1. Young sheep, aged either 2 or 6 months, were fed for various periods on diets low in either phosphorus, vitamin D, phosphorus and vitamin D, or calcium and subsequently for 12 months on control diets.

2. The effects of treatment on the mineral status of the animals were judged by the calcium and phosphorus contents of the blood, the ash contents and radiological appearance of the bones, and the clinical appearance of the limbs. The quality of the teeth produced by each treatment was judged clinically.

1. In growing sheep fed on a low-calcium diet for 12 months and for a similar period on a diet of adequate mineral content, a tendency for the incisor teeth to protrude beyond the maxillary pad (prognathism) was observed. This arose primarily during the repair period, and was apparently caused by poorer repair of the upper skull than of the mandible. This was not observed in animals fed on a control diet or one deficient in phosphorus and vitamin D.

2. A malocclusion of molar teeth associated with poorly mineralized and extremely weak mandibles, which prevented the incisor teeth from meeting the dental pad, occurred in growing sheep fed for 12 months on a diet deficient in phosphorus and vitamin D. This defect was not observed in similar animals fed on a control diet nor in those fed on a diet of low calcium content. Treatment effects on the shape of the mandible that were apparently related to this malocclusion are described.

1. The teeth of sheep that had been fed from 6 months of age for 12 months on diets low in calcium or in phosphorus and vitamin D content were compared with those of similar animals fed a control diet.

2. The low calcium diet depressed the development of both dentine and enamel but had a greater effect on enamel than dentine, while the low phosphorus and vitamin D diet depressed dentine development slightly and had practically no effect on enamel.

3. The percentages of ash of the dentine and enamel were not significantly affected by the diets fed.

1. Radioactive phosphorus was injected into young sheep that had been fed diets low in either phosphorus, phosphorus and vitamin D or calcium. Forty-eight hours after the injection the animals were killed and samples of bone and teeth were removed for specific activity determinations.

2. The specific activities of bone varied according to the site from which it was taken, but in general a strong inverse relationship was found between specific activity and the quality of the skeleton.

3. In teeth that were formed during the period the diets deficient in phosphorus or phosphorus and vitamin D were fed, the specific activities of the dentine and enamel were greater than for corresponding tissues from the control animals.

Three series of experiments are described from which minimum estimates of crop loss caused by bacterial blight were obtained. In the first two, the estimates were derived from seed-dressing trials, and in the third, seed dressing was used in conjunction with resistant varieties.

Losses amounted to as much as 354 ± 39 lb. seed cotton/acre for a susceptible variety but could be reduced both by seed dressing and by using resistant varieties. The effectiveness of resistance in moderately resistant varieties varied from one season to the next, an effect comparable with the genotype-environment interactions previously described for reactions to inoculation.

Using the continuous infusion isotope dilution technique, the glucose utilization rate has been compared in three groups of sheep on different diets. Glucose was utilized at the mean rate of 1·8 mg./kg./min. on a daily ration containing 126 g. crude protein, at the mean rate of 2·8 mg./kg./min. on a daily ration containing 197 g. crude protein, and at the mean rate of 4·3 mg./kg./min. on a daily ration containing 460 g. crude protein. The mean percentage of expired carbon dioxide that was derived from glucose was 3·5, 6·5 and 8·9 respectively on the three diets.

1. In 1959 a concentrated granular fertilizer (15% N, 10% P2O5, 20% K2O) was compared with an equivalent mixture of ammonium sulphate, superphosphate and muriate of potash (each supplying 0·75 or 1·50 cwt. N/acre) for potatoes. At Rothamsted (on heavy soil) the two fertilizers gave similar yields, but at Woburn (on light soil) the larger dressing of the concentrated fertilizer gave about 1 ton/acre more potatoes. In similar barley experiments a concentrated granular fertilizer (20% N, 10% P2O5, 10% K2O) was compared with a dilute granular fertilizer (12% N, 6% P2O5, 6% K2O); each was combine-drilled to supply 0·3 or 0·6 cwt. N/acre. At Rothamsted the two fertilizers gave identical yields, but at Woburn the concentrated fertilizer (at the double rate) gave significantly more grain.

1. Oestrous activity was studied in three groups of eight Southdown ewes exposed respectively to natural lighting (30½° S.), accentuated reversed seasonal lighting, and equatorial lighting for a period of 2 years.

2. Control ewes exhibited a restricted breeding season confined to the autumn and winter months of each year. The breeding season averaged 102–5 days in length and during it the ewes experienced an average of 7·14 ± 0·47 oestrous periods.

3. The natural breeding season was almost completely reversed by artificial reversal of the normal seasonal variation in daylength. This constitutes presumptive evidence that daylength is the major factor controlling seasonality of oestrus in Southdown ewes.

