Search

District clinical specialist teams were formed in 2012. One member of the team is the family physician. The role of the district family physician is discussed and the case made for focusing on the organisational health of the medical teams practising family medicine within the district as an effective way to improve the quality of medical care delivered in the district.

Soil profiles from limed and unlimed commercial pastures and from lime trials on pastures in the Crookwell district of the Southern Tablelands of New South Wales were sampled and pH measured at 2- or 5-cm intervals to depths ranging from 10 to 60 cm. A single application of lime (3.6-5.6 t/ha depending on the soil) incorporated into the surface 10 cm had a long-term effect and maintained pH above 5.5 in the top 30 cm for at least 12 years. Lime applied as a topdressing to soils on granite raised the pH by at least 0.2 pH units to a depth of 15 cm after 6 years. The depth affected was less on the heavier-textured basaltic soils and on the initially more acid sedimentary soils. There appears to be a role for top-dressing with lime to prevent subsurface acidity from developing under pastures and to correct it in the upper layers of light textured soils. The pH profiles from a given treatment were variable and highlighted the problem of obtaining a field measurement for soil pH that is representative of the plant's environment.

Long-term changes in some chemical properties of yellow podzolic soils under subterranean clover pastures were studied near Binda, New South Wales. The rate of decrease in pH of the surface 10 cm of soil was greatest in the early years following pasture establishment, and decreased with time. Over 50 years the decrease in pH was approximately one unit, resulting in current soil pH values of about 5.0. The increased acidity had led to increases in CaCI,-extractable manganese and exchangeable aluminium. Although the build-up of soil organic matter under a 32- year-old subterranean clover pasture was largely confined to the surface 10 cm, the decrease in pH extended to a depth in excess of 30 cm. Total soil nitrogen increased gradually throughout the 50-year period, reflecting increases in the soil organic matter. There were associated increases in cation exchange capacity and titratable acidity. Total soil phosphorus also increased with time and was correlated with the decrease in pH. This reflected the accumulation of organic and inorganic residues from phosphate fertilizers, but it seems unlikely that the acidity of the superphosphate contributed directly to the increase in soil acidity although it is essential for the establishment and maintenance of the legume, the main source of the increase in soil organic matter. It seems likely that the area of pasture soils adversely affected by acidity problems will increase in the future.

Three methods of estimating available manganese and aluminium status in acid soils were compared on three groups of soils from the Pejar district near Goulburn, New South Wales in which differences in pH had been brought about by different periods under subterranean clover pasture. Managanese extracted by 0.01 M calcium chloride gave the best correlation with the manganese concentration in rape and subterranean clover grown in pot culture, and provided the best index of available manganese. Soil solution manganese was inferior to CaCl2-extractable manganese and was more difficult to determine. Extraction with neutral ammonium acetate was unsatisfactory because this reagent overestimated available forms of manganese in soils containing high levels of reactive manganese. Aluminium extracted by 0.01 M CaCl2 was well correlated with exchangeable aluminium and with percentage aluminium saturation of the effective cation exchange capacity. None of the three measures of aluminium status alone was an effective index for predicting lime response by rape on these soils because both manganese and aluminium status were involved in this response. These three parameters were equally effective in multiple regressions for yield responses of rape to lime. Because of its relative ease of determination, CaCl2 extraction is preferred as a practical measure of aluminium status. Aluminium interacted with and increased the toxic effects of manganese in rape. Thus CaCl2-extractable manganese alone only provided a satisfactory index of a 'critical' value for manganese toxicity in rape for soils low in available aluminium. Subterranean clover was only slightly affected by aluminium and manganese levels in these soils, and manganese toxicity symptoms were only observed on soils containing 50 ppm or more CaCl2-extractable manganese. Nodulation failure in pots occurred in all soils with pH below 5.2 (water) or below 4.3 in CaCl2, whereas nodulation was normal when these soils were treated with CaCO3 to raise the pH to 5.8-6.0 (water). With one exception nodulation appeared adequate at field sites from which soils showing nodulation failure in the glasshouse had been collected.

