Field studies on leaching a highly saline sandy loam soil having a shallow groundwater table showed that application of 150 mm water in two equal parts at 10 days interval had no distinct advantage over a single application of the whole amount. On the contrary, the surface-accumulated salts were displaced to a lesser extent and the salt peak remained at a shallower depth under split application, particularly during periods of high atmospheric evaporativity when the leached salts tended to move upward between successive water applications. A soil mulch created by shallow tillage reduced evaporation losses and curtailed upward movement of salts, resulting in nearly 10% increase in leaching efficiency. Significantly a small quantity of water (0·41 cm leaching water per unit soil depth) sufficed for 70% chloride removal, indicating that under the prevailing conditions a larger fraction of the pores contributed to the leaching process. A compact layer, having a bulk density of 1·69 g/cm3, at the soil surface, also appeared to be related to the higher leaching efficiency by maintaining a preponderance of unsaturated flow.

The growth and water use of sugar beet affected by early (ED) and late (LD) drought was compared with that of irrigated (I) and unirrigated (NI) controls. Mobile shelters were used to exclude rain from ED plots during June and July, and LD plots during August and September, respectively, whereas outside these periods the ED and LD plots were irrigated as necessary.

The ED treatment affected the fibrous roots severely. Many of the roots in the top 60 cm of soil died and development of the root system below this depth was slow. Expansion of the leaf canopy slowed, radiation interception was reduced and the rate of water use fell from about 1·2 times to 0·6 times Penman potential transpiration rate. The LD treatment, which was imposed when the fibrous root system was already extensive, had little effect on the fibrous roots except in the top soil. The accessible soil water was quickly depleted and the resulting stress was accompanied by earlier senescence of leaves. The rate of converting intercepted light to crop dry matter was reduced in both treatments. However, the ED treatment was the most detrimental because the amount of light intercepted in the months of highest radiation was greatly reduced owing to the restricted leaf cover. The relative effects on growth are reflected in the final sugar yields which were 8·7, 10·5, 9·9 and 12·0 (±0·30) t/ha in the ED, LD, NI and I treatments respectively.

More of the deep soil water was used in the drought-affected plots (particularly LD) than in the irrigated controls. Maximum depths of water extraction were 140–150 cm in ED and I plots and > 170 cm in LD plots. The highest uptake rates per unit length of root (20–40 μl/cm per day) were measured in the deepest part of the root system. At all depths, uptake rates declined as the soil dried. After correcting for overestimated water use where necessary, the ratios of final dry matter and sugar yields respectively to season-long water use (June–October) were close to 1·4 and 0·8 t/ha per 25 mm for all four treatments.

For many field-grown crops, including sugar beet, there is little information on the seasonal changes in leaf water potential and its components as the soil dries. Therefore, seasonal changes in leaf water, osmotic and turgor potentials of sugar beet were measured in two seasons, in crops that experienced differing degrees of soil moisture stress. In 1983 potentials of crops exposed to early and late droughts were compared with those of irrigated crops, and in 1984 measurements were made in a non-irrigated crop. In the irrigated crop the midday leaf water potential changed little during the season, except in response to fluctuating evaporative demand. In the drought and non-irrigated treatments there was a sharp fall in leaf water potential as soon as the soil water potential decreased. The size of the midday leaf water potential was primarily determined by soil dryness. However, the leaf water potential did not decrease below about — 1·5 MPa in either year. The leaf osmotic potential declined at the same time as the leaf water potential, but the extent to which this happened differed in the two years. Only in the 1984 non-irrigated crop did the osmotic potential continue to decrease as the soil dried, suggesting that osmotic adjustment had taken place in 1984 but not in 1983. Thus higher turgor was maintained in the 1984 crop than in the 1983 drought-affected crops. Some turgors were recorded as apparently negative in 1983.

Since the leaf water potential declined to a minimum of about — 1·5 MPa, the soil water potential minima were also about — 1·5 MPa. However, deeper soil was not dried to this extent, suggesting that the extra resistance for water uptake from deep soil was limiting or the rooting density was too low.

