bluuebunny/crossref_metadata_2025 huggingface dataset:
Percepción del clima organizacional según las modalidades de contratación actual
Authors: Niño Avella Lina Isabel
Published: June 2020

Antecedentes: El clima organizacional es el medio ambiente humano y físico en el que se desarrolla el trabajo y tiene repercusiones directas en el comportamiento de las personas en su trabajo. Las percepciones de este pueden variar sujeto a diversos aspectos alrededor de las dinámicas laborales como por ejemplo las modalidades de contratación. Objetivo: Describir las características del clima organizacional percibido por los trabajadores según las modalidades de contratación actual. Métodos: estudio de caso utilizando métodos mixtos (cuantitativo y cualitativo). En la primera fase, de corte cuantitativo, se utilizó una encuesta con escala de respuesta tipo Likert; en la segunda fase, de tipo cualitativo, entrevistas semiestructuradas haciendo uso de la técnica del análisis de contenido. El estudio se llevó a cabo con trabajadores vinculados a una empresa de soluciones tecnológicas y desarrollo de software para sus empresas clientes, ubicada en Cali- Valle, con tres tipos de modalidades de contratación: contrato a término indefinido, prestación de servicios y contrato de aprendizaje SENA. Resultados: existen algunas diferencias importantes en las percepciones del Clima Organizacional dependiendo de la modalidad de contratación, principalmente en las dimensiones de compensación, plan carrera, capacitación y desarrollo y liderazgo. Conclusión: el clima organizacional presenta algunas diferencias y semejanzas respecto a las percepciones que los empleados construyen según la modalidad de contratación o tipo de contrato. Así, es evidente que el tipo de contrato influye en el clima organizacional percibido por los empleados presentando diferencias significativas, aunque se encuentren dentro de la misma organización.
Podzolic and hydromorphic soils on a coastal plain in the Cameroon Republic.
Authors: Brezowsky W.J.
Published: June 2020

The presence of typical podzols and podzolic soils in hot, humid tropical lowlands is discussed. The podzolic soils are part of a hydrological sequence; clay migration occurs in them and the thickness of the B2 horizon is only 40 cm, whereas in Pleistocene marine soils at greater altitudes breaking-down of the clay minerals occurs and the B2 horizon commonly exceeds 100 cm in thickness. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of environmental factors on the growth of alfalfa in the field.
Authors: Stanhill G.
Published: June 2020

DM production from a heavily fertilized lucerne crop grown at Gilat and irrigated daily was compared with potential photosynthesis calculated from meteorological data [see F.C.A. 12: 1940]. After corrections were applied for losses due to respiration, root growth and light wasted beneath the crop canopy, calculated amounts agreed well with those measured. The percentage of light utilized was 33% with cutting at 31-day intervals and 46% with cutting at 48-day intervals. DM production was correlated positively with solar radiation and negatively with air temperature.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Production factors in the tropics.
Authors: Best R.
Published: June 2020

During the period when there is a closed green crop canopy and the plants remain vegetative, comprising about 40% of the total life cycle, annual crop plants accumulate about 80% of their ultimate dry weight. It is argued that the optimum life period of annual crops in the tropics from the standpoint of seed yields never exceeds about 7 months, which is the approximate length of the growing season in the temperate zone. Average daily radiation during the growing season in the temperate zone is about 1.5 times as much as that in the tropics. In some tropical crop plants, e.g. rice, high temperatures tend to reduce the total amount of carbohydrate translocated into the grain. Soil conditions and temperature both tend to be more favourable in the temperate zone. Highest actual and potential yields in the tropics are obtained with perennial crops.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of temperature and light conditions on dry-matter distribution, development rate and yield in arable crops.
Authors: Van Dobben W.H.
Published: June 2020

A review.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The value of synthetic lysine in rations for fattening swine.
Authors: Dammers J. , Hirschfeld W.K. , Hogendoorn L. , Kingma G. , Ottenheym J.H.
Published: June 2020

In a co-ordinated experiment at 4 centres there were 4 different diets based on cereals and soya bean oilmeal. One diet had 6% herringmeal, another had no extra protein supplement and the others had 0.125 and 0.250% lysine; total lysine in the last diet was the same as in the first. At 2 centres the added lysine gave growth and efficiency as good as on the diet with fishmeal. At the other centres the improvement was not as great. At all centres the performance from 50 to 100 kg liveweight was as good with lysine as with fishmeal. It is suggested that requirements for amino acids are more delicately balanced in young pigs.--H. S. Bayley. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Potassium-exchange behaviour of an illite.
Authors: Van Schouwenburg J.C.H. , Schuffelen A.C.
Published: June 2020

The specificity of K adsorption on illite with respect to divalent cations can be explained by accepting the existence of three types of exchange sites, each of which shows a normal exchange process which may be described with the Gapon exchange equation. The K exchange on illite can be described mathematically as the sum of these three processes. Proof of the validity of the mathematical expression is presented. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil structure & plant growth.
Authors: Boekel P.
Published: June 2020

