bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement and interpretation of carbon dioxide fluxes in the field.
Authors: Monteith J.L.
Published: June 2020

The DM production of field crops can be estimated from their net uptake of CO2, and vertical profiles of CO2 concentration show that crop plants normally assimilate CO2 both from the atmosphere and from the soil. The atmospheric component can be estimated from the CO2-concentration at two heights and the wind speed at three heights above the crop, and the soil component by direct absorption in soda lime. Measurements over grass and field beans at Rothamsted gave a soil CO2-production of about 0.03 mg/cm2/hr and maximum gross rates of photosynthesis about 0.2 mg CO2/cm2/hr. In terms of total solar radiation (wavelength range 0.3-2 mu ), the efficiency of photosynthesis varied from about 1% in bright sunshine to 2% or more with cloud, agreeing well with measurements on selected plants in the laboratory. An attempt to establish the complete CO2-balance for beans emphasized the importance of respiratory flux in determining DM production. Conventionally assumed respiration rates are inadequate and field measurements are urgently needed. F. s.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Chemical control of crop growth and development.
Authors: Bruinsma J.
Published: June 2020

Growth-regulating substances and the following forms of plant growth regulation are very briefly reviewed: control of dormancy and germination, of rooting of cuttings, and of plant shape; stimulation of vegetative growth and development; induction of flowering and of male sterility; control of fruit setting and growth; fruit thinning; delay of abscission; and defoliation and desiccation.- D.M.L.S. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Tillage practices and mechanization.
Authors: Hawkins J.C. , Brown N.J.
Published: June 2020

A review, with special reference to the need to reconsider the cultivations required by crops following the introduction of effective chemical means of controlling weeds. The mouldboard plough as a method of controlling weeds is challenged by herbicides, but its use remains the most effective means of burying soil surfaces damaged by the passage of vehicles.-P.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A note on taste tests on rice in Northern Nigeria.
Authors: Sluyters J.A.F.M.
Published: June 2020

A significant ranking of the four varieties tested was obtained only when the tasters were able to see the rice and not when they were blindfolded, indicating that preferences depend upon qualities other than taste only. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of organic matter on the structure of clay soils.
Authors: Boekel P.
Published: June 2020

Tabular and graphical data show the effect of organic-matter levels (1-7%) on intrinsic soil structure (lower & upper plastic limit, moisture content atpF2) & actual soil structure (pore space, air content), & on the effect of organic manuring (farmyard manure, town refuse, green manure, ley) on structural properties. An increase in organic-matter content decreased the slaking sensitivity of soils, increased resistance to plastic deformation caused by mechanical forces on heavy clays under wet conditions, & improved actual structure by 0.6-0.7 points (visual estimation) for each per-cent organic matter. Lowest organic-matter content, providing good resistance to mechanical breakdown & giving proper structure for good plant growth, was required on a clay soil in which the 16 micro particles ranged between 15 & 30%, depending on soil treatment. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The labour pattern as a sociological aspect of agricultural extension work.
Authors: Perk A.
Published: June 2020

Extension workers in developing areas often fail to understand the reluctance of farmers to accept well-intentioned changes. This may be due to a lack of understanding of the communities' strict labour pattern, assigning each kind of labour according to tradition or sex, or of the social aspects which may lead to an over-estimation of available time for extra labour. It is concluded that: (1) unknown new kinds of labour are more easily acceptable than changes in traditional ones, (2) schemes promising more results with the same or less labour, such as the cultivation of perennial crops or the use of selected seed, are easier to reanze than schemes dependent on much more work. T.A. mod. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Sodium requirement of milking cows: balance trials with cows on rations of freshly mown herbage and on winter rations.
Authors: Kemp A.
Published: June 2020

Dairy cows were fed freshly mown herbage or winter rations which together with the drinking water gave Na intakes of betwen 5.8 and 91.0 g./day. The availability of the Na varied from 77 to 95% averaging 85.5%. The Na secretion in the milk averaged 0.38 g./l. varying from 0.31 to 0.49 g./l. The Na requirement for dairy cows with milk yields of 10-30 kg, /day when the Na was 75-95% available ranged from 10.0 to 23.3 g./day. D.E.C. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Animal behaviour in the sub-tropics. I. Heat tolerance in relation to grazing behaviour in sheep.
Authors: Shafie M.M. , Sharafeldin M.A.
Published: June 2020

Thirty ewes of the breeds Ossimi indigenous, Texel, Caucasian Merino and Fleisch Merino were studied in newly reclaimed desert in Egypt. Body temp., respiration rate and skin temp. of each ewe were measured four times daily, i.e. before it left the shed, on arrival at the pasture 5 km. away, before leaving the pasture, and finally when it returned to the shed. The air temp. was recorded at the time of each test. The most pronounced breed difference was in the respiration rate. The initial values at morning were only 16 respirations a minute in both Ossimi and Caucasian Merino, whereas the Texel and the Fleisch Merino had respectively four and five times this value. Walking to the pasture and grazing activity had different effects on the cardiorespiratory reactions of the different breeds, and Ossimi was the least affected. (AS). (Abstract retrieved from CAB Abstracts by CABI’s permission)
Factors influencing the sodium content of meadow grass.
Authors: Menkens C.H.
Published: June 2020