The pattern of recovery of leaf water potential overnight suggested that the rhizosphere resistance to water movement was small, even as the soil dried. However, measurement of stem water potentials in 1984 indicated that a significant resistance to water flow existed within the aerial part of sugar beet plants. This shows that the use of the water potential in leaves as an estimate of that in stems or roots can be misleading.

The effects of night enclosure and walking 3000 km on growing and breeding cattle were examined over an 8-month period. Walking consisted of an 8 h walk of 40 km every 3rd day and experimental cattle were enclosed each night for 11 h. In addition, all cattle were allowed water once every 3 days. In cattle which both walked and were enclosed, a reduction of nearly 40% in grazing time was recorded. This was associated with a depression of dry-matter intake of only 12%, suggesting an intensification of eating in response to a restriction of grazing time. The overall effects of walking and enclosing on productivity, as determined by adult weight loss, calf and weaner growth, calving percentage and birth weight, were negligible and masked by the greater effects of poor nutrition during the dry season which affected all the animals. It is concluded that the additional energetic requirements for walking are small and this is attributed to adaptation, fitness and a possible depression of metabolic rate. These factors may explain why the observed costs of walking were lower than those reported in the literature.

Water influx, i.e. total water intake from water drunk and water obtained from food, was measured using tritiated water in six groups, each containing ten single comb White Leghorn (SCWL) hens, in which each group received decreasing amounts of dry matter (D.M.) in decrements of 10%. Group 1 received 101·2 g D.M./day, an amount normally offered these hens, group 2 received 92·4 g D.M./day, group 3 received 81·0 g D.M./day, group 4 received 70·4 g D.M./day, group 5 received 61·6 g D.M./day and group 6 received 52·8 g D.M./day. In the first 4 weeks, egg production remained relatively high in the restricted fed groups compared with group 1 and body mass declined rapidly (period I); in the second 4 weeks, egg production declined to a great extent but body mass remained constant (period II). The ratio of water influx to DMI remained constant in the two periods in hens with the same DMI but with different egg production. The linear regression of DMI and/or egg production on water influx were significant within each period. DMI explained 65% of the variation in water influx, egg production explained 30/55% of the variation, and both DMI and egg production explained 66/70% of the variation. Within each period, the regressions of DMI on water influx in hens with similar egg production were generally significant, and, in contrast, the regressions of egg production on water influx within each DMI were generally not significant. It was concluded that DMI was more important than egg production in affecting water influx in laying SCWL hens.

The effect of including full-fat rapeseed (Brassica napus, cv. Jet Neuf) into diets for mature wether sheep was studied. A 4 × 4 latin square was carried out with diets containing 4% rapeseed oil in different physical forms: as intact seeds; as a mixture of rapeseed oil and rapeseed meal; or as an extruded rapeseed product. A control diet, containing rapeseed meal but no added oil, was also fed.

There was no effect of added oil on rumen fermentation or dietary fibre digestibility. Extrusion had the effect of lowering nutrient availability, both in the rumen and in the small intestine. Total nitrogen digestibility for the diet containing the extruded product was 5% lower than any other diet.

All diets produced apparent net gains between mouth and duodenum of ether extract; however, the diet containing dispersed oil and meal was the only one that did not show apparent synthesis of long-chain fatty acids in the forestomach. Apparent disappearances of fatty acids in the small intestine were highest, at 56 and 58 g/day respectively, for the diets containing the extruded product and the intact whole seeds. Extrusion had the effect of reducing apparent biohydrogenation of 18:1 in the forestomach.

The use of extruded rapeseed in this experiment showed little benefit over that of intact rapeseed, for sheep, owing to the lower digestion of nutrients for the heated supplement. The free-dispersal of rapeseed oil in the diet, however, may inhibit microbial synthesis in the rumen.

Experiments were carried out during 1978–81 in which lagoon-matured digested sludge (LMDS) was applied in November and in February to four soils which were cropped with ryegrass and the effects compared with ammonium nitrate fertilizer.

