1. Phosphorus in hydrochloric acid extracts of soil may be conveniently determined by digestion with sulphuric and nitric acids.

2. By boiling soil with hydrochloric acid (B.P. 110° C.) for 48 hours under reflux an end-point of extraction is reached.

3. Digestion of soil with sulphuric and nitric acids gives results in agreement with results by 48 hours” hydrochloric acid extraction.

4. It is suggested that the phosphorus thus extracted represents a definite category of soil phosphorus, which may be taken as the total phosphorus present in the soil.

5. Details of the suggested method are given.

An experiment has been carried out with dairy cows to measure the value of artificially dried grass, silage made with added molasses and A.I.V. fodder (silage made with mineral acid in quantity sufficient to bring the pH of the mass to between 3·0 and 4·0) in the diet, on the yield and quality of the milk. A preliminary period of 3 weeks when all cows were on the control diet was followed by an experimental period of 17 weeks. There were four treatments: a control ration consisting of hay, roots and concentrates; one in which artificially dried grass replaced part of the concentrates; a third in which molassed silage was fed; and a fourth including A.I.V. fodder. There were originally five blocks of four cows each, the four treatments being randomised in each block, each block of cows standing together in the cowshed to eliminate any possible effect of position. One block went dry after 8 weeks, but the remaining four blocks completed the experiment.

In continuation of earlier work (2) on the destruction of annual weeds in cereal crops some thirty-four replicated experiments have been carried out during 1934 and 1935 in widely different localities. Besides sulphuric acid, nitric acid, ammonium and sodium hydrogen sulphates and ammonium thiocyanate were tested, while the effect of a wetting agent was also studied.

In every experiment the solution was applied by means of a knapsack sprayer at the rate of 100 gallons per acre. In general at the time of spraying the weeds were in the seedling stage, and the cereal crop not more than 6 in. high. Counts of the weed density were made in order to estimate the degree of control, while in the majority of the trials the yield of the cereal was determined.

Sulphuric acid at a concentration of 9·2 per cent. (1 gm. H2SO4 per 100 c.c.) gave a 90 per cent. control of Brassica arvensis (average of nine experiments) and when a 13·8 per cent, strength was used it gave a 95 per cent, control of Raphanus raphanistrum (average of eight experiments). Nitric acid at equivalent concentrations was slightly but significantly more effective in three out of nine trials for the eradication of these two species. Ammonium hydrogen sulphate (21·6 per cent.), sodium hydrogen sulphate (23·6 per cent.) or ammonium thiocyanate (3–10 per cent.) did not, on the whole, compare favourably with sulphuric acid. Decreasing the concentrations of sulphuric acid by a third resulted in a less effective destruction of Brassica arvensis or Raphanus raphanistrum. This loss of efficiency at the lower concentrations was not corrected by the addition of a wetting agent (Agral 1 at 0·1 per cent.); similar results were obtained for nitric acid.

The effect of applying a nitrogenous fertiliser to wheat at seven different times and three rates, was studied in pot culture. It was found that the later the time of application the smaller was the increase in the yield of total dry matter and of straw. The increase in the yield of grain, on the other hand, was constant for the first six times of application, the last of which was made on May 25, but a later application made after ear emergence produced no increase.

Analysis of the grain yield showed that early application produced its effect by increasing the number of ears per plant. Later applications caused a smaller increase in ear number, but also increased the number of grains per ear and 1000-corn weight. There was no evidence of a critical time for tiller formation such as has been postulated by Doughty and Engledow.

The increase in total nitrogen uptake was equal for all times of application, but the ratio of nitrogen in grain to nitrogen in straw and chaff was greater, the later the time of application.

The writer wishes to thank Messrs A. M. S. Clarke, G. T. Detlefsen and S. A. W. French for much help with the experimental work, and Mr R. G. Warren for making the nitrogen determinations.

Experiments were carried out in four successive years to compare the plough and the cultivator as implements for preparing a seed bed for wheat after potatoes: in the last two years direct drilling was introduced as a third treatment. Very diverse conditions were experienced, and an attempt has been made to formulate practical recommendations.

A new method of arranging variety trials involving large numbers of varieties is described. This type of arrangement, for which the name pseudo-factorial arrangement is proposed, enables the block size to be kept small without the use of controls.

Various possible types of pseudo-factorial arrangement are discussed in detail and the necessary formulae developed. The appropriate methods of computation are illustrated by numerical examples based on the results of a uniformity trial on orange trees. It is shown that pseudofactorial arrangements are likely to be more efficient than arrangements involving the use of controls. In cases where there is considerable soil heterogeneity they are also markedly more efficient than randomized blocks containing all the varieties. In the chosen example gains in efficiency ranging from 26 to 57 per cent, were obtained.

The paper gives an account of the results obtained from the data provided by the first three years of the Sampling Observations on Wheat of the Crop-Weather Scheme.

Section I describes the Sampling Observations on Wheat of the Crop Weather Scheme which have been initiated in order that the effect of weather conditions may be studied at all stages of the wheat crop’s growth from germination to maturity.

In Section II several curves are given which illustrate the progress of the wheat crop. The shoot-number curves bear a marked resemblance to one another subsequent to the period when the shoot number is a maximum in spite of the wide divergences which exist between the maximum shoot numbers themselves.

Section III indicates the statistical processes involved in the analyses given in the succeeding sections.

Sections IV-VIII are devoted primarily to discussions of the effects of various meteorological factors on specific stages of the crop’s growth. The following results have emerged:

The length of the interval from sowing to appearance above ground is shown to be largely dependent on the mean soil temperature during this interval, the relation being well expressed by a quadratic regression. The growth rates of the plants at this time are shown to be in good agreement with those which would be obtained by applying Van ‘t Hoff’s law. Neither the rainfall nor the variation in temperature during the period appear to affect its length.

Squarehead’s Master appears above ground consistently later than Yeoman, but the amount of this lag is apparently uninfluenced by variations in soil temperature.

1. In recent papers which refer to the use of covariance there has still appeared an occasional lack of understanding of this method of statistical analysis. There have, for example, been references in the literature to methods of analysis which the writer has used in certain problems as if they were in competition with the use of covariance as described by Fisher (1, 2). It would therefore seem to be of value to indicate briefly the different situations in which covariance may prove of use, in order that the distinction between some of these situations may be clearly realised.

1. Some observations on the serum phosphatase of the domestic fowl are described. Laying hens, held to be normal birds, had higher and more variable serum phosphatase than cocks. No great difference in serum phosphatase could be found between laying hens and hens in a period of suspended egg production. Pullets from another source and which had never laid gave values comparable with the value for cocks.

2. The serum phosphatase of chicks shows a rapid increase to a maximum at about 10–12 days after hatching, followed by an equally sharp fall to a lower level at 3 weeks. Thereafter, the values for male birds fall regularly until maturity. The values for female birds correspond closely with the values for male birds until the onset of laying, when they increase again, but to a varying degree in different individuals.

3. An attempt to reduce the range of variation of serum phosphatase in laying birds by administration of 1 ml. per bird per diem radiostol B.D.H. (3000 international units vitamin D per ml.) was not successful.

4. Serum phosphatase showed a much greater increase during laying in pullets receiving a low calcium ration (0·37 per cent. CaO) than in pullets receiving the same ration supplemented with calcium carbonate (3·10 per cent. CaO).

5. Serum phosphatase is greatly increased in chicks suffering from rickets.