Sodium content of grass was largely determined by Na content and K number of the soil. At a given Na content of soil, the Na content of grass decreased with increasing K number of the soil but the decrease was small where K number was >30. Na content of grass increased with increasing soil Na; the increase was higher at low- than at high soil-K status. K fertilizing lowered grass Na at low soil-K status. Soil-Na content can be used in the Netherlands as a basis for Na-fertilizer recommendations, since K number has generally reached a level at which it has an almost constant effect on Na content of grass. Influences of the K and Na status of the soil on the Na content of grass can be expressed as the ratios (15 X K number)/(Na2O+6) for sandy soils and (25X K number)/(Na2O + 14) for clay soils, the numerator at K numbers > 30 being the same as that at K number=30. With increasing ratios, the Na content of grass decreases. The influence on herbage -Na level of a given amount of Na in K fertilizers is correlated to these ratios. The influence of N fertilizers on Na content of grass was not clear and the influence of Mg fertilizers was negligible. Chile nitrate and Nad affected the Na of grass similarly, but Chile nitrate differed from NaCl in decreasing the Ca content; both fertilizers slightly lowered the Mg content of grass. Herbs and clovers contained more Na than grass does. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The role of savanna in nomadic pastoralism: some observations from western Bornu, Nigeria.
Authors: De Leeuw P.N.
Published: June 2020

The vegetation of W. Bornu in N. Nigeria, its environment, physiognomy and flora are described. The savannah has developed under the combined influence of a severe dry season, shifting cultivation, grazing and the resulting annual fires. The savannah constitutes the grazing orbit of nomadic pastoralists who have adapted their system of cattle husbandry to the seasonal variation of the grazing land by a cyclic transhumance pattern of their families and herds. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of management and nitrogen application on the botanical composition of grassland.
Authors: Ennik G.C.
Published: June 2020

Application of 70 kg/ha N was less important in affecting botanical composition of the sward than frequency of cutting (3 weeks versus 5 weeks) and especially the system of grazing (rotational versus continuous grazing) were. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Observations on the opening of flowers, dehiscence of anthers and growth of pollen tubes in Arachis hypogaea L.
Authors: Bolhuis G.G. , Frinking H.D. , Leeu-Wangh J. , Rens R.G. , Staritsky G.
Published: June 2020

Examination of flower buds and flowers of 3 different groundnut cultivars in controlled environment disclosed that flower expansion occurs at the onset of the light period. Pollen liberation may already occur 7-8 h before flower expansion, but even then the anthers may not have dehisced in some flowers. It was calculated that pollen tubes grow at a rate of about 4 mm/h.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of daylength on vernalization of winter rye. 2. Continued experiments with short-day vernalization in winter rye.
Authors: Hartman T.A.
Published: June 2020

In vernalization trials with winter rye, short-day treatment prior to cold treatment was capable of inducing accelerated development and early ear emergence even when the temperature during the former treatment was 25 degrees C. Short days imposed during protracted cold treatments could also accelerate development provided that the optimum duration of short-day vernalization (about 14 days) was not exceeded. Results confirmed the assumption that cold vernalization and short-day vernalization were different processes. [See also F.C.A. 18: 1236].-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ditch-blasting as a method of opening-up tropical swamp forest in Surinam.
Authors: Bubberman F.C. , Vink A.T.
Published: June 2020

A fuller account of an article already noticed [cf. F.A. 27 No. 6063. KEYWORDS: Engineering forest \ Explosives, use \ opening up tropical swamps \ floating \ ditches from tropical swamps \ Surinam water transport \ Surinam (Abstract retrieved from CAB Abstracts by CABI’s permission)
The routine determination of manganese with form-aldoxime.
Authors: Van Schouwenburg J.C.
Published: June 2020

Interference from Fe can be successfully masked with KCN if measurements are taken at a wavelength of 500 mm. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The determination of micro quantities of manganese in plant material.
Authors: Van Schouwenburg J.C. , Walinga I.
Published: June 2020

After a liquid-liquid extraction with 2-thenoyltrifluoro-acetone, micro quantities of Mn in plant material can be determined with formaldoxime without interference from other elements. [A.S. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Evaluation of glassy frits as micronutrient fertilizers. 1. Copper and molybdenum frits.
Authors: Henkens C.H. , Smilde K.W.
Published: June 2020

In pot and field experiments, two Cu frits gave some control of Cu deficiency in oats and wheat, but were less effective than CuSO4. One of the frits, containing 8%Cu, was less effective than the other, containing 3.2% Cu. Mo frits were good sources of Mo. The immediate effect of Mo frits was less and the residual effect greater than that of Na molybdate. Solubility in 0.1 n H2SO4 was not satisfactory for evaluating Mo frits. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of length of the illumination period on root formation in cassava, Manihot utilissima Pohl.
Authors: Bolhuis G.G.
Published: June 2020

