(1) Exchangeable magnesium and potassium can be determined in carbonate-free soils by the use of 0.5 N acetic acid as a leaching agent.

(2) A method is described for the determination of the total exchangeable bases present as acetates in the leachings.

(3) The results obtained by this method differ from those obtained by summation of separate determinations by an amount equivalent to the sulphates and chlorides present.

(4) It is suggested that the total exchangeable bases by the proposed method gives a truer measure of the exchangeable bases than methods in which bases present as sulphates and chlorides are also reckoned in.

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

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

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

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

Finally it is a pleasure to record our indebtedness to Dr R. A. Fisher for much valuable advice and criticism: and to Mr H. J. G. Hines for assistance with the field work.

The conclusions of the 1927 experiments in spacing have been tested in greater detail in 1928 and are confirmed.

From the 64-plot scheme containing a series of spacings in quadruplicate the following points emerged:

(1) Variation of the width between the rows influenced the yields of sugar beet roots, the expectation of highest yield being on the narrowest spacings. There was a significant increase in yield to be gained by using 15” or 18” spacing instead of 21” or 24”. On the other hand width between the rows did not seem to influence the yield of tops and crowns.

(2) Variation of the distance between plants in the rows up to 10” had no significant effect on the yield of roots. There was some evidence that above that figure a reduction in yield took place. It is interesting to note that in the case of the tops, spacing between the plants influenced the tonnage. There was a significant difference between the yields on the 4″ and 8″, and 4″ and 10″, but not between the 4″ and 6″, 6″ and 8″ or 8″ and 10″ spacings.

(1) In absence of decomposing organic matter addition of nitrate led to no loss of nitrogen.

(2) On addition of small quantities of fermentable matter such as glucose there was (a) rapid depletion of nitrates and oxygen, but no denitrification, and (b) increase in acidity, carbon dioxide and bacteria. The greater part of the soluble nitrogen was assimilated by microorganisms or otherwise converted and the greater part of the added carbohydrate was transformed into lactic, acetic and butyric acids.

(3) The organic acids were formed from a variety of carbohydrates. Lactic acid was the first to be observed and appeared to be formed mainly by direct splitting of the sugar. It decomposed readily, forming acetic and butyric acids. Some acetic acid was formed by direct oxidation of lactic acid, with pyruvic acid as the intermediate product. All the acids were, on standing, converted into other forms by micro-organisms.

Methods for extraction, concentration and determination of minute quantities of soluble carbohydrates, lactic acid and volatile fatty acids have been described. Different factors affecting the accuracy of the determinations have been studied and corrections, where necessary, have been suggested.

The results of an investigation into the utilisation of sugar-beet pulp by ruminant animals were brought forward in a recent publication (I). It was demonstrated that sugar-beet pulp is highly digestible when consumed by ruminants. In respect of the digestibility of its N-free extractives and total organic matter, it compares very satisfactorily with maize meal. The process of drying the wet beet pulp in the factory does not depress its digestibility. Further, from the standpoint of digestibility, it is immaterial whether sugar-beet pulp is included in the rations of ruminants in the dry or the soaked condition. When, however, liberal allowances of the dried product are being fed to animals, it is desirable that the food should be well softened in water before feeding. This procedure ensures a higher availability of the digestible nutrients for productive purposes in the animal and also averts risk of choking trouble which sometimes arises, especially with sheep and lambs, during consumption of the dried beet pulp.

Though it is neither customary nor perhaps desirable to utilise sugar beet for feeding purposes, it is conceivable that circumstances might arise occasionally when a farmer would be desirous of feeding the whole or part of his beet crop. This is indicated by the fact that enquiries as to the value of sugar beet for pigs are received from time to time. During the carrying out of the investigation into the value for pigs of dried sugar-beet pulp and molasses-sugar beet pulp, an account of which work is given in this issue of the Journal (1), the opportunity was taken of making a similar study of whole sugar beet. A dual investigation was made, consisting of a digestion trial under the conditions of the metabolism room and a large-scale feeding trial under ordinary farm conditions. It was hoped that the evidence from this twofold line of enquiry would not only settle the question of the value of sugar beet in the feeding of pigs, but also throw light on the subject of the value of root crops in general for swine.

The scheme of soil classification which finds most favour among scientists to-day has come from Russia and is the work of a band of brilliant and enthusiastic investigators whose labours have brought some order to what was otherwise chaos. The object of this communication is to endeavour to show how it is possible to modify the views of this school so as to make them apply to British conditions, and how the majority of British soils may be brought within the envisaged scheme.

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

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

(b) Thick pastes.

(c) Weak suspensions.

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

It has been shown that dried sugar-beet pulp contains a high percentage of pectose. A number of successive digestions of 1 hour each with 0·5 per cent. ammonium oxalate at 100° C. extracts an amount of pectin equal to 34·5 per cent. of the weight of dried beet pulp, basing the determination on the weight of crude pectin precipitated when the extracts are run into 95 per cent. alcohol. A single prolonged digestion gives a yield of crude pectin equal to 32·2 per cent. of the dried beet pulp.