Changes in soil pH, manganese and aluminium as a result of long periods under subterranean clover pasture were examined in soils formed on granite, basalt and sedimentary rocks near Goulburn, New South Wales. Decreases in the pH of yellow duplex soils formed on granite, sedimentary rocks and basalt had occurred to depths of 60, 40 and 30 cm, respectively. The smaller depth of acidification in the latter two soils is considered to be due to their shallower A horizons over well buffered, clay B horizons. Under the oldest pastures (55 years) the decreases exceeded one pH unit throughout the entire sampled depth (60 cm). In some soils, under old improved pastures, calcium chloride-extractable manganese had increased to more than 20 ppm throughout the 60 cm profile and to greater than 50 ppm in the surface 10 cm. These levels are considered toxic to sensitive plant species and the highest levels may be toxic to subterranean clover. The amounts of extractable manganese in soils appear to be determined by both pH and the amounts of reactive manganese. In general, the amounts of total and reactive manganese were appreciably higher in the soils of basaltic origin. Substantial increases in extractable and exchangeable aluminium had also accompanied the decrease in pH and, in the surface 10 cm, were greatest in the soils formed on sedimentary parent materials. In many of the soils under old improved pastures, exchangeable aluminium, as a percentage of the effective cation exchange capacity, now exceeds 12%, especially in the 5-10 cm layer, and is probably harmful to sensitive species. Increases in exchangeable aluminium also occurred below the surface 10 cm and, in the granitic soils under the oldest pastures, exchangeable aluminium accounted for 30-50% of the effective cation exchange capacity throughout the 5-50 cm soil depth. The adverse changes in pH, manganese and aluminium observed in this study can be expected to continue under many improved pastures and to generate soil conditions unsuitable for many agricultural plants. The use of lime to arrest or reverse these changes seems inevitable.

HCL-extractable zinc, lead, cadmium and copper in soils as well as concentrations of these elements in bracken (Pteridium esculentum) were found to decrease along four leeward traverses at right angles to the Hume Highway near Marulan. Similar results were obtained for the above-ground portions of rye corn (Secale cereale) grown in a glasshouse on soils collected along one of these traverses. Zinc accession is similar to, but cadmium and lead accessions are considerably lower than, those observed by other workers in the United States probably owing in the case of cadmium to the use of purer zinc oxide in Australian tyre manufacture and in the case of lead to smaller cars and a smaller proportion of vehicles operating on leaded fuel. Zinc and cadmium analyses of Australian and foreign tyres confirmed the relative purity of the zinc oxide used in the manufacture of tyres in Australia. No serious health hazard appears to arise from heavy metal contamination of roadside soils and vegetation by vehicular traffic on the Hume Highway.

An investigation was made of the availability to wheat of sulphur in red-brown earths in southern New South Wales. There was no response in grain yield to the application of sulphate to phosphorus-treated or to phosphorus and nitrogen-treated plots at any of 14 field sites, although appreciable responses were obtained in pot culture using surface soil taken from eight of the sites. Under field conditions, mineralization of soil organic matter appears likely to provide adequate sulphur where crops are grown without nitrogen fertilizer. In addition, appreciable amounts of readily available sulphur may be present in the subsoil. The results indicate that triple superphosphate could be used for the fertilization of cereal crops on these soils without risk of sulphur deficiency. Use of nitrogenous fertilizer, however, would increase the possibility of sulphur deficiency.