Highest yields on heavy clay soils were obtained when Peerlkamp's visual index of structure (S. & F. XXII [2129]) was at least 5 1/2, corresponding to an air content of at least 15% (by volume) at pF2; a visual index of 5 1/3-6 for these soils corresponds to a structure characterized by dense clods of 0.5-1 cm mean diameter or by porous aggregates of 5-10 cm. A pore space of 48-50% (by volume), corresponding to an air content of 14-17% (by volume) at pF2, was required for high yields on loamy soils. Optimum air content at pF2 in sandy soils (used as an index of soil structure) was about 20-25% (by volume); higher air contents decreased yields through moisture deficiency & lower air contents caused the mechanical resistance of sand to limit root growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A study of highly phos-phatic soils in a karst region of the humid tropics.
Authors: Schroo H.
Published: June 2020

Soils developed on biothermal limestone in the Karst region of the Ajamaroe plateau contained much PO4 (up to 30% P2O5). The limestone involved was not a phosphorite, but contained 0.02-0.70% P2O5. Analysis of a silty-clay sample containing 18.6% P2O5 showed that the PO1 was present as crandallite (found in coral limestones & supposedly CaAl3(PO4)2(OH)6). Pedological investigations in the field & analytical studies of soil & limestone samples confirmed the hypothesis that the highly phosphatic soils represent the accumulation product of insoluble & secondarily precipitated compounds originally contained in the limestone strata. Six principles seem to control the outcome of the accumulative process & the final PO4 content of the soil; on account of these principic-& the relationship between specific weights of rock & soil it is conceivable that not more than 75m of limestone must dissolve to form 1m of residual soil. The occurrence of this soil type in other parts of West New Guinea & the significance of this phos-phatic material for industrial, commercial & agricultural use are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Experiences with hevea rubber in West New Guinea.
Authors: De Wilde de Ligny H.J. , Moll H.W. , Vollema J.S.
Published: June 2020

Past attempts to develop hevea in this area are reviewed. Favourable conditions have now been found in the great plain of South New Guinea. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Practical results of the improvement of clay cover soils.
Authors: Hidding A.P. , Wind G.P.
Published: June 2020

The improvement of clay soils, in respect of crop yields, by mixing sand from the subsoil with the clayey top soil can be estimated by calculating the gain in total available moisture, an increase of >10% indicating a positive effect. See also S. & F. XXV [2108]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Relation between leaf number and final leaf area of rye.
Authors: Hoogland R.F.
Published: June 2020

In rye cv. Petkus and Zelder the date of emergence of the flag leaves was almost the same for all plants irrespective of the number of leaves (10-13) produced. Correlation coefficients for the relationship between total leaf area and number of leaves were + 0.45 and + 0.44 and for that between number of spikelets per ear and number of leaves + 0.61 and + 0.69 for the 2 varieties, respectively. Average surface area per leaf increased with increasing number of leaves.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Additional illumination before and temperature after planting of early tomatoes.
Authors: Verkerk K.
Published: June 2020

Tomato plants raised with and without additional light were grown subsequently at 4 temperature regimes. Growth of stems and side shoots was not affected by extra light, but was faster at higher than at lower temperatures, resulting in longer internodes. Leaf numbers below a given truss were reduced by 2 following extra illumination. Trusses of plants raised with extra light flowered earlier, but produced less fruit (by weight) than did trusses on plants raised without extra light. The same effects were observed for lower trusses compared with higher ones and for trusses grown at higher temperatures compared with those grown at lower temperatures. The additional light accelerated ripening by 4-5 days, and an increase of 2 degrees C. in temperature accelerated ripening by 10-12 days. No interaction was found between the applied light and temperature treatments.-Lab. Tuinbouwpl., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some aspects of agricultural extension work in development countries.
Authors: Perk A.
Published: June 2020

A number of the projects usually accorded a prominent place in the programmes drawn up by the various agricultural extension services for the developing countries are discussed. There is an attempt to discover why some projects are accepted and carried out, while others are deliberately rejected although some of them are given much publicity. It would appear that the rejection of proposed improvements of local agricultural methods depends not only on technical and economic factors, but that motives of a social nature may also play a highly significant role. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A selection experiment with pigs: comparison of the effectiveness of individual selection and sib selection.
Authors: Minkema D. , Bekedam M. , Kroeske D. , Stegenga T.
Published: June 2020

