A sand-culture experiment with inoculated lucerne was made to test the effect of increasing doses of sodium nitrate upon the yield and nitrogen content of tops and roots, and upon the number and development of nodules. The pots were divided into six series receiving from 0 to 10 gm. of sodium nitrate per pot containing 12 kg. of sand.

There was no correlation between yield or nitrogen content of the lucerne, and the dose of nitrate.

The number of nodules, though unaffected by 1 gm. of sodium nitrate, was progressively decreased by the stronger doses.

The length of nodules was reduced about 30 per cent, by 1 gm. of sodium nitrate, and decreased progressively with stronger doses.

Nodules were found to show a definite relationship between their overall length and the volume of contained bacterial tissue. Using this relation, the mean volumes of bacterial tissue per nodule and per pot for each series were calculated. The reduction effected by nitrate was far greater when measured in this way, owing to the small contribution of bacterial tissue derived from nodules less than 1·5 mm. in length.

An experiment was carried out with two groups of ten cows each, made up of two Guernseys, two Ayrshires, two Friesians and four Shorthorns.

The experiment was of the change-over type, the experimental period of 20 weeks being subdivided into four periods of 5 weeks, each cow alternating between the two treatments.

In two of the periods a normal winter ration of roots, hay and concentrates was fed. In the other two periods artificially dried grass replaced a proportion of the concentrates, an average of 8 lb. being fed per head daily. The two types of ration provided equal amounts of starch equivalent and protein equivalent, but the carotene intake was greater in the “dried grass ration”.

A statistical analysis of the difference in milk yields due to the contrast “Dried grass” v. “Control” revealed no signs of any effect, and if any actual effect does exist, it is quite negligible for the 5-week periods of this experiment.

The paper records the results of an investigation into the composition, digestibility and nutritive value of marrow stem kale (both unthinned and singled-out) and thousand head kale. A number of the main findings are recorded below.

The average dry-matter content of unthinned marrow stem kale during September and October was 13·3 per cent. During the following January it had reached a slightly higher level, namely, 14·2 per cent. Singling out of the marrow stem kale appeared to exercise little effect on the dry-matter content of the crop. Thousand head kale, with an average dry-matter content of 15·8 per cent., is significantly richer in dry matter than the marrow stem kale, although this advantage was offset by the lower yield, in terms of green matter, given per acre by the thousand head kale.

(a) A comparison was made between the catalytic efficiency of selenium and of copper sulphate in the Kjeldahl method as applied to the analysis of grass. The same value for total nitrogen was eventually obtained by both methods, but with selenium it was reached some 90 min. earlier than with copper sulphate.

(b) The clearing of the digested matter was no criterion for deciding whether all the nitrogen in grass had been converted to ammonium sulphate, maximum values not being obtained with selenium until between 2 and 3 hours afterwards.

(c) The catalysts were compared for three samples of soil with digestion periods ranging from when the digested material first cleared to 32 hours afterwards. The selenium figures showed an increase for the first 3 hours, and then remained constant up to the 32-hour period. The copper sulphate figures, however, showed a steady increase for the first 24 hours, after which they became constant at the same values as those reached earlier by the selenium figures.

The results show clearly a more rapid and greater uptake of ammonium than of nitrate nitrogen by perennial rye grass grown in a sand-bentonite medium of pH 7·61. The extent to which the extra uptake with added ammonia was reflected in increased yields was dependent upon the age of the grass.

Except in the very early stages the percentage nitrogen content of the herbage was higher where nitrate nitrogen was applied than where ammonium nitrogen was applied. This indicates that any nitrate absorbed by the plant was less, efficient in increasing yields than was ammonium nitrogen.

The percentage P205 content of the grass was higher where the nitrogen was applied in the ammoniacal form than where it was applied as nitrate, and it appears that this greater P205 uptake with ammonium nitrogen resulted in increased growth.

An investigation of the relative importance in small plot pasture productivity experiments, of plot variations and of field and laboratory errors in sampling and subsampling for percentage dry matter and percentage nitrogen figures, revealed little advantage from duplicate sampling or subsampling in reducing the experimental error, which was due mainly to plot variation.

The effect of sampling errors was of even less importance in the estimation of the actual yields of dry matter or of nitrogen.

