1. A sample of marine silt taken from the foreshore of the N.W. coastal belt of the Wash was found as the result of a mineralogical examination to contain dolomite in its mineral assemblage.

2. It was surmised from this discovery that should dolomite be a normal constituent of soils derived from marine silts, its presence might modify in them certain processes such as nitrification in which the neutralising effect of a quick acting base is an essential factor.

3. This supposition was strengthened by certain culture experiments on nitrification, and was to some extent established as a fact by a detailed chemical investigation into the nature of the carbonate content of several soils of known geological and agricultural history.

Soil fertility is often spoken of as though it were an absolute property of the soil; in reality it is a particular relationship subsisting between soil conditions on the one hand and crop growth on the other. The conditions conducive to soil fertility are the resultant of two main groups of factors, the intrinsic properties of the soil which are dependent on its chemical, physical and biological nature, and those extrinsic properties impressed on the soil by topographical and climatic factors*. These two groups cannot be sharply distinguished from each other, nor can any hard and fast line be drawn between the various factors comprised in them, because few are at present susceptible of exact measurement. In other words, that particular group of conditions that make up the fertility of a soil is an equilibrium brought about by the interaction of numerous factors some of which however can be varied by the agriculturist by manurial and cultivation operations.

The methods used for the determination of — log [] fall naturally into two groups:

(a) Electrometric, and

(b) Colorimetrie methods.

Electrometric methods were first introduced into analytical practice in 1897 by Böttger(l) who determined the neutral point in titrating acids with alkalis by using a gas chain; subsequent improvements were made by Hildebrand (16), Gumming and Gilchrist(10); Hasselbalch(15), W. M. Clark(6), Michaelis(19), Walpole(28, 29) and others. The method has been applied to the measurement of [] of biological fluids with considerable success*. It was first applied to the measurement of [] of soil suspensions by G. Fischer (12) in Germany in 1914 and subsequently in America by Sharp and Hoagland(23), and by Gillespie(13, 14) and his co-workers.

The early authorities, Mulder, de Saussure, Berzelius and others, considered the whole of the precipitate obtained by adding acid to an alkaline extract of soil to be humic acid,—a single substance to which they assigned a definite formula. Hoppe-Seyler and others found, however, that the precipitate was not homogeneous; a portion dissolved in alcohol, which he named hymatomelanic acid. It was from this that Schreiner and Shorey isolated a number of organic acids, all of which were either colourless or only faintly coloured.

It was early noticed that soil on treatment with a solution of an alkali yielded a dark coloured solution which gave a black flocculent precipitate on acidification. Decomposing vegetable matter behaved in a similar way.

The feeding of concentrates after scalding with, boiling water and given to cows in winter in a sloppy condition at body temperature, increased the yield of milk by about 1 Ib. per head per day over the yield produced when the concentrates were fed in a dry state. The increase diminished with the advance in lactation.

The warm mashes produced a distinct laxative effect.

The animals took to the wet mashes better than to the dry meals.

When the concentrates were fed as dry meals in a ration containing 30 Ibs. roots with fodder and the drinking water taken from a trough in the yard, the coat of the animals got out of condition. With a change to the wet meal or when the drinking water was accessible in the byre, the coat regained its condition again.

An improved water supply did not appear to affect the milk yield.

The percentage of milk fat increased as the milk yield decreased.

Dairy equipment includes a boiler, therefore little, if any, additional capital outlay should be necessary for scalding the meals.

On an average 3·5 Ibs. of water were assimilated to 1 lb. of milk produced in a normal winter ration (see p. 89). The ratio varied with the feeding, the temperature and the period of lactation.

Drinking water and water consumed in the food amounted to about ten gallons daily, and of this between 50 and 60 per cent, was drinking water. The amount increased with an increase in the yield of milk and with a rise in the temperature. The smaller cows also consumed a relatively larger proportion of drinking water. From 25 to 30 per cent, of the total intake of water was contained in the mille.

The feeding of a large weight of roots (112 Ibs.) with meals and fodder caused the animals to scour badly. The health and the condition of the animal were also adversely affected. The milk yield which had shown a tendency to increase was converted into a definite decrease. There was an increase in the percentage of fat, although the total weight produced diminished. The fall in the milk yield was partly though not immediately arrested by a change to a moderate root ration and there was a decided increase in the percentage of, and in the total yield of, fat. Heavy root feeding would therefore appear to depress fat formation, though the supply of nutritive material in the food as judged by the usual method of calculation was not diminished.

The total weight of water consumed for 1 lb. of dry matter in the food amounted to 3·9 lbs. with the heavy and 3·3 lbs. with the moderate root ration. Some of the cows took water daily amounting on an average to between 5 and 6 per cent, of the total intake of water while on the heavy root ration.

Preliminary data relating to temperature and milk secretion were given.

Ayrshire cows were employed in the experiments.

The late Lieutenant H. A. Wyllie, B.Sc. was in charge of the 1913–14 experiment and Mr Hugh M. Young of the 1914–15 experiment. Determinations of the percentage of total solids in the milk were made by Mr Peter Caldwell.

Any additional expenditure incurred in carrying out these experiments was defrayed by the Board of Agriculture for Scotland.

During the past fifty years there have been many records of the damage done by this pest to wheat and rye on the continent.

The first record in this country is by Ormerod(i) in 1882 in wheat. She says “there is good reason for believing that it was present to a serious extent before.” Since that time numerous complaints of serious damage to wheat have been recorded in various parts of the country, but the eastern counties of England and parts of Scotland have suffered most and the intensity of the attack has varied enormously from season to season.