Showing papers on "Phosphorus published in 1969"

The comparative applied phosphate requirements of eight annual pasture species

Abstract: The effects of a wide range of applied phosphate levels were compared on eight annual pasture species. Marked differences were found between species in response by tops, roots, or whole plant, and in top/root ratio. Different forms of yield response curve were given by the non-legumes, the clovers, and the lupin. At an early growth stage cape-weed, the three clovers, and erodium were highest in phosphorus requirement for near-maximum yield. At the full flowering stage, species ranked in the following decreasing order of requirement: cupped clover > rose clover > subterranean clover > lupin > erodium = cape-weed > Wimmera ryegrass = silver grass. Yields and phosphorus concentrations are compared in relation to applied phosphorus levels. In the early vegetative stage, all species needed at least 0.7% phosphorus in the tops for maximum yield, but by flowering this requirement had fallen to very much lower levels. It is suggested that differences between the species in response to applied phosphate are large enough to influence strongly the botanical composition of pasture and its fertilizer requirements.

Toxicity and environmental requirements of a strain of Aphanizomenon flos-aquae (L.) Ralfs.

Abstract: A toxic strain of Aphanizomenon flos-aquae was isolated and cultured in a defined medium (ASM-1). This strain fixes nitrogen, has a pH optimum of 7.5, and has maximum growth rates at 5000 lux and 26 °C. Phosphorus levels of 1.0 μM readily supported populations of 1 × 105 cells/ml with stimulation of growth evident at a concentration of 0.1 μM P. Tris is inhibitory to growth of this alga at concentrations above 2.5 mM.Toxin production is related to age of culture, temperature, and light intensity but not nitrogen source.Intraperitoneal injection of toxic extracts into Fundulus heteroclitus, Cyprinodon variegatus, and white mice gave a LD100 of 0.5 mg/kg, 0.5 mg/kg, and 8 mg/kg, respectively. Assays with Notemigonus crysoleucas and Bosmina longirostris indicate that the toxin from naturally occurring bloom populations (1 × 106 cells/ml), if released all at once, would be capable of killing certain species of fish and microcrustaceans. Daphnia catawba, however, was much more resistant to toxin (LD100 = 1.0 m...

On the nutrition and metabolism of zooplankton VI. Feeding efficiency of Calanus in terms of nitrogen and phosphorus

Abstract: Total phosphorus and total nitrogen excreted by freshly-caught Calanus finmarchicus (Gunnerus) and C. helgolandicus (Claus) collected from the Clyde and Plymouth Sound have been measured during spring, summer and autumn. The quantities of phosphorus and nitrogen present in animals, plant foods and faecal pellets have also been determined.

The effect of phosphorus on the growth and chemical composition of some tropical pasture legumes. I. Growth and critical percentages of phosphorus

Abstract: Nine tropical and one temperate pasture legume species were grown in pots of soil with varying additions of phosphate. Growth responses and chemical conlposition of the plant tops were recorded, and from the latter, critical percentages of phosphorus were established. These were verified by using data from two soils in the pot culture investigation and a total of six field sites. Glycine javanica and Desmodium intortum were the most responsive species in pots, and Stylosanthes humilis and Lotononis bainesii were the least responsive species. The quantity of phosphorus per pot accumulated in the tops of the plants was greatest for Stylosanthes humilis and Lotononis bainesii at all treatment levels. Critical percentages of phosphorus in the tops of Phaseolus Iathyroides, Phaseolus atropurpureus, Stylosanthes humilis, Centrosema pubescens, Glycine javanica, Lotononis bainesii, Medicago sativa, Desmodium uncinatum, Desmodium intortum, and Vigna luteola sampled at the immediate pre-flowering stage of growth were 0.20, 0.24, 0.17, 0.16, 0.23, 0.17, 0.24, 0.23, 0.22, and 0.25% phosphorus respectively.

Ecological Factors and the Distri6ution of Cladophora glomerata in the Great Lakes

Abstract: Nutrient enrichment in the Great Lakes has provided fertile areas for growth of algal nuisances. One of these species, Cla- dop,hora glomerata, has become a major problem for many cities border- ing the Great Lakes. Ecological factors concerning its growth in Milwau- kee's Harbor were studied, and its distribution in the Great Lakes deter- mined. Phosphorus levels appear to be closely linked with Cladophora increases.

