1. A fraction of soil manganese soluble in buffered pyrophosphate solutions has been identified as three-valent manganese, present in the extract as a soluble complex salt of mangani-pyrophosphoric acid H[MnP3O7].

2. Evidence is given to show that a very significant part of soil manganese may be present as three-valent manganese, and that the product of oxidation of divalent manganese in soils is three-valent manganese. In any soil where the production of divalent manganese by reducing processes is going on at any appreciable rate, the oxidation of divalent manganese will supply three-valent manganese, which may therefore be expected to form a relatively large part of the manganese of certain soils.

1. Twenty Southdown-Romney wether lamb carcasses of a mean hot carcass weight of 39·2 lb. (range 31·2–43·8 lb.) were frozen. Each frozen carcass was divided down the back-bone to give two sides and each side was divided into four parts: leg, loin, 9–10–11 rib cut, and fore. A method of obtaining samples from the parts and from the sides is described. The samples were analysed for water, fat (uncorrected), and residue (uncorrected). The dried residue was analysed to give an ash percentage and a Soxhlet correction factor so that total fat (ether-extract), protein (dried fat-free, ash-free residue), and ash were determined.

2. The weights of the two sides of the twenty carcasses were similar, although the loins of the left sides were highly significantly heavier than those from the right sides and the right fores were highly significantly heavier than the left fores.

3. The mean percentage composition of the two sides of the carcasses studied were similar. Likewise each of the four parts showed close similarity between sides except for the residue and protein percentage of the loin in which the left sides had significantly more protein percentage than the right sides. In all the uncorrected chemical components a significant side × carcass interaction was found.

4. An analysis of the sampling errors showed that the variance of a treatment mean was decreased only slightly by increasing the number of samples per side or by sampling both sides instead of one. Any substantial increase in precision can be achieved only by increasing the number of carcasses per group.

Elliott (1962) estimated that the average grain yield of wheat in the United Kingdom increased by 6·1 cwt per acre between 1947 and 1957. By considering results of yield trials carried out by the National Institute of Agricultural Botany he attributed 3·8 cwt of this increase to greater yielding ability of new varieties and the remainder to ‘other factors’, including the increased use of fertilizers, chemical weed control, better seed dressings and combine harvesters. The genetic improvement obtained by breeding new varieties is due partly to the incorporation of characters which are comparatively easily recognized, such as resistance to various diseases and lodging. However, even when these major limiting factors are absent from the environment the new varieties give higher yields, presumably due to physiological superiority. Many investigations, reviewed by Thome (1966), have sought to identify and establish the relative importance of the responsible physiological characters, but the information is still far from complete. This shortcoming is now the chief hindrance to more efficient choice of varieties for use as parents and selection of improved genotypes by the breeder. The objective of the three experiments reported here was to provide further information on the physiological basis of varietal differences in yield in wheat.

Two experiments were carried out at Mt. Cotton, The University of Queensland, from November 1992 to July 1993, to study the effect of extent of digestion or feed type (grass or legume) on particle kinetics in the rumen. Small (0·5–1·18 mm) Yb-labelled grass or legume particles, either digested or undigested, were injected into the rumen of sheep fed on different diets, and their retention time in the reticulo-ruminal compartment measured. In Expt 1, four intact wethers were fed on either pangola grass hay, chaffed lucerne hay, pelleted lucerne hay or commercial pelleted concentrate. Digested particles from the faeces of animals fed on pangola or lucerne and undigested material from the same diets were wet-sieved and the fraction 0·5–1·18 mm collected, labelled with Yb-acetate and injected into the animals together with a solution of Cr-EDTA. Faecal samples were taken and analysed for marker concentrations. In Expt 2, four similar animals, fitted with duodenal and ruminal cannulae, were fed on different proportions of pangola grass hay and lucerne hay, and Cr-EDTA and the above mentioned labelled particles were injected through the rumen cannula. Samples were taken from the duodenum and analysed for marker concentrations.

The results indicated that diet characteristics rather than extent of digestion or particle type had the greatest influence on rates of passage of both liquid and particulate phases. Different proportions of pangola and lucerne did not result in marked differences in either the volumes of rumen contents or the rates of passage of the solid phase marker but altered the rates of passage of Cr-EDTA. Increasing the proportion of legume increased intake and decreased retention time markedly, with no additive effects on digestibility.