One young boar and 4 full sibs (2 barrows and 2 gilts) were chosen from each of 40 herdbook litters of the Dutch Landraoe breed and fattened from 22 to 90 kg. live weight. Backfat thickness and the area of the cross-section of the longissimus dorsi muscle were measured on the live boars by means of ultrasonics. The full sibs were slaughtered, and measurements were made of backfat thickness and the percentage of cutlets in the carcasses. Eight of the boars, representing some of the best and some of the poorest, as judged by their own performance or the av. performance of their full sibs, were eventually chosen for breeding on the basis of a selection index which took into consideration food conversion, daily gain, backfat thickness, and either the area of the 1. dorsi muscle (live boars) or the percentage of cutlets (hi carcasses). 20-23 [female] progeny from each boar were taken from the same number of litters and fattened from 22 to 90 kg. live weight. Food conversion, daily gain, area of 1. dorsi muscle and percentage of cutlets were determined. The last 3 characters were measured on the carcasses. Both selection methods were found to be effective, but the response was non-significantly (1-9 times) greater with individual selection than with sib selection. Theoretical considerations also showed that individual selection is superior to sib selection. An additional advantage of individual selection is that it requires fewer pens. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Sperm numbers and fertility: a kinetic approach.
Authors: Van Duijn C.
Published: June 2020

A kinetic theory is derived for the relationship between numbers of spermatozoa, sperm movement, and the probability of fertilization. The theory shows good agreement with experimental results. Cf. A.B.A., 33, Nos. 1872 and 1873. F. S. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The movement of manganese in the plant and the practical consequences.
Authors: Henkens C.H. , Jongman E.
Published: June 2020

Movement of foliar applications of Mn was investigated. Mn applied to the leaf was translocated to other parts of the plant via the roots; in the leaf, upward movement predominated. Redistribution of Mn from the roots was insufficient to prevent Mn deficiency in the foliage formed after spraying; where the soil Mn supply was insufficient, repeated spraying was necessary. In wheat, oats and sugar-beet, spraying was best done as soon as Mn deficiency symptoms became evident, and again 4 weeks later. Control of marsh spot of peas was best achieved by spraying at mid-bloom and again just after flowering.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Economic policy and statistics.
Authors: Louwes S.L.
Published: June 2020

The discrepancy between the develoment of agricultural policy and the situation of agricultural statistics in the EEC is noted and this leads to the question of the connexion between policy and statistics. An attempt is made to assemble the whole process of decision making in one analytical framework in order to attain the optimum result. An introductory section is followed by: (2) Decision theory; (3) The function of statistics in formulating economic policy; (4) The economic aspect of statistics; and (5) examples (fictitious). It is concluded that modern decision theory turns on the realization that the uncertainty involved in almost every decision must be specifically incorporated in the mechanism by which the decision is taken and cannot be eliminated by using some probability distribution, because it can only be evaluated by the decision maker. Finally, the advantages of the method for the policy-making body, the analyst and the statistician are summarized. A. T. S. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Analysis of growth, development and yield in a spacing experiment with winter rye (Secale cereals L.).
Authors: Bruinsma J.
Published: June 2020

It was concluded from an experiment with Petkus winter rye sown at 7 seed rates in the range 5-180 kg/ha that: (1) crop analysis facilitated the interpretation of yield analysis; (2) crop analysis can be confined to the counting of plants at tillering, of ears during heading and of florets per ear after anthesis, and to determinations of either dry weight or of N or chlorophyll contents per unit soil area, per plant or per organ; (3) tillering was able to compensate for lower plant densities until 1.5 dm2 of space per plant was reached; (4) at decreasing seed rates, the rate of development decreased, while the number of florets per ear, floret fertility and rate and duration of grain filling increased; (5) the number of florets per ear, their fertility and grain filling depended on the nutritive conditions during tillering and shooting, at about the time of anthesis, and during ripening, respectively; (6) there were close correlations between the amount of N and of chlorophyll in the aerial parts and the logarithm of plant or culm space, indicating that the relative space per plant or per culm rather than the absolute space per plant or per culm was the determining factor; (7) grain weight and total weight per culm increased proportionally with logarithm of culm space and, hence, yield per unit area showed an optimum value at a culm density of about 2.7 x 106 culms per ha; (8) dry-matter distribution in the culms was largely independent of the size and the nutritive conditions of the culms, grain weight always being about 30% of total weight.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Notes on agricultural training in rural areas of developing countries.
Authors: Perk A.
Published: June 2020

Many developing countries still devote too little attention to agricultural training in rural areas in spite of the fact that such training for the farmer and his family is essential for the accelerated development of agriculture. Special emphasis is placed on the training of both farmers and their sons. The relative merits of a number of training systems are discussed in detail. D. R. S.-w. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Productivity measurement and supply analysis in agriculture.
Authors: Van den Noort P.C.
Published: June 2020

Supply analysis is an important part of economic analysis, but there are still some inconsistencies and difficulties in the conventional type of analysis. Applying clearly defined concepts of agriculture and " net value added " leads to a new formulation of the supply relationship in agriculture. This formula has been used in a statistical study of Dutch agriculture; it provides some reliable estimates of short and long run supply elasticities and of technical progress in agriculture, allowing some hypotheses about agricultural supply in the Netherlands to be tested. T. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of 2-chloroethyl-trimethylammonium chloride (CCC) on yield and lodging of wheat.
Authors: De Vos N.M. , Dilz K. , Bruinsma J.
Published: June 2020