The accumulation of soil organic matter under pasture and its effect on soil properties

Abstract: Comparisons of paired virgin and pasture samples of Coolup sand showed that nitrogen had accumulated in the top 12.5 cm under pasture at an average of 24 p.p.m. per year. Carbon, sulphur, and organic phosphorus also accumulated to give C : N : S : P ratios of 118 : 10 : 1.2 : 0.47. The accumulation of sulphur accounted for about a quarter of the sulphur added in fertilizer and the accumulation of organic phosphorus accounted for about a tenth of the phosphorus added. Inorganic phosphorus had also accumulated but the amount varied between soils. The cation exchange capacity, as measured by summation of exchangeable cations and exchange acidity, increased by an average of 44 m-equiv. per g increase in nitrogen or 3.7 m-equiv. per g increase in carbon. Most of the increase was due to increases in exchange acidity. However, the buffering capacity of the soil for potassium was only slightly affected by the increase in organic matter. The water held by the soil between 0.1 bar and 15 bar suction increased by an average of 3.3 per cent per 0.1 per cent increase in soil nitrogen. When the soils were incubated the ratio of nitrogen mineralized to sulphur mineralized was large, especially when the incubation period was short. In the field there was a strong annual cycle of nitrogen and sulphur availability. Values were high in autumn, low in winter, and rose again at the end of spring.

Mineral Composition of Six Tropical Grasses as Influenced by Plant Age and Nitrogen Fertilization1 2

Abstract: This study was conducted in central Brazil on a sandy loam soil which under normal conditions receives no fertilizer. The K, P, Ca, Mg, Cu, Mn, Fe, and Zn contents were determined on six grasses: Meilinis minutiflora Beauv., Digitaria decumbens Stent., Pennisetum purpureum Schum., Pennistetum clandestinumHochst., Cynodon dactylon Pers., and Panicum maximum Jacq. var. ‘Gondlyodes Doell’ Significant decreases in K, P, Mg, Cu and Fe in the forages (P < .01) occurred with advance in plant age from 4 to 36 weeks. The average K content for all grasses at 4 weeks of age was 1.42% and at 36 weeks of age 0.30%. Kikuyugrass had the highest K content at 36 weeks of age (0.54%). The average P content for all grasses was 0.26% at 4 weeks and 0.12% at 36 weeks. Pangolagrass appeared to be a poor source of P at all ages studied (average 0.12%) Nitrogen fertilizer had no effect on any of the minerals studied except for Mn which increased with N fertilization. Under the conditions of the experiment, the forages could be deficient in K and P for cattle and borderline in zinc.

Effects of silicon on the chemical composition of rice plants

Abstract: Rice plants were grown in nutrient culture solutions. Silicon was supplied to these plants at different rates. The plant samples of early vegetative, vegetative and flowering stages were analysed for nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, silicon, protein and carbohydrate contents. The application of silicon generally decreased the nitrogen, protein and potassium content of rice plants. Its application also decreased the iron and manganese contents. The use of silicon resulted in an increase in phosphorus, calcium, magnesium, silicon and carbohydrate contents of rice plants.

The effect of phosphorus on the growth and chemical composition of some tropical pasture legumes. II. Nitrogen, calcium, magnesium, potassium, and sodium contents

Abstract: This paper describes the effect of phosphorus on nitrogen concentration and on the total and individual concentrations of the cations calcium, magnesium, potassium, and sodium in the plant tops of 10 tropical legumes and one temperate legume when grown on two soils of different type, a light-textured solodic soil and a gley soil Species used were Phaseolus lathyroides, P atropurpureus, Stylosanthes humilis, Centrosema pubescens, Glycine javanica, Lotononis bainesii, Medicago sativa, Desmodium uncinatum, D intortum, Vigna luteola, and Leucaena leucocephala The nitrogen concentrations in the plant tops were increased by phosphorus supply, and good correlations were established between the nitrogen and phosphorus concentrations in the plant tops When sodium dihydrogen phosphate was used as the source of phosphate, the sodium concentration in V luteola, M sativa, and L bainesii was increased Other species were not affected Increasing phosphate supply as monocalcium phosphate had little effect on plant calcium concentration, but brought about an increase of magnesium in P lathyroides and P atropurpureus In the solodic soil particularly, increases in phosphate supply in most species caused reductions in the potassium concentration, partly compensated by increases in the magnesium and calcium concentrations Concentrations of the cations in the plants reflected the soil exchangeable cation composition Plant species differed in their cation status P atropurpureus and P lathyroides were relatively high in magnesium, L bainesii and D intortum in potassium, V luteola, L bainesii, M sativa, and P lathyroides in sodium, and C pubescens and S humilis in calcium