Particles of the same small size escaped with the same fractional passage rate within each diet, irrespective of type (grass or legume) or status (undigested or digested), indicating identical kinetics within each rumen type.

It was concluded that rumen conditions as influenced by diet type have most influence on water and particle kinetics and that extent of digestion of the small particles used in our experiments was not important. Particles of legume or grass of the same size behaved similarly within a diet type.

The influence of ambient weather conditions on the regrowth and morphology of a perennial ryegrass sward, over the period May–October 1972, was assessed by following the performance in the field of a succession of vegetative, single genotype, simulated swards previously grown under standard conditions. Crop growth rates estimated from largely non-destructive measurements of growth components (leaf extension, leaf weight/length ratio, tillering rate and tiller density) agreed with, and were more precise than, rates determined from harvests; the components having the greatest influence on growth rate were leaf extension and leaf weight/length ratio. Leaf extension and appearance were closely dependent on temperature; leaf weight/length was only slightly affected by the weather. The growth rates of total above ground parts, especially of herbage above the cutting height, were largely determined by temperature and initial leaf-area index, and insensitive to insolation. At higher temperatures, a greater proportion of assimilates was partitioned into herbage growth.

The air quality in 82 German livestock buildings was investigated, using ammonia as a gaseous indicator. The ammonia concentrations were measured hourly and a 24 h mean was calculated. In cattle houses the mean ammonia measurement ranged between 3·7 ppm in calf houses (n = 16), 4·7 ppm in beef units (n = 10) and 6·4 ppm in dairy cattle houses (n = 8). In pig buildings the highest mean concentrations of 15·9 ppm were found in fattening pig livestocks (n = 8). In sow (n = 16) and weaner livestock buildings (n = 8) the averaged ammonia concentration varied between 13·4 ppm and 9·1 ppm, respectively. Within poultry houses, broiler flocks (n = 8) were associated with ammonia concentrations of 21·2 ppm. On the other hand, livestock buildings containing laying hens (n = 8) showed the lowest ammonia concentrations of all, namely 2·7 ppm. A significant positive correlation between temperature, relative humidity and ammonia concentrations could be found in poultry houses. Assuming an ammonia threshold limit value of 15 ppm, although no cattle house in this study exceeded this recommended limit, 31% of all the pig and poultry units investigated did, indicating a need for improved housing conditions in the future.

1. Dry-matter intake, pasture utilization and grazing pressure were studied over 3 years on a small-scale replica of a dairy cow grazing management x stocking rate trial.

2. The four treatments were:

(i) Controlled rotational grazing, light stocking rate (0.95 cow/acre).

(ii) Controlled rotational grazing, heavy stocking rate (1.19 cow/acre).

(iii) Uncontrolled, set stocked grazing, light stocking rate (0.95 cow/acre).

(iv) Uncontrolled, set stocked grazing, heavy stocking rate (1.19 cows/acre).

3. Mean D.M. intakes were: (i) 29, (ii) 21, (iii) 28 and (iv) 21 lb./cow per day. D.M. intake was reduced on average by 7 ± 2.1 lb./cow per day at the higher level of stocking.

There has been little study on the growth and morphology of individual plants constituting the population of white clover in mixed swards under grazing. Such information is required if the mechanisms governing plant productivity and persistence are to be understood.

Intact white clover plants were sampled from intensively sheep-grazed pastures under set stocking, rotational grazing, and a combination of both systems, by taking turves (250 × 250 mm), and washing out the plants, every month for a year. Characters measured for every stolon of each plant were: presence of a growing point; numbers of leaves, roots and axillary buds; stolon length. Total plant leaf and stolon dry weight were also recorded. Plants were classified according to degree of branching, and the contribution of each branching order to the population determined.

