The production of green beans was studied in sowings made from December to February, September to February, and from October to February in three seasons, and over six oonsecutive seasons for a mid-season sowing.

With September-October sowing the rate of emergence was slow, and establishment sometimes poor. Possible virus disease, and the lack of continuity of setting pods resulting from cool weather, were problems. Good yields were obtained from midseason sowings (31 October-18 December), up to 19·6 t/ha, with good yields for late sowings up to 13·9 t/ha in ^he first three seasons. In another three seasons mid-season sowings (late November-early December) resulted in poor yield due to periods of hot weather (> 35 °C max.) prior to and during flowering.

There was a relationship between quality and yield. The greatest yield and best quality green pods were obtained when conditions favoured rapid growth and rapid setting of pods, and when there was a high rate of pod maturation.

For yield of dry seed the early sowings were best, 3·6 and 2·8 t/ha in two seasons. A total of 460 mm of water was required for the first six sowings, but fell to 360 mm for the mid-February sowing (rainfall plus irrigation).

Although it was possible to grow beans over a 9-month period the January and early February sowings appeared to be the least risk prone with the present cultivars.

It has been reported that water deprivation reduces feed intake in Chokla sheep (Singh, More & Sahni, 1976; More & Sahni, 1978). Consequently, sheep production in terms of body weight, milk and lambs is also adversely affected (More & Sahni, 1980). However, no information is available on the metabolic aspects, particularly on urinary nitrogen and creatinine changes due to long-term intermittent watering. Creatinine is also used as a reference substance for evaluating urinary excretion rates of minerals (Field, 1964) and nitrogen (Powell, Plough & Baker, 1961) to avoid more laborious and time-consuming procedures, which also disturb animal behaviour and production (Langlands, 1966). The present paper attempts to examine the urinary concentration of total nitrogen, creatinine and their ratios; the ratios of potassium to creatinine and nitrogen are also considered.

The design and analysis of an experiment to compare the yield of wheat grown continuously with that of wheat grown in two phases of a four-course rotation is described and the results discussed. A method of analysis which avoids making assumptions about the covariance structure of the errors derived from repeated observations on the same plots, which could be appropriate to other sorts of rotation experiments, is given.

There were no differences between yields of the first and second wheat crops which followed oats after beans in a four-course rotation, but the average of these two crops was 0·75 t/ha greater than the yield of wheat grown continuously. The response to N was the same in the two systems of cropping. The only yield component affected by the system of cropping was grain mass.

The expected merits of the semi-hybrid variety, produced by bulk interpollination of two populations (Foster, 1971a, 6, c), are examined in relation to those of the synthetic variety. With diploid inheritance, the mean expression of both types of variety is seen to be the same. Any postulated difference in productivity must depend not only on the preferential establishment and survival of a small fraction of the total population, but on the existence of a correlation between characters determining productivity and establishment. For two populations producing a heterotic hybrid, a correlation due to loose linkage or gene association without linkage may result in the superiority of the semi-hybrid, but tight linkage or pleiotropy are more likely to favour the synthetic variety. It is concluded that superiority of the semi-hybrid mode of varietal production can only be established by means of a direct comparison with its synthetic counterpart, and not solely by the demonstration of upper-parent heterosis for productivity.

Free amino·N estimations were used to monitor the movement of free amino acids in blood passing through the hindquarters of sheep and growing pigs. The net uptakeor release of free amino·N was calculated from arterio-venous differences in the concentration of free amino·N measured in whole blood and plasma at short intervals of time.

In both species the net change was an apparent release of free amino·N into venous blood. The release increased on fasting. Net uptake of free amino·N from blood was occasionally found at single sampling times due to loss from the cell compartment in sheep and from the plasma compartment in pigs. The uptake measured in whole blood was always less than in a single compartment of blood. The greatest fluctuation in free amino·N concentration occurred in the cells of aorta blood.

