bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of spatial variability of nitrogen supply on environmentally acceptable nitrogen application rates to arable crops.
Authors: Noordwijk M. van , Wadman W.P.
Published: June 2020

A model based on a form-quadrant representation of N fertilizer experiments is presented. Calculations showed that spatial variability of mineral N in soil led to higher 'economic optimum' fertilizer rates and rates of Environmentally Acceptable Production (EAP) decreased. Without spatial variability a positive difference of 13 kg/ha was found between the N fertilizer rates for EAP and Maximum Economic Yield (MEY) even when the strictest environmental standard was applied (soil mineral N content at harvest not exceeding 34 kg/ha). At standard levels of variability there was a negative difference of 16 kg/ha, and at doubled variability the difference was 156 kg/ha. An N residue rate of 45 kg/ha at harvest could be met at standard varibility but not at doubled variability. The model showed that higher degrees of 'luxury consumption' and improved synchronization of N mineralization and crop demand had a positive effect on the difference between EAP and MEY. It was concluded that the degree of spatial variability in N supply must be taken into account for environmental and production targets. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Ultrastructural investigations of enzyme treated cell wall material from industrial by-products.
Authors: Engels F.M. , Schalk N.A.
Published: June 2020

Ultrastructural investigations of glycanase treatments of cell wall material from industrial by-products was carried out with the enzyme-thiocarbohydrazide-silver protein technique (ETAg). Driselase, gamanase and an experimental enzyme preparation with a broad spectra of hemicellulase, cellulase and pectolytic activities were used. Carbohydrate hydrolysis was found in cell walls and cell contents in 1-2 cell layers at the surface of 0.2-mm plant particles. Enzyme activity was detected to some extent inside unlignified and lignified cell walls. The absence of any reaction in some sublayers of the cell wall was indicative for the absence of polysaccharide substrate or a very tied interaction of cell wall components preventing enzymic activity or the absence of typical enzymes in crude preparations. It was concluded that the ETAg-technique can be useful to provide information about structural limitations of poorly degradable plant materials. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Dairy farming systems based on efficient nutrient management.
Authors: Aarts H.F.M. , Biewing E.E. , Keulen H. van
Published: June 2020

In Dutch dairy farming, dramatic nutrient losses occur, causing serious environmental problems, and representing an economic and energy waste. So farming systems have to be developed based on efficient nutrient management. A dairy farm is characterized as a system with soils and crops, forage, cattle, and manure as main components. Simple models of nutrient flows in and between components of the farming system were used to design a prototype system for a new experimental farm on sandy soil, which has to meet strict environmental demands. Experimental results of this farm will be used to improve the models and the models will be used again to optimize the prototype system. Initial results of modelling suggest that nutrient losses can be reduced considerably by more accurate management, and introduction of relatively cheap and simple measures. However, more radical and expensive modifications of the farming system are necessary to meet further standards of the Dutch government for max. allowable emissions. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Response of a Scots pine (Pinus sylvestris) stand to application of phosphorus, potassium, magnesium and lime. 1. Soil data
Authors: Arnold G. , Van Diest A.
Published: June 2020

In 1985-1988, a 25-yr-old Scots pine forest in Netherlands was limed and fertilized with P, K and Mg in a 24 factorial design and in an experiment with 5 liming levels, in order to alleviate potential nutrient deficiencies as a result of high N depositions (ca. 40 kg ha-1 yr-1). In this paper, effects of fertilization and liming on nutrients in forest floor and mineral soil are discussed as a basis for explanation of foliar nutrient concentrations and tree performance. Of all treatments, liming showed the widest array of effects, especially in forest floor: raised pH and lowered extractable Al in forest floor, and after 4 yr those in 0-50 cm mineral soil. These effects, except for that on forest floor pH, were stronger with increasing lime dosages. Liming showed transient effects on amounts of soil inorganic N (Ni). Until 1989, Ni in forest floor was lowered and that in mineral soil was raised by liming. This could be attributed to the formation of NO3, which is more mobile than NH4. Plots limed with 3 t lime/ha appeared to have higher Ni concentrations in the whole sampled profile than those limed with >3 t/ha or unlimed plots, the reason for which is unclear. Liming removed extractable K and Mg from forest floor probably by exchange against Ca. Residence time of added P and possibly Mg in forest floor was increased by liming, probably by solubility of added fertilizers. Added K was poorly retained in forest floor and probably quickly leached to soil layers deeper than 50 cm.
Partitioning of dietary nitrogen between body components and waste in young growing pigs
Authors: Bikker P. , Verstegen M.W.A. , Tamminga S.
Published: June 2020

