bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimum NPK management over extended cropping periods in south-west Cote d'Ivoire
Authors: Van Reuler H. , Janssen B.H.
Published: June 2020

In the Tai region of south-west Cote d'Ivoire P is the yield-limiting nutrient on (moderately) well drained soils. In order to find the optimum P application rate, a factorial experiment (2N x 4P x 2K) in three replicates was conducted at two sites during six seasons. The factors investigated were N (0 or 50 kg/ha), P (0, 12.5, 25 or 50 kg P) and K (0 or 50 kg K). N (urea) and K (muriate of potash) applications were split into two equal parts and broadcast. From the third season onwards the N application was raised to 100 kg N. P (triple superphosphate) was placed near the young plants. Upland rice and maize were used as test crops. The experimental sites were located at the crest (Site VII) and lower slope (Site VIII) of a catena. In the first season after clearing at Site VII highest yields were obtained with 12.5 kg P and at Site VIII with an application of 25 kg P. At the latter site also N application increased yields. In an extended cropping period the rice yield level could not be maintained. The efficiency of utilization of absorbed P (EUP) of rice was high in the first season after clearing but decreased in subsequent seasons. This is in contrast to EUP for maize which remained constant with time. Hence, it is concluded that the rice yield decline is caused by other factors than nutrient deficiencies. In all seasons yields were higher at Site VII than at Site VIII. The residual effect of fertilizer-P could reasonably well be described by a simple formula: RFP1 = (0.9 - RFP1)t-1 x RFP1, where RFP and RFP1 are the apparent recovery fractions of fertilizer P in year t and year 1, respectively. In all seasons, except in the first season after clearing, the potential P supply was higher at the crest (Site VII) than at the lower slope (Site VIII). Extending the cropping period proved possible when fertilizers were applied and maize was grown. For both sites fertilizer guidelines could be formulated. Comparison of soil chemical data (pH, organic C, total N and total P) before the start of the experiment and after six seasons did not show changes.
Broomrape (Orobanche cernua) control before attachment to host through chemically or biologically manipulating seed germination
Authors: Dhanapal G.N. , Struik P.C.
Published: June 2020

Seven series of laboratory and glasshouse experiments were conducted to investigate different methods of testing and studying the effect of several chemicals, root exudates of germinating crop seeds, and their interactions on Orobanche cernua. Compared to experiments in an incubator, better results were obtained when seed germination was tested in the presence of seedlings of host plants under glasshouse conditions. GR24 at 0.1 and 1.0 mg kg-1 was the most effective in stimulating the germination of O. cernua seeds, followed by gibberellic acid at 10 and 20 mg kg-1. Without the addition of chemicals, trap crops strongly increased germination, with green gram (Vigna radiata) and sunn hemp (Crotalaria juncea) being particularly effective. There was an interaction between the effects of chemicals and trap crops. A positive effect of trap crops was observed even when there was already strong stimulation by GR24 at 1.0 mg kg-1, but under these conditions, trap crops were less effective at 0.1 mg kg-1 GR24. No differences between cultivars in their effect on O. cernua germination could be detected within one host plant species.
Energy saving prospectives of combined heat and power in horticulture in the Netherlands: a simulation study
Authors: De Zwart H.F. , Bot G.P.A.
Published: June 2020

This paper studies the prospects for the use of reject heat from on-site combined heat and power generation in horticulture. In particular, the consequences of CO2-dosing with exhaust gases is studied. All computations are made with a recently developed dynamic simulation model describing the energy consumption of a greenhouse and the performance of its heating system as a function of outside weather conditions and horticultural requests of growers in the Netherlands.
The application of digital image processing in grading of begonia pot plants
Authors: Dijkstra J. , Pompe J.C.A.M. , Meuleman J. , Speelman L.
Published: June 2020

Digital image processing (DIP) is a potential tool for measuring and classifying pot plants in various growth stages in an automatic, objective and consistent way, with a high capacity and low labour input. In this study, features of begonia cuttings which could be relevant for grading were analysed. Images of unrooted and rooted Begonia elatior [B. hiemalis] cuttings were acquired and analysed with DIP. The various parts of the cuttings were identified and measured using knowledge based image processing. These measurements were shown to be consistent and to be well correlated with the features measured in conventional ways. Experts graded the rooted cuttings into 3 classes: small, medium and large. The effect of grading unrooted cuttings and growing them with similar-sized cuttings was still apparent 4 weeks later - the rooted cuttings in graded units were more uniform than those in random units. Two models were constructed to determine the quality of the rooted cuttings based on DIP measurements, one based on multiple linear regression and one based on a neural network. Both were able to grade at least 75% of the rooted cuttings in the same class as the expert. The neural network-based model performed slightly (5%) better, especially for the classification of small and large plants. The lack of objective quality criteria is a major obstacle for the development of grading models for pot plants.
Effect of repetitive impacts on subcutaneous tissue discolouration in potato tubers
Authors: Molema G.J. , Verwijs B.R. , Van Den Berg J.V. , Breteler H.
Published: June 2020

