In a former number of this Journal (1), there appeared a report on the mechanical analysis of soils by this sub-committee of the Agricultural Education Association. The report contained proposals for certain modifications of the earlier A.E.A. (1906) method, of which the most important were the introduction of hydrogen peroxide as a dispersive agent in the preliminary treatment, the use of the pipette method for the actual mechanical analysis, and the abolition of the fine gravel (3 mm.–1 mm.) fraction. This report was officially adopted by the A.E.A. and the method of mechanical analysis therein proposed was accepted as the new standard to replace the 1906 method. The full details were published in the Journal of the Association (2).

Conscious selection is the prime means of keeping the useful qualities of domestic animals at the level they have attained, and of improving them. Valuable economic qualities mostly show the polygenic type of inheritance and therefore continued selection can improve them by sorting out those genes in a herd or breed which are.most desirable for the breeder At the presenttime there is probably not one breed in existence with quantitative characters brought to the homozygous condition. It is the great genetic variation present in breeds which enables selection to be effective in bringing out desirable economic characters.

Water buffaloes (Bubalus bubalis) are reared in many tropical and subtropical countries for meat and milk production and to serve as draught animals. The improvement of milk yield in water buffaloes has been handicapped by the absence of physiological data that may provide means of rapid genetic improvement. Endocrine function is known to vary with lactation intensity. Thyroid hormones seem to have a stimulatory effect on the metabolic rate and, consequently, on the productivity of dairy animals (Lenon & Mixner, 1957; Picha, Pichova & Karasek, 1970; Swanson, 1972). Anderson (1969) also reported an increase in thyroid activity in lactating cows and rats, although other investigators (Johnson & Vanjonack, 1976; Hart et al. 1978; Hart, Bines & Morant, 1979) reported that lactation induced a decline in plasma thyroid hormones. None of these studies performed measurement of plasma thyroid stimulating hormone.

In a series of five irrigated cotton sowings (T2, T7, T9, T11, T14) evapotranspiration (Et) was determined for the period between October 1961 and October 1962 by observing frequently the changes in soil moisture storage, calculating through drainage, and solving for evapotranspiration in the water balance equation. Thus a water balance was obtained for each sowing extending over the entire crop.

The average evapotranspiration in wet season sowings was of the order of 6·5 mm day−1 and in dry season sowings of the order of 4·5 mm day−1. The highest evapotranspiration values ranged between 10 and 12 mm day−1 in T2, T7 and T9 and between 7 and 9·5 mm day−1 in T11 and T14.

Nitrosoguanidine-induced mutation frequencies for resistance to streptomycin, spectinomycin, erythromycin and novomycin were studied in Azospirillum brasilense. Lentil inoculated with A. brasilense and its mutants and Rhizobium strains produced increased nodule dry weight, nitrogenase activity of nodules and roots and grain yield compared with an uninoculated control.

The absorption and movement of 14C-labelled maleic hydrazide (2000 mg/1) and 2,4-D (250 mg/1) were studied in seedlings and mature plants of a local strain of onion (Allium cepa L.) from Kano, Nigeria, in the presence and absence of N (20 mg/1).

Plants absorbed and accumulated considerable amounts of both the chemicals. Addition of N to the treatment solution reduced the absorption of 2,4-D. Also, N reduced the mobility of the chemicals from the roots to the tops which resulted in accumulation of the chemicals in the bulbs.

1. The effect of four different planes of nutrition of lambs until they reach 30 1b. dressed carcass weight on the development of the form of the ribs is studied.

2. The growth in length of the ribs is found to be more influenced by age and less by the plane of nutrition than their growth in thickness, and is not reflected in the weight of the ribs.

Data for the quantity of ammo acids consumed and their flow rates at the proximal duodenum for 33 diets fed to sheep have been statistically analysed by both univariate and multivariate methods. Analysis of variance of net loss (g/day) between mouth and duodenum of individual and total acida was not conclusive. Canonical variate analysis which takes regard of the correlations between different acids both within and between diets provided a conoise method of discriminating between diets. The advantage of this method in generating a unified account of digestion within the rumen is that it effectively reduces the problem from one of many dimensions to a situation where only the first few transformed variables need to be considered.

Physiological problems in some Fife dairy herds were thought to be associated with mineral imbalance in grass cut for silage. Consequently trials at two sites were conducted to study the effects of three levels of nitrogen and phosphorus and two levels of potassium on yield and composition of pasture cut for silage.

Nitrogen increased yield of herbage and reduced its clover content whereas phosphorus and potassium had little effect on yield or clover content. Herbage clover content and calcium concentration declined over the period of the experiment. Mean concentrations of calcium, magnesium and phosphorus were 5·8, 1·7 and 3·4 g/kg respectively. Concentrations of these minerals varied more with time of cutting and with season than with level of applied phosphorus and potassium.