In experiment 1, 90 female pigs were fed, from 20 to 45 kg, at two energy intake levels (2x and 3x maintenance requirement) and 15 protein intakes ranging from 127 to 350 g/day. Protein deposition increased linearly with increasing protein intake until a plateau in deposition was reached at 106 and 126 g/day at the low and high energy level, respectively. Marginal efficiency of utilization of ileal digestible lysine was 0.74 for the two energy levels. In a second experiment, 24 female pigs were fed a protein-adequate diet at six levels of energy intake ranging from 1.7x maintenance to ad libitum. Protein deposition increased from 70 to 172 g/day, with increasing feed intake. The proportion of body protein deposited as lean tissue decreased from 0.62 to 0.55 with increasing feed intake. Consequences of these results for a more sustainable animal production are discussed.
Wind reduction downwind from a savanna woodland edge
Authors: Kainkwa R.M.R. , Stigter C.J.
Published: June 2020

A study was made in 1987-89 of the wind protection provided by a sparse tree canopy in a savanna woodland (mainly Acacia tortilis) edge in N. Tanzania. Wind speeds were measured at two heights (1.0 and 2.5 m) along transects perpendicular to the prevailing wind; tree density ranged from 60 to 150 stems/ha. A simple model was formulated for average wind reduction within such canopies. Average wind speeds decreased with increasing distance from the woodland edge, until they become almost constant (saturation reduction). Airflow around single trees was studied for more understanding of these results. It is suggested that preservation or regeneration of trees should be encouraged for wind protection in planning and developing crop land.
Composting of mushroom substrate in a fermentation tunnel: compost parameters and a mathematical model
Authors: Van Lier J.J.C. , Van Ginkel J.T. , Straatsma G. , Gerrits J.P.G. , Van Griensven L.J.L.D.
Published: June 2020

Phase II of composting of mushroom substrate was studied in bulk fermentation tunnels. Compost data are given on heat production, settling and mass reduction, porosity and thermal conductivity. Mass and moisture determinations at the end of the process indicated slightly positive gradients in the direction of the air stream. The highest rate of degradation occurred during the first 2 days. A mathematical model of mass and heat transfers was devised. Differential equations were solved with time-dependent analysis using a Continuous Simulation and Modelling Program (CSMP). In the calculations, the substrate was divided into theoretical layers of equal thickness but of different density and porosity. The model predicts the time-course of the process taking into account the moisture content and the filling height of the compost, and the amounts of supplied fresh air and recirculated air. The calculated data include the oxygen demand, the water and dry matter losses, the temperatures in the various layers, and the loss of conductive heat through the walls of the containers in the tunnel. Calculated data corresponded with actual process data. Temp. were correct within 3 degrees C and weight losses within 5%.
Using sustainability indicators in agricultural land use analysis: an example from Costa Rica
Authors: Jansen D.M. , Stoorvogel J.J. , Schipper R.A.
Published: June 2020

A methodology to analyse land use is applied to the Neguev settlement in the Atlantic Zone of Costa Rica. The methodology comprises a linear programming model, a geographical information system, and a customized data management tool. While options for land use are described at the field level, the methodology allows for analysis of land use at the field, the farm and the regional level. The various steps involved in making the sustainability concept operational are described. Selection and quantification of the sustainability indicators require some assumptions, affecting the period for which the analysis can assumed to be valid. The possibility of using nutrient balances and biocide indices as quantitative indicators of sustainability of agricultural land use systems is argued and demonstrated for the Neguev settlement. Some limitations and advantages of the methodology are discussed.
Crop modelling and remote sensing for yield prediction
Authors: Bouman B.A.M.
Published: June 2020

