1. A long-term investigation consisting of field, pot and laboratory experiments has been commenced to study the extent, rate, nature and significance of phosphate fixation in north Scottish soils with the ultimate objects of improving fertilizer practice and standardizing methods for determining readily soluble phosphate.

2. Quantities of a phosphate-deficient soil derived mainly from granitic drift were treated with incremental dressings of phosphate and exposed in earthenware pots in the open. The soil had an initial pH of 5·80 and a total phosphate content of 0·250% of which 28% is soluble in constant-boiling HCl solution.

3. The recovery of added phosphate by different methods from samples taken after varying periods of exposure has been studied. Data are given for extractions with calcium lactate, acetic acid, potassium bisulphate, citric acid, magnesium bicarbonate, sodium hydroxide, hydrochloric acid, and chloride and sulphate solutions, together with pot experiments and determinations by the Neubauer and aspergillus methods.

4. Complete recovery is approached only in strongly acid and strongly alkaline extracts, and about 25% of the added phosphate is very firmly bound by the soil. The solubility varies greatly with the pH of the extracts and is very low at pH values in the region of 5. At lower pH values, however, the nature and concentration of the anions present are also of considerable importance. The results indicate a high capacity for fixing phosphate in difficultly soluble form.

The blood picture for Ca, inorganic P and phosphatase during the development of rickets caused by uncomplicated vitamin D deficiency in sheep has been established. The earliest and most distinctive change was found to be in the serum Ca level.

Lambs were shown to have sufficient reserves of vitamin D to protect them against avitaminosis D for a period of about 6 weeks as judged by serum Ca levels. Rickets did not develop unless there was a moderate degree of growth and, in such cases, the serum Ca level was below 7 mg./100 ml.

The practical application of the results was discussed.

The authors desire to acknowledge the co-operation of Dr A. H. H. Fraser in the earlier planning of this work.

A comparison is made, under similar cultural conditions in pot experiments, of the behaviour of a number of varieties of wheat, barley, rye and oats on two soils on which oats had previously displayed pronounced symptoms of manganese deficiency.

All of these cereals were found to develop disease symptoms on these soils, rapid recovery from which invariably took place after the plants had been sprayed with 1% manganese sulphate solution. Variations in deficiency symptoms in the different cereals are indicated and observations on the course of the disease throughout the season are recorded for some thirty-two varieties.

An account is given of experimental work on the feeding of uncooked and cooked potatoes and sugar beet to laying stock. The available literature on the use of these foods for poultry is reviewed and an explanation is offered for the poor results which have generally followed the use of raw potatoes.

A description is given of an experiment in which there were two control groups fed on mash, two groups on 3 oz. mash and 8 oz. potatoes daily, uncooked for one group and steamed for the other, and two groups on 3 oz. mash and 8 oz. sugar beet daily, uncooked in one case and steamed in the other.

The influence of two years of bare fallow on the fertility of light land exhausted by continuous cropping with wheat or barley for fifty years has been very great, the immediate result being an increase in the crop of wheat by 50% and of barley by 140% over the average yield of the unmanured plots for the ten years before the fallow was taken. A repetition of the fallow after a further period of five years of continuous cropping without manure gave a very similar result.

Whatever had been the treatment of the land during the fifty years before the fallowing, the yield produced as a result of the bare fallow fell off very rapidly in the succeeding years, when no further manuring was given. In fact, after the first two or, at most, three years the crop, of grain went much lower than it had been before any fallowing had taken place. This falling off in yield was almost equally felt on plots which had been treated with artificial manures during the preceding fifty years as on those which had been unmanured throughout.

1. Evidence is presented in support of the view that the average daily retention of calcium from the food by the laying fowl is of the order of 50% of the intake for average daily intakes of about 1–3·5 g. calcium.

2. It is suggested that the optimal calcium requirement of the laying fowl for sustained heavy production lies in the region of 4 g. calcium daily, and that of the standards proposed by Mitchell & McClure (1937) that based on a 50% utilization is more nearly in accord with the results of metabolism experiments.