1. In a grazing experiment with sheep, cocksfoot, rye-grass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems.

2. One sheep on each plot was fitted with an oesophageal fistula, from which herbage samples were collected at fortnightly intervals. The botanical composition of samples from the mixed swards was estimated by an optical point quadrat method. Samples were analysed for crude protein and cellulose, and digestibility was estimated in vitro.

3. Treatment difference within the mixed swards were not significant in terms of botanical composition. The mean proportions selected were 73% grass, 9% clover and 18% dead matter. The proportion of clover selected did not differ significantly between sample collections.

From May 1963 to April 1964 seasonal changes in soluble nutrients were followed in soil samples taken monthly from plots having none, PK, and NPK fertilizers in experiments at Rothamsted and Woburn. Phosphorus, potassium and magnesium concentrations in equilibrium extracts of the soils made with 0.0lM-CaCl2 solution were determined. Exchangeable P was determined with an anion exchange resin. Samples were taken under five arable crops growing in rotation, and under permanent grass on the two soils.

A model relating the yield of shelled peas to maturity, as measured by the tenderomoter, has been given. The model has been fitted satisfactorily to data from pea experiments carried out over a period of 4 years and covering a range of plant densities and irrigation treatments. Comparison with other published work suggested that the model may be generally applicable to wrinkled-seeded varieties. A formula is given for interpolation of pea yields to a given maturity, although it was shown that linear interpolation is generally adequate.

1. Two series of experiments designed to investigate the effects of delaying planting potato seed tubers after drawing ridges in preparation for planting and of consolidation of soil beneath seed tubers on the growth and yield of potatoes are described and the results discussed.

2. Delayed planting reduced the yield of saleable ware-size (> I¾ in.) tubers in one year by as much as 1.7 + 0.59 tons/acre, but had little effect in the other years, and it is argued that the effect was dependent on the tilth obtained in preparation for planting, the soil moisture content at the time the ridges were drawn, the amount of moisture lost during the delay period, and the rainfall after planting.

1. In four different years, swards of perennial rye-grass/white clover were treated with nitrogenous fertilizer (0, 30 or 60 lb. N per acre) in mid-February to produce an early growth of grass. The effect of the time of the first cut, taken in March or April, on the annual yield was studied.

2. The total annual yield was reduced when an increasing quantity of grass was removed at the first cut because this interfered with the development of inflorescences and reduced yield at the second cut.

3. Fertilizer treatment increased early growth and advanced by 2-14 days the date in spring at which the yield was adequate for grazing; this improvement improvement was small compared with the extent to which this date was affected by differences in the weather from year to year.

4. The response in total annual yield to N averaged 17.2 and 14.9 lb. of dry matter per lb. N respectively for the 30 and 60 lb. N per acre applications. The highest responses were measured when little or no grass was removed at the first cut. Where a larger crop was removed at the first cut the response to N was reduced; exceptionally it was negative.

While the leaf resistance of many of Knight's B genes in a Sakel background is now much lower than that found in his original studies, that of B9K has remained unimpaired and this gene still segregates as a major gene. It is proposed to ascribe to the weak gene transferred by Knight from Wagad 8 (G. herbaceum) to Sakel the symbol B11, as gene homology tests between this gene and other B genes indicate that is non-homologous with them. The strong effect of environment on the expression of B11 was confirmed and it was noted that in Upland stocks B11 was much more effective than in Sakel, whereas the opposite was true of B9K.

While the leaf resistance of Bm Sakel is high its stem resistance is of a low level and it suggested that leaf, stem and boll resistance may be under the same control in some genetic systems but not in others.

1. In each of 6 digestibility trials, comprising a total of 21 measurement periods of 3-4 days, two steers were fed on herbage cut from the top of the sward, two on the remaining bottom growth and two on a mixture of equal parts of these fractions. Within each period the fractions were similar in digestibility although the top growth had a higher content of nitrogen.

2. The trials were divided into three groups, according to time of year, for the purpose of calculating regressions of digestibility on faecal nitrogen concentration. Regressions calculated in the usual manner on a between-period basis (i.e. within animals) had constant terms which differed significantly among animals but not from one fraction of the herbage to another.

