Ninety-four British liming materials were examined. The contents of Ca, Mg, K, P, S, Sr, B, Fe, Mn, Zn, Cu, Co, Mo, Ni, Cd and Na in the acid-soluble fraction, and Mn, Cu, Co, Mo, Ni, Sr, Ti, Cr, Ga, Pb, Sn, V, Y, Zr and Ba in the acid-insoluble fraction were determined by chemical and spectrographic analysis. Water soluble nitrate was also determined.

Only manganese, providing on average 3 kg Mn/ha for a 10 t/ha dressing, was found in agriculturally significant quantities in the acid-soluble fraction of the limestones or shell-sands analysed. Magnesium, present only in significant amounts in the dolomitic limestones, provided on average 27 kg Mg/ha from a 10 t/ha dressing.

The acid-insoluble fraction of the limestones contained, on average, a twentieth of the concentration of Mn in the acid-soluble fraction. The concentration of K was much larger and depended on the amounts and nature of the insoluble fraction. The acidinsoluble fraction contained no significant amounts of other plant nutrients. The relative concentrations of Mn and K in both fractions emphasize that results based on the total amounts of elements in limestones could overestimate their potential value as sources of plant nutrients.

Heritability in the broad sense and correlations were determined for six agronomic traits in cowpea (Vigna sinensis L.) using four parental and six F2 lines. Heritability values were found to be 75, 64, 47, 44, 35 and 15% for 100-seed weight, number of seeds per pod, number of clusters per plant, number of pods per plant, yield per plant and number of branches per plant, respectively. All of the traits studied, except number of branches per plant, showed positive significant correlations with yield. It is concluded that, for yield improvement in cowpea, number of pods per plant and number of seeds per pod have selective value equal to seed yield per plant, whereas 100-seed weight and number of clusters per plant have less selective value and number of branches per plant has no selective value.

The birthcoats of Finnish Landrace lambs showed a wide range of halo-hair grades but all had strongly checked fibre type arrays, which were either Plain or Valley. Transfer to Welsh Mountain dams reduced the effect of prenatal check, giving fewer sickle fibres and increased halo-hair and/or super sickle A percentage. Transfer to Border Leicester tended to have the opposite effect. Fibre diameter measurements made on skin samples indicated an increase in primary fibre diameter in transfers into Welsh dams, but no difference in transfers into the Border Leicester.

All Soay samples had Grade VII halo-hair density and Plateau or Saddle arrays. Transfer of Soay eggs to Finnish Landrace ewes increased the percentage of sickle fibres mainly at the expense of hairy-tip curly-tips. Skin samples from the transferred Soays indicated reduced primary fibre medullation, and evidence of retarded secondary follicle development.

Thus in both breeds the birthcoat changed slightly in the direction of that of the foster-dam. There was, however, no indication that increased prenatal check was associated with increased foetal size. It is therefore concluded that changes in birthcoat as a result of egg transfer are more probably due to direct effects of the maternal environment than to the effect of foetal size as previously postulated.

Fertilizer experiments on lettuce were carried out over 5 years on adjacent sites of the same soil. The shapes of the response curves to both N and P varied considerably from experiment to experiment even though the amounts of those nutrients that could be extracted from the soil did not show this variation. Responses to N were of an ‘overturning’ type and the level of N at which maximum yield occurred ranged from 50 to 400 kg/ha. Responses to P were of a ‘diminishing returns’ type and the maximum increases in yield brought about by applying P ranged from 75 to 700% of the yields obtained with no application.

A mathematical model was derived which fitted the results from all the experiments satisfactorily. The parameter denning the response to P, and that denning the ‘downward’ component of the response to N were linearly related to the integral of cumulative rainfall with respect to time. Insertion of these relations into the model led to an overall model that predicted lettuce yields for each treatment in each experiment from the values of two weather parameters, the levels of N, P and K and a fitted value for seed weight. This overall model accounted for about 75% of the total variance due to fertilizer applications in the nine experiments. It is argued that most of the year-to-year variation in fertilizer response could be explained in terms of rain influencing the adverse osmotic effects on growth, the leaching of nitrate down the soil profile and dispersion of P from phosphate fertilizer granules especially in the early stages of growth.