Methods for the application of crop growth models, remote sensing and their integrative use for yield forecasting and prediction are presented. First, the general principles of crop growth models are explained. When crop simulation models are used on regional scales, uncertainty and spatial variation in model parameters can result in broad bands of simulated yield. Remote sensing can be used to reduce some of this uncertainty. With optical remote sensing, standard relations between the Weighted Difference Vegetation Index and fraction ground cover and LAI were established for a number of crops. The radar backscatter of agricultural crops was found to be largely affected by canopy structure, and, for most crops, no consistent relationships with crop growth indicators were established. Two approaches are described to integrate remote sensing data with crop growth models. In the first one, measures of light interception (ground cover, LAI) estimated from optical remote sensing are used as forcing function in the models. In the second method, crop growth models are extended with remote sensing sub-models to simulate time-series of optical and radar remote sensing signals. These simulated signals are compared to measured signals, and the crop growth model is re-calibrated to match simulated with measured remote sensing data. The developed methods resulted in increased accuracy in the simulation of crop growth and yield of wheat and sugar beet in a number of case-studies.
Root density and root biomass in pure and mixed forest stands of Douglas-fir and beech
Authors: Hendriks C.M.A. , Bianchi F.J.J.A.
Published: June 2020

Below-ground interactions possibly play an important role in the success of mixed forests. Therefore, root density, root length, root biomass and rooting pattern were surveyed in representative pure and mixed stands of Douglas fir (Pseudotsuga menziesii) and beech (Fagus sylvatica) in the Veluwe area of central Netherlands. Each type of stand was represented by stands approximately 40 and 70 years old. The study was restricted to fine roots (
Components of relative growth rate and nitrogen productivity of Brussels sprouts and leeks grown at two widely differing light intensities
Authors: Van Der Werf A. , Enserink C.T. , Smit A.L. , Booij R.
Published: June 2020

Young vegetative Brussels sprout and leek plants were grown in a growth chamber at a light intensity of 550 micro mol m-2 s-1 or at only 20% of that intensity. In both light treatments, Brussels sprouts had a relative growth rate (RGR) ~90% higher than that of leeks, which was mainly explained by a higher leaf area ratio (LAR; msuperscript 2/kg plant). Only minor differences in the physiological component (net assimilation rate) were observed between the 2 species within a light treatment. The higher LAR of Brussels sprouts was mainly explained by higher specific leaf area. Brussels sprouts had a higher rate of biomass production per unit internal N (N productivity) than leeks. This was mainly explained by a higher allocation of N to leaves and a higher rate of biomass production per unit leaf N. It is suggested that the higher biomass production per unit of N taken up in Brussels sprouts than leeks as observed in the field is explained by higher N productivity. The results obtained from the growth chamber studies are discussed in relation to field experiments and data from the literature.
The spatial and temporal rooting pattern of Brussels sprouts and leeks
Authors: Smit A.L. , Booij R. , Van Der Werf A.
Published: June 2020

Rooting intensity and root distribution of Brussels sprouts and leeks were assessed in field experiments and in the Wageningen Rhizolab, a rhizotron facility built in 1990, in relation to their contrasting N uptake behaviour (Brussels sprouts usually take up N rapidly after planting, resulting in soil depletion, while leeks generally use only half of the available N). In field experiments rooting was quantified in the various layers of the profile as the volumetric root length density (RLD; cm/cmsuperscript 3) and in the Rhizolab with horizontal glass minirhizotrons as the number of roots per cmsuperscript 2 (NR). Regression of RLD and NR on thermal time (accumulated average daily temperature above ground) after planting revealed that the rooting depth of Brussels sprouts increased faster with thermal time than that of leeks (0.13 vs. 0.08 cm/degree-day, respectively in one of the Rhizolab experiments). Furthermore, leeks showed an unusual distribution of roots in the profile with maximal rooting intensity at depths of 10-20 cm. In all experiments the proliferation of roots (calculated as the increase in NR or RLD with thermal time) was slower in leeks than in Brussels sprouts, especially in the deeper layers of the soil profile. Therefore leeks can be considered as a shallow rooting crop. The field experiments generally showed the same difference between the crops, Brussels sprouts having greater root density, deeper rooting and faster root proliferation than leeks. For both crops, however, root proliferation at the deeper layers was much slower in the field than in the Rhizolab, probably due to unfavourable conditions in the subsoil caused by higher bulk densities or temporary high water tables. The consequences of different rooting patterns for N utilization are discussed.
Profitability and sustainability of peri-urban vegetable production systems in Vietnam
Authors: Jansen H.G.P. , Midmore D.J. , Binh P.H. , Valasayya S. , Tru L.C.
Published: June 2020