Spring wheat cv. Opal grown on heavy clay soil was given 0-120 kg N/ha and 0 or 2.4 kg CCC/ha. CCC increased yields at the 2 highest levels of N, the only treatments in which there was some lodging in the control plots. CCC at 3 kg/ha improved lodging resistance of winter wheat in 8 trials out of 9 at different sites [but see also F.C.A. 19: 70]. In a trial with winter wheat cv. Cleo given 0-120 kg N/ha, lodging occurred in all treatments not given CCC. Treatment with CCC at 3 kg/ha prevented lodging in plots given 0 and 30 kg N/ha and reduced it where more N was applied; the yield increases obtained, 10-15 kg grain/are, were mostly due to a 20% increase in number of grains. CCC applied at the boot stage discoloured the flag leaf and sharply decreased the grain yield. In a trial with winter wheat cv. Stella given 0-240 kg N/ha, lodging did not occur until late July, and 5 kg CCC/ha applied at Feekes stage 3 [F.C.A. 8: 876] gave only slight increases in yield though it did increase the number of grains by 2-3%. In a trial with 5 varieties of spring wheat given 80 and 200 kg N/ha, 20 kg CCC/ha applied at stage 3 was less effective than 5 kg/ha applied at stage 6. [See also F.C.A. 19: 1377, 2006]-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of the groundwater level on the botanical composition and productivity of intensively managed grassland on heavy clay soil.
Authors: Hoogerkamp M. , Woldring J.J.
Published: June 2020

In periods with a precipitation excess and in many springs the grass yield of old grassland and leys on a heavy river-clay soil was highest on the deepest drained plots. In dry periods the yield decreased with increasing depth of drainage. In the wet periods yields were affected by differences in N supply; in dry periods water supply was the main limiting factor. With grazing, grass growth and utilization were unfavourably affected by high groundwater levels in wet periods. The botanical composition of the sward changed gradually under the effect of groundwater level, but true moisture or drought indicators did not occur. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Mole activity in relation to pasture management and nitrogen fertilization.
Authors: Ennik G.C.
Published: June 2020

Mole activity, measured by numbers of molehills and nests, was progressively less under the following types of grassland management: cutting, continuous grazing, rotational grazing with low N-application, rotational grazing with high N-application. No relation between density of worms and the mole population was evident as worms were so irregularly distributed. Mole activity was little affected by a high soil-moisture level. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Evaluation of the nutrient status of wheat plants.
Authors: Kostic M. , Dijkshoorn W. , De Wit C.T.
Published: June 2020

The balance in plants of the principal ionic constituents is reviewed in relation to the requirements for each element, and for total accumulation as reflected in the total-cation, inorganic-anion and organic-anion contents. The balance in young wheat plants was investigated by adding various combinations of the principal ions to the soil. A summary, of tests on the adequacy of supply of the principal nutrient ions and the accumulation of cations, inorganic anions and organic anions, based on critical values for contents in the plant material, is presented for diagnosing nutrient status in relation to capacity for maximum growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Surface irrigation with saline water on a heavy clay soil in the Medjerda Valley, Tunisia.
Authors: Van 't Leven J.A. , Haddad M.A.
Published: June 2020

On a clay soil rich in lime, with drain spacings of 30 and 60 m, one section (A) after four crops of artichokes over a two-year period, with fairly intensive irrigation with saline water (approx 700 mm annually) showed no harmful salinity effects; in the upper 120 cm the electrical conductivity of soil extracts (EC) seldom exceeded five. On section B, with well-distributed irrigation, which was not intensive except for tomatoes in one summer, salinity was fairly uniform in the profile (EC 4-6). In section C, under continuous lucerne and with 1000-1200 mm water annually, salinity increased, especially with depth, and a fallow period was needed. In section D, under four artichoke crops followed by maize, with more intensive irrigation than in A and B, EC of the 80-120 cm layer was 7-8, and maize growth was retarded slightly. In addition to fallowing, the inclusion in rotations of winter crops and of perennials with a resting period in summer, e.g. artichokes, is recommended. A drain spacing of 60 m was adequate. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On soil genesis In temperate humid climate. 6. The formation of a glossudalf in loess (silt loam).
Authors: Bouma J. , Pons L.J. , Van Schuylenborgh J.
Published: June 2020