Sprouted cuttings of 6 cassava cultivars were subjected to light periods of: 10 h daylight, 10 h daylight plus 2 h weak light, 10 h daylight plus 4 h weak light and 10 h daylight plus 6 h weak artificial light, respectively, to study root formation under these conditions. The optimal light period was about 12 h; longer light periods inhibited root formation. Cassava was considered to be a short-day plant.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Graft-induced phenotypic changes in tomato mutants.
Authors: Kedar N. , Verkerk K.
Published: June 2020

Reciprocal grafts were made between normal tomato lines and 36 mutants characterized by different leaf shape and colour or by shortened internodes. Some yellow-top mutants temporarily became darker green after grafting them on normal green stocks. The height of short-internode and of normal scions was only slightly affected by the genotype of the stock, and the genotype of the scion was expressed almost independently of the genotype of the stock. No evidence was found for any effects resulting from the movement of growth inhibiting or accelerating substances from stock to scion or from scion to stock. The same held true for substances inducing virus-like symptoms. In one graft combination normal scions on stocks of a short-internode mutant with a tendency to wilt were greatly reduced in total length, stem diameter and length of leaves. The mutant line grafted on a normal rootstock showed increased vigour. The effects of the mutant as well as of the normal type were expressed in one direction only, that is from stock to scion but not vice versa. The "wilty" condition was induced in a normal scion grafted on the mutant stock. Mutant scions grafted on normal stocks still showed signs of wilting. These effects are thought to result from a deficient transport system in the "wilty" mutant.-Hebrew Univ. of Jerusalem, Rehovot, and agric. Univ., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Evaluation of glassy frits as micronutrient fertilizers. II. Manganese frits.
Authors: Henkens C.H. , Smilde K.W.
Published: June 2020

In pot and field tests MnSO4 and the frits FTE Z 4 (13 % Mn), HZ 1 (15.9 % Mn) and HZ 17 (21 % Mn) increased reducible soil Mn for at least 1 1/2-2 years. Mn content of pasture increased four-fold in the first cut after application of 400 kg/ha MnSO4 but sharply decreased in later cuts and became negligible by the second year. 400 kg/ha HZ 17 did not affect pasture Mn. In peas 400 kg of soil- or foliar applied MnSO4 controlled marsh spot better than 800 kg HZ 1; spraying at the middle and again at the end of the blooming stage gave the best control. With sugar beet, soil dressings of MnSO4, HZ 1 and HZ 17 equally increased yield, sugar production and leaf Mn, and decreased incidence of Mn deficiency. When the rates of these fertilizers were increased from 100, 179 and 86 kg respectively to 400, 714 and 343 kg, sugar production was not significantly improved; leaf Mn and incidence of deficiency symptoms responded to the higher Mn rates. Soil application was rather better than foliar treatment. No treatment controlled Mn deficiency throughout the entire season. The % of Mn-deficient plants was related, negatively, to leaf and reducible soil Mn, but not to yield. Soil-applied Mn did not control gray spot in oats or increase yields but sprayed Mn did. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Preliminary results of a grazing trial in the Syrian Steppe.
Authors: Van der Veen J.P.H.
Published: June 2020

A trial was begun in 1963 at the Wadi al A'azib Range and Sheep Experiment Station to compare stocking rates of 9.0, 6.0 and 4.5 ha/sheep on animal production (liveweight of ram and ewe lambs, milk production and unwashed wool yield) and on the composition and density of the vegetation which was classified into 5 units: (a) valley stream-bed and floodplain on alluvial silt, (b) valley terrace on higher floodplain, (c) Artemisia herbaalba associations on marly soils, (d) Haloxylon articulation associations in small valleys and on hill-slopes, (e) Haloxylon articulatum/Noea mucronata associations on shallow, stony, grey desert soil on folded limestone hills. Fresh herbage yields in 1964 were 3129, 1126, 1312 and 859 kg/ha for areas (a), (b), (d) and (e), respectively. Average yields were lower at the higher stocking rate in the drought year 1966, but results were generally inconclusive. It was concluded that, pending further work, a stocking rate of 4.5 ha/adult ewe would not seriously deplete the grazable herbage.-M.G.W. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Selection of rye on leaf-emergence rhythm.
Authors: Hoogland R.F.
Published: June 2020

The emergence rhythm of leaves on the main axis was shown to be a heritable character in Zelder. This rhythm, which is correlated with leaf size, may be the same before and after ear initiation, or different. By selection, four different rhythms were obtained; a low rhythm before and after ear initiation resulted in shorter straw and more rapid ear emergence. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The possibilities of breeding long fibre agaves with a high rate of leaf unfurling and a high rate of increase in leaf length.
Authors: Wienk J.F.
Published: June 2020