There were strong seasonal variations in plant size (leaf and stolon dry weight, stolon length, and numbers of stolons and leaves per plant) which showed a significant decrease in spring with recovery over the following summer. This was paralleled by a rapid increase in the proportion of less branched plants (1st and 2nd branching order) in the population from 60 to 80% in spring, as higher-order plants broke up into smaller- and lower-ordered plants at this time. Numbers of roots per plant increased over winter to peak in early spring then declined in the following summer-autumn. While system of grazing management had no significant effect on branching structure of plants, it had a large effect on plant dry weight; rotationally grazed plants were 2·5 times larger than set stocked plants (0·182 cf. 0·073 g respectively).

Other general features of plant morphology were that each successive order of branch stolons was shorter and length before branching was less than that of their preceding parent stolon. The highest branching order observed was 6th order. There was no relationship between branching and numbers of roots; in branched plants only 55% of stolons were rooted regardless of plant order, but rooted stolons accounted for 85% of total stolon length and carried 62, 48 and 90% of the leaves, growing points and axillary buds per plant, respectively.

Comparison with other studies suggests that the processes outlined in this report may be common to white clover growth under grazing over a wide range of favourable environments.

Prairie grass (Bromus catharticus) straw (13·7 g N/kg DM) was fed ad libitum to six goats and seven sheep kept in metabolism cages at Palmerston North, New Zealand in 1986 and 1987.

Goats had greater voluntary feed intake (VFI) (56 v. 36 g DM/kg W0·75 per day), greater apparent DM digestibility (36·8 v. 32·6%) and a larger rumen pool of DM and liquid (W0·75) than sheep. Goats also had greater apparent digestibility of fibre, especially of lignin, and greater rumen fractional degradation rates (FDR) of cellulose, hemicellulose and lignin. Goats had a higher rumen ammonia concentration (115 v. 80 mg N/l), lower rumen pH (6·73 v. 6·90), a smaller proportion of large particles and greater proportion of small particles in rumen contents than sheep. Passage through a 1 mm sieve was established as the threshold particle size to have a high probability of leaving the rumen in both goats and sheep. Voluntary water intake/unit DM consumed was lower in goats than in sheep and, whilst rumen fractional outflow rate (FOR) of water and particulate matter also tended to be lower in goats, the difference was not significant. Irreversible loss rate of rumen NH3 and the amount of N calculated as recycled to the rumen, both expressed as mg N/kg W0·75 per day, were greater for goats than for sheep.

It was concluded that the ability of goats to maintain a higher rumen NH3, concentration than sheep, their larger rumen pool and the higher proportion of small particles in rumen contents were all contributing factors to their greater VFI and fibre digestion of this low-quality roughage.

The seeds of many species of plants have a habit of germinating in unexpected places under various conditions, and the question of the vitality of seeds is one that has frequently engaged the attention of scientists. It has often been claimed that seeds obtained from old pyramids and sepulchres have germinated when placed in favourable circumstances, but Becquerel states that strict enquiry and experiment show that authentic seeds of such origin will not germinate, but that the seeds so obtained which do germinate have proved to be frauds inserted by the fellaheen for the sake of gain. Various writers (quoted by Becquerel) have claimed the power of germination for seeds buried for very long periods. Michelet claimed that seeds of Galium anglicum, buried 3000 years ago in the valley of Doubs, had retained their power of growth; von Heldreich, that Glaucium Serpieri from land covered by excavated scoriae 1500 years ago, was still viable; much doubt, however, has been thrown on the authenticity of such seeds.

The reciprocal relationship commonly used in the analysis of plant yield-density relationships in monoculture is extended to allow a similar treatment of binary mixtures, using the model:

w–1a = Aa × Baapa × Babpb

where wa is the plant weight of component a in mixture with component b, and pa and pb are the plant densities of a and b respectively. The model gives a good fit to fresh weights taken from a glasshouse experiment involving monocultures and mixtures of red clover (T. pratense L.) and Italian ryegrass (L. multiflorum L.) in different proportions, all grown at a range of plant densities. The interpretive and predictive uses of the model are discussed.

1. The chemical nature of the nitrogen in humic acid preparations isolated from 0·5M-sodium hydroxide and 0·1M-sodium pyrophosphate (pH 7·0) extracts of nine different soils has been studied by determining the amounts of acid-soluble-N, ammonia-N, amino-sugar-N and α-amino-N liberated by acid hydrolysis of the preparations and by paper chromatographic analysis of their acid hydrolysates.