In a well-drained gray brown podzolic soil (in S. Limburg), considered to be a Holocene soil formation in originally calcareous wind deposits, continuing development of the textural B horizon under the infiltration conditions occurring in flat areas leads to polygonal cracking in dry periods. In the wet season the soil surrounding these cracks becomes saturated. Reduction processes arise, leading to bleaching, and the appearance, in vertical sections, of light-coloured tongues bordered with a yellowish red band, and at some distance, Mn mottles and concretions. In the tongues strong clay leaching occurs. The largest amount of micro-morphologically determined orientated clay bodies (notably channel and ped argillans) occurs in the B3 horizon, whereas the B2t horizon has the highest clay content. Classification of the profile as an aquic glossudalf was based on a consideration of chemical and morphological data. (Abstract retrieved from CAB Abstracts by CABI’s permission)
An economic approach to establish design capacities for storm drams in the Indus Plain, West Pakistan.
Authors: Van der Graaf A.
Published: June 2020

Most drainage systems established to cope with heavy monsoon rains in the Indus plain of W. Pakistan have too low a capacity. A method of calculating their economic capacity is proposed. Its application to the Lahore area indicated that a capacity around 0.5 1/ha./sec., resulting in a mean annual crop loss of 3.3 per cent., would be economically justified at the present level of crop management. Bases of the calculations are: probabilities of 24- and 48-hour rainfalls exceeding certain values, US data on runoff, data on peak floods in the Punjab, the assumptions that crops will not be harmed by inundation during five days and that mean annual losses without drainage would be 25 per cent. costs of systems with various capacities, and crop yields and returns. T. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ammonium fixation and availability of fixed ammonium In some Dutch loam and clay soils.
Authors: Van Schreven D.A.
Published: June 2020

Samples of loam and clay soils containing young common (Fithian) illite recently reclaimed from Lake IJssel and samples of old river clays (fertilized with 0, 250, 450, 650 and 1000 kg/ha/yr of K2SO4) and containing old open (Ammersooite) illite were treated with 100 ppm N applied as (NH4)2SO4 to determine ammonium fixation, the effect of K on ammonium fixation and the availability of fixed ammonium to nitrifying bacteria. The young polder soils fixed 3-10% of the added ammonium N and fixation was completed within 24 hours. Old river clay with no history of K fertilization fixed 87 % of the added ammonium-N in 72 hours. In old river clays the total amount of fixed ammonium and the fixation period both decreased as rate of K fertilization increased. None of the ammonium fixed by a young polder soil was nitrified during four months' incubation. 70% of the ammonium fixed by an old river clay was nitrified within two months but no nitrification occurred during a further two months' incubation. The addition of K prevented nitrification of fixed ammonium in old river clay. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The relationship between number, position in the fruit and genotype of tomato seeds.
Authors: Kedar N. , Verkerk K.
Published: June 2020

After pollination with two genetically different types of pollen, the proportion of seeds carrying certain seedling markers was in many cases found to be statistically different in the two fruit halves. Pollen tubes first reaching the ovary, appeared to fertilize an unproportionally high number of ovules situated in the blossom half of the ovary. "F1 seeds, resulting from pollination of Lyco-persicum esculentum with mixtures of pollen from L. esculentum and L. hirsutum, could be differentiated according to seed size. Seeds resulting from fertilization with L. hirsutum were definitely smaller than other seeds. "Some implications of the findings are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some energy balances of dairy cows at high day and moderate night temperatures.
Authors: Es A.J.H. van , Verstegen M.W.A. , Saleh Youssef M.S. , Nijkamp H.J.
Published: June 2020

2 lactating Friesian cows, producing 14 and 10 kg milk/day, were used in 3 energy balance expt., each lasting 4 wk. Rations consisted of concentrates with varying amounts of hay or straw. Combinations of day and night temp, examined were 16 degrees /16 degrees , 20 degrees /20 degrees , 25 degrees /25 degrees , 30 degrees /30 degrees and 30 degrees /25 degrees C. At 30 degrees /30 degrees and 30 degrees /25 degrees C, roughage intake was reduced particularly on a high roughage ration. At 30 degrees /25 degrees C there was no influence on methane or urinary energy losses, a small positive effect on digestibility and no or only a small negative effect on the utilization of metabolizable energy for maintenance and production. JDL. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The aggregate supply functions of US agriculture 1910-1965.
Authors: Van den Noort P.C.
Published: June 2020

Some of the problems involved in knowledge of the agricultural supply function can be solved by applying such concepts as net product, net price and net productivity and a new interpretation of the " normal price" concept for dynamic conditions. From this the short-run and long-run elasticities for US agriculture are estimated for various periods, and then used to test some hypotheses on supply behaviour of US farmers. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On measuring properties of soils by thermal methods with special reference to the contact method.
Authors: Stigter C.J.
Published: June 2020

A review of the problems limiting the accuracy of determinations of thermal properties and moisture contents of soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Observations on the rate of flow of digesta through the duodenum of sheep and on the recovery of polyethylene glycol and chromium sesquioxide from duodenal contents.
Authors: Van 't Klooster A.T. , Rogers P.A.M. , Sharma H.R.
Published: June 2020