The model was slightly improved by replacing the parameter ‘time’ with cumulative evaporation from an open water surface, but not with cumulative day degrees, or cumulative evaporation divided by vapour pressure deficit.

Effects of set size, density of planting, harvest date and spatial arrangement on yield and size grading of potatoes were examined using the cultivar Maris Peer. The results indicate that highest economic returns would be obtained by growing crops at between 70 and 110 eyes/m2, using small sets for late season production and large ones only for very early production, with as near a square pattern of planting as possible.

Based on these findings four growing systems were tested on a field scale, a 1·5 m raised bed with four rows, a 0·6 m ridge, a 0·9 m ridge containing two rows 0·3 m apart, and a 0·75 m ridge. Highest yields and returns were obtained from the two-row, 0·9 m, ridge system, which also had certain cultural advantages.

Preharvest sprays with 6-hydroxy-3-(2H)-pyridazinone (MH), or immersion in solutions of MH, 2,4-dichlorophenoxyacetic acid (2,4-D), 2-chloroethylphosphonic acid (ethephon), coumarin or (2-chloroethyl) trimethylammonium chloride (CCC) inhibited both sprouting and rooting of treated carrots during storage at 0 °C whencompared with water-dipped or untreated carrots, while N-6-benzyl-adenine (BA) dips stimulated extensive rooting and sprouting. In contrast, immersion in gibberellic acid (GA3) solutions had very little effect.

Storage atmospheres containing 1, 2.5, 5 or 10% oxygen inhibited both sprouting and rooting but increased mould infection. Atmospheres containing 21% (air) or 40% oxygen reduced mould infection, but increased sprouting and rooting of stored carrots. Washing carrots in water before storage did not significantly affect mould infection, while washing in 0.5% clorox increased it. However, washing in water followed by immersion in MH inhibited both sprouting and rooting and also reduced mould infection. ‘Jumbo’ and large-size carrots stored better than medium and small carrots.

Three experiments (1970–2) on calcareous sandy loan tested all combinations of four plant densities (18500–124000 plants/ha), two amounts of potassium (0, 156 kg/K/ha) and sodium (0, 247 kg/Na/ha) fertilizer and two watering treatments on yield and chemical composition of sugar beet. The main effects of the treatments in all three experiments confirmed that at least 75000 plants/ha were needed for maximum sugar yield, that sodium fertilizer increased sugar yield more than potassium (+0.76 and +0.29 t/ha respectively) and that the crop responded to irrigation in some years (+1.35 t sugar/ha in 1970 and +1.67 t/ha in 1972).

Analysis of the growth of the crop showed that increasing the plant density increased leaf growth per unit area from singling onwards and giving irrigation increased it from July; the effects persisted until harvest and were reflected in increased sugar yields. Fertilizer increased leaf growth early in the season but the effect disappeared later, although sugar yield was still increased. Interactions between plant density, fertilizer treatment and irrigation were small every year but there were some consistent effects on sugar yield. The results suggest that in commercial practice the optimum density is 75000 plants/ha; where irrigation is not practised, 247 kg/ha of sodium and 70 kg/ha of potassium fertilizer should be given. Where irrigation is applied, only 247 kg/ha of sodium needs to be given as the extra water increases the uptake of soil potassium.

The amount of soil moisture used by sugar beet was determined weekly between May and October (1970–2) in plots testing 18500 and 124000 plants/ha with and without irrigation. When leaves covered more than 60% of the ground (after mid-June with the large density and after mid-July with the small density) the crop used water at the potential transpiration rate even with soil moisture deficits on plots without irrigation of up to 170 mm. Therefore as irrigation greatly increased sugar yield in 1970 and 1972, it probably did not do so simply by satisfying the crop's water need.