Finely-ground calcinated C-grade phosphate from Christmas Island was compared with other forms of phosphate as a source of phosphorus for plants. In the glasshouse there was little P uptake from Christmas Island phosphate at first harvests of subterranean clover and ryegrass, but uptake by both species increased at later harvests, both in absolute amount and relative to that from soluble phosphate. The availability of the calcined phosphate varied from soil to soil. In the field, pasture plants made appreciable use of the phosphate only in second or subsequent years ; mixtures of calcined C-grade phosphate with ,superphosphate (1:1) were more effective in the first year on pasture than the C-grade phosphate alone, and produced similar responses to equivalent amounts of superphosphate. Wheat made little use of C-grade phosphate in the field.

A group of podzolic soils from the Crookwell district of New South Wales was examined for potassium status by field, pot culture, and laboratory experiments. Close relationships were found between the exchangeable potassium and the potassium content of the plant material and uptake of potassium both in the field and in pot culture. However, the measured decreases in exchangeable potassium in soil during plant growth were insufficient to account for the total uptake, indicating that other sources of soil potassium were also available. It is probable that the pasture plants themselves contribute to the conversion of non-exchangeable potassium to exchangeable forms. The results suggest that the range 0.25–0.30 m-equiv. exchangeable potassium per 100 g may be critical for these soils. Exchangeable potassium built up under the subterranean clover pastures plays an important part in eliminating a potential potassium deficiency. Removal of hay from these pastures would seriously deplete this available potassium reserve.

A range of soils from eastern Australia hare been examined for a number of fractions of soil sulphur. These have been compared with plant sulphur uptake and yield of oats grown in pot culture in order to assess their possible values as indices of available sulphur. In all of the soils examined, most of the sulphur was present in organic forms and in most cases at least 50 per cent. could be extracted by 0.1N sodium hydroxide. Similar amounts were released as sulphate by ignition of the soil and similar amounts were also estimated by a reduction method. These three fractions were highly correlated with one another and with the total sulphur, but each was poorly correlated with the sulphur uptake and yield of oats in pot culture experiments. The results indicated that an appreciable proportion of the soil sulphur may consist of organic sulphates. The amounts of free water-soluble sulphate were small and were unsatisfactory as indices of yield. In addition to free sulphate, aqueous extracts also contained some organic sulphur which was easily oxidized to free sulphate by dilute hydrogen peroxide. The amount of water-soluble sulphur could be substantially increased by heating the soil prior to extraction. The fraction of the soil sulphur which was extracted after heating with water on a boiling water-bath, followed by heating for 1 hr in a hot-air oven (heat-soluble sulphur), was found to be highly correlated with both sulphur uptake and yield of oats grown in pot culture. It seems likely that this heat-soluble fraction ma3 provide a satisfactory index of available sulphur.

The results of pot culture experiments, laboratory incubations, and soil chemical studies on phosphate availability are reported for a neutral loam from Griffith, N.S.W. Phosphorus-free organic matter (glucose) was incubated aerobically and anaerobically in soil to which known, relatively unavailable phosphorus sources had been added. These included rock phosphate, strengite (FePO4.2H20), and variscite (AlPO4. 2H2O). Native soil phosphate and added strengite became more available following anaerobic incubation. This effect was sometimes but not always increased when glucose had been incubated with the soil. Added rock phosphate and variscite were rendered less available following anaerobic incubation. These effects were prevented when glucose had been present. The organic acids produced during the anaerobic incubation of glucose in the soil seem to have played little part in determining the availability of phosphate in these experiments. Anaerobic conditions as such appear to have played a major role.