The vegetative development of the sisal plant is described with particular reference to the rate of leaf unfurling and the rate of increase in leaf length. The significance of these characteristics, particularly the latter, for fibre production is discussed. It is shown that a high rate of increase in leaf length is a desirable characteristic of a long-fibre agave. Observations made on a number of Agave hybrids, however, indicate that there is a marked negative correlation between rate of leaf unfurling and rate of increase in leaf length. The consequences are discussed.-Sisal Res. Stat., Mlingano, Tanzania. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The determination of the drainage factor as a criterion for the soils of the Indos Plains.
Authors: Hulsbos W.C.
Published: June 2020

Drainage factors (DF) were used as design criteria for comparing relative costs of horizontal and tubewell drainage of mainly medium-textured silty loams, especially in saline groundwater areas. DF calculated from recharge estimates were higher than those calculated from leaching requirements. For tubewell drainage (normally maintaining a water-table lower than is possible with horizontal drainage) DF from recharge estimates should serve as criteria for establishing the capacity of the installation. For calculating the required spacing for horizontal drainage, DF slightly higher than those derived from leaching requirements are desirable to take into account drainage or seepage from line sources. If wide spacings are calculated with relatively small DF, the reaction of the water-table halfway between the drains to intermittent recharge may be too slow, and a smaller spacing may be required. Because of limited accuracy of the DF, additional data on hydraulic conductivity of the soil are desirable. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of weather and nitrogen fertilization on white clover percentage of permanent grassland.
Authors: Kleter H.J.
Published: June 2020

On humus sandy soil little affected by moisture deficiency, and on compact river clay with somewhat lower water-table (40-180 cm) and occurrence of water deficiency during the summer months, herbage sampling during 1960-1966 showed that the percentage of Trifolium repens present in any month was significantly correlated with temperature and total radiation for the previous month. The mean clover percentage for a single season correlated significantly with mean April temperature. At temperatures common in April, growth of clover is considerably more affected by a rise in temperature than is that of the competing grasses Loliuni perenne and Poa trivialis. The clover percentage was unfavourably affected by N application but unaffected by precipitation or potential evaporation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Growth-promoting effects of some biocides on grass.
Authors: Ennik G.C.
Published: June 2020

Single applications of Nemafos in spring 1966 and 1967, or split applications at each cut, increased grass yield in a grass/clover sward by 15% and also improved clover yield to some extent. The population density of free-living root nematodes was greatly reduced, but this did not entirely account for the yield increase. AAvlitox(20% O-2, 4-dichlorophenyl O, O-diethyl phosphorothioate) had similar but smaller effects.-A.M.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Dry matter production and light interception of crop surfaces. 4. Maximum herbage production as compared with predicted values.
Authors: Alberda T.
Published: June 2020

With the aid of previously obtained data on the rate of DM production of a closed sward, and of data on rate of regrowth after cutting and the interval between cutting and re-attainment of a closed sward, a table was constructed to predict with reasonable accuracy the total herbage production for a given cutting regime.-A.M.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Weed biology-a future.
Authors: Sagar G.R.
Published: June 2020

The author attempts to estimate the value of studies of weed biology to weed control practice. It is agreed that much of the biological information available on weeds is not helpful in control and often is not intended to be. A series of proposals is made to provide evidence that a knowledge of some neglected aspects of the biology of weeds might greatly assist in achieving the weed-free environment. The need for a much closer liaison between weed biologists and those concerned with the control of weeds is stressed.-s. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The transformation from traditional to commercial family farming.
Authors: Joosten J.H.L.
Published: June 2020

The central role the farmer and his family are playing in the process of agricultural development is emphasized. In the transformation from subsistence to commercial farming there is an increase in the number of factors influencing the decisions the farmer has to make. Farms are classified by the proportion of gross product marketed. This classification explains a number of problems encountered by economists. The relationship is examined between farm size and other factors, such as the production per unit area, consumers per family, welfare index, costs of non-agricultural inputs. The impact on the portion of gross product that has to be sold is shown for an assumed growth of welfare and costs of non-agricultural inputs. Simple arithmetic reveals the crucial importance of expanding domestic or foreign markets for agricultural products. Finally future research in agrarian economics is considered. The need for farm management research, to anticipate farmers' problems and to keep them informed is stressed as are the aspects of infra-structure. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Prediction of forage digestibility from some laboratory procedures.
Authors: Duinum B. , Van Soest P.J.
Published: June 2020

Digestibility of 106 samples of hay, grass, grass silage and legume forage was estimated by regression from cell contents and cell wall constituents estimated chemically. Cell wall constituents were cellulose, hemicelluloses, lignin, cutin, plant silica and soil contamination. Values were not as closely related to digestibility in vivo by sheep as were values obtained by digestion with rumen fluid in vitro. Correlation between digestibility of cell wall constituents and lignin content was poor, and this and other reasons for the poor results from chemical analysis are discussed.-T. D. B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some responses of the root and the shoot of Vida faba plants to water stress.
Authors: El Nadi A.H. , Brouwer R. , Locher J.T.
Published: June 2020