The relation between one or more impacts at one tuber site and the resulting volume and depth of discoloured tissue were investigated. Tubers were impacted at the desired rate by a computer-controlled pendulum. The tubers were from plants grown at 2 potassium levels (i.e. susceptibilities to tissue discoloration - high and low) and stored for 3, 5 or 7 months. Splitting of the impact energy into various (up to 9) doses reduced the volume of discoloured tissue by up to 64%. The depth of tissue damage was less affected (33% reduction) by splitting the impact energy than was the volume. The volume and depth of discoloured tissue increased with the number of 0.3 J impacts. A decreasing and an increasing order of impact energy caused the same tissue damage. Despite experimental simplification and standardization, the observed effects of the energy and frequency of impacts on the degree of subcutaneous tissue discoloration yielded relevant suggestions for practical potato handling.
Evaluation of quality characteristics in official trials with silage maize varieties in Belgium
Authors: Van Waes J. , Carlier L. , Van Waes C. , Van Bockstaele E.
Published: June 2020

Digestibility of >550 silage maize cultivars in official Belgian trials was analysed using the near infrared reflectance spectroscopy (NIRS) method based on an in vitro method with cellulase. Comparison of results with this method with those from a NIRS method based on an in vitro method with rumen fluid of fistulated sheep showed a highly significant correlation. However, after each new harvest a certain percentage of the samples should be analysed in a classical way to validate the calibration equation against a sample set with new genetic material. In contrast to previously reported studies, there was no clear tendency for NIRS to overestimate the digestibility of early cultivars or underestimate that of late cultivars. The results of NIRS starch analyses showed a significant correlation between earliness and starch content. Since digestibility and starch are not well correlated, the incorporation of starch as a new criterion is valuable and it can give additional information about the net energy content of silage maize cultivars.
Oil palm: domestication achieved?
Authors: Gerritsma W. , Wessel M.
Published: June 2020

The natural habitat of the oil palm comprises very wet and relatively dry niches in the lowland rain forest in West and Central Africa. The domestication of the oil palm started with the extraction of fruits from wild forest resources. When forests were cleared for shifting cultivation, oil palms were not felled and in the subsequent regeneration period they obtained a favourable position resulting in semi-wild palm groves. Thinning of groves gave rise to semi-permanent or permanent intercropping systems of palms and food crops. After the transfer of oil palm to SE Asia in the 19th century, a mono-crop oil palm evolved. Its success was based on a favourable climate, breeding, improved cultivation and processing practices and the absence of major pests and diseases. The high-yielding production systems are sustainable at high input levels and pollution can be kept within acceptable limits. Oil yields and production costs compare favourably to those from other oil crops. The domestication of oil palm for oil yield so far can be considered as a success story. Physiological studies indicate that there is still considerable scope for further increase in yield. The adaptation of oil palm to new environments will continue and produce diversification puts new demands on domestication. This paper reviews the different stages in the domestication process especially adaptation to plantation agriculture, the simultaneous genetic improvement, and the prospects of reaching full yield potential in different environments.
Modelling the residual N effect of slurry applied to maize land on dairy farms in the Netherlands
Authors: Schroder J.J. , Van Keulen H.
Published: June 2020

The decomposition rate of soil organic N was estimated from data of a long-term field experiment and used in a simulation model. Subsequently, the model was used to estimate the effects of Dutch manuring practice on maize land. The time course of the N mineralization rate was estimated for three scenarios: (i) following actual manure applications which have declined with time (scenario A); (ii) assuming continuous applications in accordance with the present and anticipated legislation (scenario P); (iii) assuming annual applications of 200 kg mineral fertilizer N/ha only (scenario M). The actual mineralization rate (following scenario A) in 1995 was estimated at 23-31 kg N/ha higher than when manure had been applied at moderate rates (following scenario P). Corresponding estimates for the year 2005 were 18-19 kg N/ha per year. The calculations suggest that it may be difficult to maintain soil organic N pools with mineral fertilizer only. Consequently, the mineralization rate following scenario M decreased with time as did the yields of silage maize. The magnitude of the residual effect indicates that there is need and scope for fine tuning of N fertilizer recommendations. The simple model used seems suitable for exploring the magnitude of the residual effect of manures.
Use of a scoring technique to assess the effect of field variability on yield of pearl millet grown on three Alfisols in Niger
Authors: Gandah M. , Bouma J. , Brouwer J. , Van Duivenbooden N.
Published: June 2020