In 1970 irrigation appeared to act partly by decreasing the time taken to attain complete leaf cover but in 1972 irrigation had only a slight effect on leaf cover but greatly increased sugar yield, particularly of the large population. With little rainfall, the large density rapidly exhausted the available moisture from the plough layer. It seems likely therefore that irrigation increased yield by giving more leaf cover early and by improving nutrient supply but not by supplying extra water for transpiration.

The use of body weight, red cell volume and tritiated water space in the prediction of the body water, body-fat and soft tissue protein contents of hill sheep was investigated. Sixteen Blackface sheep, ranging in age from 2½ to 6½ years, were used before mating in November when in peak body condition and 21, of similar age distribution, were used in mid-lactation in June when in very poor body condition. Mean fat concentrations in the empty body were 188 and 28 g/kg in November and June, respectively.

Body weight alone accounted for 46 and 14% of the variation in body-fat content in November and June, respectively. The inclusion of red cell volume as a second independent variate did not improve the efficiency of the prediction equations. When tritiated water space and body weight were used 77% of the variation in body-fat content was accounted for in both November and June. Separate equations for the November and June groups gave the most accurate estimate of body-fat content, but it was concluded that for most practical purposes a single relationship would be sufficiently accurate. Soft tissue protein content was best described as a simple function of body weight.

The application of prediction equations from the literature to the present populations of sheep led to overestimates of body-fat content by up to 100%. It is suggested that prediction equations need to be specific to the experimental conditions operating or to the particular population under study.

Three experiments are reported which investigated the effects of planting density and variety on the relationship between tuber dry-matter percentage and tuber size. In the first experiment dry-matter determinations were made on samples of tubers less than 3·8 cm and greater than 3·8 cm from different planting densities obtained at eight fortnightly harvests. Standard analysis of variance was used for each harvest date and apart from Maris Piper giving consistently higher dry-matter percentages than Pentland Crown for the same tuber sizes, effects were small and difficult to interpret. The reasons for the problems in interpretation, which were mainly due to differences in tuber size distribution, are discussed.

In the second and third experiments the effects of tuber-size distribution were removed by regression analyses of tuber dry-matter percentage on tuber size in definable grades and curves were fitted to the data. These curves revealed that tuber dry-matter percentage tends to show a quadratic response to increasing tuber size and is affected by variety and stem density. The significance of these results is discussed.

A number of herbicide treatments involving the use of trifluralin, preforan and igran were compared together with hand weeding as methods for the control of weeds in a cultivar of Phaseolus vulgaris sown on 19 January 1972.

Favourable increases in yield of beans were obtained by combinations of preforan and igran which were associated with an increase in the number of pods produced per plant. Hand weeding failed to give a significant increase in final yield.

Within 14 days from sowing there was an appreciable weed cover in the control and hand-weeded plots but little evidence of weeds in the herbicide-treated plots. At 41 days there were still no significant differences between the control and the plots to be hand weeded. There was, however, a considerable reduction in percentage cover of weeds on the herbicide treated plots. Trifluralin and preforan were equally effective in reducing weed cover.

Lactation in ewes is associated with hypertrophy of the liver, due to cell proliferation and enlargement. The mean diameter of hepatic parenchymal cell nuclei increased after parturition to reach a maximum at 6 weeks, after which there was a decline.

The liver regressed in weight after weaning but total DNA declined less than liver weight and remained elevated in comparison with livers of unmated ewes, while DNA concentration increased. Total liver DNA remained relatively high for approximately 6 months. It is suggested that the final fall to control values was associated with cell death and disorganization of the hepatic parenchyma.

These results imply that the life span of one type of liver parenchymal cell may be at least 6 months.

Sheep prepared either with a rumen cannula, or with a rumen cannula plus re-entrant cannulae in the duodenum and ileum were fed fresh ‘Ruanui’ perennial ryegrass (R), ‘Manawa’ short-rotation ryegrass (M) and white clover (C) at dry-matter intakes ranging from 450 to 1000 g/24 h.