It is concluded that both blood cells and plasma have independent roles in the net flux of free amino·N requiring determinations of amino acids in both whole blood and plasma to describe the exchange of blood free amino acids with tissue. A negative arteriovenous difference of free amino·N in blood across skeletal muscle is normal for healthy well-fed animals. Fasting increases the negativity.

1. Heat tolerance in nine hair-coated wethers on a maintenance diet was studied during the hottest period of the year near Salisbury, Southern Rhodesia.

Four soils, sterilized by steam at 100° C, with unsteamed controls for three soils, were examined at intervals up to 62 days to study the microbiology in relation to the abundance of ammonia, nitrites and nitrates of all the soils, the C/N ratios of two, and the pH and moisture content of three. After steaming, the soils were flooded with sterilized tap water equivalent in amount to 3 in. of rainfall at intervals varying with the particular soil. The soil of the first trial remained under water until very near the end of the experiment. In all the soils, the production of ammonia up to 14 days after steaming was associated with increased biological activity, generally a multiplication of bacteria associated with multiplication of Protozoa. The production of nitrites and nitrates was associated with a similar biological activity. Those bacteria that survived steaming had simple growth requirements as compared with those of the subsequent microflora. The Protozoa showed a series of ‘pulses’ of maximum and minimum abundance and there was also a succession of species in all the soils. A predilection of Protozoa for certain bacteria was shown by the association of certain species with particular groups of bacteria identified by Gram's staining. In two of the soils, there were ‘pulses’ of maximum and minimum abundance of diatoms, and in one soil diatoms possibly affected soil texture. The investigation showed that despite the contrasting characters of the soils, the major chemical changes were almost wholly attributable to biological activity, and that after steaming the same general reactions occurred in all. The investigation proved the importance of considering the microbiology of steamed soils as a problem in ecology.

1. In the seeding year the total dry-matter yield in swards sown without a cover crop was increased by infrequent defoliation, but the yield of crude protein was decreased. The highest production of starch equivalent was obtained when a cover crop was used.

2. In the absence of a cover crop, the yield of red clover was higher under infrequent defoliation, but the yield of white clover was higher under frequent grazing.

3. Frequent grazing, and the use of a cover crop, reduced the ingress of weeds more than infrequent defoliation. Nitrogen applied to the cover crop also reduced the growth of weeds.

4. Nitro-chalk increased the total yield of herbage except when under a cover crop; it reduced the growth of red and white clovers, but this was not so marked under frequent grazing.

5. Nitro-chalk increased the annual yield of crude protein under frequent grazing, but decreased it in all herbage mixtures under infrequent defoliation; nitrogen had no effect when a cover crop was used. The increase in yield of starch equivalent due to the application of nitrogen and its apparent recovery was greater under frequent grazing than under the other two managements. Under infrequent defoliation, in the absence of a cover crop, the recovery of nitrogen was particularly low.

6. The ryegrass mixture and ryegrass-dominant general-purpose mixture made more growth, and suppressed clover and weeds to a greater extent than did the timothy and cocksfoot mixtures. This was modified by management in that ryegrass was particularly aggressive under frequent grazing (management 1) but not under managements 2 and 3.

7. In the autumn of the seeding year the yield of total herbage was highest under infrequent defoliation, particularly in the cocksfoot, and general-purpose swards. All undersown mixtures gave lower yields than when no cover crop was used.

8. Nitrogen increased the yield of herbage in May and June under frequent grazing, and in the August cut under infrequent defoliation, but in the autumn particularly it was reduced where a cover crop was used.

9. The application of nitrogen decreased the protein content in all herbage mixtures when a cover crop was used or when defoliation was infrequent. Under frequent grazing the nitrogen increased the percentage of crude protein in the first two grazings, but decreased it in the September grazing.