Within-field spatial variability of pearl millet (Pennisetum glaucum) was studied at three different sites on Alfisols in Niger. Grain yields in fields on a North-South gradient were 8-383, 2-1343, 7-815 kg/ha, with a coefficient of variation of 61, 55, and 53%, respectively. Variability was explained by soil chemical factors for only 5 to 28%. A simple method of scoring millet growth for individual hills a few weeks before harvest was tested by measuring yield variability in a field as an alternative for expensive soil chemical analyses. The median score value explained 25, 67, and 8% of the variability for the same gradient, respectively. As a verification step, map pattern comparisons of millet grain and straw yields with median score values gave low taxonomic distances (0.01-1.7), indicating significant similarities in variability. The hill scoring method is an appropriate tool to identify millet grain and straw yield variability.
Integrating farmers' knowledge, attitude and practice in the development of sustainable Striga control interventions in southern Mali
Authors: Debrah S.K. , Defoer T. , Bengaly M.
Published: June 2020

Technologies for Striga control have not been widely adopted because of the mismatch between technologies and farmers' socio-economic conditions. This study used a participatory rural appraisal technique at the village, household and plot levels to diagnose the extent of the Striga problem in two agro-ecological zones in southern Mali. This has resulted in an understanding of farmers' attitudes and constraints to Striga control, and opportunities for the development of sustainable technologies suitable for a wide range of farming conditions. Results show that the degree of Striga infestation, levels of farmer knowledge and control practices vary substantially across village territories and fields, and that the severity of the infestation is clearly linked with soil fertility condition and farming practices. It was concluded that in general, the Striga control interventions that would most likely appeal to farmers would be those that will simultaneously improve soil fertility and suppress the development of Striga.
Termites and agricultural production in the Sahel: from enemy to friend?
Authors: Mando A. , Van Rheenen T.
Published: June 2020

Termites are an important component of agroecosystems, particularly in developing countries where they are an alternative to high priced inputs. Given the major problems in the Sahel of soil crusting and nutrient depletion, this paper shows that termites associated with proper management techniques can play a vital role. Termites contribute to the rehabilitation of crusted soils, i.e. by opening up voids on the sealed surface leading to improved infiltration capacity, and consequently improved water availability. It is recommended, however, that participatory on-farm research should be carried out on how to increase the contribution of termites towards soil management and to reduce the harmful effects.
The importance of animal traction and defoliation of pearl millet in a Sahelian agro-pastoral system in the Seno-Bankass, Mali
Authors: Tielkes E. , Cisse B. , Yossi I.
Published: June 2020

In the pearl millet (Pennisetum glaucum) based agro-pastoral systems in the south-eastern part of Mali weeding is either done by hand or using animal (donkeys, cattle) traction. To feed the draught animals farmers are harvesting fodder. One of these comprise stripped millet leaves. To evaluate these millet production systems including draught animals, and defoliation, qualitative interviews were conducted in eight villages in the Seno-Bankass area (1991) and day-to-day activities were monitored in one village (1992). The existing defoliation practice was compared with results obtained from on-station defoliation trials. These showed that the farmers practice of leaving the upper leaves from stalks with grains in milk stage, and defoliating only plants on manured fields, results in an optimal balance between grain yield reduction and fodder quality of the harvested biomass. It is concluded that the use of animal traction for weeding increases efficiency on manured fields only. Furthermore, a reduction in millet grain yield through partial defoliation can be compensated in at least average rainfall years by the benefits of the obtained good quality fodder by either selling the fodder or feeding it to selected animals.
Application of zai and rock bunds in the northwest region of Burkina Faso: study of its impact on household level by using a stochastic linear programming model
Authors: Maatman A. , Sawadogo H. , Schweigman C. , Ouedraogo A.
Published: June 2020

Agricultural production in the NW Burkina Faso is seriously endangered by soil erosion and an overall decline in soil fertility. In the past 15 years various anti-erosion methods have been adopted in this region with some success. The widespread promotion of rock bunds is an important example. Land conservation methods alone without increased efforts to maintain (or to increase) soil fertility levels does not suffice in the long run. The potential impact of a combination of rock bunds and zai, a local technology to improve water infiltration and efficiency of manure application, was investigated. The analysis is carried out at farm level with a stochastic linear programming model. It includes sequential decision making to cope with rainfall risks. The study shows the important potential of rock bunds and application of zai, and limitations due to labour and manure constraints. The techniques are largely applied on common fields. Changes in labour organization and use of manure have to be introduced before women may profit from these techniques on their individual fields. The results show that the impact on farm-level food security is more limited than is sometimes supposed on the basis of a simple extrapolation of plot-level results.
Nitrogen recovery and dry matter production of silage maize (Zea mays L.) as affected by subsurface band application of mineral nitrogen fertilizer
Authors: Van Dijk W. , Brouwer G.
Published: June 2020

In 1991-94 the effects of subsurface band application of mineral N fertilizer on the N recovery and dry matter (DM) yield of silage maize were studied in nine field experiments on sandy and clay soils in the Netherlands. In the early crop stages and especially in the clay soil experiments, banded N had a significant negative effect on the N uptake and DM yield compared to broadcast N, possibly due to salt damage. At final harvest, however, banding significantly increased the N uptake and DM yield in most of the experiments. The apparent N recovery increased by circa 20-25% (absolute). The positive effects indicated that band application improved the efficiency of the N fertilizer. It could be calculated that banding allowed a reduction in the N rate of 20-30% without significant effects on the N uptake and DM yield of the silage maize. Benefits of banding were positively (P
Fine roots of pedunculate oak (Quercus robur L.) in the Netherlands seven years after liming
Authors: Bakker M.R.
Published: June 2020