To each of two Texel sheep with re-entrant cannulae in the distal part of the duodenum were given daily in two equal feeds either 100 g straw pellets and 390 g of a concentrate mixture or 1000g hay and 120 g maizemeal. Polyethylene glycol 10 g and Cr2O3 2 or l.94g were mixed with the concentrates for 6 days before each collection period and throughout the 72 or 120h of collection. Water was given to appetite. The material which flowed out of the proximal cannula was collected, measured and sampled and returned to the gut at 40 degrees C. The mean flow rate of duodenal contents over all experiments with both sheep was about 14 to 20 litres per day but there were appreciable between-day and between-sheep variations. The highest flow rate was before and during feeding in one sheep. In both the rate tended to increase during the night. Overall recovery of both markers used was almost100% with the sampling technique used. A random sampling technique which was one of the two systems used and involved the withdrawal of 7 ml digesta every 4 h for 120 h yielded a representative sample of the soluble components, but was less suitable for the insoluble components, though modification could improve it. In this way it should be possible to use a simple cannula in place of re-entrant cannulae. J. G. G. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Measuring thermal conductivity of soils under laboratory conditions.
Authors: Golovanov A.I.
Published: June 2020

Experiments were made to determine the influence of size of soil sample, convection and water flow on the determination of thermal conductivity of soils using a thin needle (0.05 cm radius, 8.5 cm in length) as the heating element and copper cylinders for sample containers. For measurements during a period of 100 seconds the diameter of the sample must be at least 4 cm and to avoid any influence of convection measurements should not exceed 100 seconds. When heating elements are placed horizontally to measure simultaneously the thermal conductivity of different soil layers they should be placed at least 10 cm apart. Thermal conductivity measurements could be used to determine flow velocities of water in coarse sand samples provided that the real flow velocity was highev than 0.35 cm/ min. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A study on the suitability of some soils in Northern Surinam for Pinus caribaea var. Hondurensis.
Authors: Slager S. , Schulz J.P.
Published: June 2020

The soils developed on the Coesewijne deposits and belonging to the entisol, spodosol and oxisol orders, were grouped into five sub-divided classes according to their suitability. Characteristics used to determine suitability were influence of ground-water, texture, organic matter distribution and distribution of biopores. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of temperature, light energy and photoperiod on flowering of Brodiaea laxa Wats.
Authors: Fortanier E.J.
Published: June 2020

Temperature and light requirements for a satisfactory forcing of Brodiaea laxa 'Koningin Fabiola' were studied. Corms were planted under different temperature and light conditions in a phytotron and in different photoperiods in the open. Long days accelerated flower development and the termination of growth and enhanced corm formation. Considering both earliness and number of flowers, the most acceptable results with regard to flower production were obtained at 18 degrees C. in short photoperiods. Forcing at higher temperatures and in longer photoperiods resulted in a reduction in the number of flowers because of bud blasting. This also occurred when the natural short day was extended by high light intensities. Forced and retarded corms reacted similarly but the latter flowered sooner and more satisfactorily. Flowering was preceded under all conditions by corm formation and in longer photoperiods even by senescence of the leaves. Year-round production of flowers is possible if 25 cal./sq.cm./day of light energy or more are available.- Agric. Univ., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Growth relations between individual fruits, and between fruits and roots in cucumber.
Authors: De Stigter H.C.M.
Published: June 2020

In a severely pruned "shoot-fruit-root" system pronounced relations were observed between individual fruits and between root and fruit growth, viz. the dominance of a single fruit, usually the first, over subsequent fruits with marked inhibition of their growth, and a similar inhibiting effect of developing fruit on root growth. These effects, related to the individual organs, are probably of the same nature as the more indirect mass effects described by others in conventional plants under more normal growing conditions. The system described offers better possibilities for physiological studies.-Centre Plant physiol. Res., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Yield loase" in barley caused by mildew attack.
Authors: Slootmaker L.A.J. , Van Essen A.
Published: June 2020

A yield trial with five replicates was carried out with 2 cv. of spring barley, one suceptible and the other resistant to mildew. Both were treated with two specific mildew-controlling fungicides, one (BASF F 2201) applied as a leaf spray, the other (ICI PP 149) as a seed dressing. From the seedling stage onwards, the susceptible cv. was heavily attacked by mildew; a 20% reduction in yield was found compared with the potential yield. F.s.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Plant Physiology and some aspects of future agriculture.
Authors: Wassink E.C.
Published: June 2020

From considerations of solar energy conversion data it is suggested that the total area required for feeding the entire human population of the world according to present agricultural practices and nutritional standards is relatively small, being about 2000 x 2000 km. This area includes roads etc. and that needed for crop production would be only 25% of this figure. The author proposes that agricultural production may benefit from the setting up, in various parts of the world, of 3000 units each about 30 x 40 km in area and devoted to a limited number of crops and served by its own research station. Some consequences of this suggestion are discussed.-F.A.S. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of vitamin C on egg shell quality under high environmental temperatures.
Authors: El Boushy A.R. , Van Albada M.
Published: June 2020

