摘要:

AbstractThe crops and grass grown in U.K. in any one year need about one million tons each of N and K2O and about one‐third as much P2O5. Sales of cash crops, milk and stock, and the losses involved in feeding crops and grass on farms may result in about one‐third of these quantities of plant foods being lost to agriculture. Fertilisers and imported feeding stuffs provide sufficient plant foods to balance approximately the total losses of nitrogen and potassium and they supply much more phosphorus than is lost. These sources of plant food currently provide only half of the nitrogen and less than half of the potassium that is needed for a year's cropping. In contrast, fertilisers alone supply more phosphorus in any one year than is taken up by the crops and grass grown.The history of the use of fertilisers in U.K. is discussed. About 7 m. tons of N, 17 m. tons of P2O5, and 5 m. tons of K2O, have been applied to the soils of U.K. through the use of fertilisers in the last 120 years. In the 18 years from 1940 to 1957, fertilisers supplied as much nitrogen, twice as much potassium, and half as much phosphorus, as was applied in the previous 100 years. The surface layers of the cultivated soils of U.K. contain plant foods equivalent to about 200 years ‘supply of nitrogen, 100 years’ supply of phosphorus, and 1000 years′ supply of potassium at current rates of fertiliser use. The amounts of phosphorus applied to U.K. soils have exceeded losses of this nutrient for at least 80 years, but only in recent years have the potassium fertilisers used been sufficient to avoid depleting soil‐potassium reserves. The size and nature of the reserves of soil phosphorus which have accumulated in British soils as a result of manuring tend to be more important for the nutrition of arable crops than the supply of ‘native’ soil phosphorus. In contrast, the reserves of potassium built up by residues from purchased fertilisers and feeding stuffs are relatively small and the capacity of soil minerals to supply potassium to crops is very important.Future prospects for increases in the use of fertiliser are examined. Most arable crops grown for sale are now receiving about as much fertiliser as can be justified, but more nitrogen is needed to grow full crops of cereals and practically all crops grown for animal feeding are, on average, undermanured. Anymajorincrease in the total amount of fertiliser used is likely to be achieved by better manuri

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091201

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractUnsaturation in fatty acids follows definite patterns. In the mono‐ethylenic acids a nine‐carbon chain occurs frequently on one side or the other of the double bond, a fact probably significant in relation to the structure of oleic acid. The non‐conjugated polyenoic acids fall mainly into three series, showing affinities with oleic, linoleic and linolenic acid respectively when considered from the terminal methyl carbon. This may result largely from positional limitations during metabolism of these three acids by animals. Saturated and unsaturated fatty acids are treated selectively by enzymes when being esterified with glycerol, but this selectivity follows a different course in triglycerides and lecithins. Nevertheless, there appear to be some common features in the patterns of enzymic synthesis of these and some other lipids. Characteristic differences in the fatty acids of triglycerides, glycero‐phosphatides, sphingolipids and cholesterol esters are another feature of selective enzymic acylation, particularly intriguing because of dynamic equilibrium with a common metabolic pool of fatty acids. Many lipids, including those based on glycerol, sphingosine and phyto‐sphingosine, show structural and enzymic inter‐re

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091202

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractImprovements concerning the iodometric determination of lipid peroxides are suggested. They relate to (a) the adoption of a procedure allowing continuous de‐aeration to reduce the errors caused by induced oxidation and (b) the development of a micro‐spectrophotometric method yielding accurate results at very low peroxide concentrations. The latter covers a range of samples containing 0‐02 to 5 μmoles of pe

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091203

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractA method is presented for the colorimetric estimation of glycerol in the presence of the metabolism products which it yields when submitted to the action ofAcetobacter acetigenum.The interference of dihydroxyacetone (DHA) is eliminated by selective oxidation with ceric sulphate and hypoiodite. The method is suitable for multiple routine analyses and allows 0.1‐0.5 mg. of glycerol to be determined accurately in the presence of 0.76 mg. of DHA. The precision of the method is related to the accuracy of prediction, from standard curves, of the glycerol content of unknown solutions, for which 95% confidence limits at the extreme values of the determinative range are given as 0.1 ± 0.01 mg. and 0.5 ± 0.011