A further investigation has been made on soils examined by Donald and Williams (1955) in a survey of the influence of superphosphate and subterranean clover (Trifolium subterraneum L.) on podzolic soils formed on granodiorite in the Crookwell district of New South Wales. The soil organic matter was found to have approximately constant proportions of carbon, nitrogen, sulphur, and phosphorus in the ratio 155 : 10 : 1.4 : 0.68, and it is suggested that the rate of build-up of soil organic matter under the clover pastures may have been limited by the amounts of sulphur supplied in the superphosphate top-dressings. The soil organic matter was found to have a cation-exchange capacity a t pH 7.0 of about 220 m-equiv./100 g, and increases in soil organic matter have led to substantial increases in the cation-exchange capacity of the soil. About 75 per cent. of the total cation-exchange capacity of the unimproved soils was due to organic matter while, in the most improved soils, this figure approached 90 per cent. The increases in cation-exchange capacity included increases in exchangeable hydrogen and were accompanied by decreases in soil pH. There were increases equivalent to 6.5 lb of exchangeable potassium, 25.5 Ib of exchangeable calcium, and 5.2 lb of exchangeable magnesium per acre in the surface 4 in. of soil for each hundredweight of superphosphate applied per acre. Increases in soil organic matter also resulted in increases in the field capacity which may reflect improvements in soil structure. Results indicate that heavier rates of superphosphate application would increase the rate of fertility build-up.

A study has been made of red-brown earths cultivated for wheat on a narrow rotation of fallow-wheat-volunteer pasture in the Ariah Park district of Xew South Wales. Surface soil samples from 55 cropped paddocks currently under fallow and from matched adjoining areas with no history of cultivation were examined in laboratory, pot culture, and field studies. Many of the soils had carried at least 20 crops since being brought under cultivation and had lost an average of 30% of their organic matter during this period. However, only 17% of the organic phosphorus had been mineralized. The mean ratio of carbon : nitrogen : sulphur : organic phosphorus in the uncultivated soils was 178.3 : 10 : 1.37 : 0.63 while that for the cultivated soils was 170.9 : 10 : 1.41 : 0.74. As a result of the decrease in organic matter content the cation exchange capacity decreased under cultivation. Losses of the exchangeable cations also occurred, but the relative proportions of the metal ions in the cultivated soils were the same as those in the uncultivated. Removal of cations in crops could not account for all of the losses observed. There had been a net loss of sulphur from the surface soils over and above that likely by crop removal. The nitrate content of the surface samples was insufficient to provide the nitrogen uptake by the crop either in pots or in the field. Evidence is presented suggesting that other sources, including leached nitrate, were utilized in the field. Mineralization of organic phosphorus and fertilizer addition had increased the amounts of inorganic, plant-available forms, but the total phosphorus was unchanged in the cultivated soils. However, the phosphorus status of' the cultivated soils was still extremely low and responses to phosphorus were obtained at all sites. There seems little prospect of reducing current superphosphate rates on these soils.

In glasshouse experiments, the responses of plants to the phosphorus and sulphur in top-dressed superphosphate were affected by its particle size. On four soils, yields of subterranean clover differed by 12–25% owing to differences in particle size of applied superphosphate. Both rate of solution and spatial distribution of the fertilizer affected plant response. Under non-leaching conditions, the sulphur in large particles of superphosphate was always less available than that in fine. The phosphorus in large particles was slightly less available when superphosphate was applied to soils of low, or moderate, capacities to sorb phosphate but more available when applied to a soil of high capacity to sorb phosphate.Pastures would probably respond better to granulated superphosphate than to normal on sulphur-deficient soils subject to strong leaching, or on soils of high capacity to sorb phosphate. On many soils, however, no difference would be expected, and on some sulphur-deficient soils the granulated product may even be inferior in some seasons.

Compared with growth on undisturbed soil, uniform mixing of the surface 4 in. of pasture soils caused a decrease in the yield of subterranean clover grown in pot culture. This was shown to be due to lowered availability of the soil phosphorus and was probably brought about by sorption of the available phosphorus, which had accumulated at the soil surface, by the unsaturated subsurface soil. Short periods of waterlogging (1–2 days) also brought about lowered availability of soil phosphorus. This occurred both with undisturbed soil cores and with mixed soils, but was much more severe when the soil was mixed. The effect appeared to be due to the conversion of phosphate to non-available forms during the short period of anaerobic conditions. The phosphate sorption capacity of the soil was increased by the waterlogging treatment but decreased to its original value when the soil was air-dried.