It has long been held that the treatment of grassland with nitrogenous fertilizers, and especially with ammonium salts, reduces the clover content. This method has been applied also to the treatment of lawns and sports fields with a view to reducing the clover content of the turf. It has been suggested that the effect of the ammonium salts is to encourage the growth of the grass in competition with the clover, and also that the ammonium ions are specifically toxic to the clover plant. Since there is a growing volume of evidence that ammonium ions are, in fact, available to many plants and may be used by them directly, without nitrate-formation, it was thought desirable to examine the effect of the application of ammonium sulphate to clover plants grown in pots, where competition from grasses was not a factor in the consideration of the effect of manurial treatment.

These observations have shown that the strains of Azotobacter occurring in certain Malayan soils are unable to initiate growth on standard media, except after a lag phase of considerable duration. Evidence has been obtained which suggests that this inability is not necessarily an indication of a scarcity of the organisms in the soil used as an inoculum, but may be due to factors associated with the composition of the culture medium.

In particular the strains of Azotobacter developing from these soils are checked by the presence of calcium carbonate in the medium. They will grow well in a medium in which calcium chloride replaces calcium carbonate, but equally well where the medium contains but traces of calcium.

These strains can tolerate a wide range of hydrogen-ion concentration extending on the acid side to pH. 3·6. Their existence invalidates the use for these soils of all such microbiological tests of lime requirement as make use of Azotobacter as indicator.

The effect of the air content of the medium on the development and function of the nodule was studied with sterile cultures of peas inoculated with their appropriate strain of nodule bacteria.

In water cultures the plant grows well without added nitrogen, even though all nodules are submerged, if air is bubbled through the medium during the period of growth. Abundant nodulation occurs also in nonaerated liquid cultures; the nodules, however, are much smaller than in aerated cultures, and the plant grows poorly. Subsequent aeration of such cultures results in a distinct increase in the size of the nodules and improvement in the growth of the plant.

Nodulation is completely prevented by passing a stream of gaseous N through the medium. That oxygen is indispensable for the function of the nodules is shown also by the fact that the peas grow excellently on added nitrogen in non-aerated cultures.

The effect of different cutting practices on the carbohydrate root reserves of Finnish red clover was studied. Cutting causes a rapid decrease in the insoluble sugars. The minimum is reached in about 12–15 days, independently of the time of cutting. However, the initial carbohydrate level is reached much more quickly in autumn than in June-July. The carbohydrate content of the roots in autumn is higher the later the second cut.

Cutting does not significantly affect the content of sucrose and other soluble sugars, the values for which are very low during June-August, but rise towards autumn.

1. Two methods of castrating male lambs have been compared—the Burdizzo and knife methods. No difference was found in subsequent growth rate.

2. Two methods of docking male and female lambs have also been compared—searing and crushing with the Burdizzo. No difference was found in subsequent growth rate.

3. There was a tendency for ram lambs to have a higher initial weight than ewe lambs, and their rate of growth between the ages of 2 and 10 weeks was definitely greater than that of ewe lambs.

A description is given of the statistical procedure appropriate for the analysis of a Latin square having missing the whole of one row, one column or one treatment, or one row and one column, or either and a treatment. These are the only types of incomplete Latin squares (except those which can be dealt with by the missing plot technique) for which a neat statistical analysis is possible.

It is shown that incomplete Latin squares of these types give unbiased estimates of error and are therefore valid experimental arrangements. They are consequently likely to be of use when the experimental material is such as to preclude the use of a complete Latin square owing to the fact that the number in one or both of the natural groups is one less than the number of treatments to be tested.

1. Over a period of six years seven field experiments were carried out to study the effect of the time of application of sulphate of ammonia to autumn-sown wheat.

2. Three experiments were located on light gravelly soil which had been farmed highly for some years, and in those three cases sulphate of ammonia decreased yield, irrespective of time of application; the reduction in yield was of the order of 10 per cent. and is ascribed to more lodging and greater incidence of “foot-rot”.

3. Three experiments were located on heavy clay soil in poor condition; in these sulphate of ammonia gave percentage increases in yield of 18, 20 and 7.

4. Evidence is produced that early dressings of sulphate of ammonia do not affect germination or plant establishment, but that they tend to increase tiller formation by the end of February.

1. A comparison is made of Δ for the blood of sheep with Δ for the contents of the stomach compartments. It is suggested that the approximate identity of the two sets of values is best explained by the view that absorption takes place from the compartments.

2. A variation of 0·570–0·630 is recorded for Δ for the blood of sheep.