The effects of bird droppings on chemical and biological dynamics in brackish water rockpools

Abstract: In the Baltic, some brackish water rockpools, heavily polluted by bird droppings, were investigated in order to study some of the general patterns of biochemical cycling of the nutrients. The seasonal variations of the following parameters were studied: salinity, temperature, rainfall, pH, algal biomass, detrital content, NH4-N, N02-N, N03-N, P04-P, suspended and soluble organic nitrogen and phosphorus. The diurnal variations of pH, P04-P and oxygen were measured. The faunal composition is discussed. The bird feces provided nutrients well beyond the needs of the algal biomass throughout the vegetation period. High concentrations of phosphate were always found, and this resulted in extremely low N/P ratios reflecting the chemical composition of the bird feces. Ammonia was always the dominating inorganic nitrogen compound and only during the period of maximum algal growth in the spring were considerable amounts of nitrate found. A possible inhibition of the nitrification processes resulting in an accumulation of ammonia is discussed. The high concentrations of ammonia might have a toxic effect on the algae, especially at the prevailing high pH-values. Most of the algal biomass was decomposed in the beginning of July. The diurnal variation of inorganic phosphate was found to be very large even in the absence of algae. This is mainly attributed to the activity of both autotrophic and heterotrophic bacteria. The difficulties in relating these fluctuations to productivity measurements are discussed. The nutritive value of the detrital layer, which consists mostly of fecal pellets, is discussed. Pe3IoMe

Field and laboratory evaluations of bioassays for nitrogen and phosphorus with algae and aquatic weeds1

Abstract: ABSTBACIY The rate of absorption of ammonia in the dark and the amount of orthophosphate extracted by boiling water can be used to follow changes in the nutritional status of nitrogen and phosphorus in algae and aquatic weeds with relation to changes in supply of these elements. Measurements of alkaline phosphatase activity carried out in phosphorusfree media can also be used to follow changes in the phosphorus nutrition of aquatic plants; growth under conditions of surplus available phosphorus reduces (by dilution) their alkaline phosphatase activity. Only terminal portions of aquatic weeds should be used for nutritional bioassays because of nutritional differences between young and old portions of the same plant. The importance of testing each species of plants separately is shown by contrasting results obtained with nitrogen-fixing (phosphorus-limited) and nonfixing ( nitrogen-limited ) bl ue-green algae from the same environment. These methods provide simple but useful bioassays for studies of eutrophication.

Uptake of phosphorus-32 by vesicular-arbuscular mycorrhizae

Abstract: The uptake and accumulation of phosphorus by mycorrhizal and nonmycorrhizal onion plants were compared. The results of the experiments indicate: 1. Mycorrhizal onion plants accumulated significantly more phosphorus in the roots and tops than nonmycorrhizal plants. 2. Vesicular-arbuscular mycorrhizae are sites of increased phosphorus accumulation compared to nonmycorrhizal roots. 3. A fungitoxicant (parachloronitrobenzene) reduced phosphate accumulation by mycorrhizae but did not significantly affect phosphate accumulation by nonmycorrhizal roots.

The ectotrophic mycorrhizas of alnus viridis (chaix) d.c. and their significance in respect to phosphorus uptake

Abstract: Summary Three subtypes of mycorrhizas, sensu Dominik (1955), were found on roots of Alnus viridis growing in New Zealand. Roots with 60% of their rootlets mycorrhizal absorbed phosphate five times as rapidly as non-mycorrhizal roots. Root nodules appear unable to absorb labelled phosphorus actively from externally supplied solution.