Over the whole experimental series the nitrogen in spring-applied LMDS was 47·6% as effective in producing dry matter as nitrogen in ammonium nitrate fertilizer, and was 40·2% as effective in nitrogen uptake. Overall, 20·3% of the N available from the LMDS was derived from mineralization of sludge organic nitrogen, equivalent to a 1st-year release from the organic-N in sludge of about 9%. This compares with reported values of 15–16% for 1st-year release of organic-N liquid digested sludge. Overall, autumn-applied LMDS sludge gave poorer results than when applied in spring. This did not apply to a silty loam with a pH of about 5, but poorer results with autumn-applied LMDS were associated with soils with pH values of 7·5 or more. On average an application of 140 m3 LMDS/ha provided 178 kg available-N/ha and 36 kg potassium/ha; this is an N:K ratio of 4·9:1.

There were increases of Cd, Cu and Zn in herbage as a result of applications of both fertilizer and of sludge; the effects were additive. Sludge increased herbage Ni concentrations but fertilizer-N reduced them. Three years' applications hardly raised Cu and Zn herbage concentrations to the threshold level for deficiency for ruminant animals, and were not near toxic levels for plant growth or animal nutrition.

Two sets of experiments were carried out during 1978–82 in order to compare the value of nitrogen in liquid undigested sludge (LUDS) with that in ‘Nitro-Chalk’. One set took place in the area of north Hertfordshire-south Bedfordshire, and the other at the University of Leeds. In the first growing season after application the relative effectiveness of LUDS-N was about 20%. In subsequent years it was about 40% though it was less on a soil initially very deficient in soil-N. At Leeds the 2nd-year value was 60–75%.

In the growing season immediately following treatment, N mineralized from LUDS became available too late to increase D.M. yields greatly; much of this appeared to be retained in the turf mat and increased the yield of D.M. the following year. When the lower 1st-year responses were taken into account there did not appear to be any yield penalty in making autumn (November) applications, compared with spring (February). This overall result concealed differences between soils.

In a year when it was dry during the main growing period yields were reduced by about 25%. It seems that LUDS-N is most valuable when it is applied regularly to the same area, and in the wetter parts of the country. Much LUDS comes from smaller rural sewage treatment works which are much less likely to carry contamination from potentially toxic elements.

Flowers were present over a period of approximately 6 weeks in 12 varieties of oil-seed rape. A linear relationship was found between flower cover (maximum 74%) and photon reflectivity (400–700 nm) which increased from around 0·047 during vegetative growth to 0·195 for a canopy in full flower. Reflexion and absorption of photons by flowers reduced light available to the leaf canopy and immature pods. Spectral measurements indicate that flowering canopies reflect substantially more radiation and absorb less than vegetative canopies between 500 and 700 nm but reflect less and absorb slightly more between 400 and 500 nm.

Seed yield was not strongly correlated with estimates of the radiation absorbed by the leaf canopy under the flower layer. It appears that whilst increased flower density in a canopy might be expected to contribute to increased seed yield, increased reflectivity by petals may have a negative effect on yield. Breeding for reduced petal size or for apetalous lines may result in improved yields by producing more efficient light distribution within the canopy.

Urea with molasses and starch, casein, and fish meal with maize gluten meal were compared with a urea control as different nitrogen and energy sources in straw diets fed ad libitum to four mature non-lactating Swedish Red and White cows in a 4 × 4 latinsquare design. Cows fed fish meal with maize gluten meal had increased neutral detergent (ND) fibre intake, digestibility, and total digestion compared with those fed the urea control. When fed casein, cows tended to have higher ND fibre intake, lower ND fibre digestibility, and higher total ND fibre digestion than the urea control. Cows fed urea with molasses and starch had the same ND fibre intake, lower ND fibre digestibility, and lower total ND fibre digestion than the control. Treatments had no influence on rumen pH, rumen in sacco ND fibre kinetics, rumen residence times and median faecal particle size. Rumen ammonia concentrations were lower for the urea with molasses and starch as well as for the fish meal with maize gluten meal treatments when compared with the urea control. Rumen volatile fatty acid concentrations for supplemented diets were either unchanged or higher than for the control diet.

