1. The pattern of downward movement of nitrate in light soil is different from that in heavy clay soil of the kind used in this work.

2. In light sandy soils, where vertical structural fissures are absent, nitrate becomes distributed down the profile on leaching.

3. In heavy soils, which are well fissured and possess a gleyed horizon of partially decomposed plant debris at cultivation depth, most of the nitrate disappears from the profile after removal, by leaching or denitrification, from the cultivation layer.

4. There is little difference in the amount of rain required to remove nitrate from the surface layers of light or heavy soil.

5. Heavy and continuous rain is required to remove nitrate completely from either light or heavy soils.

6. Nitrification of ammonium sulphate is more rapid in summer than winter, but nitrification does proceed slowly during winter.

7. Ammonium nitrogen is not leached from the surface layer of either light or heavy soil.

A study has been made of the internal volume of the different parts of the alimentary tract of geese and fowls.

It has been shown that although the adult geese were two or three times as heavy as the adult fowls, the mean total gut capacity, exclusive of the crop, was proportionately less. Although the gizzard was much greater in weight than in the fowl, its capacity in proportion to body weight is only half that of the fowl, whilst the caeca are relatively even smaller. The distended oesophagus of the goose, which replaces the crop of the fowl, was at all times smaller relative to body weight.

The gut capacities of both chicks and goslings increased rapidly when they began to feed, and reached a maximum, relative to body weight, within the first fortnight after hatching. At 16 weeks, the capacity of the alimentary canal had almost the same relation to body weight as in the adult.

In both, the small intestine constitutes the major proportion of the volume in the adult, being 33–40% in the fowl and more than 50% in the goose.

Feeding a diet containing 21% crude fibre and supplemented with procaine penicillin G produced chicks with relatively greater gut capacities, and this effect was enhanced by the concurrent inclusion of procaine penicillin G, but where the fibre was reduced to 17·4%, the gut capacities were not significantly different, in relation to body weight, than in the control group.

Histological examination of the wall of the gut of chickens raised on different diets showed marked abrasion on high-fibre diets, and a much thinner intestinal wall in those birds receiving antibiotic.

1. A small-scale plot experiment was conducted for a 3-year period, 1958–60, to study the comparative effect of applications of liquid manure, water and dry fertilizer on the yield and quality of an established meadow fescue and white clover sward.

2. The liquid manure was collected from a cowshed and contained on average 0·23% N, 0·003% P2O6 and 0·48%K2O.

3. The treatments applied each year were: (1) control, no fertilizer; (2) and (3) a low and a high rate of water equal in weight to the liquid manure applied in treatments (4) and (5) respectively; (4) a low rate of liquid manure supplying 75 lb. nitrogen and 159 lb. K2O; (5) a high rate of liquid manure supplying 150 lb. nitrogen and 318 lb. K2O/acre; (6) and (7) liquid manure as in (4) and (5) plus 82 lb. P2O6/acre; (8) a low rate of normal dry fertilizer supplying 87 lb. nitrogen, 82 lb. P2O6 and 84 lb. K2O/acre; and (9) a high rate supplying 174 lb. nitrogen, 82 lb. P2O5 and 168 lb. K2O/acre.

All treatments were applied in five equal dressings each year, one for each cut, except the P2O5 which was applied twice a year.

4. The yields of herbage dry matter and crude protein were not affected by the water treatments, but both the liquid-manure and dry-fertilizer treatments caused significant increases in yield. The application of phosphate on the liquid-manure treatments had no significant effect on yields.

5. The crude-protein contents of the herbage on the different treatments did not show any large or consistent differences.

6. The botanical compositions of the swards were significantly different at the end of the third experimental year. On the liquid-manure treatments the content of clover had increased and the meadow fescue and dicotyledonous weeds decreased compared with the control. The mean content of clover in the swards at the end of the trial was 32, 18 and 15% on the liquid-manure, dry-fertilizer and control treatments respectively.

7. There were no major differences between either the pH values or the contents of P2O5 in samples of soil on the different treatments after 3 years, but the average K2O value on the control and two water treatments was almost half that on the high liquid-manure treatment.