The effects of varying static and changing moisture contents on mineralization of nitrogen after incubation (28° C.) for 3, 6 and 12 weeks were studied.

Mineral-nitrogen, accounted for entirely by nitrate, increased with increasing static moisture content up to 40-50% water-holding capacity (W.H.C). With further increasing moisture up to waterlogging, both mineral-nitrogen and nitrate decreased, the latter to negative values, indicating disappearance of nitrate originally present in the soil. Ammonia accumulated only at moisture contents above 50 % W.H.C. and its extent of accumulation increased with moisture content.

When soils with moisture contents of 10-50% W.H.C. during an initial 6-week period were changed to waterlogging for a second 6-week period, mineralnitrogen and nitrate accumulation decreased with increasing initial moisture in comparison with soils left at initial moisture contents for the second period.

Concentrations of rumen volatile fatty acids, ammonium and protein nitrogen and free microbial count in groups of sheep fed fresh herbage have been compared with concentrations in groups supplemented with pure carbohydrates.

Rumen ammonia concentrations in sucrose and cellulose-supplemented sheep tended to be lower before feeding than in sheep fed herbage only, but this difference disappeared after feeding. Ammonia concentrations in sheep supplemented with starch, and those receiving herbage only were similar before feeding, but the rise after feeding was less for the starch-supplemented group. The rise in volatile fatty acids after feeding was greater when part of the herbage was replaced with an equal weight of dry matter of starch, but lower when replaced with ucrose or cellulose.

1. Twenty-four individually fed yearling Ayrshire heifers were used to compare diets consisting of (1) long barley straw and concentrates; (2) the same quantities of similar foods as in (1) but with most of the barley straw ground and pelleted with a proportion of the concentrates in a ratio of 70:30; (3) replacement of the whole of diet (1) by the pelleted 70:30 mixture to provide a similar theoretical starch-equivalent intake.

2. Live-weight gains over an experimental period of 10 weeks were: treatment 1, 0.55 lb./day; treatment 2,0.99 lb./day; treatment 3,1.23 lb./day. These differences were statistically significant and indicated a marked response in energy value due to processing the straw.

Variations during 12 months in the concentrations of soil P and K soluble in 0-01M CaCl2 solution were measured on several sites with contrasted histories at both Rothamsted and Woburn. Concentrations were always less in fresh than in airdried soils.

P concentrations in the heavy soils at Rothamsted were remarkably constant, seasonal variation only occurring where FYM or phosphate fertilizers had been applied during the year. At Woburn P concentrations were also constant in the poorer soils, but varied during the year in rich soils.

On Barnfield at Rothamsted the plots receiving FYM each year contained more soluble P than those treated with superphosphate. Where both FYM and superphosphate were applied, P concentrations were greater than the sum of values on plots receiving FYM and superphosphate separately because a given amount of P remained more soluble when FYM was regularly applied. P also remained more soluble on plots given ammonium sulphate.

Observations on the onset of the breeding season in a flock ofSouthdown ewes in subtropical Australia (latitude 27° S.) indicated that the mean date of onset during the years 1962-65 was 3 March, with annual means ranging from 11 February to 17 March. There was evidence that, under some circumstances, ovarian activity may be initiated before the summer solstice.

The onset of the breeding season was later in ewe lambs than in yearling and adult ewes and the mean age at puberty was 239 days.

1. Two experiments were conducted in a lowtemperature cabinet. In the first experiment three grass varieties (two North African fescues and S 22 Italian rye-grass) were subjected to two cutting treatments (herbage cut from 8 in. to 2 in. and from 4 in. to 1 in.). Dry-matter production, dry-matter content and tiller number were recorded from plots of 9, 16 or 25 plants. The second experiment, a uniformity trial, was planted with a uniform population of a North African fescue. The optimum plot size and shape within the cabinet, and the optimum arrangement of blocks, was determined using a Titan autocode programme.

2. Treatment and variety differences could be detected using very small plots. For the material and apparatus used, an 18-plant plot was the optimum size.