10. The production from the various mixtures was modified by management: under frequent grazing in May the ryegrass-dominant mixtures were higher yielding than the others, but in July the general-purpose and cocksfoot swards were the most productive. Under infrequent defoliation in August the timothy mixture had the highest yield and cocksfoot the lowest, and under this management cocksfoot and timothy swards had the highest yield in the autumn of the seeding year.

Yields from lucerne cultivars grown on land infested with Verticillium albo-atrum, a cause of wilt disease, were studied over the period 1969–77. Field experiments established in 1969, 1971, 1972 and 1973 were maintained for periods of 4–6 years. Reactions by cvs Europe and Vertus were of principal interest. Europe is considered to be moderately susceptible, initially producing yields exceeding those of resistant types on uninfested land. In comparison cv. Vertus has considerable resistance derived from a polygenic system. In the first 2 cropping years on infested land, Europe yielded similarly to Vertus with only slight symptom expression. In year 3, Europe maintained comparable yields to Vertus but with increasing disease expression. During succeeding years Europe was badly affected by discase and yields were below those achieved by Vertus. Data from other cultivars indicated a positive correlation between symptoms in years 4 and 5, a negative correlation between dry-matter yield in year 5 and symptom severity in year 4, and a negative correlation between symptom severity and yield in year 5. Symptom expression and pathogen build-up appear to occur at similar rates in the latter years of a lucerne crop. Disease development in one season has a considerable effect on future productivity. These findings are discussed in terms of the primary (extra-vascular) and secondary (intra-vascular) determinants of resistance to wilt pathogens. It is suggested that the apparent moderate susceptibility of cv. Europe in seasons two and three relates to a rapid growth rate.

A plot trial tested the fertilizer value of dung and urine evenly spread on Hyparrhenia veld which was very deficient in N and was also deficient, although less seriously, in P.

There exists a large body of soil-water theory for ‘modelling’ soil-water movement and distribution. Yet simpler and sometimes cruder methods are often preferred. In part this preference is due to the fact that theory is not yet able to solve completely the more complicated situations that occur naturally, such as the intermittent application or removal of water in the presence of very hysteric soil-water properties. But in many instances it is due to the apparent difficulty of the analysis for the non-mathematically minded. For example, descriptions have been given of soil-water models, based on direct physical arguments, that are in fact finite difference analyses of the governing partial differential equations, but which make no reference to such equations or their existence. Indeed, the impression is sometimes given that soil-water physicists produce unnecessary, irrelevant and complicated analyses for something that is really quite simple. Unfortunately, the simpler approaches bypass possible complications that are revealed by the mathematically based analyses. It is therefore the purpose of this paper to take advantage of the close relation between the two approaches, and to draw attention to the steps that may be taken to avoid or reduce possible difficulties when following the simpler methods. In particular, it is hoped that the paper will lead to a more efficient use of computing facilities.

Seeds of the plant Crotalaria retusa L., containing 4·4% of the pyrrolizidine alkaloid monocrotaline, were fed in a finely ground form to groups of four pigs from 6 weeks of age. Six levels, 0·004, 0·01, 0·02, 0·05, 0·10 and 0·50% by weight of seed in the diet, were fed continuously for up to 19 weeks. In addition a separate regime, designed to mirror an outbreak of poisoning at a local piggery, consisted of feeding 0·10% for 3 weeks followed by 0·05% for 1 week.

Exposure to more than 0·01%, whether fed continuously or not, resulted in reduced voluntary feed intake and live-weight gain, and high mortality. At 0·50% a reduction in feed conversion efficiency was also obvious. Levels of 0·004% and 0·01% had no significant effect on the production performance of the pigs.

The results of this trial suggest that no more than 0·01% ground C. retusa seed should be included in the diets of pigs. When 0·004%–0·01% is included care should be taken as the long-term effect of the subclinical disease produced is not known.

In a study with chicks, the metabolizable energy (ME) values of two maize and two wheat offal samples were estimated using regression procedures in which the ME of the fishmeal supplement, common to all diets, was first calculated.