8. The mineral contents of the herbage were determined. In 2 of the 3 years the liquid-manure treatments produced herbage with high K and lowered Ca, Mg and Na contents. The Mg content of the herbage on the four liquid-manure treatments averaged 0·26%.

Indigenous (Bos indicus) oxen fed ad lib. were used to measure the changes in the apparent digestibility of mature Hyparrhenia veld during the dry season, and also the apparent digestibility of late-cut veld hay and nitrogen-fertilized veld hay. The forages were those used in a field trial, and the present results complement previous work.

1. Mature Hyparrhenia veld harvested at the end of the rains as veld hay or green forage, contains approximately 50% digestible o.m. and 0·6% digestible c.p. The low level of approx. 3% c.p. resulted in a low apparent c.p. digestibility and consequent protein deficiency.

2. The nutritive value of the mature Hyparrhenia grassland as ‘standing hay’ progressively dropped to 38% digestible o.m. and negative c.p. digestibility by mid-dry-season in July.

3. There was an accompanying decline in voluntary intake of forage from approximately 12 lb. d.m./1000 lb. animal/day at the end of the rains to 8 lb. d.m./1000 lb. animal/day in mid dry season.

4. The seasonal drop in digestibility values is accentuated by the drop in dry-matter intake so that a diet of mature veld herbage in mid dry season is grossly deficient in both energy and protein.

5. The feeding of supplementary protein or urea resulted in a 40–60% increase in the intake of mature Hyparrhenia forage. Urea and groundnut meal were of equal value in their effect on herbage intake at the level of feeding used in this trial.

6. The main factor limiting the utilization of the mature Hyparrhenia veld appears to be a dietary protein deficiency. Increasing the dietary protein level, either by using nitrogen fertilizers to raise the herbage crude protein, per cent, or by supplementary feeding of protein or urea, not only relieved the dietary protein deficiency, but, due to the resultant increase in forage intake, also corrected the deficiency in dietary energy. The nutritive value of mature Hyparrhenia forage was thus raised from a submaintenance to a supra-maintenance level.

Four experiments have been conducted with sheep, housed and fed in pens, to determine the maintenance and live-weight gain requirements of sheep under such conditions.

1. Fifteen Corriedale sheep of initial live weight 115 lb. were fed at maintenance for 13 weeks. Daily DOM (digestible organic matter) requirement for maintenance was 0·92 ± 0·07 lb.

2. Twelve Romney ewes of mean live weight 106 lb. over the period were fed for 5 months, six on submaintenance and six on super-maintenance levels. Daily DOM requirement for maintenance was 0·99 ± 0·05 lb., and requirement for gain 2·29 ± 0·20 lb. DOM per lb. gain or loss.

3. Thirteen Romney ewes of mean live weight 110 lb. over the period were fed at sub- and supermaintenance levels for 8 weeks yielding the result: daily DOM intake for maintenance 1·04 ± 0·13 lb. and for gain 2·25 ± 0·24 lb. DOM per lb. gain.

4. Twenty-four Romney ewes of initial live weight 107 lb. were randomized into five groups and fed fresh grass, dried grass, sheep pellets, lucerne hay and rye-grass straw for 11 weeks at slightly below maintenance. There were no significant differences between groups and the mean estimate of maintenance was 1·00 ± 0·11 lb. DOM per day.

Converting these estimates to those of a 100 lb. sheep using the ¾ power of live weight, and then taking the mean gives the final estimate for maintenance of a 100 lb. sheep 0·92 lb. DOM, 0·96 TDN or 0·89 lb. SE.

The intake of grazing sheep in terms of digestible organic matter, DOM, has been measured by faecal index methods, employing chromic oxide to measure faecal output and faecal nitrogen for digestibility of pasture. A regression equation for the prediction of digestibility from faecal nitrogen (organic matter basis) was developed from several series of digestibility trials with pasture, the equation being

digestibility of organic matter = 30·84 +

Four trials to measure maintenance and gain were conducted, as follows:

(i) Thirty-eight sheep, comprising twelve wethers of mean weight 112 lb., thirteen small or thin Romney ewes of mean live weight 110 lb. and thirteen large or fat Romney ewes of mean live weight 166 lb. were grazed all together for 17 weeks on a rye-grass-white clover sward at an intensity such that live weight was just maintained. Corrections to intake were made for small live-weight changes.

