Avalon winter wheat was grown in 1983 on a light-textured, sandy loam (Cottenham series) which had a subsoil pan with a maximum dry bulk density of 1·8 g/cm3 at 35 cm depth. This was destroyed on part of the site with a ‘Wye Double Digger’ so that crop growth in panned and pan-free soils could be compared. The interaction of the pan with soil water supply was studied by sheltering the crops during May, June and July and either withholding water completely or irrigating weekly back to field capacity.

The pan had a major effect on the vertical extension rate of the root system as monitored both by coring and from observation tubes. Roots were largely confined above the pan until March, but compensatory growth occurred within this soil layer and the total length of root was unaffected. At anthesis, roots had reached a maximum depth of 100 cm in the panned soil compared with 140 cm in the pan-free soil.

Early shoot growth and N content were substantially reduced by the pan because of the inaccessibility of mineral N in the subsoil. However, both the growth of the crop and N uptake recovered following top dressings of N fertilizer and, when water was not limiting, the pan had a negligible effect on grain yield.

Root and shoot growth were reduced by the fixed shelter, but the imposed drought did ot affect water use by the crops until after anthesis when the root systems were already fully developed. Without irrigation, the crop growing on the double-dug soil yielded 5% more than that growing on the panned soil, but there was no evidence for extra water use from the subsoil by the former crop. The best treatment (double-dug with irrigation) outyielded the worst (panned soil with drought) by 8%.

Faecal output of 287 beef cows consisting of Hereford (H × H), Simmental × Hereford (S × H), Friesian × Hereford (F × H) and Brahman × Hereford (B × H) breeding was estimated using controlled release of chromic oxide (Cr2O3). All cows were from 6 to 10 years of age and had grazed on one of three pasture systems in the subtropics of New South Wales since they were 7–8 months of age. These pastures were designated as being of high, medium and low nutritive value. Faecal organic matter output (FOMO) was estimated in each of four periods (early lactation, mid lactation, late lactation, and non-lactating) during one annual production cycle.

Herbage mass exceeded 2 t/ha on all pasture systems, but estimates of organic-matter digestibility, nitrogen content and pasture composition indicated large differences in pasture quality (high > medium > low). Live weight of cows averaged 604, 488 and 393 kg live weight on the high, medium and low pastures, respectively. There were significant differences in live weight between genotypes on the medium (B × H > F × H and H × H) and low (S × H ≡ F × H ≡ B × H > H × H) pastures but not on the high pasture).

FOMO and dry-matter intake (DMI) differed significantly between genotypes among lactating cows on all pasture systems. Rankings on high pastures were reasonably consistent in all periods: S × H ≡ F × H ≥ B × H ≥ H × H, as were those on low pastures, B × H ≥ S × H ≡ F × H ≥ H × H. Differences on medium pastures were significant only during mid-lactation when B × H ≡ S × H ≡ F × H > H × H. Significant differences between genotypes were observed among non-lactating cows on high pastures only, where H × H ≡ S × H ≡ F × H > B × H. Lactating females had significantly higher FOMO and DMI than non-lactating females when compared across genotypes during early lactation on all pastures.

A telemetry system based on calibrated radio transmitters implanted in the right sublumbar fossa of cattle is described. It was evaluated in different situations. Rectal temperature was used as a standard measure of body temperature. Implant temperatures were on average 0·2 °C higher than rectal temperatures. The magnitude of changes in the two temperatures in response to environmental stimuli were very similar but the implants changed faster in response to heat stress, feeding and exercise. When cattle were confined in unshaded yards the repeatability (within-animal correlation) of implant temperatures measured at different times of the day was 0·41 ± 0·05, compared with 0·30 ± 0·05 for rectal temperatures. It was concluded that there was less extraneous variation associated with telemetric measurement.

The telemetry system proved effective for monitoring the body temperature of grazing cattle within a range of 300 m. The repeatabilities of individual daily maximum and minimum temperatures were 0·43 ± 0·12 and 0·43 ± 0·11 respectively. Observations confirmed that cattle in part regulate their body temperatures by behaviours such as shading, grazing and exposure to wind. Thus body temperature whilst grazing was alone not a good index of physiological heat tolerance.