Nitrogen tended to reduce calcium concentration in mixed herbage and to increase magnesium concentration in the grass component; it did not affect herbage phosphorus concentrations, but narrowed the calcium-phosphorus ratio in the second cuts. Applied phosphorus increased herbage phosphorus concentration only at the site with the lower soil phosphorus status. Potassium tended to reduce magnesium concentration in clover and, at one site, in mixed herbage; it also tended to reduce herbage phosphorus concentrations in second cuts.

Mineral uptake was increased by applied nitrogen. Mean annual uptake of calcium magnesium and phosphorus was 34, 10 and 20 kg/ha respectively.

The effects of treatments on concentration and balance of these minerals are discussed in relation to ruminant requirements and maintenance of suitable levels of the minerals in the soil.

It is concluded that normal applications of NPK fertilizer are not detrimental to satisfactory mineral balance in pasture.

Between 1953 and 1955 a series of field experiments have been carried out in Great Britain to assess the effect of sowing date on the extent and the rate of emergence of a number of varieties of maize.

The range of sowing dates was from late March till May. Records were kept of the soil temperatures, these will be reported later, and in certain experiments the water content of the soil was maintained at field capacity. In all experiments a northern flint variety and a southern dent variety were sown, in the first year only flint × dent hybrids were also grown.

There was an increase in final emergence with the later sowing dates. The northern flint varieties were superior to the southern dent varieties, while the flint × dent hybrids occupied an intermediate position. The lower final emergence of the southern dent variety was most marked at the earlier sowing dates.

Differences between varieties in the speed of emergence, taken as the number of days from sowing until half of the surviving seedlings had emerged, was observed at several centres. The open-pollinated varieties usually emerged more slowly than the flint × dent hybrids. There was a very marked difference between early- and late-sowing dates in speed of emergence.

It was possible in the second year to compare seed of high quality with that of low quality as determined by the ‘cold test’ of germination capacity. The lowquality seed gave greatly reduced final emergence, the experiments stressing the need for the adoption of a standard ‘cold test’ for maize seed, especially of that intended for sowing in north-western Europe.

The high final emergence of the northern flint varieties suggest that a gene source for resistance to soil pathogen attack is readily available. The possibilities in north-western Europe for expansion of growing grain maize would be greatly strengthened by development of varieties capable of growth at low temperatures. The experiments suggest that until such varieties are available little advantage in time of emergence will be gained by sowing maize before late April in Britain.

Over a period of 3 years 18 autumn-calving, single suckled, April-weaned cows were stocked at three rates at pasture to gain 132, 70 or 25 kg (H, M and L respectively) between April and August and fed to lose 100, 54 or – 13 kg (H, M and L respectively) while housed between November and April, the relative total energy intake over winter being 0·64, 0·83 and 1·00 respectively. Milk yield was reduced by 2·68 kg/day on the H and 1·25 kg/day on the M treatment and as a result calves gained 37 and 10 kg less respectively over winter than on the L treatment. However, despite poorer calf performance economic considerations would indicate a preference for high weight gain during the grazing season and a corresponding loss over winter.

Two pairs of rams with different degrees of scrotal cover were subjected to hot room temperatures ranging from 26.7 to 4.5 °C to study the effect of elevated ambient temperatures on rectal temperature, respiration rate, scrotal length, flank temperature, scrotal temperature and intra-scrotal temperature.

Increase in room temperature caused increase in intra-scrotal temperature, but there was no significant difference between the two pairs.

An erect, 60-day cultivar of cowpea, IT84S–2246, was grown with adequate soil moisture at two locations in Nigeria in 1990/91, Ibadan (7° N) and Kano (12° N), contrasting in total incident radiation (Q) and at plant population densities of 1·9–7·7 and 5·4–16·3 plants/m2, respectively. Leaf area, radiation interception and dry matter (DM) accumulation and partitioning were measured. Total shoot and seed dry weights were greater at Kano (mean 4·10 and 1·61 t/ha, respectively) than at Ibadan (mean 1·89 and 0·68 t/ha, respectively), and greater athigher plant densities. Relationships between the reciprocal of total shoot (Wt) and seed dry weight (Ws) per plant and plant population density (Np) determined at Kano and Ibadan were linear and parallel; intercepts, however, were significantly different (P < 0·005). The theoretical maximum potential Wt and Ws per unit area (i.e. 1/b) was therefore the same at Kano and at Ibadan, 448 and 170 g/m2, respectively. However, the optimum Np at Kano and Ibadan was markedly different, c. 10 and 40 plants/m2, respectively. These differences in the relations between DM yields and Np at Kano and Ibadan are examined in terms of leaf area, radiation interception and the partitioning coefficient, and the implications for the design of other agronomic investigations in cowpea are discussed.

