disturbances in the growth of the pea.

Experiments have been carried out from 1930 to 1935, to investigate the composition, digestibility and yield of meadow hay cut at a normal time, and also of hay cut some 3–5 weeks earlier. Due consideration has been given to the “aftermath” growth occurring on the areas cut for the early hay between the times of cutting of the early and ordinary hay.

As was expected, the early hay, being less mature, was of better composition and digestibility than the ordinary hay. The average crude protein contents were 12·2 and 7·9 per cent of the dry matter respectively.

The yield data, average of 5 years, are summarized below, stated as lb. per acre, the early hay values including the aftermath yields.

The digestibility for poultry of a variety of huskless oats recently placed on the market has been investigated, and a comparison made with a widely grown variety of more usual fibre content.

It was shown that the fibre of the huskless oats was completely undigested, while that of the control variety had a digestibility coefficient of 8·8 per cent.

The digestibility of the crude protein in huskless oats was higher than in the variety Victory. It is suggested that this difference has resulted from the same cause as that which operates in ruminants, whereby fibre has a depressant effect on protein digestibility.

Both the organic matter and N-free extract were digested to a greater extent in the huskless oats than in the control variety. This is in keeping with the findings of other workers on the relation between fibre content and the digestibility of these constituents.

In the process of manufacture of sugar from sugar beet, the sugar is first extracted from the beet by appropriate means, and the wet residue or pulp is then dried and sold for cattle feeding. The composition of the dried pulp or slices differs somewhat according to the nature of the process used in the extraction of the sugar. In the “diffusion” process, in which water is used, the extraction is very efficient, with the result that the sugar content of the dried pulp is low. In the Steffen process, in which press methods are used, a fair amount of sugar is left in the dried residues. In the de Vecchi process the sliced beets are dried before the extraction of the sugar takes place, and a certain proportion of these slices is occasionally marketed on the Continent as cattle food. The characteristic differences between these three types of pulp are shown by analyses given by Fangauf and Waldow(1).

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.

1. The solubility of the phosphorus of soils and of other phosphatic materials in solutions of sodium hydroxide has been investigated. A method for the extraction and determination of the soluble phosphorus is described.

2. With acid soils, especially when the exchangeable calcium has been removed by leaching, an approximately constant amount of phosphorus is extracted by sodium hydroxide solution of strengths from 2 per cent to 20 per cent. The soda-soluble fraction amounts to 90 per cent of the total phosphorus.

3. Soils containing free calcium carbonate vary in the solubility of their phosphorus in sodium hydroxide solutions. Some behave similarly to acid soils, whilst others show only a small fraction of their total phosphorus to be soda-soluble. The extraction is complicated by the presence of calcium carbonate, which can precipitate from solution compounds which, in its absence, are soda-soluble.

The composition, both organic and inorganic, and the digestibility of three grades of meat meal of widely differing fat content have been investigated. Large White hogs were used in the digestion trials.

The methods of manufacture of the meat meals have been described. They contained, on the basis of dry matter, 18·8, 11·1 and 3·2 per cent of fat respectively.

All three grades had a very high digestibility. The digestion coefficient of the main constituent, namely, the crude protein, ranged from 87·9 per cent in grade C (low fat) to 93·9 per cent in grade B (medium fat), these values comparing satisfactorily with the corresponding value for white fish meal, namely, 90·2 per cent.

The pigs digested the fat of the meat meals very efficiently. The fat of the grade A meat meal, forming 18·8 per cent of the dry matter, was digested to the extent of 95·4 per cent.

The grade B meat meal (medium fat) was the most digestible of the three grades tested. This is the grade that is marketed for feeding to livestock. The slightly lower digestibility of grade A (high fat) is attributed to the influence of the high fat content in causing a slight lowering of the extent to which the crude protein is digested.

The grade C meat meal (low fat) was produced from the grade B by “de-greasing” with petroleum benzine at 300° F. The results suggest that this process may result in a distinct lowering of the digestibility of the meal. The grade C meat meal is the most comparable with white fish meal in both digestible and mineral composition. In comparing the meat meals with white fish meal, however, it must be kept in mind that the former contain a much higher proportion of non-protein nitrogenous material.

The present paper records some investigations on the growth of the clover- and pea-nodule organisms (Rhizobium trifolii Dangeard and Rh. leguminosarum Frank), and the nitrogen fixation of the pea, at low temperatures. Growth of the bacteria was studied with pure culture experiments in large flasks, in which the bacteria were grown on a solid gelatine medium. The amount of nitrogen in the bacterial mass thus obtained was used as the basis of comparison. The fixation of nitrogen by peas was studied with a pot-culture experiment in a relatively cold greenhouse. Inoculated plants were grown in quartz sand, and were supplied at an early stage with mineral nitrogen either as Ca(NO3)2 or (NH4)2SO4. The plants were harvested after flowering and analysed. The main results of these experiments were the following:

(1) Pure-culture experiments with five strains of clover-nodule bacteria and four strains of pea-nodule bacteria showed that at 6–13° C. the strains imported from more temperate climates grew distinctly less well than did the northern European strains. Even between the Swedish and Finnish strains there were clear differences: the latter formed the more bacterial matter in the cold. It may be appropriate to consider such differences when selecting cultures for inoculating leguminous crops.

(2) In the pot-culture experiment, the application of mineral nitrogen (30 mg. N per plant) to inoculated peas kept at relatively low temperatures had very little effect on the amount of dry matter produced. The slightness of this effect was similar to what has been previously observed in experiments at more favourable temperatures. Nitrogenous fertilization slightly lowered the amounts and percentages of total N present as protein and amino nitrogen, in the crop; but nitrate application somewhat increased the nitrate content of the crop. Hence, it may be concluded that, even under these low-temperature conditions, the application of artificial nitrogen has not had a favourable effect on the size or quality of the crop.

Although silage Has Been Made in this country for more than 50 years, the exact nature of the chemical and bacterial changes which occur during the period of ripening is still very imperfectly understood. There are several reasons for this.

(1) The chemical changes are compounded of those due to plant respiration and those brought about by bacterial growth, and since these take place to a large extent simultaneously, it is difficult to apportion the amount of the total change to each factor separately.

(2) There is good reason to believe that the extent and rapidity of the changes which occur in the body of the silo are influenced by such variable factors as the external temperature, the moisture content, botanical species and age of the crop, and the season of the year when cut.

(3) They are also dependent upon the method of packing at the time of ensiling, since this ensures more or less anaerobic conditions, and will therefore affect both the nature of the plant respiratory changes and the kind of bacterial flora which develops.

An account is given of a preliminary experiment on artificial insemination of cross-bred Merino sheep in Kenya. 202 ewes were inseminated and 74·3 per cent conceived. The practical application of artificial insemination to sheep breeding in Kenya is discussed.

The water consumption was determined of thirty-seven Large White suckling sows that were tethered on grass. The mean consumption was 43 lb. a day, the variation between sows, and of particular sows from day to day, being particularly wide. The consumption was practically unaffected by weather and was nearly the same in summer and winter; it was impossible to demonstrate any relation between consumption and number or weight of litter, but there was evidence of a slight decrease as lactation progressed.

It is evident from a brief discussion that exact balance experiments as to the partitions of water for its various uses in the body of the pig are badly needed. It is hoped that the facts given here may draw attention to this point which has been neglected in animal nutrition studies.

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 the pH 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 the pH 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.

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.