Dorset Horn and Corriedale ewes (breeds with low and high wool growing capabilities respectively) with single lambs were fed ad libitum on a pelleted roughage-concentrate diet. Following weaning at 6–7 weeks of age (live weight (LW) ca. 15 kg), ten entire male, ten female and ten castrate male lambs of each breed were housed in single pens and fed the same diet ad libitum. Body composition (fat, protein, water, ash and energy) was estimated from tritiated water space at 5 kg LW increments from 10 to 55 kg. Fleece weight was also estimated on each occasion.

The relationship between the weight of body components and fleece-free fasted live weight (W) for each sheep was described by a two-phase piecewise linear model, the slope in each phase representing the average composition of weight gain. In the first phase, the composition of weight gain did not differ between breeds and contained similar amounts of fat and protein (14%), 66% water and 5% ash. Within breeds females tended to be fattest. There were significant differences due to breed and sex in all body components in the second (fattening) phase. The fat content of gain was lower in Dorset Horn ewes and wethers (45 and 51% respectively) than in corresponding Corriedales (64 and 58%) with the males being even lower (44 and 41% respectively). Dorset Horns entered the fattening phase at a significantly higher W (26 kg) than Corriedales (23 kg), there being no sex difference within breeds. The combined effect of lower slope and higher weight at the commencement of the phase change in the Dorset Horns was to produce a considerable breed difference in fatness in the second phase of growth in ewes and wethers. Possible physiological reasons for the differences are discussed.

Digestibility trials were conducted at two stages of lactation with each of 107 Friesian cows using three diets (60:40, 75:25, 90:10 proportions of compound feed to medium quality hay fed long). Each cow received throughout lactation fixed daily allowances of one of these diets at either 2·26 or 2·63 times average maintenance requirements (MM), or was fed ad libitum, average intake equalling 3·07 MM. The digestibilities of the diets were also measured on immature cattle at 0·76 and 1·33 MM and sheep at 0·65 and 1·27 MM.

For all classes of stock the digestibility of dry matter increased linearly and that of fibre decreased curvilinearly with increasing proportion of compound in the diet. There was no interaction of effects of diet composition and amount consumed on digestibility of feed. The digestibility of both dietary components declined for the young cattle and sheep with increased intake. The digestibilities for lactating cows were lower than for other stock but did not change with amount consumed or milk yield. Digestibility was slightly higher for first and second calf cows than for adult cows; and was higher for organic matter in mid lactation compared with early lactation for adult cows.

These results for dairy cows conflict with the generally accepted interpretation that a linear decline in digestibility occurs from once to five times maintenance intake, embracing all classes of stock.

Mean digestible energy (DE) intakes of 147 cows of three parities receiving three levels of DE including one ad libitum (about 2·2, 2·6 and 3·3 multiples of maintenance (MM)) drawn from three mixed diets containing hay and 60, 75 or 90% compound were calculated.

Rumen samples were taken from three-quarters of the cows at monthly intervals throughout the experiment. Molar proportions of volatile fatty acids (VFA) in the rumen were not affected by stage of lactation over the 36 weeks of the experiment. The proportion of acetic acid decreased and that of propionic acid increased with greater intakes and with higher proportions of compound in the diet. The proportion of n-butyric acid was little affected by level of intake but decreased with increasing proportions of compound. In young, non-lactating cattle given the same diets but at lower levels of intake, VFA proportions were unaffected by diet composition at intakes of about 0·7 MM but at intakes of about 1·3 MM the proportion of acetate decreased and that of propionate increased when the proportion of compound was increased from 75 to 90%.

The efficiency of milk energy production in relation to DE or metabolizable energy (ME) above maintenance decreased with increasing level of intake but was little affected by the proportion of compound. Partition towards live weight increased with level of intake in early lactation but not in late lactation. It also increased with higher proportions of compound in mid and late lactation but not in early lactation.

Estimates of the ME requirement for live-weight change (LWC) were in reasonable agreement with recently published standards in early lactation when live weight was decreasing, but later in lactation when live-weight gain was occurring, a much higher value was calculated which is difficult to reconcile with these standards.

Rumen VFA proportions were related to dietary fibre concentration and level of intake additively. The relationship to VFA proportions was close for milk fat concentration, but less so for energy partition towards live weight and none was apparent for the efficiency of ME utilization for milk energy production. It is suggested that both the reduction in milk fat concentration and the increase in milk yield in response to reductions in the fibre content of diets may be independently related to the increase in the proportion of propionate in the rumen VFA.

It is concluded that further progress in studies of the dietary factors affecting the efficiency of milk production will require measurements of nutrient uptake from the digestive tract and description of milk production and LWC in terms of their chemical composition rather than energy alone.