V. faba plants were grown at 15 degrees or 25 degrees C in alternating wet and dry periods. Drying of the soil promoted deeper root growth. Total root weight was not affected. Shoots grew less with a dry treatment in both the vegetative and the flowering phase.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Radiation-induced easy peeling and oblong fruit mutants of the tomato.
Authors: Verkerk K. , Contant R.B.
Published: June 2020

The genetics of two radiation-induced mutants of cv. Moneymaker, "easy peeling" and "oblong fruit with strong skin", were studied. Both were governed by a single recessive gene. The combination of both traits was achieved by crossing, but it was impossible to break the association between oblong fruit and strong skin. Hybrid easy peeling material with round or oblong fruit shape was selected for yield and improvements up to 30% over Moneymaker were reached under experimental conditions. The easy peeling trait may be of interest both for the canning industry and for fresh consumption.-Univ. Wageningen & Neth. Inst. atomic Sci. Agric. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of root and shoot damage on the growth of tea plants.
Authors: Visser T.
Published: June 2020

Experiments were carried out under various conditions of elevation and climate, in which young vegetatively propagated plants of selected tea clones were subjected to pruning operations at or after transplanting. Generally the removal of a substantial portion of shoot, root or both caused a temporary set back in growth and, in many instances, increased mortality. The subsequent reduction in total growth depended on the amount initially removed, except when only the immature apical part of the shoot was cut off, in which case the plants grew as well as the untreated ones. Retarded root growth and mortality as a consequence of pruning were associated with a marked depletion of the carbohydrate reserves of the roots, which was more serious when the original level (in Ceylon primarily determined by altitude) was low. Bringing a young tea plant into bearing as soon as possible requires the induction of lateral branching while avoiding growth restriction as far as possible; the practice of bending was found to be less detrimental to growth than other methods involving repeated pinching of apical shoots, cutting across at about two-thirds of the height of the plant, centering and modifications of these methods.-Inst. hort. Plant Breed., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On soil genesis in temperate humid climate. VII. The formation of a glossaqualf in a silt-loam terrace deposit.
Authors: Bouma J. , Van Schuylenborgh J.
Published: June 2020

The physical, chemical and micromorphological properties of a poorly drained soil profile developed on clayey parent material covered by a thin layer of loess are described. Clay skins on peds were absent in the B-horizon which is considered to be of Pleistocene age. In thin sections, however, oriented clay was observed inside peds occurring undisturbed as free grain and channel argillans, and disturbed by pedoturbation as quasicutans and papules. Clay was leached vertically through the B horizon along planar voids between prisms, leaving accumulations of skeleton grains. Some clay was also leached from the A2 horizon. Kaolinite was more mobile than illite or smectite. Reduction processes resulted in strongly bleached areas around prisms and in well developed mangans on ped faces and around channels. The profile was classified as an aerie glossaqualf. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Maturation in peas. 2. Spread in maturity.
Authors: Schippers P.A.
Published: June 2020

A good impression could be obtained of the spread in maturity within a crop of green peas at 'optimal harvest date' by applying the method described in the previous abstract. It was found that differences between varieties existed, but also that varieties showed differences in reaction to growing conditions. At optimum harvest date an appreciable proportion of pods contained peas which were too old, but a considerable proportion of other pods contained peas which were far too young. Therefore, under commercial conditions of once-over harvest, the actual yield of good-quality peas remained far below the potential yield.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Calculation of evapotranspiration from potatoes.
Authors: Endrodi G. , Rijtema P.E.
Published: June 2020

Data from sprinkler irrigation experiments with potatoes were used to calculate the actual and potential evapotranspiration from the crop during the growing season, using standard meteorologie data. During the experiments the moisture extraction from the effective root zone was determined by soil sampling. The water-use by the crop for the different periods was also derived from the water balance and both values were in good agreement in periods without extreme conditions of precipitation, this showing that the derived relations between crop height and surface roughness, between soil cover, light intensity, crop characteristics, soil characteristics and diffusion resistance, and between maturation and internal plant resistance were reasonably established. F.s.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of soil structure and air content on gas diffusion in soils.
Authors: Bakker J.W. , Hidding A.P.
Published: June 2020

A method is described of determining the diffusion coefficient of O2 in undisturbed soil samples. Calculations were made of errors involved when neglecting the storage term, temperature and pressure variations, O2 consumption and resistance of ambient air. The diffusion coefficient (Ds) is a function of air porosity (eg) and soil structure. At values of eg below 0.2, the effect of a puddled soil surface becomes evident. In puddled soils values of Ds at equal eg are far below those in non-puddled soils and the differences increase with decreasing eg. A wet soil crust can severely limit gas exchange by diffusion. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Socio-economic development in Guatemala through incentives to the subsistence sector.
Authors: Manger Cats S.C.
Published: June 2020