A survey was made of the influence of the use of superphosphate and subterranean clover (Trifolium subterraneum L.) on podzolic soils formed on granodiorite in the Crookwell district of New South Wales (average rainfall, 32.7 in. per annum). Forty-four paddocks were sampled; they varied from untreated native pasture to paddocks which had been for 26 years continuously under clover and which had received a total of 13 cwt of superphosphate per acre. In all instances there had been no cultivation during treatment, and the land use mas uniformly one of sheep raising, principally for wool but with some emphasis on fat lamb production on highly improved pastures. Criteria used in this study were the changes in yield and botanical composition of the pasture, changes or trends in the chemical composition of the 0-4 in. depth of soil, and the yield of oats produced by each of the soils in pot culture with varying superimposed applications of phosphorus, sulphur, and nitrogen. The native pasture species disappear under the competition by subterranean clover, which gives a fourfold increase in the yield of pasture. Within the limits of experimental error, the phosphorus and sulphur applied as superphosphate, even that applied many years previously, can be accounted for in the surface 4 in. of soil. Losses by removal in wool and carcases are small. The added phosphorus is present in approximately equal amounts as organic phosphorus and readily extractable inorganic phosphorus. The applied sulphur appears to become a part of the organic complex. Eighty-five pounds of nitrogen has been added in the surface 4 in. of soil by rhizobial activity for each hundredweight of superphosphate applied per acre. Initially the most acute deficiencies affecting plant growth on these soils are those of phosphorus and nitrogen, with a less pronounced deficiency of sulphur. After a period of several years of superphosphate and clover, each of these deficiencies is much reduced, the order of the intensity of deficiencies then being nitrogen, sulphur, and phosphorus. Soil pH falls with superphosphate application at the rate of about 0.06 units per hundredweight of fertilizer per acre, but may reach an equilibrium value at about 5.1. This could be due to the increase in exchange capacity of the soil as a result of the increase in organic matter. A field experiment on two sites also indicated the increase in fertility under subterranean clover pasture and demonstrated the capacity of the improved soils to produce a satisfactory field crop of oats.

This paper presents further results of a study of phosphorus in the red-brown earths and solonized brown soils of South Australia. The investigation involved both field and pot-culture experiments in which different amounts of superphosphate were applied to soils which had received previous superphosphate applications ranging from 0 to nearly 30 cwt. per acre. Only a small part of the phosphorus applied has been removed in crops and the residual phosphorus has remained in the soil in fairly readily available inorganic forms. Where previous applications of superphosphate exceeded 15 cwt. per acre, little if any response in yield of wheat grain was obtained with current superphosphate dressings, although yields of straw were sometimes increased. The phosphorus content of wheat grown under South Australian conditions is lower than that of overseas crops and is dependent on the phosphorus status of the soil. It is only slightly increased by moderate applications of superphosphate. Evidence is presented of a relationship between response to superphosphate and the nitrogen status of the soil which suggests that no appreciable response to applied phosphate is likely with stubble-sown crops other than legumes on soils of improved phosphorus status.

Algerian oats were grown on 13 soils in the glass-house. Plants were harvested at intervals throughout the growing period, and when large enough were divided into leaf, stem, and (in later harvests) flowers or fruits. Copper, zinc, manganese, and molybdenum were determined on the separate plant fractions. Characteristic changes in the trace metal contents of the plant with growth were found for each element. These changes were generally similar irrespective of the soil on which the plants were grown. With the exception of manganese, the availability of the element in the soil did not affect the trend of the changes as the plant matured, but only the amount present. The uptake of each of the four elements continued through the whole period of growth. The total amounts of copper and zinc in both the leaf and the stem decreased after flowering as translocation to the grain proceeded. The amount of manganese in the leaf increased throughout the period of growth, although the rate of increase was less after flowering. The amount of molybdenum in the leaf increased until flowering, after which there was little further change. The rate of uptake of manganese was approximately equal to the rate of production of dry matter, whereas that of molybdenum, copper, and zinc was relatively greater in the early stages of growth. There was no observable influence of soil pH on the availability of copper and zinc, but that of manganese decreased with increasing pH. The availability of molybdenum was affected by the combined influences of soil pH and soil iron.