The effect of inoculation with Azospirillum brasilense on growth, water status and yield of dryland sorghum (cv. RS 610 and cv. H-226) growing on stored soil moisture was examined in three field experiments conducted during the years 1983–5.

Plants were sampled at regular intervals, and the following characteristics were measured: dry-matter accumulation, leaf area, grain yield, percentage nitrogen and phosphorus in leaves, leaf water potential, canopy temperature, transpiration, stomatal conductance and soil water depletion.

Inoculation led to an average increase of 19% in total stover dry-matter yield, as a result of higher rates of dry-matter accumulation during the early stages of growth. Azospirillum inoculation caused a 15–18% increase in grain yield in all three experiments. This increase was associated with a greater number of seeds per panicle.

The water regime of sorghum plants was improved by inoculation, as seen in their higher leaf water potential, lower canopy temperatures and greater stomatal conductance and transpiration. Total extraction of soil moisture by inoculated plants was greater (by about 15%) and occurred from deeper soil layers, compared with non-inoculated controls.

These findings indicate that inoculation with Azospirillum can lead to yield increases in dryland grain sorghum, primarily through improved utilization of soil moisture.

Carbofuran at 1·5 kg a.i./ha applied around the seeds during sowing in spring controlled lucerne stem nematode and Sitona damage to lucerne and increased herbage yields in the susceptible cv. Europe. Such treatment was also beneficial to Europe in soil not infested with lucerne stem nematode and to the ‘resistant’ cv. Euver sown in infested soil. Subsequent treatment of the soil in spring each year with thiabendazole did not enhance lucerne yield but aldicarb at 1·5 kg a.i./ha watered onto the stubble and hydraulic or electrostatic sprays of carbendazim, thiabendazole hypophosphite, thiodicarb, dimethoate or pirimiphos methyl applied to new foliage after each herbage harvest lessened stem nematode injury and increased herbage yields in one experiment but had less or no effect in another.

The results of 173 field experiments carried out between 1957 and 1986 are presented comparing ammonium nitrate and urea as top-dressings for winter cereals and grassland.

The trials show that urea was an inferior nitrogen source to ammonium nitrate. The yield from ammonium nitrate was significantly greater than that from urea for winter wheat, winter barley and for first, second and third cut silage. The results suggest (a) that winter wheat and winter barley respond differently to the two nitrogen sources and (b) that yield losses from urea are just as likely on first cut silage as second or third cut.

A breakdown of results according to soil texture, soil pH and region showed no consistent differences in yield loss. This indicates that broad generalizations based on soil characters and geographical location are not helpful in distinguishing situations where urea performance may be either better or worse than average.

Data from 11 sugar-beet crops grown at different sites, in different years and with some variations in husbandry have been used to re-examine the process of dry-matter partitioning. Two-phase linear models did not describe adequately the distribution of dry matter. There was no evidence of a discontinuity in the partitioning between root and shoot at any point in crop development. It is suggested that, contrary to a recent view, events in the shoot, rather than the storage root, largely determine how dry matter is allocated between growth and sugar storage.

Under intermediate deepwater (15–50 cm) conditions, sulphur-coated urea (SOU) drilled behind the plough at sowing was superior to other coated (neem, lac, coaltar) urea materials and broadcast incorporation of prilled urea in increasing the yield of direct-sown rice. In transplanted rice, the grain yield was highest with urea super granules (USG) placed 30 days after transplanting (DAT) followed by SOU broadcast incorporation at planting. N-use efficiency increased considerably with SCU drilled behind the plough or USG placed 20 days after sowing in shallow standing water in direct-sown rice and SCU broadcast incorporation or USG placed 30 DAT in transplanted rice.

This paper describes a comparison of acid insoluble ash (AIA) and acid detergent lignin (ADL) ratio techniques for estimating digestibility with the conventional total collection method using sheep fed a range of feeds. In only two of 17 digestibility trials were the results obtained by AIA ratio techniques significantly different from those obtained by the total collection method. In the case of ADL no significant differences occurred between the results obtained by the ratio technique and total collection method.

In a trial using sheep in metabolism cages the AIA and ADL contents of faeces excreted in consecutive 4 h periods covering 48 h did not show any significant variation either within or between the two 24 h periods.