Lactose, lactic acid and mineral equilibria in Cheddar cheese manufacture

Abstract: In experimental small-scale manufacture of Cheddar cheese a study was made of the movement of lactose, lactic acid, calcium and phosphorus between curd and whey, and of the effect of high acidity developed in the curd before whey separation, on the pH and physical properties of the cheese. It was found that while the curd particles remain in contact with the whey, the lactose fermented in the curd is replaced by lactose diffusing from the whey. Lactic acid produced in the curd diffuses into the whey rather slowly.When a high lactic acid level is attained rapidly the curd does not cheddar well, the pH of the cheese is low, the flavour is sour and bitter, the body is crumbly and the cheese is bleached. When a high lactic acid level is reached slowly, the curd also does not cheddar properly but the pH of the cheese may be within normal limits up to 3 weeks, at which age its body is coherent and its colour is normal. However, on maturing, the cheese becomes acid, the body crumbly and liquid separation occurs even at 2 months of age. This points to a risk in grading cheese at an early age.It is suggested that the abnormal behaviour in cheddaring of ‘high-acid’ curds is connected with an excessive loss of calcium. When high acidity is developed over an extended time in the whey, the curd retains more lactose but loses more phosphorus so that its buffering capacity is reduced. Cheese made from such curd becomes highly acid at maturity and this leads to the development of a bitter flavour.It is, therefore, concluded that both the rate of development of acidity, and the time the curd is in the whey, are critical factors in controlling the quality of Cheddar cheese.

Soil‐Plant Relationships in a Eucalyptus Forest on the South Coast of New South Wales

Abstract: The chemical and physical soil characteristics of the Eucalyptus associations in Benandra State Forest are described. Changes in species associations occur over a gradient of increasing moisture and nutrient status of soils from ridge to gully sites. Concentrations of major nutrients in leaves and bark of dominant trees on these sites generally follow the soil gradients. In particular, leaf phosphorus and bark calcium are correlated with the corresponding soil nutrients. Soil calcium and magnesium are also correlated with leaf phosphorus, indicating a possible interaction between these soil nutrients and phosphorus uptake by the trees. Soil magnesium is similarly correlated with bark calcium. Aluminum is the major exchangeable cation in soils of the poorer ridge sites which are the most acid. It is hypothesized that soil aluminum competes with other nutrient cations such as calcium and magnesium for sites of absorption on plant roots. In addition to the effect of soil pH on phosphate solubility, competiti...

Phosphorus transformations in a chronosequence of soils developed on wind‐blown sand in new zealand

Abstract: Summary The rate of transformation of inorganic phosphorus fractions and forms was investigated in a chronosequence of weakly weathered soils developed on windblown sand. The net decline of acid-extractable Ca-P during 104 years of soil development was approximately 2600 kg/ha m profile. This fraction was progressively removed from surface horizons and had virtually disappeared from the oldest soil. Residual inorganic P, considered to be included apatite which is not extracted by 0·5 and 1N HC1, was relatively constant in profiles of the chronosequence but decreased in the oldest soil. In the younger soils, the NH4F-P fraction was low but, with increasing time, the weight of this fraction increased, initially in surface horizons. The net accumulation of non-occluded secondary inorganic P during 104 years was 360 kg/ha m profile and this was largely due to an increase in the NH4F-P, rather than the 1st NaOH-P fraction. There was no net shift from non-occluded to occluded secondary inorganic P. Although apatite is initially present as inclusions within primary minerals in the wind-blown sand, an extensive loss of P has occurred during 104 years.

Effects of Water Deficit on Phosphorus Nutrition of Tomato Plants

Abstract: Measurements were made of phosphorus uptake by intact tomato plants from solutions labelled with 32P. The plants were exposed to low water potentials by the addition of mannitol to culture solutions. The amounts of labelled phosphorus in the roots and in the shoots wore determined after a one- or two-hour period. Down to -5.4 atmospheres, the amount of labelled phosphorus in the roots remained constant, hut the amount transported to the shoots was reduced. However, potentials of -10.4 atm reduced the amount of labelled phosphorus in both the root and the shoot. Similar results were obtained when plants were tested immediately after water stress was imposed and when tested after water potentials had been lowered gradually. Plants were treated for one hour at low water potentials and then returned to control solutions (−0.4 atm). For a considerable time, these plants had a much lower phosphorus uptake than plants which had remained continuously at −0.4 atm. These data support the idea that a disturbance in mineral nutrition is partly responsible for reduced growth in plants which experience a moderate water deficit.