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091204

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractThe processes of mineralisation and immobilisation of nitrogen are defined, and the contribution of mass isotope (15N) studies to our knowledge of these simultaneous transformations in soil is briefly reviewed.Studies of immobilisation of nitrogen in soils treated with organic materials are reviewed with particular reference to the nitrogen content and carbon/nitrogen ratio of the added substances. Laboratory studies on carbon/nitrogen relationships in glasshouse soils incubated with mixtures of sucrose and inorganic nitrogen are summarised, together with comparative data for a wide range of other soils. The amounts of nitrogen immobilised in acid ‘maiden’ soils on incubation with sucrose were increased by the addition of lime and phosphate, but did not reach the levels of activity of old glasshouse soils; these findings are discussed in relation to the carbon/nitrogen ratios of the untreated soils and to their rates of evolution of carbon dioxide.Recent studies on the simultaneous mineralisation of carbon, nitrogen and phosphorus are briefly described. Data are presented for 32 soils showing relationships between initial soil pH and the percentages of the total soil nitrogen mineralised after liming or hydrolysed by autoclaving with acid. The observation that acid soils appear to contain a reserve of nitrogenous constituents which is readily mineralised on liming is discussed with reference to recent views on the chemistry of the nitrogenous components of soil organic matter.Reference is made to some recent work on laboratory incubation tests as a guide to the availability of soil nitrogen and the prediction of crop response to nitrogenous fertilis

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091205

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractA study has been made of the tocopherol contents of the maize, wheat, barley and pea plants. The four plants have been germinated from seed in the laboratory and grown to maturity under field conditions. Using two‐dimensional paper chromatography, detailed tocopherol patterns have been established at different stages of the life‐history of each plant. The young growing plants all synthesise predominantly α‐tocopherol, whereas non‐α‐tocopherols are mainly specific products of the seeds. Theoretical implications and synthetic mechanisms are discussed and lead to the conclusion that the tocopherols are interconvertibl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091206

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractAn extract of fresh ox‐muscle was prepared in the laboratory under conditions designed to minimise any chemical change. A complete analysis was made of this extract and compared with that of commercial meat extract.Despite the different methods of extraction and subsequent treatment, the two extracts showed remarkably similar composition. The major difference was the loss of free amino‐acids and sugars from the muscle extract and the formation of brown pigmented substances, presumed to be of the Maillard type, in the commercial material.A substance reducing triphenyltetrazolium chloride, believed to be a sugar derivative, was found in the muscle extract but not in the commercial meat extract.A method is described for the estimation of carnit

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091207

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractWhen ready‐to‐eat, fully gelatinised crisp oatflakes are prepared from raw enzyme‐active groats, the natural stability of the oat fat is destroyed during the cooking with live steam. When enzyme‐inactive groats are used, the degree of stability retained in the fat depends on the duration of the steam cooking, the subsequent method of drying and the final moisture content of the flakes. The last is critical, and the optimum moisture content is determined by the temperature of

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091208

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractExperiments were conducted to exploit the potentialities ofP. spinulosumto produce fat in submerged cultures. The organism was grown in shaken submerged cultures with different levels of glucose content. The addition of the sugar to preformed mycelium was also examined and the mould was cultivated in a Waldhof fermentor. Finally, a study was made of the effect on the behaviour of the organism of the metabolism solution obtained from previous experiments.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091209

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY

摘要:

AbstractThe two oils each contain small quantities of carboxylic acids with 4‐7 carbon atoms, as well as camphene, cineole, thujone and (—)‐camphor.A. brevifoliaalso containsp‐cymene and possibly α and β‐thujake

ISSN:0022-5142    

DOI:10.1002/jsfa.2740091210

出版商:John Wiley&Sons, Ltd    

年代:1958

数据来源: WILEY