Daily DOM intake (lb.) for maintenance = 0·062 maintenance for a 100 lb. sheep becomes 1·48 ± 0·08 lb. DOM/day.

(ii) Thirty-six weaned Romney ewe lambs of mean initial live weight 56 lb. were grazed for 8 weeks on a rye-grass-white clover pasture and allowed to gain in weight. Regression of intake on gain gave the equation

daily DOM intake (56 lb. lamb) = 0·93 (±0·07) + 0·90 g

where g = gain in lb./day. Combining this lamb data with that of the previous trial yields the equation

DOM intake (lb.) for maintenance = 0·052

(iii) Forty ewes, comprising eight Southdowns, twelve Romneys, eight Border Leicesters and twelve Border-Romney crossbreds were grazed together on short pasture (rye-grass-white clover) for 12 weeks. The ewes were of widely differing live weight and the mean gains or losses of the groups over the period varied from + 1·5 to −4·5 lb.

Daily DOM intake (lb.) for maintenance = 0·061 which for a 100 lb. sheep becomes 1·63 ± 0·13 lb. DOM.

(iv) Seven Romney ewes were grazed in high and eight ewes in low intake groups for 8 weeks. Regression of intake on gain gave the equation

daily DOM intake (130 lb. ewe) = 1·58 (±0·06) + 1·98 g.

For a 100 lb. sheep this becomes 1·36 (± 0·06) lb. DOM/day for maintenance.

The three estimates of maintenance of a grazing sheep of 100 lb. live weight 1·48, 1·63 and 1·36 lb. DOM/day are greatly in excess of the estimate of 0·92 lb. DOM/day for pen-fed sheep. It is believed that this difference is outside experimental error and represents a true increase in energy cost due to grazing. It is suggested that the cause of this derives from the energy costs of walking and harvesting the pasture together with climatic factors wind, cold and rain. The exponent of live weight agrees well with the estimates of other workers based on pen-fed animals. The energy cost of gain is less than that of pen-fed sheep and it is suggested that this is due to the maintenance cost decreasing with increasing availability of pasture and with increasing gain.

The effects of copper supplements on the performance up to 45 lb. live weight of early weaned pigs were measured in two experiments. Copper sulphate included as 0·1% of the diet had no apparent adverse effect on the piglets, even when it was introduced immediately after weaning at about 8 lb. live weight, but improved rate of gain by 6 and 12% and feed conversion efficiency by 5 and 6% in the two experiments, respectively. The length of the period of slow growth after weaning was reduced in both experiments. There was no clear advantage in delaying the introduction of the high-copper diet until the pigs weighed 17 or 26 lb.

The second experiment was a 2 x 2 factorial, the second factor being the presence or absence in the diet of antibiotic (present throughout in the first experiment). Antibiotic appeared to have slight beneficial effects on growth rate and feed conversion, which were additive to the effects of copper so that the best results were obtained from the diet containing both copper and antibiotic.

In a continuation of the first experiment it was found that the early copper treatment had no effect on rates of gain and feed conversion between 55 and 200 lb. live weight or on carcass measurements. The inclusion of a copper supplement in the diet from 55 to 200 lb. improved feed conversion by 4% and rate of gain by 3·5%, reduced the thickness of streak and increased the ratio of width to depth of eye muscle. None of these responses was affected by the copper treatment prior to 55 lb. live weight.

A comparison is made between a maize-rich diet containing 7% white-fish meal and a similar diet in which the protein supplement consisted of 6% ex. soya bean meal together with 0.3% L-lysine hydrochloride and 0.2% DL-methionine. The vegetable protein diet plus the amino acids proved in every way equal to the fish meal diet.

When the essential amino acids in the diet of weanling pigs are properly balanced as little as 10% digestible crude protein will support maximum growth.

The results obtained when 6% ex. dec. groundnut meal was used as a protein-rich supplement were not so favourable.

