1. At the completion of a 50-year cycle of continuous cropping with both wheat and barley on a light sandy soil at the Woburn Experimental Station, soil samples from all of the plots were analysed for replaceable bases.

2. The soil had little or no calcium carbonate originally and comparison with early soil samples showed that the unmanured plots lost about half of their replaceable calcium in the 50 years. The loss of calcium was much greater on plots with ammonium sulphate, and the crops failed completely in about 20 years. Plots with sodium nitrate or farmyard manure retained considerably more calcium than the unmanured plots.

3. Plots with mineral manures, essentially superphosphate and potassium sulphate, had less replaceable calcium in the earlier years but more in the surface soil at the end of the experiment than those without mineral manures. The effect of superphosphate was so slight that for practical purposes it may be regarded as without effect on the replaceable bases.

It may be concluded from this trial that the making of stack silage is a useful method of conserving surplus grass, particularly of the after-math type, when good haymaking weather may not obtain. Though no actual feeding trials were carried out with the silage, it was fed to stock with satisfactory results and formed a large proportion of their winterration.

1. Six per cent. peroxide is found to be unsuitable as a reagent for the determination of the “degree of humification” of soil organic matter, as it oxidises not only compounds containing carbon and nitrogen but also a varying amount of a substance containing carbon but no nitrogen, this amount depending on the volume of reagent used and the total amount of carbon originally present in the quantity of soil employed.

2. There are apparently two phases in the attack of peroxide on soil organic matter. In the first phase, material containing carbon and nitrogen is oxidised, whilst in the second phase the material oxidised consists solely of nitrogen-free carbon compounds.

3. By the use of 3 per cent. peroxide (2 per cent, or less may be preferable for some soils) the attack on soil organic matter can be restricted to the first phase. The material thus oxidised appears to be built up by the association of a protein complex with a carbohydrate complex of high carbon content. Its carbon-nitrogen ratio is about 10:1.

1. The analytical methods of Tattersfield, Hobson and Gimingham(6) and Gnadinger and Corl(1) for the determination of the pyrethrins in pyrethrum flowers are compared, and certain modifications in technique suggested.

2. Good concordances have been obtained between analytical data and insecticidal tests employing Aphis rumicis.

3. A new method for the rapid and approximate evaluation of unadulterated samples, employing small quantities of material, is described.

4. Observations on the pyrethrin content of individual flowers in the various stages of development are recorded, making use of a modification of the method indicated under (3).

The results of a number of experiments carried out at Hillsborough on the growth of chickens, covering two seasons and involving 45 groups of 30 to 100 chickens, are discussed with particular reference to the variability of the live weights. It is concluded that the weights of cockerels or pullets taken separately should not show a standard deviation very much greater than 15 per cent. of the mean weight for the group, unless the experimental treatment or other conditions have seriously interfered with the rate of growth. It is pointed out that comparisons of mean weights and of standard deviations may be misleading unless cockerels and pullets are considered separately. Smallest significant differences between the mean weights of groups are tabulated for standard deviations of 15 per cent., 17·5 per cent, and 20 per cent., and for groups of 10 to 100 birds.

From the herd book records of six leading breeds of cattle in Great Britain (Shorthorn, Aberdeen-Angus, Hereford, Ayrshire, Jersey and British Friesian) the ages of the parents of 2618 pedigree calves born in 1925 were tabulated.

The average age of cows at calving is found to be 5·722 years ± 0·04, with a standard deviation of 2·816. In four dairy breeds the average age is 5·485 years ± 0·05, while for the three beef breeds it is 6·022 ± 0·05.

The “annual replacement percentage” is the number of heifers drafted annually into a herd or breed as first calvers expressed as a percentage of the total number of actively producing cows in the herd or breed. It is in effect the number required annually to make good the losses, and can be calculated from the average age of the cows at calving. This is found to be at least 27 per cent. and agrees substantially with the work of other investigators.

1. These field experiments show that equilibrium after applications of lime may be attained on arable land between one and two years later.

2. The quantitative correcting effects of a given dressing seem to be about equal on different soils.

3. Added calcium carbonate is quickly converted into exchangeable calcium base to an extent which depends on the individual soil.

1. The Woburn field experiments on wheat after green manures are briefly reviewed. Contrary to the original expectations the wheat was less good after two summer crops of tares than after two mustard crops. This result was obtained many times and in recent years the wheat yields were extremely low after both green manures.

2. Regular soil analyses for nitrate and ammonia through 1928 and 1929 showed that the mean nitrate content was extremely low (1·2 parts of nitric nitrogen per million of soil). During the cold dry winter of 1928–9 the ammonia nitrogen was several times greater than the nitrate nitrogen.

3. Further evidence of an acute nitrogen deficiency during the critical period for the wheat plant in May and June was afforded by the large responses to top dressings of sodium nitrate both in the 1929 and the 1930 wheat crop.

Silage has been made satisfactorily in a pit from grass cut at the flowering stage when it was impossible to make hay. The digestibilities of all the constituents compare favourably with meadow hay with the exception of the protein which shows a depression.

The silage is richer in starch equivalent than meadow hay, if compared on a dry matter basis, and equal in digestible protein content to poor meadow hay though not to good meadow hay. It is therefore better to make grass silage when weather conditions are bad rather than attempt to make hay which, under such conditions, would be of poor quality.

The silage was used within four weeks of being made and was eaten readily by dairy cows on grass.