Evans & Roberts (1979) considered that loworder polynomials such as mean, linear and quadratic were adequate to describe the trends that occur in treatment contrasts in long-term agricultural experiments. This conclusion was based on experience with experiments on levels of fertilizers and rates of stocking on similar pastures. In such experiments, the marked seasonal pattern in the data disappears when comparisons between treatments are followed. However, further experience with experiments comparing cultivars has shown that some comparisons still show a seasonal pattern. Such patterns may be accounted for by periodic regression (Bliss, 1970).

Seven non-pregnant Murrah buffalo heifers aged 20–34 months and weighing 170–260 kg were used in a 7 × 4 incomplete latin square design to study the effect of feeding mixed diets on voluntary intake over a period of 84 days. Voluntary intake and rate of passage were determined during the last 10 days and digestibility of feed nutrients during the last 6 days of each 21-day experimental period.

Maize stover, dry grass and wheat straw were fed ad libitum mixed with either a fixed quantity of berseem hay (MH, GH and WH rations, respectively) or concentrates (MC, GC and WC rations, respectively) to total co. 0·80% of body weight (BW). Berseem hay fed free choice mixed with limited (0·70% BW) concentrates (HC ration) comprised another treatment. The mean daily total dry-matter intake (DMI g/kgW0·75) and total digestible nutrient intake (given in parenthesis) by animals were 62·2 (1·94), 72·2 (2·20), 74·3 (2·30), 75·2 (2·94), 79·5 (2·59), 85·9 (2·78) and 88·5 (2·98), respectively on MH, GH, WH, HC, MC, WC and GC rations. The digestible crude protein intake on the HC ration was higher than on the remaining six rations. Feeding a fixed quantity of either berseem hay or concentrates resulted in lower consumption of basal roughages suggesting that the physical capacity of the gut limited intake.

Dry-matter digestibility (%) and mean retention time (h), given in parenthesis, were 57·6 (69·4), 56·3 (64·6), 56·7 (67·5), 72·2 (79·9), 59·2 (620), 59·4 (620) and 58·9 (66·0), respectively on MH, GH, WH, HC, MC, GC and WC rations. The digestibilities of D.M. and proximate principles, except crude fibre (CF), of the HC ration were higher than those of the remaining six mixed diets. Concentrate feeding tended to hasten the movement of digesta of the roughage portion of the mixed diet through the digestive tract. The longest mean retention and rumen retention times were associated with the highest digestibilities. The wheat straw-berseem hay mixed diet was as good as dry grass or maize stover-berseem hay mixed diets with regard to its nutrient intake and weight gain by the heifers.

Although the infertility of the subsoil in humid, semi-arid and arid regions has received much attention from investigators in Europe and America, in South Africa, as far as the writer is aware, no such work has been done.

When maize forms a large part of the diet of any group of people, pellagra can be prevented by increasing the amount of nicotinic acid or by increasing the amount of tryptophane in the diet. The possibility of increasing the nicotinic acid content of maize by genetical means presents a promising field.

An experiment was carried out to study the effect of early weaning on body weight and growth rate of Awassi lambs raised at Abu-Ghurib Experiment Station, Baghdad, Iraq. Sex, type of birth and weaning age significantly influenced the body weight and growth rate of lambs at all the ages studied. Dam's age and weight at lambing, however, did not affect the growth rate of the lambs. The average body weights of lambs at 4 and 6 months of age were 23·8±0·28 and 32·3 ± 0·36 kg. The average daily gain in weight up to 120 and 180 days of age was 162·3 ±2·57 and 153·7 ±1·94 g/day respectively. Males were heavier than females and singles were heavier than twins at all the ages. Lambs weaned at 60 days of age were heavier and had a faster growth rate than those weaned at 90 or 120 days of age. Males born to 2-year-old dams grew fastest while the females born to them had the lowest body weights and growth rate.

1. Four experiments in 1958 and five in 1959 compared responses to potassium (as combinedrilled muriate of potash) in the absence of nitrogen and in the presence of single and double doses of nitrogen (as broadcast sulphate of ammonia) on soils selected because they contained very little acid-soluble potassium.

2. Responses to 0·5 cwt. K2O/acre were obtained at six centres (two significant), but the effects of a further 0·5 cwt. K2O/acre were more variable and gains and losses (each at four centres) were almost equally balanced.

3. Gains from nitrogen were associated with previous cropping. N1 raised yields at seven centres (six significantly), but N2 raised yields further at only five centres (three significantly) and depressed yields significantly at three centres where barley followed a root crop or ley.

4. Potash did little to improve the strength of straw and therefore standing capacity in a wet season (1958) and had little effect upon the size of the grain, whereas nitrogen increased lodging and reduced the average size of the grain.

5. Increases in potassium uptake were associated with yield increases, whereas increases in nitrogen uptake were associated with both higher nitrogen percentage in grain and higher yields.