For a month 24 pullets 7 months old were kept in 2 rooms at 65 degrees to 70 degrees F and relative humidity 50 to 60% and were given a layer's mash with 2.75% Ca. The temperature of one room was then reduced to 55 degrees . For 6 months that of the other was raised to 85 degrees and the humidity to 75 to 80% for 2 months then reduced to the original conditions for 2.5 months and raised again for the rest of the experimental period. Ascorbic acid was given for the last 2 months. Sp. gr. of eggs and shell deformation, breaking strength and percentage shell, but not thickness, tended to fall throughout the trial. Heat stress significantly reduced all aspects of shell quality. In the cold room ascorbic acid did not significantly affect shell quality. In the hot room it increased sp. gr., weight and percentage shell but not shell thickness, breaking strength or deformation. In the cold room plasma Ca did not change significantly. High temperature and humidity significantly reduced plasma Ca, and ascorbic acid in the hot room raised it.-G. F. H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Fertility and milk production in Dutch Friesian cattle.
Authors: Metz J.H.M. , Politiek R.D.
Published: June 2020

Fertility data, compiled for the 1st and 2nd breeding periods of 1943 heifers, were related to milk yield in the 1st lactation. Number of AI services required in 1st and 2nd breeding periods were higher (1.39 and 1.44) than for natural service (1.23 and 1.28). No significant relationships were found between milk yield and fertility either within or between herds, Heritabilities were estimated to be 0.31 for milk yield, and 0.08 for number of inseminations necessary for 1st and 2nd pregnancies and for age at 1st calving. JDL. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Growth, flowering and fruiting in tomatoes in relation to temperature, cycocel and GA.
Authors: Abdalla A.A. , Verkerk K.
Published: June 2020

The effects were assessed of CCC and GA on tomatoes grown either under a high temperature regime (35 degrees day and 25 degrees C. night) or at normal temperatures (22 degrees and 18 degrees ). CCC (0.4%) was applied to the soil in the pots either 2 days after transplanting or at the start of flowering; G A was applied by dipping the first truss in GA (50 p.p.m.). CCC greatly retarded the growth rate of the stems of the plants under both temperature regimes; this effect persisted for about 17 and 24 days under the high and normal temperature regimes, respectively. With plants grown at high temperatures CCC applied at the start of flowering greatly reduced flower shedding and slightly increased the fruit set and fruit development of hand-pollinated flowers. With plants grown at normal temperatures, however, the effects of CCC were slight. CCC-treated plants were sturdy with dark-green leaves which remained green longer, especially under the high temperature regime. More N accumulated in the tissues of plants grown at high temperatures than at normal temperatures, and the N content of the latter plants was considerably increased by CCC treatment. The root development of the CCC-treated plants was much more extensive than that of the untreated plants. The numbers of seeds in the hand-pollinated fruit were not affected by CCC, but at high temperatures there were considerably less seeds than at low temperatures. GA enhanced fruit set of the high-temperature plants, but the fruits were small and seedless. GA also accelerated fruit ripening by 2 and 3 weeks in the plants grown at high and normal temperatures, respectively.-Agric. Univ., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Growth reactions of carnation, measured by net photosynthesis, on different air contents of the soil.
Authors: Van Wijk A.L.M. , Buitendijk J.
Published: June 2020

In pot experiments, Dianthus caryophyllus plants grown for 2 1/2 months at soil-air levels of 20, 10 or 5% (v/v) produced approx. equal amounts of dry matter, but fresh-matter production at 5 and 10% soil air was 13 and 2% lower than at 20% soil air. The effect of aeration on growth (photosynthesis) increased with increasing light intensity. Decreasing content of soil air from 20, 10 and 5% to 5 and 2.5% respectively was accompanied by an immediate reduction of photosynthesis to a fairly constant level. This reduction increased with increasing light intensity. An increase in soil air from 2.5 to 20, 10 or 5% gave a recovery of photosynthesis which at the two lowest light intensities was complete within 1-3 days when the period of low air content was not >14 days. At the highest light intensity the recovery of photosynthesis was slower. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of soil steaming on some properties of the soil and on the growth and heading of winter glasshouse lettuce. III. The influence of nitrogen form, manganese level and shading studied in sand culture experiments with trickle irrigation.
Authors: Jager G. , Van der Boon J. , Rauw G.J.G
Published: June 2020

Heading of winter lettuce was impaired by poor light, and by NH4 and Mn accumulation resulting from soil steaming. The latter should be postponed until spring or done under relatively dry conditions, restricting the temperature and duration of treatment to a minimum. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil-physical aspects of zero-tillage experiments.
Authors: Van Ouwerkerk C. , Boone F.R.
Published: June 2020