1. An alizarin-adsorption method discovered by Schmelev has been successfully applied, with suitable modification, to the identification and approximate estimation of the free sesquioxide components of clays and soils.

2. Details of the tested procedure are presented, together with some preliminary results obtained.

3. The free alumina component of clays and soils appears to adsorb alizarin only after ignition, whereas the free iron oxide component adsorbs it only in the fresh, unignited state. Hence, by applying the procedure to the fresh, as well as to the ignited material, an approximate estimate of both components may be accomplished in a relatively short time.

The object of this series of investigations is to secure detailed information concerning the composition, digestibility and nutritive value of pasture herbage in its different stages of growth. The results which were obtained in these respects by cutting the herbage of the experimental pasture plot at weekly, fortnightly and 3-weekly intervals have been described in previous communications. During the seasons of the present investigations (1929 and 1930), the trials have been carried a stage further by the adoption of a system of cutting at monthly intervals. The results, therefore, are invested with special significance, in that a period of four weeks has been tentatively adopted in this country as the interval which is allowed to lapse, in rotational grazing practice, between successive grazings of pasture enclosures.

The writers do not mean to infer that the maintenance requirement of the adult sheep, as calculated by Wood and Capstick, is incorrect. The value obtained by these investigators is probably as reliable as any other which could be calculated from their data. The writers fully agree that Wood and Capstick's value is probably more accurate than previously estimated values of the maintenance requirement of the adult sheep.

Keen and Coutts(8) and Coutts(1) have suggested that the percentage of water in a soil at the sticky point is related to the colloidal content of the soil, as measured by “loss on ignition,” in the following manner:

S = mI + c,

i.e. by a rectilinear equation, and point out that the figure obtained for c approximates to the theoretical percentage of water held in the interstitial spaces of an ideal soil.

There is still much difference of opinion as to the effect of temperature on milk production from the point of view of its effect on both quantity and quality at successive milkings or on successive days.

1. The use of freshly prepared solutions of sodium hypobromite instead of boiling hydrogen peroxide solutions in the pretreatment of soils for mechanical analysis by the pipette method has the following advantages:

(a) Soils containing manganese dioxide or large amounts of organic matter may be oxidised rapidly without heat, whereas oxidation of such soils by hydrogen peroxide is a tedious operation requiring large amounts of reagent.

(b) Possible changes in the clay through heating and the dissolution of considerable amounts of sesquioxides are avoided.

(c) The reagents are cheaper and more stable, especially in the tropics.

(d) It makes possible further simplification in the technique of mechanical analysis.

1. Five typical British Guiana soil profiles, derived under humid tropical conditions from igneous rocks of different silica contents, are described, and the results of their detailed petrographical, chemical and ecological examination are presented and discussed.

2. Each kind of rock has produced a sandy, acidic, nutrient-deficient surface soil, but the katamorphic changes that have occurred during rock alteration, weathering and leaching have been fundamentally different.

3. The basic and intermediate igneous rocks have given rise within the zone of alteration to “primary gibbsitic laterite”, covering the parent rock in a thin crusty layer. Within the zone of secondary changes, the laterite has been resilicated, presumably through the agency of ground water containing soluble silica or alkali silicates (partially in the more basic rock profiles, and completely in the intermediate types), into kaolinitic earths, coloured yellow and red by hydrous iron oxides. Residuary gibbsite and iron oxides have accumulated in the more basic profiles as concretionary gravelly masses.

Recent work on the solubility of manganese compounds in the soil, leading to a general consensus of opinion that the solubility of this element is intimately controlled by the soil reaction and by the oxidation-reduction equilibrium, is shown to have an important bearing on the availability of this element to plants. This has been established by means of laboratory tests and pot experiments on three different soil types, characteristically deficient in available manganese. It has been shown that normal plant growth can be established on such soils either by increasing the acidity of the soil or by subjecting the soil to reducing conditions such as those brought about by high water saturation or temporary waterlogging. On these soils the increases in growth amounted to several hundred per cent. These responses are in every respect similar to those obtained by the application of manganese sulphate to the soils.

1. A simple form of two-compartment electrodialysis cell is described for the determination of replaceable bases in sets of six soils at a time. The determination requires little attention and the total replaceable bases are obtained by direct titration.

2. The disturbing influence of water-soluble salts is examined and it is shown that the technique may be modified so as to exclude the kations of soluble salts from either the total bases as determined by direct titration of the dialysate or from the individual bases as determined by analysis.

This paper describes a uniformity trial with irrigated broadcast rice and shows the large inter- and intra-field variation which exists.

The standard deviations decrease with the increased size of plots and vary from 20–1 per cent, with 1/436 acre plots to 7–8 per cent, with 1/22 acre plots.

The decrease of the standard deviation is small with plots larger than 1/87 acre. This size of plot is considered to be the most practicable for field trials.

The influence of proximity to bunds, irrigation channels and drains on increasing yields is discussed and methods of reducing errors due to this cause are suggested.

It is shown that the use of a Latin square extending over more than one field has not produced a more accurate experiment than the use of randomised blocks. The latter method would therefore appear to be the more suitable for manurial and other trials, under the particular conditions of rice growing.

1. The antimony oxide electrode has been applied in a simple form to measure the pH value of soils.

2. The pH values of representative Australian soils have been determined by means of the hydrogen, quinhydrone and antimony oxide electrodes and the results compared.

3. The limitations of the quinhydrone electrode have been investigated and their nature elucidated, special attention being paid to alkaline and manganiferous soils.