Thirty Ossimi lambs were used in an experiment to compare those whose tail was docked shortly after birth with controls. After weaning at 4 months of age the groups were further subdivided and two of the four groups closely shorn according to a 2 × 2 factorial design.

Male lambs at 20 kg were subjected to intensive finishing until the age of 50 weeks and nine were then slaughtered to determine carcass characteristics.

There was a trend for increased live-weight gain in the docked lambs in the preweaning stage (up to 16 weeks).

This trend was also present, although not statistically significant, in the final phase of intensive feeding from 20 kg weight to 50 weeks. Shearing significantly improved daily gain in this final period (P < 0·05). These increases in gain were also apparently associated with improvements in efficiency, as judged on a group basis.

Docking and shearing also tended to cause increases in body measurements: height, chest girth and abdomen girth in the case of docking (P < 0·05) and chest girth, chest depth and abdomen girth in the case of shearing (P < 0–05).

Carcass characteristics, measured on a relatively small sample, indicated several effects of docking and shearing on carcass traits although most of these were consistent with the expected differences stemming from the higher carcass weights acheived at 50 weeks of age by docked and sheared lambs.

Environmental and cultural factors that may limit the yield of short-duration pigeonpea were investigated over three seasons. Plants in the peninsular Indian environment at Patancheru grew less and produced less dry matter by first-flush maturity than at Hisar, a location in northern India where the environment is considered favourable for the growth of short-duration pigeonpea. However, with a similar sowing date in June, the mean seed yields of three genotypes, ICPL 4, ICPL 81 and ICPL 87, were very similar, at about 2·3 t/ha, in both environments. This was mainly due to the higher ratio of grain to above-ground dry matter at Patancheru. In addition to the first harvest, all genotypes showed a potential for two more harvests owing to the warm winters at Patancheru. The potential for multiple harvests was particularly high in ICPL 87, which yielded 5·2 t/ha from three harvests in 1982–3, 3·6 t/ha from two harvests in 1983–4, and 4·l t/ha from three harvests in 1984–5. The optimum plant population density at Patancheru was 25–35 plants/m2 for ICPL 87, but was higher for the other two genotypes.

At Patancheru, the total dry-matter and seed yield of first and subsequent harvests were significantly reduced by delaying sowing beyond June. Generally, the second- and the third-harvest yields were lower on vertisol than on alfisol under both irrigated and unirrigated conditions.

The total yield of ICPL 87 from two harvests was far higher than that of a well-adapted medium-duration genotype BDN 1, grown over a similar period. The yield advantage was greater on the alfisol because of the better multiple harvest potential of this soil. The results of this study demonstrate that properly managed short-duration genotypes of pigeonpea may have considerable potential for increased yield from multiple harvests in environments where winters are warm enough to permit continued growth.

Twenty-five male Shugor, 25 female Shugor, 25 male Watish and 25 female Watish lambs, individually fed for 57 days, were used to study post-weaning growth performance and carcass composition of these breed types when subjected to a period of intensive feeding.

Means and standard error of means of daily gain on experiment were 191·0±5·81, 166·0±5·81, 150·0±5·81 and 134·0±5·81 g for Shugor males, Watish males, Shugor females and Watish females, respectively. The means and S.E. for feed conversion ratio (FCR) were 5·79±0·190, 7·30±0·190, 7·47±0·190 and 8·00±0·190 in the same order. Shugor and male lambs had better gain (P < 0·001) and FCR (P < 0·01)than Watish and female lambs respectively.

Shugor had heavier slaughter weight and cold carcass weight than Watish (P < 0·01). Males were superior to females in slaughter weight, carcass weight and dressing percentage (P < 0·01). No difference was detected in lean, fat or bone percentage between breed type or sex (P < 0·05). Males had larger muscle area (P < 0·001) than females. On the other hand, females had more percentage kidney knob and channel fat (P < 0·001) and thicker fat depth (P <0·01) than males. Shugor were superior (P < 0·01) in fat depth to Watish.