1. The effects of applied nitrogen (0, 200, 400, 600, and 800 lb. per acre per annum) and spacing (widely spaced plants and simulated monoculture swards) on average yields and yield components of eight clones of Lolium perenne are reported for four harvests taken each year during 1962 and 1963.

2. During both years, higher yields per unit area were obtained from swards than from spaced plants; the degree of difference varied from harvest to harvest.

3. A greater effect of nitrogen on yield was detected in 1963 than in 1962, an effect especially marked in swards at lower rates of nitrogen application. A highly significant nitrogen x spacing interaction on yield was detected in 1963.

1. The yields and yield components are recorded for selected clones of Lolium perenne, grown at different levels of applied nitrogen (0, 200, 400, 600 and 800 lb. of nitrogen per acre per annum) and at two spacings (widely spaced plants and simulated monoculture swards). Four harvests were taken in each of the two years 1962 and 1963.

2. In both years there were significant and consistent differences between clones in their drymatter production per unit area, detectable at both spacings. A genotype x spacing interaction was detected only in 1962. A genotype x nitrogen interaction at some harvests was not found on annual totals.

1. An investigation into the effects of plant population level and irregularity of plant spacing on the yield and quality of swedes is reported.

2. There was no significant evidence that irregular plant spacing, such as might be produced by mechanical singling, gave a lower yield than regular spacing.

3. Total yield of roots was similar for all plant populations tested (range 15,000–50,000) but at low populations both the number and weight of diseased roots was greater than at higher populations.

4. As the population was increased, the drymatter percentage in the roots increased due to the higher proportion of skin on small roots compared with large roots.

Artificial rearing involves the replacement of those contributions made by the ewe which are essential to the growth and development of the lamb. This not only includes the supply of food but also the warmth, shelter and ‘mothering’ normally provided by the ewe.

Relatively little information is available on the artificial rearing of lambs. The earliest report, perhaps, is that of Mumford (1901) who bottle-fed the milk produced by eight ewes to four lambs. The more practical aspects of rearing orphan lambs have been described by Preston (1958) and Caldwell (1957). More recent reports on the artificial rearing of lambs have been made by the Grassland Research Institute (1959–60, 1960–61), Cunningham, Edwards & Simpson (1961) and Large (1962).

1. The effects of irrigation and fertilizer nitrogen treatments on four swards were studied for 3 years in an experiment at the Hannah Institute. This paper describes only the effects of the fertilizer nitrogen treatments and their interactions with the presence or absence of clover in the sward, since those of the irrigation treatments have been reported previously.

2. Annual applications of 0, 104, 208 or 312 lb. of fertilizer nitrogen per acre were made on swards of S 23 rye-grass or S 37 cocksfoot with or without S100 white clover.

3. The yields of the grass + clover swards exceeded those of the pure-grass swards at all fertilizer nitrogen application rates in the first 2 years and at the 0 and 104 lb./acre rates in the third year.

1. Four varieties of marrow stem kale in the first season, and thirteen in the second, were sampled on three occasions during the first half of the winter. Intervals between samplings were up to 1 month. The plants in the samples were divided into leaf, top half of the stem, and bottom half. The levels of dry matter, proximate constituents and minerals were determined in each sample.

2. The differences in composition between the three main fractions of the plant were highly significant for all the chemical constituents, except magnesium. The values for the chemical constituents in the top half of the stem were intermediate between those of the leaf and the bottom half of the stem for most constituents; it had the lowest values for dry matter and the highest for potassium and phosphorus. The distribution of chemical constituents between the whole stem and the leaf were similar to those reported previously.

Three diets, with silica contents ranging from 0·10–2·84% SiO2 in the dry matter, were fed to sheep and the distribution of silica between the faeces and urine was measured, together with the concentrations of silica in the rumen liquor and the blood. The sum of the amounts of silica excreted in the urine and faeces was within 1% of the amounts ingested. The amounts excreted in the urine increased with increasing silica content of the diet but reached no more than 205 mg. SiO2/day, apparently being limited by the solubility of silica in the rumen. Since the concentration of silica in the blood remained practically constant it is concluded that the silica which enters the blood stream from the alimentary tract passes rapidly into the urine. The amounts of silica excreted in the urine represented small proportions only of the amounts ingested and since the recoveries of silica in the faeces were so nearly complete it is suggested that silica be re-examined as an indicator for digestibility studies.

1. Thirty Rhodesian soils were cropped with weeping love-grass (Eragrostis curvula) for up to 11 months in the glasshouse, the potassium released on cropping being compared with soil contents and that released on prolonged suspension in dilute CaCl2 or by reaction with H-exchange resin.

2. Love-grass produced up to 33 tons of dry matter and removed up to 700 lb. of K2O/acre, and releases of non-exchangeable potassium ranged from 3 to 2931b. K2O/acre. With some soils potassium uptake by love-grass (and K-release) was about 60% of that reported for perennial rye-grass, showing that different crops have differing abilities to use non-exchangeable potassium reserves.