Over a 3-year period 900 m3/ha of copper-rich pig slurry were spread during the growing season on a 0·6 ha permanent grassland sward and the grass continually grazed off each season with the same sheep. A total of 47 kg Cu/ha were applied to the area and this increased the EDTA-extractable copper in the topsoil. Herbage copper concentrations clearly showed that sheep grazing the area were continually exposed to high concentrations, and that most of the copper was present as surface contamination. Large quantities of copper were excreted in the sheep faeces indicating that copper passed through the animal.

Monthly blood samples from the sheep showed that the enzyme glutamic-oxaloacetic transaminase (GOT) concentrations were slightly higher than those in sheep grazing an area which received no copper over the same period. By the end of the second season (October 1971) over 2000 i.u. GOT/1 were recorded in some sheep grazing the slurry treated area indicating severe liver breakdown at that time. However, during the winter when the sheep were inwintered, serum GOT concentrations decreased considerably. In the final grazing season a 0·2 ha area received monthly applications of copper sulphate instead of slurry. All sheep were slaughtered in November 1972 for post-mortem examination. There was little difference in the copper concentrations in the liver and kidneys of the sheep grazing the control and the slurry areas, although the sheep which grazed the copper sulphate area in the final season had higher concentrations.

As no sheep died from chronic copper poisoning during the course of the investigation there would appear to be little or no danger to the health of sheep from grazing land which is receiving pig slurry at rates which supply less than 16 kg Cu/ha/year.

A technique is described which uses the ratio of the natural 12C and 13C isotopes of carbon to calculate the proportions of Calvin pathway (or C3) species and C4 dicarboxylic acid pathway (or C4) species in mixed samples of shoots, roots or seeds. Mean percentage of a particular component can be predicted to within ± 2% of actual values with average standard errors of less than 1% with two component mixtures under good conditions using threefold replication. The technique is particularly useful for estimating the proportion of C3 and C4 species in samples of visually indistinguishable, intermingled root systems from mixed field communities or from competition experiments. The proportion of C3 and C4 species in both oesophageal fistula and feed samples can be obtained using this technique, and it is proposed that data from fistula and pasture samples could be used to determine the extent to which animals selectively eat C3 or C4 species. The advantages and disadvantages of the technique are discussed.

Despite much experimental evidence showing that sodium fertilizer increases sugar–beet yield and decreases need for potassium, there is resistance to its use on some soil types through fears of deterioration in soil structure. Twelve field experiments with sugar beet were made in Eastern England, testing all combinations of autumn and spring applications of 0, 150 and 300 kg Na/ha and 0, 83 and 333 kg K/ha. Fields were chosen with soils of loamy very fine sand, very fine sandy loam, sandy clay loam and clay loam textures. Micro–plot and controlled environment studies were also made with the same soils to examine effects of sodium on seedling emergence and growth.

Visual assessments of soil physical state following sodium application revealed no effect in the year sugar beet was grown nor in the following spring when cereals were grown. Measurements of physical properties of soils treated with sodium suggested that applications of several times the recommended amounts of sodium fertilizer would not damage soil structure. However, sodium fertilizer increased the osmotic suction of soil solution which, under some circumstances, e.g. dry springs or giving the fertilizer close to the time of sowing, decreased germination and seedling growth. For this reason and not because it has a detrimental effect on soil physical condition, sodium fertilizer best given in the autumn or some weeks before sowing.

Three spring barley varieties, Proctor, Vada and Mosanne, were inoculated with Rhynchosporium secalis(Oudem.) J. J. Davies at Growth Stages 3, 7, 10·1 and 10·5 (Large, 1954). The treatments included single inoculation at each growth stage and multiple inoculations at two, three and four of the above growth stages. There was no effect of inoculation oil the number of fertile tillers. Thousand-grain weight was reduced in all seven inoculation treatments in Mosanne but only the quadruple inoculation adversely affected the other two varieties. Numbers of grains of both Mosanne and Vada were reduced by treatments which included an inoculation at ear emergence but Proctor was affected only by the quadruple inoculation. In terms of disease assessment Mosanne was very susceptible and Proctor moderately resistant but Vada, with symptom scores only slightly better than Mosanne, exhibited a degree of tolerance which was reflected by the grain weight results in which small increases were recorded. This tolerance mechanism, possibly acting through compensation in this variety, is compared with compensation reported in wheat.