Subfamily farms (under 7 ha.) defined as too small to fully occupy the operator's family and to provide him with an adequate income, if worked traditionally, now number some 370, 000 in Guatemala. Access to new land and the distribution of production inputs and credit are limited. In the light of this situation some indirect and direct measures are described to reduce the relative importance of this subsistence group. A number of successful projects prove that there is a potential for improvement. T.A. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Studies on pod and bean values of Theobroma cacao L. in Nigeria. I. Environmental effects on West African amelonado with particular attention to annual rainfall distribution.
Authors: Toxopeus H. , Wessel M.
Published: June 2020

All pod and bean values except the pod length/width ratio and the weight of oven-dried shell and seed coat per bean were affected by season. Pods which developed in a period of considerable water stress had much lower values than pods which developed during periods of adequate water supply. Under conditions of water stress the positive correlations between most pod characters disappeared. The mean weight, however, of oven-dry beans was independent of any other pod value irrespective of the water supply to the trees. Percentage butterfat was positively, and shell content negatively related to bean size. Butterfat content of beans in the same weight class was higher in September than in June, and the shell content of beans was lower. The mean weight of cured beans was highly correlated (r = 0.82) to the total rainfall of the first 4 months of pod development. [See also H.A., 40: 4853 and the following abstract.]-Neth, int. agric. Cent., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Production of carboxylates (C-A) by young sugar-beet plants grown in nutrient solution.
Authors: Van Egmond F. , Houba V.J.G.
Published: June 2020

In growth-chamber experiments, sugar beet seedlings were grown in nutrient solution. Plants were harvested 30, 36, 39, 43, 46 or 51 days after germination, leaf blades (including midribs), petioles and storage roots plus fibrous roots were analysed for Na, K, Ca, Mg, H2PO4, NO3, Cl, SOt, total N and 5 organic acids, and fresh and dry weights were recorded. The total content of carboxylates (C-A) was calculated by subtracting the sum of inorganic anions from the sum of inorganic cations. Amounts of C-A and organic N were about equal; there was no release of carboxylates resulting from NO3- and SO4- reduction in the leaves of sugar beet. Only a small amount of carboxylates reached the root system and no excess uptake of inorganic anions over inorganic cations accompanied by a decarboxylation of carboxylates occurred. In sugar beet plants the C-A content was not constant during the growth period studied. The NO3- reduction per g leaf/day decreased rapidly with time and was accompanied by a decrease in oxalate production. The high oxalate content in the leaves was thought to account for the decrease in NO3- reduction. GMC. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Remarks on soil structure in relation to zero-tillage.
Authors: Boone F.R. , Kuipers H.
Published: June 2020

Effects of tillage on density and structural homogeneity, requirements for good root penetration and growth in soil, and types of soil structure most suitable for plant growth are discussed. It is suggested that tillage normally creates a sufficiently heterogeneous soil structure, while soil structure after zero-tillage gradually becomes more homogeneous. (Abstract retrieved from CAB Abstracts by CABI’s permission)
First experiences with direct drilling in Germany.
Authors: Baeumer K.
Published: June 2020

Conventional tillage methods were compared with direct drilling, using machines of 3 types, for wheat, barley, oats, maize and sugar beet on marginal and other soils. Each method of direct drilling sometimes gave substantial yield increments, though generally yields failed to equal or exceed those from conventional practice. Reasons for the differences are discussed. CCT. (Abstract retrieved from CAB Abstracts by CABI’s permission)
No-tillage as compared to tillage practices in dry-land farming of a semi-arid climate.
Authors: Stibbe E. , Ariel D.
Published: June 2020

The influence of zero-tillage practice on soil, weed control during winter fallow and growth behaviour of sorghum and cotton is discussed in relation to conventional practice. In a year of partial drought when all yields were reduced, zero-tillage gave slightly superior results, but when moisture was adequate it depressed yields by up to 40%. The yields of following crops of wheat and vetch after sorghum, were depressed in the zero-tillage plots by 5-30% in 2 field experiments, compared with conventional practice. CCT. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of crop and tillage on mites and springtails in arable soil.
Authors: Van de Bund C.F.
Published: June 2020

Experimental data from Holland are discussed on the effects of soil type (light sandy soil to heavy clay and peaty soil) and crop (potato, oats, fallow etc.), as well as of cultivation (compared to no-tillage), on frequency and distribution of Collembola and Acari. In untilled soil, almost all the arthropods occurred in the top 5 cm, while in normally cultivated soil the soil fauna (including nematodes and earthworms) was more evenly distributed in the top horizons. Collembola and Acari were particularly affected by soil structure, moisture condition, the microflora present, and vegetal cover. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of defoliation and nitrogen on the regrowth of Rhodes grass (Chloris gayana Kunth). 1. Dry matter production and tillering.
Authors: Dovrat A. , Dirven G.P. , Dienum B.
Published: June 2020