Jeffries's magnesium ribbon – potassium oxalate method for the removal of free iron oxide from soils has been examined and compared with Beck's modification of the method of Drosdoff and Truog. Iron oxide minerals, whether hydrated or unhydrated, were readily dissolved by the nascent hydrogen – oxalate treatment provided they were in a sufficiently finely divided state. Alumino-silicate clay minerals were not attacked to any appreciable extent, and in general the degree of attack on silicate iron did not appear to be very great. However, biotite was quite seriously attacked by the treatment and relatively large errors could be expected in the estimation of free iron oxide in soils containing much of this mineral. The amounts of silica dissolved from soils by Jeffries's treatment were of the same order as those dissolved by Beck's treatment. The nascent hydrogen method was more efficient than the hydrogen sulphide method, particularly for yellow soils and soils high in free iron oxide.

The cadmium content of phosphatic fertilizers manufactured in New South Wales ranged from 18 to 91 p.p.m. and was closely correlated with phosphorus content. Superphosphate contained 38-48 p.p.m. cadmium. The evidence suggests that the rock phosphate raw material was the sole source of the fertilizer cadmium. The cadmium in superphosphate was soluble in water and was associated with both the phosphate and sulphate components of the fertilizer. It appeared to be as readily. available to plants as the cadmium in cadmium chloride. Cadmium impurities in superphosphate accumulated in the soil, mostly in the surface 10 cm, principally in a cation exchangeable form, and this increased the supply of available cadmium to plants. This accumulated cadmium was extracted from the soil by hydrochloric acid. Increases of up to five-fold in total soil cadmium were found in soils which had been fertilized with superphosphate, and in one soil there was a 12-fold increase in hydrochloric acid-soluble cadmium. Plant uptake of cadmium from soil was generally small and ranged from 0.4 to 7% of that available. Uptake was greatly influenced by soil type, and addition of calcium carbonate reduced the uptake by subterranean clover from cadmium residues in soil. Plant species differed greatly in their ability to take up cadmium, and the concentration of cadmium varied widely within the plant. Generally only 12-18 % of the cadmium in cereal plant tops was translocated to the grain which had a lower cadmium content than any other part of the plant. The addition of cadmium to soil, either as cadmium chloride or in superphosphate, always increased the cadmium content of the grain of cereals or the edible portion of vegetables. Top-dressing of improved pastures with superphosphate brought about considerable increases in the cadmium content of pasture species, especially that of subterranean clover. Analyses of wheat grain and cereal breakfast foods indicated that, although Australian cereal growing soils have long histories of superphosphate usage, the cadmium content of the grain produced is low, the range found being 0.012 to 0.036 p.p.m. Low values, < 0.010 to 0.015 p.p.m., were also found in processed green peas.

Phosphate moving into moist soil from particles of surface-applied superphosphate penetrated a hemispherical zone beneath the particle. The size of this zone and the distribution of phosphate through it were governed by the phosphate sorption capacity of the soil, the size of the particle, and the soil moisture. In calcareous soils the calcium carbonate content was important in determining phosphate penetration. Phosphate from superphosphate particles penetrated rapidly into moist (100 cm tension) soil during the first 5 or 6 days after contact and continued to move through the soil at a decreasing rate throughout the whole of an 8-week period. Movement of sulphate from surface-applied superphosphate into soil was governed by the particle size of the fertilizer and the soil moisture, both of which influenced the rate of solution of the calcium sulphate. The distribution of the sulphate through the soil was influenced by the sulphate sorption capacity of the soil. The rate of penetration of sulphate from surface-applied superphosphate into calcareous soil was considerably less than when the superphosphate was applied to acid soils. Leaching influenced the movement of both phosphorus and sulphur into the soil. It caused distortion of the hemispherical distribution of phosphate beneath superphosphate particles, resulting in deeper penetration of phosphate below the particles and smaller horizontal movement away from them. It also greatly enhanced the solution of sulphate, especially from small particles. The results indicate that the optimum particle size of superphosphate will vary from soil to soil, but a 2.5 mm diameter particle is likely to satisfy a wide range of soil and environmental conditions.