Percentage non-carcass components showed that females had more percentage omental and mesenteric fat (P < 0·001) and percentage full stomach (P < 0·01). Breed type and sex showed significant effect (P < 0·001) on percentage liver.

In linear measurements, Shugor had greater carcass length and femur length (P < 0·01). Males had bigger circumference of buttocks and chest depth (P < 0·001).

For carcass joints as a percentage of side weight, the only clear effect of breed type was on percentage loin (P < 0·05). Males had bigger percentage middle neck (P < 0·001) and shoulder and percentage scrag (P < 0·01) than females, whereas females had higher percentage loin and chump.

Heritability estimates of some carcass traits, admittedly based on limited numbers, ranged from 0·32 (S.E. 0·183) for leg to 0·18 (S.E. 0·180) for loin weights. Linear carcass measurements showed low heritability of around 0·10 (S.E. 0·160).

Frequently in near-infrared reflectance spectroscopy, a calibration is developed using very restricted data sets, e.g. material from one season, a small area or of a limited type: consequently, the predictions may have limited validity. This paper describes the use of both restricted and wide calibration sets for the prediction of crude protein in grass, silage and hay. Results show that predictions from the wider calibration sets are often as good as or better than predictions from restricted calibration sets. Therefore the use of wide calibration sets should be considered much more frequently in near-infrared reflectance.

The suitability of stained food and [103Ru]phenanthroline-treated food as markers for measuring dietary retention time was examined in sheep. The digestibility of oat husk, assessed by incubation of samples contained in nylon bags in the rumen, was greatly depressed by staining with brilliant green, and slightly depressed by basic fuschsin. The latter effect appeared largely to be due to boiling rather than the stain itself.

When milled hay treated with both basic fuschsin and [103Ru]phenanthroline was introduced into the rumen, the mean retention time estimated with the stain was about 40% longer than that estimated with [103Ru]phenanthroline.

The digestion and retention times of milled hay diets were first studied in three sheep fitted with rumen and abomasal cannulae. The hay was milled through 5, 20 or 40 mm screens. Solubility of dry matter (D.M.) in water and rate of loss of D.M. from hay in nylon bags suspended in the rumen increased with fineness of grinding. Apparent digestibility of D.M. within the gut tended to fall with fineness of grinding, as did mean retention time (MRT) of a particulate marker, [103Ru]phenanthroline ([103Ru]phen), within the gut and of [103Ru]phen and a liquid marker, [51Cr]EDTA, within the rumen. Dry-sieved abomasal particles were much smaller than particles of any of the hay preparations, most passing through a 0·6 mm screen.

A second experiment was made on four other sheep, fitted with rumen cannulae and given a similar hay, chopped to 50 mm or milled through 2, 5 or 20 mm screens. Apparent digestibility of D.M. within the gut fell significantly with fineness of grinding, from 55% with the chopped hay to 46% with the 2 mm hay, as did MRT, from 45 to 40 h respectively. Rumen pH at 1 h after feeding decreased with fineness of grinding.

In a third experiment, using the four sheep given chopped or 2 mm hay, retention times of particulate matter and of fluid in the reticulo-rumen and in the caecum-colon were measured. [103Ru]phen and [51Cr]EDTA were dosed together into either the rumen or the terminal ileum, and the rates of decline of marker concentration in rumen samples or faeces respectively were used to calculate the appropriate half times(t½). In the rumen particulate and fluid markers showed significantly shorter t½ values with the 2 mm hay (20·8 and 12·4 h, respectively) than with the chopped hay (25·9 and 15·6 h, respectively) without a significant difference in rumen outflow (0·437 and 0·492 l/h, respectively). In the caecum-colon the corresponding t½ values were 6·4 and 6·3 h, and 7·1 and 6·6 h, there being no significant difference either between markers or between diets.

Samples of chopped hay and of 20, 5 and 2 mm hays were suspended in bags in the rumen of sheep given either chopped or 2 mm hay to eat. The fine hays lost D.M. more rapidly than the coarse hays but D.M. loss was slower when the sheep's diet was 2 mm hay that when it was chopped hay.