Structural determinations (visual rating, penetro-meter resistance, core sampling) in zero-tillage experiments on various soils (marine loam, river clay, sand etc) showed greater soil densities in unfilled plots than after plowing (20 cm), while mean pore-space and standard deviation of pore-space were generally lower in untilled plots. Moisture content at pF2 was often lower on untilled plots, and the latter possessed many more spots of low air content than ploughed plots did. Satisfactory yields of potato of good quality were produced, at least on medium-textured soils, after several years of zero-tillage. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Experience with minimum tillage and nitrogen fertilization.
Authors: Kupers L.J.P. , Ellen J.
Published: June 2020

In long-term experiments with spring wheat, potatoes and sugar beet on ploughed or unploughed river clay soil, yield differences and differences in response to fertilizers were tentatively explained in terms of the limited size and activity of the root systems in the unploughed plots. CCT. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Native grasslands of the Mesopotamia region of Argentina.
Authors: Van der Sluijs D.H.
Published: June 2020

A description is given of the characteristics and ecology of the major grassland types of the Corrientes and Entre Rios provinces of Argentina, and a map is provided showing the distribution of short grassland, medium tall grassland, tussock grassland and poorly drained treeless grassland. Species present are listed.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil mixing intensity measurements.
Authors: De Haan F.A.M. , Beuving J.
Published: June 2020

A method is proposed for the determination of the mean lump size of individual components based on the frequency distribution of the composition of samples. Comparison between the calculated and the experimentally determined distribution leads to a value of mean lump volume and thus to a numerical expression for mixing intensity. The proposed method was tested on mixtures of sand and peat. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Prediction of forage digestibility from some laboratory procedures. 2. Comparison of in vivo digestibility at two institutes.
Authors: Deinum B.
Published: June 2020

For part 1 see Abst. 1564, Vol. 40. 2. The relation between digestibilities of organic matter in vivo and in vitro did not differ significantly between the institutes at Hoorn and Wageningen. No difference was found in digestibility of the cell wall constituents in relation to the lignin content, nor was there a significant difference in the relation between the percentage of digestible cell contents and the percentage of cell contents in forage from well managed pastures. Twelve forages of highly digestible perennial ryegrass deviated from these farm forages at Wageningen, showing smaller excretion of bacterial and endogenous residue. Comparison of the 2 lignin procedures showed that 72% sulfuric acid lignin gave consistent residual standard deviations of digestibility of cell wall constituents; permanganate lignin gave smaller errors in forages at Wageningen but greater errors in forages at Hoorn. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrogen nutrition of rice plants measured by growth and nutrient content in pot experiments. 1. Ionic balance and selective uptake.
Authors: Ismunadji M. , Dijkshoorn W.
Published: June 2020

Rice cv. IR5 was grown in sand culture at various levels of NO3, NH4 and K. Complete analysis for major ionic constituents showed that both plant weight and carboxylate content were reduced by K shortage. At the highest KNO3 level, substituting NH4 for NO3 and supplying K as K2SO4 decreased the carboxylate level from 1000 meq/kg DM to 800 meq/kg and resulted in a further increase in plant weight and tiller number/plant. It was concluded that the level of carboxylates permitting maximum growth was exceeded where NO3 was the N source, and that the preference of rice for NH4 was related to the reduced rate of carboxylate production. The situation was considered to be analogous to lime-induced chlorosis. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Climate, nitrogen and grass. 4. The influence of age on chemical composition and in vitro digestibility of maize (Zea mays L.) and tall fescue (Festuca arundinacea Schreb.).
Authors: Deinum B. , Dirven J.G.P.
Published: June 2020

In a field experiment with maize it was found that in vitro digestibility of leaves decreased somewhat during undisturbed growth, whereas digestibility of stems decreased appreciably. This decrease in leaf digestibility was caused by a lower digestibility of later-developed leaves and by a slight decrease in digestibility during ageing of each individual leaf. In a pot experiment with tall fescue grown at 15/10, 20/15 and 25/20 deg C, it was found that a higher temperature resulted in higher concentrations of cell-wall constituents and lower digestibility, whereas during ageing the percentage of cell-wall constituents remained constant or even decreased, digestibility decreasing slightly. Results suggested that in a constant climate the effect of age on digestibility would be small, and that the great effect of age on forage quality in spring is mainly due to rising temperature and stem formation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some considerations on the diurnal variation of transpiration.
Authors: De Vries D.A. , Van Ruin R.H.A.
Published: June 2020

The diurnal variation of the measured transpiration from pots with alfalfa plants and the readings of several evaporimeters for a case reported by Briggs and Shantz are compared with the calculated values according to Penman's theory. The influence of radiation on transpiration and evaporation is clearly illustrated. The ratio between transpiration and calculated evaporation is almost constant and shows less variation than the transpiration/evaporimeter-reading ratios. The differences in magnitude between the transpiration and the evaporation values and the limitations of the theoretical treatment are discussed. It is pointed out that the evaporation from isolated plants or groups of plants which project above their surroundings will usually be greater than the evaporation from a closed homogeneous vegetation with the same height as these plants. (Abstract retrieved from CAB Abstracts by CABI’s permission)