The results obtained from ‘grab’ samples of faeces (25–40 g) taken per rectum or from faeces bags attached to sheep fed communally can be expected to give acceptable agreement with total collection provided the marker concentration in the faeces represents a number of sheep sampled on several days, since variation between individual samples of faeces may be high.

High-temperature-adapted strains RAU 1, RAU 2 and RAU 3 of Azospirillum brasilense C 7 were isolated from stepwise transfer to higher temperature (30 to 42 °C). One of the strains (RAU 1) showed more growth, greater nitrogenase and hydrogenase activities at 30 and 42 °C than parental and other temperature-adapted strains. This strain also showed growth and more nitrogenase activity from pH 6·5 to 8·0. Strain RAU 1 showed cross-resistance to penicillin (300/µg/ml) but not to streptomycin, kanamycin, viomycin and polymixin B at 30 and 42 °C. It was demonstrated in field plots in calcareous soil that seed inoculation with RAU 1 enhanced mineral uptake of cheena. Inoculation with RAU 1 led to a significant increase in associative nitrogen fixation, dry weight of roots, grain and straw yield of cheena compared with the uninoculated control with or without applied N, but the effect of seed inoculation with high-temperature-adapted strains was variable with different genotypes of cheena.

Field experiments, conducted on alluvial soil of Jalandhar during 1984–5 and 1985–6 with four rates of application each of N, P and K and four potato cultivars, Badshah, Bahar, Lalima and Jyoti, revealed significant responses to N and K. Badshah, Bahar and Lalima responded to 240 kg N/ha while Jyoti responded to 160 kg N/ha. Badshah did not respond to K. Bahar responded to 150 K/ha whereas both Jyoti and Lalima responded to 50 kg K/ha. Varietal responses to N were related to yield and crop duration while the responses to K were related to K composition of tubers. N showed inconsistent effect on percentage dry matter of tubers, but K decreased it. N increased concentration of N and P but decreased that of K.

Azolla and blue-green algae (BGA) biofertilizers in rice cultures were compared with farmyard manure (FYM), Azolla and Eichhornia compost, green manuring with Sesbania and chemical nitrogen fertilizer as urea. Growing Azolla crop in rice field once before transplanting and twice after transplanting produced a fresh biomass of Azolla of 46·7–47·6 and 36·4–40·6 t/ha, containing 83·4–92·2 and 64·7–70·4 kg N/ha, with the rice varieties IR-36 and Mahsuri, respectively. The BGA produced only 7·9–8·9 and 5·2–7·2 t fresh biomass/ha, containing 19·5–20·6 and 14·8–19·3 kg N/ha with IR-36 and Mahsuri, respectively.

In the 1st year of the experiment application of FYM, Eichhornia and Azolla compost and green manuring of Sesbania produced lower grain and straw yields and panicles than 60 kg N/ha as urea, but during the 2nd year all these treatments showed responses equal to that of 60 kg N/ha as urea. Nitrogen concentration and uptake by rice in these treatments were, however, lower than that of 60 kg N/ha as urea. Growing and incorporating Azolla once before and twice after transplanting produced higher grain and straw yields, and more panicles, and also showed higher nitrogen concentration and uptake by rice than those of organic and green manures. The BGA inoculation to rice with 30 kg N/ha as urea produced less grain and straw, and fewer panicles, and also showed lower nitrogen concentration and uptake by rice than 60 kg N/ha as urea and other organic manures. Of the two rice varieties, IR-36 produced more grain and panicles than Mahsuri, but Mahsuri produced more straw.

Total nitrogen, organic carbon and available phosphorus of soil after harvest of the rice increased owing to the application of organic manures, green manures and Azolla and BGA biofertilizers. The green manuring of Sesbania and using Azolla once before and twice after transplanting and FYM showed highest organic carbon and available phosphorus in soil after harvest.

Experiments harvested in 1984, 1985 and 1986 tested the effects of combinations of three seed rates (12, 24 and 36 seeds sown/m2), with three sowing dates (late September and approximately 28 and 56 days later) and two sowing methods (conventionally drilled and ploughed-in after broadcasting) on field beans grown on Clay-with-Flints soil at Rothamsted.

Grain yield was always largest with the earliest sowing, smallest with the latest. The seed rate needed to achieve the largest yields increased with lateness of sowing. For September sowings the smallest seed rate was sufficient in 1984 and 1985 but 24 seeds/m2 were needed in 1986 when the exceptionally severe winter killed many plants. In all years 36 seeds/m2 were needed for the latest sowing date.