2. Humic acid preparations isolated from alkali and pyrophosphate extracts of the same soil differ markedly in total nitrogen content and in nitrogen distribution after acid hydrolysis. The alkali-extracted preparations have a higher nitrogen content and a higher proportion of acid-soluble-N and α-amino-N.

3. A considerable fraction (20–60%) of the nitrogen in the preparations examined was not dissolved by acid hydrolysis. The major fraction of the nitrogen dissolved was in the form of amino-acids.

4. At least 31–48% of the nitrogen in the alkaliextracted preparations and 20–35% of the nitrogen in the pyrophosphate-extracted preparations was in the form of protein. From 3 to 10% of the nitrogen in the preparations was in the form of amino-sugars.

5. The results obtained by paper chromatographic analysis of acid hydrolysates of the preparations indicated that the protein materials in humic acids isolated from different soils by alkali or pyrophosphate are similar in their amino-acid composition. The following nineteen amino-acids were detected in every hydrolysate examined: phenylalanine, leucine, isoleucine, valine, alanine, glycine, threonine, serine, aspartic acid, glutamic acid, lysine, arginine, histidine, proline, hydroxyproline, α-amino-n-butyric acid, β-alanine, γ-aminobutyric acid and tyrosine. Two unidentified ninhydrin-reacting substances, oxidation products of cystine and methionine, and amino-sugars were also detected in every hydrolysate examined. A third unidentified ninhydrin-reacting substance and a substance provisionally identified as α,ε-diaminopimelic acid were found in some of the hydrolysates.

The majority of cotton produced in Australia is exported. The Australian cotton industry must maintain product quality in order to remain globally competitive. In addition, carbon-conscious consumers need reassurance that the system used to grow the product is environmentally sustainable. The aim of the present study was to estimate greenhouse gas (GHG) emissions due to various farm inputs in three common types of cotton farming systems on the Darling Downs region, southern Queensland. Analysis revealed that GHG emissions for dryland solid-plant and dryland double-skip cotton farming systems are similar, but emissions are much higher for irrigated solid-plant cotton farming (1367, 1274 and 4841 kg CO2e/ha, respectively). However, if comparisons of GHG emissions are based on yield (per tonne), the positions of dryland double-skip farming and dryland solid-plant farming are reversed, but the position of irrigated cotton farming still remains as the highest GHG emitter. If the cotton industry comes under the Australian Government Carbon Pollution Reduction Scheme (CPRS) without any subsidies and preconditions, and with a carbon price of A$25/t CO2e, the costs borne by each system would be A$66.8/t for the irrigated cotton industry, A$39.7/t for the dryland solid-plant cotton industry and A$43.6/t for the dryland double-skip cotton industry. This suggests that irrigated cotton would be more profitable in financial terms but with heavy environmental sustainability costs.

To quantify changes in rates of metabolism and nutrient uptake of gravid uteiine, foetal and utero-placental tissues throughout gestation, mature Hereford cows received surgery at 132 ± 0·6 (n = 12), 176 ± 0·5 (n = 8), 220 ±0·4 (n = 11) and 245 ±1·5 (n = 7) days after mating. Indwelling catheters were implanted into a uterine artery and vein of all cows. Foetal catheters also were implanted into an umbilical vein and foetal femoral artery and vein (days 176 and 220) or into a placental artery and two placental veins (days 132 and 245). Approximately 5 days after surgery, deuterium oxide was infused into a foetal femoral venous or placental venous catheter during a 3 h period to quantify uterine and umbilical blood flows by steady-state diffusion methods. Oxygen, glucose, lactate and α-amino acid nitrogen concentrations were determined for uterine and foetal blood samples collected during this procedure.