The re-entrant cannulated sheep were given paper impregnated with chromic oxide (Cr2O3) once daily via the rumen fistula as a marker; recoveries of Cr2O3 at the duodenum, ileum and faeces were approximately 75, 69 and 100% respectively. Regressions of Cr2O3-corrected digesta constituent flows (g/24 h) on intake were constructed and from these were calculated the sites of digestion of OM, gross energy, readily fermentable carbohydrate, structural carbohydrate and lipid between the stomach, small intestine and large intestine.

There were differences between pasture species in partition of OM and energy digestion. With M, digestion in the stomach was significantly less (P < 0·01) and digestion in the small intestine was significantly more (P < 0·05) than with either R or C. These partitions of OM and energy digestion changed with level of feed intake. A substantial proportion (9–18%) of the digestible OM and energy was apparently digested in the large intestine with all three herbages.

With all three herbages approximately 93% of the digestible readily fermentable carbohydrate and 90% of the digestible structural carbohydrate was digested in the stomach region.

Reasons for differences in gross efficiency of utilization between the pasture species in the order C > M > R were examined.

Sheep prepared either with a rumen cannula, or with a rumen cannula plus re-entrant cannulae in the duodenum and ileum were fed fresh ‘Ruanui’ perennial ryegrass (R), ‘Manawa’ short rotation ryegrass (M) and white clover (C) at dry-matter intakes ranging from 450 to 1000 g/24 h. Paper impregnated with chromic oxide was given once daily via the rumen fistula as a marker.

Amounts of non-ammonia-nitrogen (NAN) entering and leaving the small intestine and nitrogen (N) excreted in the faeces were regressed against the intake of N for each sheep and these equations (all significant P < 0·05) were used to calculate the extent of digestion in the stomach, the small intestine and the large intestine at two levels of OM intake (500 and 800 g daily). Amino acid analyses of feed and digesta samples are also presented together with calculations of the apparent absorptions of individual amino acids from the small intestine.

At an intake of 500 g OM amounts of NAN entering the small intestine were significantly greater (P < 0·05) in sheep given M than in sheep given R or C. At an intake of 800 g OM amounts in sheep given M were significantly greater (P < 0·01) than in sheep given R. NAN leaving the small intestine and N excreted in the faeces were similar for all three diets.

At an intake of 800 g OM apparent absorptions of NAN from the small intestine of sheep given M (0·47 × N intake + 2·8 g/24 h) and sheep given C (0·51 × N intake – 1·3 g/24 h) were significantly greater (P < 0·01 and P < 0·05 respectively) than of sheep given R (0·41 × N intake – 0·5 g/24 h). As intake of herbage was increased the partition of digestion altered.

Only small differences between herbages were found in the amino acid composition (g amino acid/100 g protein) of either duodenal or ileal digesta, but because of the large differences in the flows of NAN, the apparent absorptions of individual amino acids from the small intestine were much higher in sheep given M than in sheep given the other two species.

The results are discussed in the light of available information on sites of digestion of herbage diets in sheep.

Sheep prepared either with a rumen cannula, or with a rumen cannula plus re-entrant cannulae in the duodenum and ileum were fed fresh ‘Ruanui’ perennial ryegrass (R), ‘Manawa’ short-rotation ryegrass (M) and white clover (C) at dry-matter intakes ranging from 450 to 1000 g/24 h. Paper impregnated with chromic oxide was given once daily via the rumen fistula as a marker.

Amounts of Mg, Ca, P, K and Na entering and leaving the small intestine and excreted in the faeces were regressed against the intake of each element for each sheep and these equations (all, other than the faecal excretion of Na, significant (P < 0·05)) were used to calculate the extent of apparent absorption or secretion in the stomach, the small intestine and the large intestine at two levels of OM intake (500 and 800 g daily).

