The effect of systematic plot distribution upon the estimate of error of a field-plot experiment of 5 × 5 plots has been studied on ninety-one blocks taken from eight different uniformity trials, representing a wide variation in plot size and plot shape, crop, climate, and soil.

The arrangements studied are: two different knight's moves, two different diagonal arrangements, and eight irregular arrangements, seven of which have been chosen at random.

The investigation has shown that the use of systematic plans introduces a bias in the estimate of the error of the experiment. The use of the knight's move arrangement causes an over-estimation of the error, whereas the use of the diagonal causes an under-estimation.

The Papaya tree is common in all parts of India and is grown also in the Philippine Islands, Federated Malay States, Java, Ceylon, and other tropical countries.

1. The mineral content of pastures farmed under the Intensive System of Grassland Management, and representing three to five weeks'growth, from three centres in two seasons, is reported.

2. The lime content fluctuated considerably during the season, but the fluctuations showed no definite seasonal trend. The average seasonal content was practically identical in all cases.

3. The phosphoric acid content showed a definite seasonal variation, falling during drought or the early summer flush period and recovering again after the drought or flush period respectively. The phosphoric acid showed consistently a very highly significant positive correlation with the nitrogen content of the herbage. The bearing of this correlation on the metabolism of the plant and on the phosphatic and nitrogenous manuring of pastures is discussed.

Seventeen samples of pasture collected from May to December, 1929, have been analysed for mineral constituents.

1. The results show that drought conditions seriously affect the mineral composition of pastures.

2. The calcium content showed a slight fall during the months of drought, and a more marked fall in the months of heavy rain from October to December.

3. The phosphorus content fell during the drought period and rose rapidly at the end of the year.

The data collected under the Agricultural Meteorological Scheme of the Ministry of Agriculture have provided information for a number of years in a number of places on the dates of sowing and appearance above ground of wheat, winter oats, spring oats, spring barley, turnips and swedes.

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. 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.

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.

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.

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.

Preliminary experiments carried out in the summer of 1928 had indicated that sampling methods might be used to obtain a satisfactorily precise estimate of the yield of small cereal plots(1). It was thought desirable to test the method more thoroughly, and to compare the estimates with figures obtained by large-scale methods. Accordingly samples were taken from all the plots of the three Rothamsted cereal experiments of 1928, the plots later being harvested with a binder in the ordinary manner. Samples were also taken from the 16 plots of a small experiment on barley at Wellingore, Lines., but no direct measurement of total yield was made for these plots. There were 210 plots in all, but of these 50 were sampled in four sections, corresponding with minor differences in manurial treatment; so that the total number of plots dealt with amounted to 360. The large-scale method, however, treated each of the 50 as a single plot, and thus provided only 210 yield figures.

On the adoption of a sampling method for the estimation of the yield of small experimental plots, the need arose for a threshing machine capable of threshing quickly and accurately the small sampling-units which comprise the sample from an individual plot. These sampling-units contain various numbers of ears from some three or four to twenty or more, and there is no commercial machine which deals adequately with such small quantities of grain. The number of sampling-units from a typical randomised block experiment may amount to 2500, and to thresh and winnow such numbers in two distinct operations would take no inconsiderable time. As a direct result of this, a machine was constructed in which these two operations were successively performed, without the need of handling the intermediate products. It is the object of this paper to describe this machine and the manner in which it was used for this purpose at Rothamsted last season. Wheat, oats and barley were treated, only minor alterations of the size of the screens, the speed of rotation and the strength of the blast for the separation of the chaff being necessary.

1. Four cereal experiments, comprising 210 plots each about l/40th acre in area, were harvested by a sampling method. Three of the experiments were later harvested by large-scale methods, so that a direct comparison could be made.

2. The field technique is described, and an account is given of the small combined thresher and winnower which was constructed for the purpose of dealing rapidly with the numerous small sheaflets.

3. The results are analysed in detail and it is shown that the samplingerrors per plot lie between 5 and 6 per cent. of the mean yield, and that these errors are sufficiently low for there to be little loss of information.