Uterine blood flow increased 4·5-fold (2·92–13·181/min) and umbilical blood flow increased 21-fold (0·28–5·861–min) during the interval of gestation studied. The relative rate of increase of umbilical blood flow was about twice as great as that of uterine blood flow. Uterine arterial and umbilical venous concentrations as well as uterine arterial-venous and umbilical venous-arterial concentration differences in metabolites changed little with stage of gestation. However, because rates of blood flow increased, uptakes of O2, glucose and α-amino N by the gravid uterus and foetus increased as gestation advanced. The proportion of gravid uterine uptakes utilized by the foetus increased from day 137 to 226 for O2 (24–58%) and from day 137 to 180 for glucose (4–19%), then remained relatively constant. The proportion of gravid uterine α-amino N uptake utilized by the foetus remained relatively constant and averaged 60%. A net secretion of lactate from the utero-placenta to the uterine and foetal circulations was observed and increased as gestation advanced. These data indicate that increased rates of uptake or secretion of metabolites by tissues of the gravid uterus can be explained primarily by increased rates of uterine and umbilical blood flows.

A field experiment lasting 9 years was initiated in 1987 to study the effect of integrated nutrient management involving incorporation of wheat straw (WS) or farmyard manure (FYM) alone or in combination with inorganic fertilizer on a fine loamy mixed hyperthermic udic Ustochrept. Soil physical properties and the productivity of a rice–lentil cropping sequence were examined in a dry land farming system.

At the end of the ninth cropping season, addition of organic materials had increased organic carbon, aggregate stability, moisture retention capacity and infiltration rate of the surface soil while reducing the bulk density. Application of inorganic fertilizer alone decreased the stability of macro aggregates and moisture retention capacity but increased the bulk density values. Treatment effects on moisture retentivity were more pronounced in the higher (0·3–1·5 MPa) suction range. During the first six experimental years, sole application of inorganic fertilizers produced 10–17% higher grain yield of rice, compared to sole application of organic sources or combined organic and inorganic sources. Annual applications of wheat straw and farmyard manure gave higher grain yields of rice from the seventh year onwards. Grain yields of lentil were higher with organic sources either alone or combined with inorganic nutrients.

The sex and number of calves born to a breeding herd of red deer kept under farm conditions are analysed together with information on mortality and on growth rate of the calves until weaning in September–October. The results showed some anomalous deviations of the sex ratio from a 50:50 expectation. Birth weight was related to the weight of the hind at the time of the rut, and so too was the subsequent daily rate of gain of the calf. Stag calves weighed more than hind calves and there was no effect of age of hind on birth weight once weight of hind had been discounted. Mortality was divided into two components; perinatal mortality included stillbirths, deaths at parturition and during the first 24 h of life and an unidentified mortality representing failure to find a calf although the hind had calved. Postnatal mortality was defined to include all deaths from after 24 h of life to weaning. Mortality was related to the weight of the calf at birth, being 100 % for calves weighing less than 4·0 kg and declining to 5 % for calves weighing 6·0–7·0 kg. The data are discussed and the effect of size of hind at the time of the rut on her fertility, the time at which she calves, the birth weight and growth rate of her calf and its survival rate are combined to estimate the annual number of viable weaned calves and the total weight of calves produced by herds of hinds of different weights. An increase in hind weight of 50 % (from 60 to 90 kg) results in a doubling of the number of calves born and surviving to September and an increase in the weight of the calf crop by 160%. Reasons are given to suggest that total calf mortality could be reduced to 7 %.

A method for measuring the rate of passage of meal through the alimentary tract of pigs by feeding a stained marker is described. The results are given of sixty-four experiments made under standardized conditions on four fattening pigs with live weights ranging from 49·9 to 185·5 lb. and six experiments on a sow weighing 500 lb.

Results were expressed by means of excretion curves. These were sigmoid in shape and from them a value termed R, the mean retention time (hr.) of all the stained particles in the alimentary tract, directly proportional to the area to the left of the curve, was calculated.

In the fattening piga the first appearance of the marker in the faeces occurred 10–24 hr. after feeding, and the mean 5 and 95% excretion times were 21 and 53 hr. respectively. The marker was completely excreted after approximately 80–90 hr. The R value averaged 34·2 hr.

A marker fed at the morning feed (9 a.m.) had earlier 5 and 95% excretion times and the R value was significantly smaller.

There was no statistically significant relationship between the R values and live weight, digestibility of the dry matter of the ration or the dry-matter content of the faeces.

In the sow the 5 and 95% excretion times were 38 and 68 hr. respectively, and the R value averaged 51·1 hr.

Counts of stained particles in the intestines of two of the pigs after slaughter showed that food was delayed mainly in the large intestine.