The phosphorus and calcium contents of the fertilizer solution from surfaceapplied superphosphate in contact with moist soil were shown to be similar to those of the metastable triple-point solution (MTPS) produced when an excess of monocalcium phosphate is shaken with water. The average phosphorus, calcium, and sulphur concentrations of saturated aqueous extracts of superphosphate at 20C were 4.0M, 1.5M , and 0.023M respectively. The pH of these extracts ranged from 1.60 to 1.92 (0.15-0.47 units higher than that of MTPS). The sulphur content of the fertilizer solution was generally one-fiftieth to one-hundredth of the phosphorus content. In the absence of leaching both diffusion and capillarity were involved in the movement of phosphate from superphosphate particles into moist soil. The fertilizer solutes entered the soil mainly by diffusion but on soils of low moisture content the increase in pore size of the fertilizer particles, which resulted from the dissolution of monocalcium phosphate, led to a reversal of the suction gradient between soil and particle which caused movement of some of the fertilizer solution into the soil by capillarity. Leaching of superphosphate applied to dry soils by rainwater is likely to yield fertilizer solutions which have higher pH, lower phosphorus and calcium contents, and higher sulphur contents than the saturated solutions arising from superphosphate particles in contact with moist soil. When synthetic fertilizer solution reacted with acid soils the rate of removal of phosphate and calcium from solution depended upon the phosphate sorption capacity of the soil. In calcareous soil the calcium carbonate played a major part in phosphate precipitation. Appreciable amounts of iron and particularly aluminium were dissolved from each of the soils studied by the synthetic fertilizer solution to give solutions which, on standing, readily formed precipitates of phosphate. Both sulphate and organic sulphur compounds were displaced from the acid soils by the fertilizer solution but, in the calcareous soil, sulphate was coprecipitated with the phosphate.

Incubation for short periods at a high moisture content reduced the subsequent plant uptake of phosphorus from recently applied monocalcium phosphate in several soils. The effects on phosphorus uptake were reflected in the amounts of phosphate extracted by 0.5M sodium bicarbonate and by 0.01M calcium chloride. Phosphate availability decreased with increasing moisture content up to saturation. At saturation, availability decreased with increasing incubation period up to 4 days, but was not reversed by several weeks of subsequent incubation at 100 cm tension. The effect of waterlogging usually was greater on the air-dried soil than on soil which had undergone moist pre-incubation. The results suggest that the decrease in phosphate availability was closely associated with the reduction of iron during the anaerobic phase and its subsequent oxidation. Preincubation at 100 cm tension progressively decreased the amount of iron released, and phosphate subsequently immobilized. This appeared to be caused by oxidation of organic substrate during the aerobic phase, thus delaying the onset of anaerobiosis during waterlogging. Phosphate applied to the surface was affected by waterlogging in a similar way to phosphate mixed into the soil.