A liming experiment was initiated in 1988 in which an equivalent dose of 1.6 t/ha CaO was applied to a young and an old stand of Q. robur (planted in 1980 and 19953, respectively), growing on acidic sandy soils in southeast Netherlands. Seven years after the liming treatments, the effects on soil and roots were intensively studied. Prior to liming, the young stand suffered from a deficiency in N, P, Mg, Zn and Fe, whereas the older stand had a deficiency in Mg and Zn. The results indicated that, 7 years after the application of lime, cation availability and soil pH were increased. Liming increased specific root length and number of apices with mycorrhizas per cm of fine root length in most of the profile in the young stand, but stimulated fine root biomass and length only in the top soil of the old stand. The leaf nutrient status was improved the most in the youngest stand, where lime had greatest impact on the area of soil exploited by the root and mycorrhizas system.
Ammonia emission from dairy cow buildings: a review of measurement techniques, influencing factors and possibilities for reduction
Authors: Monteny G.J. , Erisman J.W.
Published: June 2020

This study aimed to make an analytical inventory of ammonia emission data of dairy housing systems and to assess possibilities for reduction, based upon the analysis of processes and factors involved in the production and volatilization of ammonia. Mass balance methods for the determination of air exchange rates for naturally ventilated dairy cow buildings that are based upon natural or introduced tracers may have good potential for application in emission studies. Differences occur in housing systems, floor types and manure collection and manure storage systems. Ammonia emission levels for cubicle (loose) houses are higher (20-45 g/day/cow) than for tie stalls (5-27 g/day/cow), and variation in emissions by housing type is large. Integration of knowledge of ammonia emission related processes and factors will support a more detailed analysis of differences and variation, and will allow optimization of possibilities for emission reduction. Substantial emission reductions of up to 50% for cubicle houses with slatted floors can be achieved through each of the following measures: flushing of floors with water or diluted formaldehyde, optimised feeding strategies, and slurry acidification. Highest reductions are possible through V-shaped, solid floors (52%) as a single measure, or in combination with flushing with water (65%) or diluted formaldehyde (80%). Providing that drawbacks are solved, nationwide introduction of one or more these measures will lead to a maximal reduction of the NH3 emission in the Netherlands to 18 kt per year.
The influence of the accessibility of concentrate on the behaviour of cows milked in an automatic milking system
Authors: Ketelaar-De Lauwere C.C. , Ipema A.H. , Metz J.H.M. , Noordhuizen J.P.T.M. , Schouten W.G.P.
Published: June 2020

The advantages and disadvantages are discussed of forcing cows to visit the automatic milking parlour regularly by making it the only way for them to obtain supplementary feeds, vs. allowing cows to choose the frequency of their visits to the parlour. An alternative routing method was studied, in which the cows could move freely between the feeding and lying areas, but were stimulated to visit the automatic parlour by making it the only way of accessing the concentrate feeder. Two experiments were conducted, each with 2 treatments and 20 Holstein Friesian dairy cows. In the first treatment of experiment 1, the concentrate feeder was accessible only via the automatic parlour, and in the second treatment of experiment 1, concentrates were freely accessible. In both cases a new portion of concentrate became available once every 2 h. In experiment 2, the concentrate feeder was available only via the automatic parlour. A new portion of concentrate became available every 2 h during the first treatment of this experiment and every 4 h during the second treatment. Results showed that allocation of concentrate in a feeder which can only be reached via the automatic parlour is a good stimulus to attract cows to the parlour on a regular basis, because the milking frequency of these groups increased, and the waiting time in front of the concentrate feeder and the number of aggressive interactions in this area decreased. It is concluded that it is better to make concentrate available once every 4 h than once every 2 h, because this increases concentrate intake and rest in the barn.
Analytical growth equations and their Genstat 5 equivalents
Authors: Heinen M.
Published: June 2020

Two ways of representing some of the existing growth functions, (the exponential, the monomolecular or Mitscherlich, the logistic or autocatalytic, the Gompertz, and the Richards equations) are compared. In the first, growth is expressed in the parameters mass at time zero W0, mass at time infinity Wf, and a measure for the relative growth rate k. In the second, different parameters are used because of robust parameter optimization (e.g., by the statistical software package Genstat). The relationships between these fitted parameters and the parameters W0, Wf and k are demonstrated. The properties of these models, such as physical meaning of the parameters, properties at the point of inflection (if it exists), and the growth rate at a limit W -> 0, are examined. The second order exponential polynomial was rewritten in such a way that use was made of a proportionality constant, equal to the relative growth rate at the point of inflection. Application of the growth models is demonstrated using data for lettuce grown in a nutrient film system. Finally, it is shown that, except for the exponential polynomial, all growth equations originate from one single equation.
Bulk density and porosity distributions in a compost pile
Authors: Van Ginkel J.T. , Raats P.A.C. , Van Haneghem I.A.
Published: June 2020