In pot experiments Rhodes grass (cv. "Common" and "Katambora") was fertilized with 1.43 and 8.29 meq N/100 g soil over a period of 56 days and was cut every 14 or 28 days. Cutting at 28 days considerably increased total shoot weight. Root weight per pot of low-N plants was 31 and 23% higher than that of high-N plants at 14- and 28-day cutting intervals, respectively. N application generally increased the average number of harvest tillers, but individual tillers regrew a fewer number of times than those receiving low N. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Methyl bromide fumigation versus other ways to prevent the spread of mushroom virus disease.
Authors: Dieleman-van Zaayen A.
Published: June 2020

The treatments comprised methyl bromide (MB) fumigation v. 2% sodium pentachlorophenate (SPCP) treatment of wooden trays in which virus-infected mushrooms had been grown; MB v. formaldehyde fumigation of healthy and virus-infected spores and mycelium; and MB fumigation of compost permeated with virus-infected mushroom mycelium. MB fumigation of the trays did not eradicate virus in the subsequent crop, whereas SPCP treatment eliminated infection. Germination by diseased spores was almost completely inhibited by MB at low concentration time products and the growth of healthy spores was greatly retarded. Mycelium was not killed by MB but growth was retarded, as was that of mycelium from fumigated spawn. Formaldehyde treatment for 24 h killed spores and mycelium. MB fumigation of compost was ineffective. Thus MB fumigation cannot replace the traditional method of cooking-out mushroom houses with live steam, followed by treatment of the wood with SPCP. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Chromosome numbers in. Begonia. 2.
Authors: Legro R.A.H. , Doorenbos J.
Published: June 2020

The somatic chromosome numbers are presented of 90 Begonia spp. of African, Asian and American origin, including a few of those previously listed [see H.A., 40: 1600] whose nomenclature or chromosome numbers are reconsidered. Sixteen different numbers were found, ranging between 16 and 76. The most common were 28 (26 species), 38 (10 species) and 56 (15 species). [For related work see H.A., 41: 7120.]. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A production trial with layers of four hybrids under different environmental conditions in the Eastern Province of Saudi Arabia.
Authors: Appelman H. , Bonhof B.J.
Published: June 2020

161 Australorp X Rhode Island Red (RIR) X New Hampshire (NH) and 166 White Leghorn (WL) imported fowls were kept in insulated housing; 161 Australorp X RIR X NH, 166 WL, 154 RIR X WL and 148 RIR X NH X RIR fowls were kept in open houses. In the 6 groups resp., live weight at 126 days of age averaged 1602, 1227, 1578, 1234, 1397 and 1539 g, food consumption 4.02, 4.49, 4.03, 4.47, 4.25 and 4.17 kg/kg gain, overall laying percentage 56.6, 56.4, 52.5, 53.4, 55.0 and 37.5, egg production/hen 202, 201, 188, 191, 196 and 134, and egg weight 56.3, 56.3, 55.0, 55.8, 55.0 and 57.5 g. Egg mass averaged 1335, 1323, 1191, 1151, 1126 and 796 kg and food consumed/kg eggs produced 3.68, 3.53, 3.71, 3.25, 3.37 and 4.74 kg. Live weight at 16 mth of age averaged 2894, 2040, 2665, 1874, 2132 and 2517 g, and mortality 12.8, 11.1, 33.6, 43.5, 52.8 and 50.4%. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Grain yield of winter rye and winter wheat in relation to leaf number and leaf age.
Authors: Gmelig Meyling H.D.
Published: June 2020

In trials in 1966-7, removal of the upper leaves of wheat and rye at heading gave lower yields of grain and straw than removal of the lower leaves. Removal of all leaves reduced grain yields of winter rye by 44% and winter wheat by 43%. The proportional increase in stem weight after flowering compared with that of ear weight, was appreciably greater in rye than in wheat. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Feed intake by grazing dairy cows. 3. Comparison of lactating and dry pregnant cows.
Authors: Dijkstra N.D.
Published: June 2020

Lactating cows fed polythene capsules as markers consumed 15.2 kg DM/day when strip-grazed. Dry cows 1-2 months before calving ate significantly less, 11.7 kg DM/day; these intakes were equivalent to 9.2 and 7.1 kg SE and 3.5 and 2.7 kg DCP for the 2 types of animal, respectively. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The agricultural value of awns in cereals.
Authors: Vervelde G.J.
Published: June 2020

A preliminary examination of the F2 of crosses between awnless wheats and bearded varieties at the Laboratory for Crop Husbandry, Wageningen, indicated that the bearded offspring were more vigourous and produced more ears and more grains per ear than the awnless progenies. The apparent vigour of bearded wheats was, however, due to an inexact separation of bearded and awnless types; vigourous awnless plants, homozygous for short tips on their glumes, were classified as bearded, while some of the less vigourous plants, heterozygous for bearded glumes, were taken for awnless individuals. Following accurate classification, verified by examining F3 progenies, awns were shown to contribute 3-5% to grain yield due to photosynthetic activity, not to linkage. This conclusion was supported by comparing yields of deawned plants and bearded controls. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On 4³ factorial designs with confounding.
Authors: Kuiper N.H.
Published: June 2020

