1. The proximate analysis of a number of widely differing soil profiles has been carried out, employing a slight modification of the scheme used by Waksman and Shewan. This included a nitrogen fractionation with water and acid, similar to that of Waksman and of Shewan. It was supplemented by ammonia and nitrate estimations. The data are expressed on the basis of total organic matter.

2. The soils ranged in quality from peat and forest soils to grassland profiles. This gradation of quality was brought out by many of the figures of the proximate analysis. The better quality soils are associated with:

(a) a lower average content of fats and waxes, hemicelluloses and cellulose;

(b) a rapid decrease in cellulose with increasing depth;

(c) higher total nitrogen and various fractions, including higher ammonia and nitrate and a higher ratio of nitrate to ammonia;

1. The decomposition of the organic matter of four medium to large-scale composts has been studied by analysis of samples taken at intervals.

2. The bulk materials of the composts were grass-cuttings, oat-straw, Sphagnum peat and an Eriophorum and Sphagnum peat. All were made up to the same nutrient-content and relative water content.

3. The analytical method used was a modification of the scheme of proximate analysis used by Waksman and by Shewan. It was supplemented by ammonia and nitrate determinations, using Olsen's method.

4. Observations.

A. All composts.

(i) An increase in ammonia, water-soluble nitrogen and water-soluble organic matter took place during the first month.

(ii) Only low nitrate concentrations were developed.

(iii) Very closely parallel changes in H2SO4-soluble nitrogen and residual nitrogen were recorded.

(iv) Other nitrogen changes can be described as slight and on the whole as mutually compensating fluctuations.

There are many areas throughout Britain where soil parent materials cannot be differentiated on the basis of solid geology alone, and difficulties are frequently experienced in classifying and mapping the soils. The object of this investigation was to study the parent materials and soils in a complex area of this kind.

The area selected is in north-east Scotland, and about half of it is covered by acid igneous and metamorphic rocks and the rest by sedimentary rocks of Old Red Sandstone age. The geology is complicated by three glaciations giving rise to diverse soil parent materials.

Five main groups of parent materials have been recognized, based on origin, texture and mineralogical composition. The first group consists of drift derived from acid igneous rocks and schists; the second of boulder clay from similar material plus an admixture of sedimentary rocks; the third of fluvioglacial deposits of varied textures; the fourth of conglomerate or thin drift from Old Red Sandstone rocks; and the fifth of boulder clay derived from Old Red Sandstone rocks where the influence of marls and shales in the drift is strong. Groups 1 and 5 are of major importance in this region and also elsewhere because of their widespread distribution. The others are more local.

In April 1938 I published a method for the determination of carbon in soils (Alper, 1938). This method consists of digesting the soil with a mixture of sulphuric acid and potassium bichromate, passing the products of combustion through a heated combustion tube and absorbing the carbon dioxide produced in barium hydroxide. Digestion and absorption take place in a closed system which allows neither the escape nor entrance of carbon dioxide. The absorption flask is evacuated and separated from the digestion flask by a glass tap. During the process of digestion, as the pressure in the system increases, this tap is manipulated, allowing the escape of gas into the absorption flask. A pressure gauge in the system indicates when the tap should be opened.

The sensitivity of this mercury pressure gauge causes some difficulty in technique. It is necessary to watch the experiment throughout the digestion and to manipulate the tap constantly. In order to obviate this difficulty an improvement in the apparatus has been effected. The pressure gauge has been replaced by an elastic bladder (a child's balloon serves the purpose admirably) which is connected to the system by means of a glass ┬-piece. At the commencement of the experiment the pressure within the system is slightly less than atmospheric owing to the suction of CO2-free air through the apparatus. This causes the complete deflation of the balloon. As digestion continues the balloon becomes distended. The distension of the balloon must not be allowed to go too far as too great a pressure in the system will result in losses through leakage.

Rotation of crops is based in most countries upon the accumulated experience of past years; experiments testing the relative merits of various rotations are rarely resorted to unless some serious disturbance arises, such as the inclusion of a new crop. But in the Sudan Gezira (lat. 14–15° N., long. 33–34° E.) the need for rotation experiments was urgent, since growing cotton by artificial irrigation was a recent introduction, and, moreover, the soil was known to be intractable. Any improvement in rotation which would allay seasonal fluctuation in yield and raise the general level would greatly add t o the prosperity of the area.