Quantities of Mg (at high intake), Ca and K (except sheep fed M) leaving the stomach were significantly lower (P < 0·05), while the amounts of P and Na were significantly higher (P < 0·01) than the amounts consumed. Quantities of Mg (at high intakes) and Ca leaving the small intestine were significantly higher (P < 0·05) while amounts of P, K and Na (at high intakes) were significantly lower (P < 0·05) than the corresponding quantities entering the small intestine. At both intakes in the case of Na and at the higher intakes in the case of the other mineral elements, quantities of Mg, Ca (except sheep fed C), P, K and Na excreted in the faeces were significantly less (P < 0·05) than the amounts entering the large intestine.

Thus at the higher intakes there were net absorptions of Mg, Ca and K (except sheep fed M) from, and net secretions of P and Na into, the stomach. The small intestine was the major site of net absorption for P and K and a minor site for Na, while a net secretion of Mg and Ca occurred into this region. Net absorption of Mg, Ca, P, K and Na occurred from the large intestine at the higher intakes.

The retention of Mg, Ca and P is discussed in relation to the animals' minimal daily requirements of these elements.

This article attempts to discuss the relations between the nitrogen sources in data from a large field experiment in which various levels of fertilizer nitrogen were applied to various grass mixtures in the presence and absence of white clover. It was seen that a number of effects occurred, among them the strong depression of clover nitrogen by fertilizer nitrogen (to the extent that equations predicting their contribution to grass nitrogen could not be produced directly by multiple regression but had to be constructed separately), a further apparent depression of clover nitrogen transfer effectiveness, a more significant relationship between grass nitrogen increase and the previous year's clover nitrogen than the current year's clover nitrogen, and apparent competition between grass and clover despite the latter's contribution to increased grass yield.

As some of the effects are counteractive, in each comparison made a balance appears to exist. This varies between sites and years in such a way that although the variation in grass nitrogen is always largely dependent on the clover and fertilizer nitrogen the relations are not consistent as shown by the mathematical equation representing them, and cannot be extrapolated or predicted for other sites. It is suggested that a mathematical model be constructed to simulate such an interactive system and that predictions when necessary be made using this, rather than using simple equations.

Leaf burn and gradual death were the characteristic symptoms of injury in P. vulgaris sown on a sodic soil. Plant growth, total leaf area per plant, number of stomata and epidermal cells per unit leaf area, and relative water content were drastically reduced in injured plants; these were associated with large sodium accumulation in the shoot resulting in cation imbalance.

Field experiments were conducted on clay and sandy clay-loam soils to investigate the effects of sowing date on the incidence of plant losses. Early sowing dates from 2 to 23 September resulted in very low seed yield (360 kg/ha) mainly because fewer plants survived. High air temperature increased the rate of plant death which was highly correlated with degree days, r = +0·95.

Number of plants/m2 was the predominant factor determining seed yield and number of pods/plant could not compensate for loss of plants.

Body weights at birth, weaning, yearling and 2 years of age were studied on 710 lambs born from 1956 to 1967 and representing Barki, Merino and their F1 and backcross. Body weights ofthe lambs of the two cross-bred groups were intermediate between those of the two pure-breds at birth and exceeded them at weaning. Merino lambs were 0·61 kg heavier than Barki lambs at birth and maintained that advantage throughout the study.

Age of dam, type of birth, sex, and year of birth were significant sources of variation on the weights studied. The effect of age of dam and type of birth declined after weaning while that of sex increased.

As an indication of heritable variation between genotypes, the response of diploid and autotetraploid homozygous inbred lines of rye to varying applications of inorganic nutrients and to temperature ‘shocks’ during growth was studied. The results indicated first that developmental differences occur between lines and between diploids and tetraploids under comparable conditions of growth. Secondly, the consequences of altering growing conditions can differ between lines and between diploids and tetraploids. Thirdly, the effect of polyploidy upon the response to these treatments was shown to vary between lines. It is concluded that an assessment of plant growth and development must take into consideration the genie, chromosomal and environmental interactions.