Two dwarf pigeon pea cultivars, each at two spacings, were planted at 4-weekly intervals over a year. Differences in height and number of branches between cultivars and spacings were generally small but planting date had much greater effects. Heights at reaping were > 2 m in plantings made in March or April, but decreased with later planting to ca. 1 m in November–February plantings. Time from planting to reaping varied from ca. 120 days in September-February plantings to > 225 days in March or April plantings. Four of the 13 plantings showed loss of mainstem dominance. Defoliation by rust disease showed no seasonal pattern, nor any association with yield. March plantings showed a ‘preliminary’ flowering in which only some wide-spaced and perimeter plants flowered in late July. Yields varied from 0–5 to 10 t/ha as green pods, but one cultivar at a spacing of 0·45 × 0·45 m (49385/ha) gave a mean yield of ca. 5 ±0·57 t/ha. Late-May planting appeared the most efficient, giving a large number of pods per day, per flowering branch and per metre of height, but plants exceeded 2 m in height and took 200 days from planting to reaping. December or January planting gave smaller plants, taking ca. 125 days from planting to reaping. Day-length was a dominant factor influencing growth and yield, but part of this may have been a response to radiation rather than to photoperiod.

The rate of production of bacteria in the rumen of buffalo calves kept on two rations was measured using 14C labelled Streptococcus bovis and 35S whole ruminal bacterial cells. The animals received daily either 15–20 kg green maize or 25–30 kg green cow pea in 12 equal amounts at 2-h intervals. The bacterial cells from the rumen of animals maintained on the same diet were tagged with 35S by in vitro incubation in the presence of 35S-sodium sulphate. Similarly Streptococcus bovis of rumen origin was grown in the presence of U-14C dl-leucine. The cells were injected into the rumen in a single dose. The dilution of the specific radioactivity of bacterial cells in the rumen with time was taken for calculation of the turnover time and rate of production of bacteria.

The average production rates of bacteria were 88·3 ± 3·88 and 92·3 ± 1·82 g/kg digestible organic matter and 101·8 ± 1·55 and 103·3 ± 1·49 g/kg digestible organic matter in animals fed green maize and cow pea, when estimated by using mixed rumen whole bacterial cells and Streptococcus bovis respectively. There was no significant difference in the rate of bacteria production when estimated by either method.

In two field experiments, Mussoorie rock phosphate with or without pyrite, farmyard manure or straw was compared with concentrated superphosphate when applied to guar and groundnut. The treatments included rates of 10, 20 and 30 kg P/ha and were located on a soil low in available phosphorus.

Mussoorie rock phosphate was 44–52% as efficient as concentrated superphosphate. The incorporation of Amjhore pyrite, farmyard manure or straw in the soil with rock phosphate increased the effectiveness of Mussoorie rock phosphate.

Extractability coefficient ratios obtained upon laboratory incubation of soil with concentrated superphosphate and rock phosphate correlated fairly well with the availability coefficient ratios obtained from measurements with plants in the field experiments.

A radiography unit was developed with which two technicians and two assistants were able to diagnose number of foetuses in 400–600 ewes per day on farms. Diagnoses made between 100 and 120 days of gestation in flocks where weekly mating records were made were 95–98% accurate as judged by lambing records. In most flocks more than 90% of twin pregnancies were correctly diagnosed. Agreement between diagnoses and lambing records was reduced when weekly mating records were not available. The radiographic examination had no detrimental effects on ewes or lambs.

The possibility of a sub-clinical state of thiamine deficiency in young cattle and sheep is discussed. A trial was carried out on six MAFF experimental husbandry farms in which groups of animals were given 100 mg of thiamine per day orally throughout the rearing period. Measurement of erythrocyte transketolase showed that the dosed group gave a significantly lower percentage thiamine pyrophosphate effect than the control group. There was no difference in weight gain of the two groups during the limited period of the trial.