This paper mainly deals with the description of the initial distribution of bulk density and porosity at the moment a compost pile is built or rebuilt. A relationship between bulk density and vertical position in a pile is deduced from theoretical and empirical considerations. Formulae to calculate the air filled volume fraction and the true densities of the solid phase and of the organic matter are derived. The true density of dry matter is used in the computation of porosity distributions. The relationships between bulk density and height and between air-filled volume fraction and height are shown to be valid for composting material consisting of chopped wheat straw and chicken manure. The check of this validity is limited to total bulk density values ranging from 150 to 950 kg/msuperscript 3, with values of dry matter content varying between 18 and 28% (w.b.). Moreover, the gravimetric dry matter content must be constant throughout the total cross section of the pile. The error in the calculated bulk densities and air-filled volume fractions was found to be 12% at a reliability level of 95%. It was concluded that the presented equations will give reasonable results for other values of dry matter content and other kinds of chopped fibrous materials as long as the gravimetric dry matter content remains independent of height.
Efficient resource management in dairy farming on sandy soil
Authors: Aarts H.F.M. , Habekotte B. , Hilhorst G.J. , Koskamp G.J. , Van Der Schans F.C. , De Vries C.K.
Published: June 2020

Sandy soils in the Netherlands are mainly used for dairy farming. As a result of intensification of dairy farming in the recent past, valued functions of sandy regions now are threatened by high emissions of nitrogen (N) and phosphorus (P) and by increased water consumption by forage crops. Improved utilization efficiency of resources is proposed as a strategy to realise environmental targets in an economically viable way. Experimental results of the prototype system 'De Marke' indicate that an average intensive commercial farm can halve inputs of fertilizers and feeds at least, without the need to reduce milk yield/ha or to export slurry. Water consumption can be reduced by 13%, increasing groundwater 'production' by 570 msuperscript 3/ha. Nitrate concentration in the upper groundwater decreased from 200 to 50 mg/litre. Changes in soil fertility did not lead to serious agricultural problems but costs of milk production increased by 5%. However, additional costs may be compensated for if the extra groundwater is 'harvested' by water companies, because of high cost of purification of surface water and consumer preference for drinking groundwater instead of river-water. In 1999, the examined strategy of improved resource management was implemented on 12 commercial farms, representing the full range of conditions for dairy farming in the Netherlands.
The effect of the rate and method of nitrogen application on nitrogen uptake and utilization by broccoli (Brassica oleracea var. italica)
Authors: Everaarts A.P. , De Willigen P.
Published: June 2020

The effect of the rate and method of nitrogen application on nitrogen uptake and utilization by broccoli (Brassica oleracea var. italica) was studied in four field experiments. The methods of application were broadcast application vs band placement and split application. Maximum uptake of nitrogen by the crop was around 300 kg ha-1. In one experiment, band placement positively influenced nitrogen uptake. Split application did not influence nitrogen uptake. Nitrogen application resulted in a higher head dry matter production, but the efficiency of nitrogen utilization for the production of head dry matter decreased with higher amounts of nitrogen applied. Nitrogen application decreased the dry matter content of the heads. In half of the experiments, band placement of nitrogen fertilizer resulted in extra head dry matter production and lower head dry matter contents. At the optimum rates of band placed nitrogen application, the nitrogen harvest index in the experiments ranged from 27 to 30%. The amount of mineral nitrogen in the soil at harvest generally increased with increasing amounts of nitrogen applied. Band placement resulted only in one experiment in lower amounts of mineral nitrogen in the soil at harvest. The mineral nitrogen in the soil at harvest can be unevenly horizontally distributed, both with broadcast application and band placement of nitrogen fertilizer. The amount of nitrogen unaccounted for at harvest increased with increasing amounts of nitrogen applied, but was always less than the amount of nitrogen in crop residues. At the optimum rates of band placed nitrogen application, the amount of nitrogen in crop residues ranged from 120 to 155 kg ha-1. With broccoli cultivation, the nitrogen in the crop residues forms the single largest source of potential loss of nitrogen to the environment.
Overall animal welfare assessment reviewed. Part 1: Is it possible?
Authors: Bracke M.B.M. , Spruijt B.M. , Metz J.H.M.
Published: June 2020