From chemical analysis, the wheat offal samples would have been expected to yield at least as much ME as oats, but results fell short of expectation by as much as a quarter in the case of one sample of wheat middlings. The significance of these findings is discussed.

By comparison with previously determined ME values on the same samples fed to sheep, the chicken tended to metabolize more of the maize energy and less of the wheat offal energy.

A field experiment was made in rabi seasons (November–April) of 1981–2 and 1982–3 to study the relative efficency of urea and urea supergranules (USG) for spring wheat. USG showed no advantage over prilled urea for spring wheat.

For 8 weeks after farrowing, sows were fed their standard ration (depending on the number of piglets being suckled) in either thirteen or fourteen feeds per week. The omission of one feed per week did not affect the performance of the 3-week-old litters whether reared indoors or outdoors. The response of the 8-week-old litters to sow-feeding system, however, appeared, from the limited data available, to be inconsistent over rearing environments, those reared outdoors being more affected by feeding system than those reared indoors. The outdoor reared litters consumed significantly more creep feed and were significantly heavier at 8 weeks of age than litters reared indoors, confirming previous observations. During the suckling period the sows lost on average 74·4 lb. in weight; weight loss was not influenced by environment or feeding system.

An attempt has been made in the present communication to assess the value for pigs of urban swill collected during the winter months, when the main ingredients are potato peelings, cabbage leaves and other vegetable residues, and also during the summer months, at which period of the year the quality of the swill is at its lowest level, the product containing substantial proportions of pea pods, cabbage leaves and cabbage stalks. The form known as concentrated swill was used in the digestion trials, since regular and adequate supplies of this could be guaranteed, and, being already cooked, it did not require any heat treatment before feeding.

Chemical analysis showed that the winter swill, on account of the presence of the potato peelings, was distinctly richer in N-free extractives than the summer product. The latter, however, was richer i n protein and lime, and, as a result of the replacement of potato peelings by pea pods as the main ingredient, displayed a much more fibrous character than the winter swill.

Each of the three uppermost leaves of wheat canopies studied in 1975 and 1976 showed a downward movement after its emergence. The variations with time of leaf angle were greatest in the flag leaf. Genotypes differed markedly in the rate of change with age in flag-leaf angle. Leaf curvature did not vary with age. There were differences between years in the rate of leaf movement, but cultivars ranked roughly the same in terms of leaf angle in each year. Grain yield per hectare was not related to leaf angle change. Most of the higher-yielding genotypes included in the study had straight leaves, the correlation between curvature and yield being —0·30 in 1975 and —0·60 in 1976.

The relative importance of variation in the components of wool production to variation in wool production itself was estimated by two methods of analysis. About 30% of the attributable variation in total fleece weight was found to be due to variation in surface area and 70% was due to wool production per unit skin area. Between 50 and 60% of the variation amongst sheep in the latter character was found to be due to variation in fibre weight, the rest being attributed to variation in number of fibres per unit area (fibre density). The variation in mean fibre weight was further partitioned into 50 to 70% due to variation in mean cross-sectional area and the remainder to variation in mean fibre length.

Variation in wool production per unit skin area was also analysed according to growth period and position on the body. The results are discussed in relation to the partition of variance in wool production of other breeds.

Stylosanthes humilis was grown at Brisbane at densities of 10, 50, 250, 850 and 3800 plants/m2 in boxes of sand which received basal nutrients, applications of 0, 10 and 50 kg P/ha as calcium dihydrogen phosphate, and frequent irrigation.

Maximum seed yield was 69 g/m2 at a density of 850 plants/m2. Seed yield was linearly related to the logarithm of density up to 250 plants/m2, and was comparatively stable over the upper density range, declining slightly at supra-optimal density. Inflorescence density exerted the primary control over seed yield, but seed set per floret and floret number per inflorescence were also influential.

The application of 50 kg P/ha increased yield of plant tops by 54% and seed yield by 20%.

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.