Ploughing-in the seed gave an average benefit to grain yield, relative to conventional drilling, of 0·3 t/ha but the benefit increased to about 2 t/ha for the latest sowing for the 1986 harvest.

The earliest sowing advanced flowering date by 2 weeks relative to the latest but did not affect harvest date. Early sowing did not increase susceptibility to winter kill and only slightly increased the risk of chocolate spot disease (Botrytis fabae Sard.).

In all years the largest yields came from combinations of treatments which led to about 35–50 pod-bearing stems per m2 at maturity. The best combinations of treatments gave grain yields of 5·6, 50 and 62 t/ha in the 3 years respectively. These reflect the benefits of correct combinations of agronomic treatments and were probably also the result of good control of pests and pathogens.

All combinations of four harvesting treatments and two sowing dates were compared in each of 2 years in field experiments near Nicosia. In one of the years, two levels of applied nitrogen were compared. The harvesting treatments were: (1) a milk-stage cut, (2) a boot-stage cut and a regrowth cut, (3) a grazing-stage cut and a regrowth cut, and (4) three grazing-stage cuts and a regrowth cut. The sowing dates were (1) normal (12 November) and (2) early (15 October), with sufficient irrigation to ensure establishment.

Applied nitrogen had virtually no effect on leaf growth, evidently because of high reserves of available nitrogen in the soil. Early sowing increased the rates of leaf emergence, extension and expansion up to the time of the first ‘grazing’ cut (when the first node was showing) and reduced the number of leaves which died in that period. Where growth was uninterrupted to the milk stage, early sowing did not affect the number of leaves produced by a main stem or primary tiller, but increased the longevity of the later leaves. Where there were three ‘grazing’ cuts, early sowing allowed time for the production of more and larger leaf blades, with longer sheaths, between the third 'grazing’ cut and the final harvest.

The ‘grazing’ cuts considerably reduced the rates of extension and expansion and the final size of the leaves which emerged soon after a cut. There was good recovery subsequently, however, in rates of extension and expansion and final leaf size, particularly with October sowing.

During almost all the period of leaf production on a main stem or primary tiller, several leaves (up to six) were expanding at the same time. The stage, during the period between emergence and death, at which a leaf blade reached its full length was typically half-way between emergence and death. Where growth was uninterrupted, area per leaf blade was positively correlated with both the number of days between the emergence of successive leaves and the number of days between emergence and death.

Experiments with seed advancement and devernalization identified treatments which both increased rate of emergence and establishment and decreased bolting. Treatment temperature and duration were more critical for devernalization than for improving establishment. Exposing seeds to 15 °C for 6 days (at restricted moisture availability to prevent premature germination) sometimes promoted slight devernalization but sometimes enhanced bolting; 20 °C for 3 days had little effect whereas 20 °C for 6 days was moderately effective. The best treatment for both improving establishment and decreasing bolting was to steep the seed in water for 3 h at 25 °C, dry it to between 115 and 120% of its original air-dry weight, store it for 4 days at 25 °C and then air dry.

Results in 1985 showed that the improvements are insufficient to allow sowing as early as 1 March. Following sowing on 17 March 1986, seed advancement increased establishment for two bulks of seed from 54 to 76% and from 63 to 77% respectively while bolting was decreased from 9·1 to 1·2% and from 5·9 to 0·7%. This suggests that in future it may be possible to recommend that sowing starts about a week earlier than at present.

The results also suggested that only a previous vernalizing experience could be reversed. There was no indication that a devernalizing stimulus could be stored by seeds and used to offset the effects of cold after sowing. However, the best treatment in 1985 would have reversed a much more severe vernalizing stimulus than that likely to be encountered by the seeds while on their mother plant.

Legumes like Aschynomene, Neptunia and Sesbania possess nodules on their stems in addition to those on the roots (Barrios & Gonzelez, 1971; Dreyfus & Dommergues, 1981) and have the ability to grow under water. The most distinctive characteristic of all stem nodulating legumes in the presence of predetermined nodulation sites on the stem, the formation of which is independent of Rhizobiwm infection (Arora, 1954; Subba Rao, Tilak & Singh, 1980).

The influence of dietary nutrients on carcass composition, rate of tissue deposition and the development of specific tissues, major and minor muscles in particular has been well documented for pigs reared in a temperate environment. Attempts have also been made in this environment to simulate artificial tropical conditions and, on the consequence of such conditions, to predict the nutrition and growth of the pigs.