Several authors have concluded that scientists should not attempt to perform overall animal welfare assessment (OWA). They argue that scientists have continued to fail to make progress in this area and that value judgements are inherently involved in OWA for which science cannot provide answers. We take a more positive attitude toward OWA and argue that scientists should avoid creating a self-fulfilling prophecy. OWA is necessary for making actual moral and political decisions. Science has already accumulated much relevant information about welfare and this information should be applied in decision making. The task of OWA is to assess welfare based on knowledge of the biological needs of animals. Weighting of welfare relevant factors constitutes a problem. However, when scientists cannot provide empirical data to solve weighting issues, this does not mean that rational answers cannot be found, e.g. in the form of procedural rules. OWA is conceived as a problem of multi-criteria decision making with fuzzy information. If focuses on the descriptive aspect of welfare, i.e. on what the welfare status of the animals really is without taking an ethical stance. The welfare status of animals depends on their biology and on the way animals assess their own welfare. It does not depend on how it happens to be perceived by us. Even though OWA necessarily remains a human activity, it is not arbitrary, nor does it allow of multiple 'correct' answers. OWA is a descriptive activity that can achieve more and more accuracy as science proceeds.
Overall animal welfare reviewed. Part 3: welfare assessment based on needs and supported by expert opinion
Authors: Bracke M.B.M. , Spruijt B.M. , Metz J.H.M.
Published: June 2020

Welfare concerns that matter to animals is their state of need. Satisfaction and frustration of needs are associated with emotional states, the subjective experience of which directly determines the welfare status of an animal. Because emotional states are difficult to assess, overall welfare assessment (OWA) is best approached as an assessment of needs. For actual OWA, a list of needs must be formulated. Different authors have formulated different lists. From these lists a concept need-list was constructed. For validation the needs-based approach for OWA was discussed in interviews with experts (n=21) in the field of ethology and other welfare related sciences. These experts generally used mental terminology to define welfare, but when asked to classify their definition of welfare, many preferred a definition in terms of measurable parameters or a combination of both mental terms (feelings) and measurables. Most experts believed that welfare can be assessed objectively and that the problem of OWA is indeed best approached through an assessment of needs. Experts differ as to the exact composition of the list of needs. A list of needs is formulated which we intend to use for OWA in the case of sows.
Physical properties of cervical mucus in relation to bovine fertility.
Authors: Scott Blair G.W.
Published: June 2020

A review of the literature has confirmed the hypothesis that the changes which occur in the physical properties of the cervical mucus during the oestrous cycle and early pregnancy in the cow (as revealed by rheological and ultra-violet absorption studies) are closely related to hormonal levels, particularly the levels of oestrogen and progesterone. Although such a relationship is useful in the diagnosis of oestrus and of pregnancy, it can lead to false diagnoses where hormonal conditions are abnormal. In a recent experiment pregnancy would have been wrongly diagnosed in about 5% of the cows if no allowance had been made for their non-pregnant hormonal condition. It is suggested that studies of the physical and chemical properties of the cervical secretions in relation to hormonal levels may throw light on those cases of bovine subfertility which are known to be related to hormonal imbalance. A. P. G. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A difference-method for predicting night-frost.
Authors: Sestoft I.
Published: June 2020

A formula is presented whereby the minimum temperature for the coming night can be estimated. It has been tested with fairly good results in Denmark.-Danske met. Inst., Copenhagen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Soil consistency as a factor determining the soil structure of clay soils.
Authors: Boekel P. , Peerlkamp P.L.
Published: June 2020

The deterioration of the aggregation of several Dutch clay soils during the period after plowing seems to be caused by a plastic transformation of the soil aggregates under the influence of mechanical forces, even very weak ones such as the weight of the top soil. It depends on the consistency and moisture characteristics of the soil, the drainage of the top soil, etc. The location of the point pF 1.9 ("field capacity") on the moisture percentage scale with regard to the upper plastic limit, the sticky point and the lower plastic limit appears to be a better index for the structure of clay soils than figures obtained from a wet-sieving analysis, and some results of experiments on the effects of lime, gypsum and soil conditioners on soil structure illustrate this.-From authors' summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On the evaluation of the thermal (or eddy) diffusivity from the diurnal temperature wave.
Authors: De Vries D.A.
Published: June 2020

The theory of the evaluation of the thermal (or eddy) diffusivity a from determinations of the amptitude and phase of the diurnal temperature wave in a non-homogeneous medium is briefly discussed. It is shown by an example pertaining to the lower air layers that the often-used procedure of applying the theory for a homogeneous medium to successive layers of a non-homogeneous medium may lead to values of a that are in error by more than a factor ten. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Justification of the cost of research on breeding and on varieties of crop plants. [French]
Authors: De Haan H.
Published: June 2020

The work of the University of Agriculture, Wageningen, Netherlands, in carrying out research on crop plants, breeding new varieties and advising farmers on the best varieties to grow is reviewed briefly. Present work is concentrated on breeding for resistance to Phytophthora infestans in potatoes and for resistance to various diseases in flax and the bitter lupin. It is concluded that expenditure on research in the Netherlands is fully justified by the increased yields obtained from improved varieties of crop plants. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of the mineral nutrition of potato plants on the biochemistry and the physiology of the tubers.
Authors: Mulder E.G.
Published: June 2020