Capillary uptake of soil water appeared to be more important than hygroscopic uptake of moisture by monocalcium phosphate in the wetting of surface-applied superphosphate particles. For hygroscopic uptake of water a relative humidity greater than 89% was found necessary, but particles on the soil surface are exposed to atmospheric humidity which is frequently well below 89%. This may prevent uptake of moisture from soils of low moisture content. The rate of moisture uptake from the vapour phase by superphosphate increased directly with increase in relative humidity above 89%. The rate of uptake was also influenced by temperature and surface area of the particle. Capillary uptake of soil water was influenced by soil moisture content, density of the particles, and the degree of contact between soil and particle. Movement of phosphate from the moist particle into the soil was rapid but the rate was affected by soil moisture, temperature, contact with the soil, and certain physical properties of the particle. In contrast to phosphate, movement of sulphate into the soil was slow because of the low solubility of calcium sulphate, and was greatly influenced by particle size. Leaching by rainfall may be an important factor in the movement of sulphate from coarse particles.

Seasonal changes in sulphate sulphur were studied in a soil under subterranean clover pasture. Fluctuations in sulphate content were found to be similar to those in nitrate. Both sulphate and nitrate accumulated in the surface soil during summer, immediately after senescence of the pasture. High concentrations were maintained throughout the summer-autumn period and these decreased to low values in winter and spring. The higher values in summer probably resulted from mineralization of soil organic matter under favourable moisture and temperature conditions, and lack of plant uptake. Minor fluctuations were associated with partial leaching by rainwater. The low values in winter and spring were probably brought about by leaching and plant uptake, together with low rates of mineralization at low soil temperatures.

A study was made of the total amount of inositol penta- plus hexaphosphate in a range of Australian soils. The amounts varied widely, ranging from 1.0 to 356 p.p.m. P, and accounted for 0.4-38% of the total organic phosphorus, with an average value of 16%. Neither the absolute content of inositol phosphate nor its proportion to the total organic phosphorus could be closely associated with any particular soil property. In undisturbed soil profiles the inositol phosphates tended to be concentrated near the soil surface. Inositol phosphates were shown to accumulate in soils when organic matter accumulated under leguminous pasture and to decrease when organic matter was lost from soils as a result of cultivation. The relative decrease of inositol phosphates in the cultivated soils was much smaller than that of the organic phosphorus as a whole.

Calcium and strontium in eastern Australian soils and their uptake by plants have been examined in pot culture and under field conditions. The ratio of calcium to strontium in the plant material was closely related to the ratio of exchangeable calcium to exchangeable strontium in the soil, although the plants always contained a higher proportion of calcium. This was probably due to the difference in the adsorption of calcium and strontium by the soil colloids, and to small differences in the relative movement of calcium and strontium from the roots to the plant tops. The proportion of calcium to strontium in the plant material was similar to that in a water extract of the soil; this suggests that the two ions are taken up through the soil solution without any marked discrimination between them. While the proportion of calcium to strontium in the plant roots of oats and cocksfoot was generally similar to that in the plant tops, the roots of subterranean clover and Erodium botrys contained an appreciably higher proportion of strontium. However, since less than 20% of the total calcium and strontium uptake by these two species remained in the roots the effect of this on the proportions in the plant tops was small. Decreases in exchangeable calcium and strontium in soils following the growth of subterranean clover plants in pots were sufficient to account for almost 80 % of their total uptake by the plants. The amounts of calcium and strontium taken up by the clover in pots were related to the amounts of the exchangeable ions in the soil but the smaller uptake of calcium by oats was more closely related to the water-soluble calcium. When soluble calcium and strontium were added to soils in pot culture the ratio Ca/Sr (plant tops) in oats was closely related to the ratio Ca/Sr (exchangeable + added). The addition of calcium carbonate to the surface of three soils in pots markedly increased the ratio of calcium to strontium in the plant tops of subterranean clover in each case. Under field conditions the uptake of calcium and strontium by subterranean clover appeared to be related to the exchangeable forms in the surface 4 in. of soil. With wheat, however, other factors seemed to Influence their uptake including the soil calcium and strontium at depths below 4 in. The accumulation of calcium from superphosphate in the exchangeable form under subterranean clover pastures increased the ratio Ca/Sr (exchangeable) in the surface soil.