1. Forty-nine 33 factorial experiments in 1957–60 tested the response of sugar beet to 0·6,1·2, 1·8 cwt. N, 0·0,0·5,1·0 cwt. P2O5 and 0·8 1·6 2·4 cwt. K2O per acre. On forty-one of the sites, the experiment was repeated in the presence of 12 tons FYM per acre. There were also six trials in which the rates of mineral fertilizer had been altered to suit local conditions.

2. Optimum dressings for sugar yield without FYM were 1·0 cwt. N, 0·5 cwt. P2O6 and 1·6 cwt. K2O per acre. This closely agrees with results of experiments made in 1934–39. Exceeding the optimum nitrogen dressing decreased sugar yield although the yield of tops was increased. The main value of dung for beet was in the N, P and K it provided. With FYM, optimum dressings were only 0·6 cwt. N, 0·0 cwt. P2O5 and 0·8 cwt. K2O per acre.

3. Response to nitrogen differed greatly from field to field and the best guide to the nitrogen requirement of a field was the previous cropping. Beet which followed two or more cereal crops needed more nitrogen on average than beet which did not. Response to phosphate and potash did not differ much in different experiments and the national optimum would have been satisfactory for nearly all fields. The only use of soil analysis was to identify the very few fields which needed more than the average dressing of phosphate. The efficiency of phosphate and potash manuring could be slightly increased by taking soil type into account.

Denitrification has been studied in a range of near-neutral Ghanaian soils. The technique used was to add nitrate, alone or with glucose, to 10 or 15 g. samples and incubate at 30° C. and 70 or 160% of the water holding capacity. Changes in the nitrate and total nitrogen contents were then determined over a period of 14 days. Only small or non-significant losses of nitrogen occurred in the unsaturated soils, but larger and rapid losses were observed in the saturated samples. In the samples from under standing forest or old grassland denitrification proceeded without addition of a carbonaceous substrate, but a small addition was required in the cultivated and young grassland soils. The amount needed was much less than has been shown necessary for an equivalent nitrogen loss in a number of temperate zone soils. Evidence was obtained that nitrification and denitrification could proceed simultaneously in the same sample. It is c6nsidered that this supports the concept of a micro-mosaic of aerobic and anaerobic spots in a wet soil.

1. Gibberellic acid had no effect on the germination of six species of small-seeded legumes.

2. Seven varieties of Trifolium repens L. plants were treated with gibberellic acid and their responses determined. All varieties showed an increase in petiole length and individual leaf area due to an increase in cell numbers; a decrease in stolon numbers and length was also noted. The total leaf area per plant remained unchanged. Total dry weight, shoot dry weight and root dry weight were each significantly reduced.

3. The stolons lost their normal diageotropic response and became negatively geotropic and it is postulated that the stoloniferous habit may be due to a gibberellic acid/indole-acetic acid interaction.

4. Because treated plants of Wild white clover closely resembled untreated plants of Ladino clover it is postulated that endogenous levels of gibberellins may play an important part in the development of varieties and in the evolutionary process as a whole.

The effect of undersowing on a spring oat crop with four long-term ley mixtures was investigated. Ryegrass, cocksfoot, timothy and general-purpose mixtures were used; broad red and white clovers were included in all mixtures and two levels of nitrogen applied, no nitrogen (n0) and Nitro-Chalk at 3 cwt./acre.

1. Panicle number was reduced by all the undersown mixtures except when cocksfoot was the only grass sown (mixture B).

2. The weight of individual grains was slightly reduced by undersowing with a ryegrass-dominant general-purpose mixture (D) in the absence of Nitro-Chalk, and there was also an indication of a lowering of the total number of grains per panicle when Nitro-Chalk was applied.

3. All the herbage mixtures reduced the percentage of kernel at both nitrogen levels under the ryegrass-dominant mixture (A), but only at one level of nitrogen when cocksfoot (mixture B) or timothy (mixture C) were the only grasses sown.

1. A co-ordinated trial has been carried out at twenty-one centres to study the effects of feeding to growing pigs oxytetracycline (10 g./ton) and copper sulphate (2 lb./ton) separately and together. Fifteen centres repeated the test and thus there was a total of thirty-six pens with 245 pigs on each of the four treatments.