The effects of N, P and K nutrition on the amino-acid composition of tubers was studied. The composition of the soluble non-protein N was much affected by the mineral nutrition, whereas the protein composition remained fixed. Stem-end blackening of tubers and bluish-green coloration after boiling were found to be due to inadequate K-supply, which was correlated with a high tyrosine content, susceptibility to injury and increased respiration rate. Change in concentration of N, P, Mg or Gu had much less effect on this rate. Bruising stimulated the respiration of healthy cells. -J.F.C. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of alteration of temperature upon the cationic composition in perennial ryegrass.
Authors: Dijkshoorn W. , T Hart M.L.
Published: June 2020

Pot experiments were carried out with perennial ryegrass during the spring of 1955 and 1956. The mineral composition of the grass grown for varying lengths of time over a temperature range of 10-20 degrees G. was followed. It was found that a transition from cold to warm usually led to an increase in the cation content of the plants, the K-content undergoing the greatest change. Results were in agreement with the conclusions drawn by Kemp and 't Hart. [See Abs. 1028] from results of field experiments.-M.P. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The pollination of tomatoes.
Authors: Verkerk K.
Published: June 2020

Studies were carried out on the effect of pollination on fruit set, normal fruit growth, earliness of yield and size of fruit. A high positive correlation was found between the number of seeds per fruit and the fruit weight. When flowers were pollinated with a mixture of inert powder and pollen, fruits were larger and earlier as the proportion of pollen in the mixture was increased. Heavier pollination resulted in larger, earlier fruits with more seeds. A negative correlation was found between fruit weight per seed and number of seeds on the plant when seed growth began. Good pollination was obtained by using an electric vibrator, resulting in earlier ripening and better quality fruits. Auxin sprays increased the number of large fruits containing few seeds. Under poor light conditions extra lighting improved the production of normal flowers.-Lab. Tuinbouwpl., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Results of a ground water level experimental field with arable crops on clay soil.
Authors: Van Hoorn J.W.
Published: June 2020

On a heavy clay soil with large moisture-retaining capacity, aeration and root development are reduced by a shallow water table, and therefore plant nutrients, in particular N, are in short supply. The effect of the depth of the water table on yield is mainly determined by the different effects of N on crops and by the level of N dressings. The depression in yield caused by a shallow water table can be compensated for by increasing the N dressing. When the water table is shallow there is a decrease in the percentage of large pores and permeability. If the groundwater level is kept at 40 cm throughout the year, the structure of the surface layer deteriorates and tillage becomes difficult. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On the genesis and classification of soils derived from andesitic tuffs under humid tropical conditions.
Authors: Van Schuylenborgh J.
Published: June 2020

The classification distinguishes humic grey-brown podzolic soils at 1, 600-1, 300 m, grey-brown podzolic soils at 1, 300-1, 000 m, acid brown forest soils at 1, 000-600 m, podzolic brown latosols at 600-300 m and latosolic soils at 300 m to sea level. Morphological and chemical data are discussed with reference to destruction of organic matter, diffusion of the CO2 produced and type of clay mineral present. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of potash fertilization on dry matter production of permanent pasture throughout the season.
Authors: De Vries P. , De Wit C.T.
Published: June 2020

On sandy soil of low K availability, permanent pasture cut 5 times during the year received up to 200 kg/ha K2O as 40% KC1 before or after one of the cuts. The effect of K fertilizing in autumn depended largely on K withdrawal with previous cuts. K uptake was not determined by growth. Except for the first cut K uptake was greater than that needed for reasonable growth. No effect of temperature on K response was found. The best treatment was 200 kg/ha K2O applied in spring. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On the fertilization of sugar cane.
Authors: Van Schuylenborgh J. , Sarjadi R.M.
Published: June 2020

Soil and leaf analyses in Indonesia have shown that the sugar cane crop removes an average of 100 kg. N, 100 kg. PO4, 350 kg. K, 30 kg. Ca and 20 kg. Mg per ha. per annum from the soil. Results from fertilizer trials have emphasized the relationship between sucrose percentage and N, P and K contents. When the leaf N content was sufficiently high, the sucrose percentage and the K/PO4 ratio in the leaf were related, with the optimum value for the ratio appearing to lie between 5.5 and 6.5. With adequate N and PO4 contents, there was a direct relationship between the sucrose percentage and the leaf K content. The sucrose percentage was also related to the K/PO4+N, K/PO4 and K/N ratios. When the leaf K content was adequate, the sucrose percentage and the PO4/N ratio in the leaf were related, with an optimum value of 0.215. Nitrogen had the greatest effect on cane production, but tended to reduce sugar yields. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of gibberellic acid on sprouting of potatoes.
Authors: Doorenbos J.
Published: June 2020

Eyes of dormant tubers of 9 potato varieties were treated with GA. Only in the variety Rode Star was the period of dormancy appreciably reduced by treatment. The rate of sprout growth was hastened by GA in all varieties. GA applied to the lateral eyes of Gineke and Eigenheimer tubers caused more rapid sprouting of the apical eye. More lateral sprouts were produced by tubers treated with GA than by untreated controls.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The economic evaluation of land development projects.
Authors: Groenveld D.
Published: June 2020