Thus when the Gezira Research Farm was inaugurated in 1918 some unreplicated plots of various two-course rotations, and of continuous cotton, were laid down. These were supplemented in 1925–6 by a replicated trial comparing various three-course rotations, designed by E. M. Crowther of Rothamsted. Later, in 1931–2, a new ‘Combined Rotation’ experiment, designed by M. A. Bailey and E. M. Crowther, was added, and this comprised comparisons of one-, two-, three- and four-course rotations. These last

McLean's shorter method of H2SO4-HNO3 digestion of the soil for total P2O5 failed on some red soils from Ceylon, although Hall's HC1 method gave satisfactory results. The cause of failure of the McLean method was interference by the larger quantities of various bases extracted by H2SO4-HNO3.

After first separating the total phosphoric acid as ferric phosphate, McLean's method produced results closely agreeing with those obtained by Hall's method. Total phosphates were separated by first neutralizing the acids in the soil digest and then precipitating the HC1 solutions of the neutralized product by sodium acetate and acetic acid. On boiling, all the phosphoric acid in the soil extract was separated as ferric phosphate. HNO3 solution of this ferric phosphate when precipitated in the usual way gave a clean yellow precipitate of ammonium phospho-molybdate.

H2SO4-Se served as a good substitute for H2SO4-HNO3 in soil digestions and the results obtained were substantially the same as by Hall's method or by the modified McLean's method. H2SO4-Se digestion has certain advantages, such as the possibility of determining both nitrogen and phosphoric acid on the same soil digest.

When selenium is used as catalyst and the phosphate separated by ammonium acetate and acetic acid, the HNO3 solution of total phosphates produces a white precipitate of a complex ammonium selenito-molybdate along with ammonium phospho-molybdate when precipitated by ammonium molybdate. This defect was eliminated after replacing ammonium acetate by sodium acetate.

Attention is drawn to the unexpected behaviour of selenium compounds of phosphoric acid formed during soil digestion towards the reagents used for precipitating total phosphates.

1. A filter apparatus cannot be relied upon to give a correct reading of the suction of soil water when this exceeds about 400 cm. of water.

2. Owing to the contribution of dissolved matter to the freezing-point depression the suction in a soil of normal low salt content can only be obtained from the freezing-point depression with reasonable accuracy when it exceeds about 4000 cm. of water (freezing-point depression greater than 0–3° C).

3. Suctions in the range 400 to 4000 cm. have been measured with the aid of calibrated absorbers consisting of thin plates of Portland stone.

4. The plates were calibrated up to 1000 cm. by the application of suction through a filter, and above 1000 cm. by measuring the vapour-pressure depression by a new technique.

5. When applied direct to soil, the new vapour-pressure technique is more reliable than the freezing-point method, and can be applied to materials which do not exhibit a well-defined freezing-point.

6. A suitable soil was washed free from salts and brought to 1000 cm. suction on a filter. Measurements of the vapour-pressure depression and the freezing-point depression checked well with the thermodynamic formulae.

The influence upon milk production of changes in level of feeding and in proportion of bulky foods has been investigated, using all available experimental material.

The experimental results show that increases in level of feeding, to rates well in excess of conventional English standards, are capable of giving substantial increases in milk production (Fig. 1).

It is shown that physiological efficiency falls off as food intake is increased. A curve representing physiological efficiency has been constructed by taking account of changes in live weight as well as changes in yield of milk (Fig. 4).

Several cases of ergot in barley encountered in 1941 have been investigated, and records have been examined of the occurrence of ergot in cereal crops in this country during the past 24 years. These indicate that ergot is found more frequently on rye than on wheat, barley or oat, this, in descending order, being their relative susceptibility. A more detailed examination of records of the occurrence on rye in the seasons 1939–42 indicates that the disease is more prevalent in northern districts than elsewhere; of 500 acres of rye surveyed in Suffolk and Norfolk in 1942 only three crops comprising 80 acres showed a trace of ergot. It is rare on both wheat and barley and little is known as to the susceptibility of their varieties, although on several occasions it has been noted on Rivet wheat, and has been recorded on Rivet and Triticum vulgare crosses. In this country there is no record of it having been found on oat, apart from the one specimen found in a field of mixed corn in Cambridgeshire.