A design is given for three factors each at four levels in three blocks of 8 x 8 plots. In each block in the field, fertility in the direction of columns and of rows is not neglected. The main effects are not confounded. The interactions are partially confounded. The part is
Potential evapo-transpiration.
Authors: Van Wijk W.R. , De Vries D.A. , Van Duin R.H.A.
Published: June 2020

Potential evapotranspiration calculated with Thornthwaite's empirical formula is compared with the values following from Penman's theory. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some results of field determinations of the moisture content of soil from thermal conductivity measurements.
Authors: De Vries D.A.
Published: June 2020

The soil-moisture content at 4-I6-cm depth is compared with precipitation and potential evapotranspiration for periods of one month. During May the moisture contents fluctuated under the influence of frequent rainfall. From the end of May evapotranspiration exceeded precipitation and, during the dry months June and July, rainfall affected only the measurements at 4-cmdepth; moisture contents at 8 and I6 cm became constant after initial drying. During August, rainfall exceeded evapotranspiration and there was a general increase in moisture content. Diurnal variation in moisture content is shown in graphs. For accurate determinations of soil-moisture content from thermal conductivity measurements sandy soils are more suitable than clay soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Reclaiming land flooded with salt water.
Authors: Beekom C.W.C.
Published: June 2020

The effect of sea floods on grassland is described and recommendations are made for the restoration of inundated grassland. Turf may be heavily damaged after +or- 4 weeks inundation with water containing more than 20 g. NaCl per 1. At lower salt concentrations Poa sp. and Trifolium repens are still badly damaged but other species, notably Lolium perenne, Agrostis stolonifera and Alopecurus sp., are capable of immediate regrowth after drainage. If grassland remains submerged during spring, rising temperatures promote active growth of the grasses followed by rapid decay caused by lack of oxygen. L. perenne is especially sensitive to submergence in warm weather. The dominant weed communities which appear on land on which the turf has been destroyed by sea-water are described. Reseeding is recommended as the quickest method of restoring badly damaged turf. The flooded land should first be thoroughly drained and then repeatedly harrowed to produce a shallow seed-bed on which herbage mixtures can be sown without the application of gypsum. Given average weather conditions, normal permanent grassland mixtures can be sown at salt concentrations, measured in spring, of up to 8-10 g. NaCl per 1. of moisture in the 5-20 cm. soil layer. At a salt concentration of about 10 g. per 1. measured in spring, L. perenne tends to dominate over other species while Poa sp. and T. repens suffer during the summer. At a salt concentration of 10-15 g. per 1. in spring, Poa sp. and T. repens should be omitted from seed mixtures, instead mixtures consisting of different types of L. perenne, Festuca pratensis and Phleum pratense should be sown. When the salt concentration of the soil moisture is higher that 15 g. per 1. in spring, sowing should be delayed and the weeds checked by mowing or grazing. Temporary rises of the salt concentration in dry symmers to 25 g. per 1. are tolerated by L. perenne, F. pratensis and Ph. pratense; similar rises up to 15-18 g. per 1. are tolerated by Poa sp. and T. repens.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Stability of carotene in mixed feeds.
Authors: Dammers J.
Published: June 2020

Dried grass meal and a mixed feed, containing cereals, oilseed residues, mineral salts and 10 per cent. of the dried grass meal, were stored in paper bags. Carotene was estimated weekly. The average weekly percentage loss was 3.01 +or- 0.19 from the mixed feed and 4.48 +or- 0.29 from the grass meal. In another experiment the mixture contained meatmeal and fishmeal but no by-product of the oil industry. The average weekly percentage loss was 0.87 +or- 0.14 from the mixture and 0.81 +or- 0.24 from the meal. The first experiment was made in summer, the second in winter, which may explain the great difference in rate of loss. It is concluded that destruction of carotene in dried grass meal during storage is not increased by the presence of other feedingstuffs. V. H. Booth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nitrogen nutrition of rice plants measured by growth and nutrient content in pot experiments. 2. Uptake of ammonium and nitrate from a waterlogged soil.
Authors: Dijkshoorn W. , Ismunadji M.
Published: June 2020

Rice cv. IR5 was grown in pots in waterlogged soil with varying levels of K, Na, Mg, Ca, NH4, NO3, Cl, PO4 and SO4. Where NO3 but no NH4 was supplied, denitrification resulted in N shortage and restricted N uptake. With NH4, uptake of N was determined by plant growth and capacity to incorporate N. When KNO3 was replaced by NH4Cl, plant growth was less than where (NH4)2SO4 was the replacement salt; this was related to the greater accumulation of Cl ions in the tissues and a consequent marked fall in carboxylates to a very low level indicative of nutritional stress. (Abstract retrieved from CAB Abstracts by CABI’s permission)