Fifteen sheep were fed ad libitum from 2 days to 27 months of age, and another 15 sheep were each fed exactly half the average amount consumed by the first group, age for age. The body composition of each sheep (water, fat, protein, energy) was estimated from tritiated water space on 13 occasions during this period.

To describe the course of growth in individual sheep in terms of the relationships between the various body components and body weight, a model was set up in which 4 phases of growth were distinguished, viz. the milk-feeding phase, the period of rumen development, and a prefattening followed by a fattening ruminant phase. Each phase was represented by a linear equation.

Except for phase 1, mean composition within each phase differed significantly between well-fed animals and those which had been given a restricted diet. Individual animals differed in the body weight at which the final phase commenced; the average weight was ca. 31 kg. Fat storage was zero or negative during the main period of rumen development; otherwise the fat and therefore energy content of weight gain increased from phase to phase. The protein and water content of gain was high in phases 1 and 2 and decreased subsequently.

Calculations based on data in the literature indicated that, in phase 4, the composition of weight loss was the same as that of weight gain. It is also suggested that the body weight at which this fattening phase commences is related to mature weight, with animals of large ultimate size starting to fatten at heavier body weights than those of small ultimate size.

The application of the results to the determination of nutrient requirements is discussed.

An investigation was carried out to determine the extent of the maternal influence on size of calves at birth and during subsequent stages of growth, by making reciprocal matings between large South Devon and small Dexter cattle. As a preliminary to the experimental results, data concerning the respective parent breeds were analysed. From the first part of the study the following information was obtained:

1. The mean weight at birth of purebred South Devon calves was 100·3 ± 1·47 lb. with a tendency, though not statistically significant, for male calves to be heavier. Calves born during the months April to July appeared to be heavier than those born at other times, but the age of the dam had no definite effect on the birth weight of offspring. It was found, however, that the sire may influence birth weight to a significant degree.

2. The mean period of pregnancy for South Devon females, carrying purebred foetuses, was 287·0 ± 0·42 days, the tendency being for males to be carried longer, but the difference of 0·97 days was not statistically significant. A statistically significant difference indicated that winter calvers carry their foetuses longer as a rule, but though heifers have shorter gestation periods than cows, the difference of 1·6 days was not significant.

Watermelon is a crop with a high water demand and is frequently grown under conditions of higher than normal root-zone salinity. In the present study, seedlings of watermelon (cv. Fantasy, Citrullus lanatus (Thunb.) Matsum & Nakai) were grown either ungrafted or grafted on three rootstocks: Strong Tosa, S1 (both Cucurbita maxima×Cucurbita moschata), or Emphasis (Lagenaria siceraria). All the plants were exposed to an NaCl-induced salinity stress (electrical conductivity, EC=2·2, 4·0, or 6·0 dS/m). The vegetative growth of all the plants substantially reduced after 2 weeks of exposure to 6·0 dS/m; however, growth of the plants grafted on Strong Tosa reduced less than that of the others. The leaf water content and specific leaf area (SLA, m2/g) decreased with an increasing salinity in grafted plants, but not in ungrafted plants. Salinity induced an increase of superoxide dismutase (SOD) activity in grafted plants up to two-fold depending on the rootstock, whereas it had no effect on this enzyme activity in ungrafted plants. Leaf Na+ concentration increased with increasing salinity in ungrafted and S1 grafted plants, whereas there was no significant leaf Na+ accumulation in Emphasis and Strong Tosa grafted plants. Leaf K+ concentration was affected by the rootstock but not by salinity, thus, the ability to keep a high K+/Na+ ratio was achieved mainly by limiting leaf Na+ concentration. The rootstock determined the leaf Cl− accumulation, with lower overall concentrations found if plants were grafted on the S1 rootstock than on Emphasis or ungrafted plants. Salinity significantly decreased the leaf NO3− concentration on Emphasis grafted plants only, while the NO3−/Cl− ratio was reduced in all the rootstocks. The capacity of Strong Tosa to withstand salt stress better than other tested rootstocks was probably due to the ability to induce anatomical adaptation (SLA) and SOD activity in response to salt stress, and also to the efficiency of Na+ exclusion from the shoot.