Traditional methods to evaluate agricultural development projects cannot be used in underdeveloped countries, as net outputs are difficult to calculate. In these cases the method to be used is the calculation of the capital/gross output ration. R.V.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Interaction of vernalization, photoperiod and light intensity in floral initiation of endive.
Authors: Harrington J.F. , Verkerk K. , Doorenbos J.
Published: June 2020

Vernalization of germinating endive seed or of young endive plants hastened floral initiation, but at the expense of vegetative growth. High temperatures after vernalization promoted bolting. Long days hastened bolting in both vernalized and non-vernalized plants, again at the expense of vegetative growth. A limited period of short days immediately after sowing also promoted flowering, and it is suggested that such short-day treatment may act as a partial substitute for low temperature. High light intensity had a supplementary effect in promoting bolting but, in contrast to vernalization and long days, caused more rapid vegetative growth than low light intensity.-Lab. TuinbPl., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A study of shifting cultivation.
Authors: De Haan J.H.
Published: June 2020

A programme for a survey of shifting cultivation in tropical regions is proposed.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The rate of uptake of chloride, phosphate and sulphate in perennial ryegrass.
Authors: Dijkshoorn W.
Published: June 2020

Pot- and solution-culture experiments indicated that the rate of uptake decreases in the order: Cl >P >S. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of daylength, gibberellin, seed-vernalization and their interaction on spinach.
Authors: Verkerk K. , Yadlin E.V.
Published: June 2020

Two varieties of spinach bolted quickly in long days, but neither gibberellin nor vernalization treatment had much effect. In short days bolting was delayed, and the gibberellin and vernalization treatments had a more pronounced effect. Growth was stimulated in all experiments by gibberellin. The response to vernalization increased as conditions favouring growth improved. The effect of each treatment was diminished when it was combined with either of the other treatments.-Lab. Tuinbouwpl., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Acute zinc deficiency observed in cacao on certain soil types in Netherlands New Guinea.
Authors: Schroo H.
Published: June 2020

Leaf symptoms in young cacao were observed on two different soil types. On one, a very old, much leached, infertile, quartzitic silty loam, low Zn content was responsible; heavy drought which crippled the root systems made the hidden shortage acute. On the other soil, low Zn content was greatly accentuated by adverse soil conditions which impaired the uptake of Zn by the roots; high pH, excessive PO4, poor water-retaining capacity in dry weather and poor aeration in the wet season probably induced deficiency. Deficient trees recovered in 7 months with Zn sprays. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nematodes in relation to plant growth. I. The nematode distribution pattern of typical farms and nurseries.
Authors: Kleyburg P. , Oostenbrink M.
Published: June 2020

The distribution of nematodes in fields on ten farms was influenced by soil type, cropping and manuring. The total number of active nematodes per 100 ml. of soil ranged from 1, 005 to 16, 105 with an average of 3, 004. Known and suspected phytophagous nematodes ranged from 120 to 3, 510 per 100 ml. of soil with an average of 909. The prevalent phytophagous genera were Heterodera, Paratylenchus, Pratylenchus, Rotylenchus, Tylenchorhynchus and Meloidogyne. The authors suggest that such surveys are a starting point for further research into several obscure crop husbandry problems. H. R. Wallace. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Leaching of saline soils in Iraq.
Authors: Hulsbos W.C. , Boumans J.H.
Published: June 2020

Salinity data from a few project areas on the Lower Mesopotamian Plain are summarized. An example of the degree of salt movement in the top soil and of overall discharge of salt from an area is cited; it is concluded that even with intensive drainage and leaching the subsoil and drain water will remain salty for at least 15-20 years. A leaching curve for one site is constructed; it is compared with others and the limits of its use are explained; with the curve and knowledge of the salinity before leaching the amount of water needed to produce a particular salinity level can be estimated; to assist such calculations a leaching graph has been constructed to show the drain-water depth per unit depth of soil as a function of the salinity before leaching and of three different levels after leaching. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of the photoperiod on the oil percentage of sesame seeds (Sesamum indicum L.).
Authors: Kluijver H. , Smilde K.W.
Published: June 2020

Sesame of the U.S. variety Early Russian was grown in a glasshouse in 1959 at maximum temperatures of 31-35 degrees C, minimum temperatures of 15-20 degrees C, and (a) 6, (b) 8, (c) 10, (d) 13 hr daylight, with (a) 0, 4, 7, 14, (b) 0, 2, 8, 12, (c) 0, 3, 6, 10 hr fluorescent supplementary light at 2000 ergs/sec/sq.cm. The percentage of oil in the seeds increased with increasing photoperiods in excess of 10 hr. Within photoperiods, those plants receiving the highest percentage of daylight produced seed containing most oil.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)