2. Growth rate and efficiency of food conversion were significantly improved by addition to the ration of copper sulphate (9·7 and 7·9% respectively) and of oxytetracycline (3·1 and 2·3% respectively). The improvement due to copper sulphate was significantly greater than that due to oxytetracycline. There was no further improvement when both supplements were fed together.

3. The cold dead weight of the pigs was significantly increased by the two supplements, the carcasses were shorter, and the streaks thicker. Supplementation with oxytetracycline resulted in slightly increased fat over the eye muscle and supplementation with copper resulted in increased depth of eye muscle. Percentage yields of fore-end, middle and gammon were not affected by either supplement.

4. None of the treatment × centre interactions was significant.

1. The water intakes of ten Holstein × Zebu milking cows, yielding between one and two gallons of milk a day, were analysed on the basis of (a) freewater drunk, and (b) feed-water consumed with the herbage. Trials took place during a 10-day period in both the wet season, 1959 and the dry season, 1960. During both seasons the cows were rotationally grazed on Pangola grass pastures.

2. The results showed a difference of only 24% in total water intake between seasons. However, the mean intake of free water increased from 18·5 lb. per cow in the wet season to 81·5 lb. per cow per day in the dry season, and the intake of feed water decreased from 94·9 to 59·2 lb. per cow per day, respectively. The between cow coefficients of variation were 9·7 and 8·7%, respectively.

3. Results are presented for the drinking habits of Holstein × Zebu cattle grazing Pangola grass pastures. For 567 observed cow-days in the wet season, the cattle were found to drink water on average 0·8 times per day from troughs present in the pastures. For 332 observed cow-days in the dry season, the cattle increased their drinking habits to a mean figure of 1·4 times each day.

1. Five varieties of thousand-headed kale, grown in singled and unsingled plots, were sampled three times during the winter at monthly intervals. The plants were divided into leaf, top half of the stem and bottom half. Dry matter, the proximate constituents and minerals were determined in the samples.

2. The differences in the composition of the leaf and stem of the plant were similar to those found previously and the top half of the stem was intermediate in composition between the leaf and the bottom half of the stem for all the constituents except potassium.

3. The proportions of the various constituents occurring in the three portions of the plant were calculated and considered in terms of the incomplete utilization of the crop by grazing animals.

4. There were significant increases in the percentage of dry matter in all three portions of the plant as the season advanced. The only other significant changes in composition with advancing season were in the leaf in which the levels of crude protein, crude fibre, ash, calcium, phosphorus and sulphate varied.

5. Singling the crop had no significant effects on its composition, but there was a tendency for the stems of the singled crop to be lower in crude fibre and higher in crude protein and several of the minerals.

6. There were very few differences in the composition of the varieties. They were mainly due to the higher mineral levels in one variety.

7. Samples of the two halves of the stem of thousand-headed kale were divided into their main tissues, e.g. rind, xylem and marrow. These were analysed in the same manner as the samples in the main investigation. The results were used in an attempt to explain the effects of singling, advancing season and variety in terms of different ratios of these tissues.

1. Fractionation studies are reported which show that in young spring pasture of low magnesium content, more than 50% of the magnesium is watersoluble, the proportion being higher in pasture at the seeding stage than in young leafy material.

2. Insoluble magnesium constituted about onethird of the magnesium in young leafy pasture and about one-fifth to one-quarter in pasture at the seeding stage.

3. Acetone-soluble magnesium varied from about 12% of the total in young leafy grass to 5% or less in grass at seeding.

4. Fertilizer treatments, though affecting the total magnesium contents, apparently did not affect the proportions in the different fractions.

1. During the years 1954–57 thirty field experiments were carried out on the magnesium requirement of main crop potatoes; eighteen covered a range of typical potato soils while the remainder were sited on sands and loams. In nine of the experiments the effect of heavy applications of potash on magnesium requirements was also investigated.

2. Magnesium application to the seed-bed as kieserite raised yield in four of the experiments; the largest yield increase was 2·15 ton/acre of tubers from 45·lb./acre of MgO. Apart from these four experiments there was also a small mean increase in yield over all the remaining sites.

3. Application of a very high rate of potash depressed yield compared with a normal rate, but only in one experiment could this be attributed to induced magnesium deficiency, and there was no indication of such an effect in the average results.