Digestion with acidic reagents, such as 0·5 per cent. oxalic acid, 0·6 per cent. tartaric acid, N/20 hydrochloric acid, etc., leads to a quicker extraction of pectin, owing to a speeding up of the pectose to pectin hydrolysis. The yield of pectin, however, is not thereby necessarily enhanced, since under such conditions the pectin undergoes a slow secondary hydrolysis during the extraction with the formation of reducing substances not precipitated by alcohol.

Prolonged digestion at 100· C. of dried sugar-beet pulp with water alone also leads to a satisfactory extraction of pectin.

The severe climatic conditions under which cotton is grown in the Gezira make it desirable to establish relations between meteorological data and irrigation practice. By means of a rapid and fairly accurate balance it is practicable to measure water loss when small boxes containing moist soil are exposed for short periods and under different conditions. The scope of this method has been ascertained by preliminary experiments as to (1) the dependence of water loss on moisture content of the soil, (2) the distribution of water loss through the day, (3) the comparison of water loss from sand and from. Gezira soil, and (4) the comparison of water loss from shaded and unshaded soil. The application of data so obtained to field problems is facilitated by the fact that in respect to distribution and amount losses from soil are related to loss shown by a Piché evaporimeter. Within the canalised area alternation of irrigated and fallow land is responsible for local variations in atmospheric conditions. A daily fluctuation in the moisture content of surface soil from fallow land is recorded and may be instrumental in favourably modifying its physical properties. The heat of wetting of Gezira soil has been measured.

(1) A gasometric method for the determination of organic carbon in soils by the use of sulphuric-chromic acid mixtures at 100° C., as suggested by Watts in 1902, is described, and recommended for use in routine soil analysis.

(2) The method is compared with the Kjeldahl procedure recently introduced by Robinson, McLean and Williams, and is found to give results which are generally similar, though numerically slightly lower.

(3) The wet combustion method is somewhat simpler than the Kjeldahl method, but it has the disadvantage that nitrogen determinations cannot be made simultaneously, so that its usefulness in studies on soil organic matter is decidedly less.

(1) Soil surveys are classified into (i) preliminary reconnaissance surveys, (ii) broad ecological surveys, (iii) detailed physiological-ecological surveys, and (iv) special-purposes surveys. The objects of each are briefly discussed.

(2) Particular consideration is given to the methods of physiological ecology, which attempt to assess the chief soil factors controlling plant growth.

(3) Soil factors are grouped into (A) static factors, which do not fluctuate appreciably during a growing season, and (B) dynamic factors that may exhibit marked fluctuations within a season, or during years when climatic conditions vary.

(1) The physiological effects of calcium-deficiency on pregnant sows are briefly discussed. Results are given which demonstrate that a deficiency of lime in the food has no detrimental effect on the live weight of the young piglings at birth thus showing that up to parturition it is the mother organism that suffers and not the offspring.

(2) Storage of nitrogen takes place throughout pregnancy but the results indicate a considerably enhanced conservation within three weeks of parturition. The average daily retention of nitrogen by the high-calcium group of sows was 12·51 gm. and by the calcium-deficient group 9·78 gm. The normal sows therefore stored 1439 gm. N and the calcium-deficient 1125 gm. N during the gestation period. It is shown that storage of protein during pregnancy is greatly in excess of the foetal requirement, so that the mother organism, during gestation, adds on a reserve supply of protein in preparation for parturition and lactation.

(3) Ash ingredients were retained at all stages of gestation by both groups of sows. The addition of calcium carbonate to the food, however, resulted in an increased retention of ash. The percentage of the ash intake in the faeces was very similar in both groups, but the percentage of the intake in the urine was distinctly higher in the calcium-deficient sows indicating a more economical utilisation of ash by this group.

(1) Animals on a calcium-deficient diet suffer periodically from loss of appetite though the ration is in every other respect satisfactory.

(2) The results of twenty-two digestion trials show no enhanced effect on the digestibility of the organic constituents of the food on adding calcium carbonate to a lime-deficient ration.

In conclusion, I wish to express my thanks to Prof. T. B. Wood, F.R.S., for giving me the necessary facilities to carry out the work; to Mr H. R. Davidson, M.A., for placing the experimental animals at my disposal and also to Dr H. E. Woodman for his active interest and supervision at all stages of the work.

(1) The mineralogical composition of the fine sand fraction of certain soils from the south-east of Scotland is described.

(2) The soils are shown to possess a fairly high content of silicate minerals in a comparatively fresh state.

(3) The distribution and amount of potash, phosphate and lime-bearing minerals in the soils is discussed.

(4) The soils can be grouped according to their mineral content and this grouping is found to depend on the geology of the parent material.

(5) All the soils are formed on glacial drift and the results suggest that the local rocks have a preponderating influence on the composition of the matrix of the drift.