It is concluded that three factors accounted for the effect of milling on digestibility: retention time in the reticulo-rumen, D.M. degradation rate in the rumen, and the potential digestibility of the hay preparation (asymptotic D.M. loss as measured in the rumen bag studies). It appeared that fine grinding reduced the digestibility of the hay because the effects of shortened MRT in reducing duration of digestion and of lowered rumen pH in depressing cellulolysis outweighed the effects of grinding in accelerating digestion and increasing potential digestibility within the rumen.

A simple mathematical model of the distribution of potato tuber yield between size grades is presented. It has two parameters, μ, a measure of crop tuber size and σ, a measure of the spread of yield across size grades. The model is shown to be useful for the analysis of field experiments, the prediction and physiological study of tuber size distribution, and the economic analysis of management decisions. The model is applied to a variety of dataandthe practical control of tuber size discussed.

The influences of the temperature during plant raising and the age of plants at transplanting on the time of hearting and head weight at maturity of the crisp lettuce variety Saladin R100 were determined in seven experiments between 1984 and 1986.

Plants raised at ambient temperatures and transplanted before the end of May produced heads which were heavier and matured later than those from plants raised at higher temperatures under glass. The influence of transplant age on head weight was much smaller than that of raising conditions and there were inconsistent effects on the time of crop maturity. When the head weights at maturity of all treatments were considered there were highly significant positive correlations with total solar radiation in the periods 7 and 10 days before 50% hearting occurred. Further examination of this effect revealed that heads heavier than 800 g were strongly associated with mean daily solar radiation exceeding 15MJ/m2 in the periods 7 and 14 days before 50% hearting. This suggests that breeding for stability of head weight from crop to crop is likely to be aided by selection for consistency of head weight under a range of light levels in the prehearting phase.

The coefficient of variation of the period from transplanting to maturity, measured in terms of various environmental characters, was lowest using effective day-degrees, which take account of different levels of solar radiation at the same mean temperature. This suggests that effective day-degrees may be the best indicator of the duration of crop growth and therefore of benefit in developing techniques to predict the time of crop maturity.

The quantitative partitioning of digestion between the stomachs, small intestine and large intestine was compared in kids and lambs offered a high quality meadow hay (organic-matter digestibility, 0·74; N, 23·9 g/kg D.M.) in amounts between maintenance and ad libitum.

Nutrient flow past the abomasum and terminal ileum and in the faeces was measured by reference to 51Cr-EDTA and 103Ru-phenanthroline. Digestion of D.M., neutral detergent fibre (NDF) and non-ammonia N (NAN) in the rumen (R), small intestine (SI) and large intestine (LI) was estimated from the regression of nutrient flow on nutrient intake.

No difference was observed between the species in digestion of D.M., NDF and NAN at any site. Approximately 0·60, 0·29 and 0·13 of the total in vivo D.M. digestion (0·74) occurredin the R, SI and LI, respectively, and approximately 0·94 of the total in vivo NDF digestion (0·79) occurred in the rumen of both species.

There was a gain of total N and NAN of 22 and 15%, respectively, in the rumen of both species whilst net disappearance of NAN in the small intestine and of N in the large intestine was approximately 0·62 and 0·27, respectively. All these characteristics varied slightly with level of feeding.

It is concluded that there may be little difference in the partitioning of digestion of D.M., NDF and NAN in the digestive tract of kids and lambs when consuming high quality forages.

Short-duration pigeonpea can give up to three harvests in environments with mild winters (e.g. minimum temperature above 10 °C) such as those prevailing in peninsular India (Sharma, Saxena & Green. 1978; Chauhan, Venkataratnam & Sheldrake, 1984). This is mainly due to the short time (about 120 days) taken to produce the first flush, and the strong perennial character of pigeonpea. The seed yield of short-duration pigeonpea in this multiple-harvest system may reach 5·2 t/ha (Chauhan et al. 1984).