Results are reported of a study of the income and cropping systems of peri-urban vegetable farmers around Ho Chi Minh City, Vietnam, as well as the constraints and opportunities for vegetable production and marketing. Urban population growth is fuelling the demand for timely supplies of fresh vegetables. Much of this increased demand, particularly for the more perishable species, is satisfied through peri-urban production which has significantly increased since the change from centrally planned and collective systems to a market economy. Around Ho Chi Minh City farms are small (on average about 0.8 ha), 65% which are de facto owned and with about 60% dedicated to vegetables. Most vegetable farmers also grow rice and/or groundnuts, while cabbage is the most commonly grown vegetable crop. Vegetables provide about $1000 total revenues, or $650 added value (returns to labour, land and management) per farm per year. Added value per ha per day of vegetables is double or more than that for rice, providing employment for five or more times the number for rice, despite very high labour use. The negative correlation between farm size and cropping intensity suggests that labour is a factor limiting vegetable production enterprises. One of the major demands on labour is for irrigation. Major input costs relate to organic materials, chemical fertilizers and pesticides, although much variability exists between crops. Pests, and low and variable vegetable prices, are the most commonly cited constraints. There is a clear trough in vegetable supply during August to October following the hot-wet months, and an apparent overuse of chemical fertilizers and insecticides. Lack of communal purchase of inputs and marketing limit the success of market-oriented vegetable farms.
Developments in application of light and scanning electron microscopy techniques for cell wall degradation studies
Authors: Engels F.M.
Published: June 2020

The results of recent technological developments in light and scanning electron microscopy closely used for research on forage cell wall degradation in ruminants, are reviewed. The indigestibility of forages by rumen microorganisms used to be ascribed mainly to an overall presence of lignin in the plant material. However, early light microscopic observations without application of histochemical staining revealed that some leaf and stem tissues were degraded completely. The early use of lignin detecting dyes, such as acid phloroglucinol or safranin, in light microscopy made it possible to discriminate between lignified undegradable and unlignified degradable plant tissues. The introduction of the scanning electron microscope enabled a further discrimination between degradable and undegradable cell wall and cell wall layers in plant tissues. As a result of continuous improvement of the techniques used in microscopy, e.g. section to slide, mirror sectioning, microspectrophotometry and cryo-ultramilling, forage indigestibility can now be attributed to the specific deposition and location of cutin/suberin or lignin layers inside the plant cell wall. These structural layers form barriers hindering access of rumen microorganisms to degradable parts of the cell wall.
Effects of floor design and floor cleaning on ammonia emission from cubicle houses for dairy cows
Authors: Braam C.R. , Ketelaars J.J.M.H. , Smits M.C.J.
Published: June 2020

The traditional slatted floor was compared with 2 different solid floor systems: a non-sloped (L) and a 3% one-sided sloped floor (S), combined with a highly frequent (96 times/day) or normal (12 times/day) removal of manure by a scraper. NH3 emissions were measured continuously over 2 separate 2-week periods between 14 March and 4 July 1995. Urease activity on the solid floors was measured as the accumulation of ammoniacal N in a urea solution in contact with the floor surface, expressed as g NH3/msuperscript 2 per h. NH3 emission from L12 was similar to that from the compartment with a slatted floor but S12 decreased NH3 emission by 21%. Increasing the scraping frequency from 12 to 96 times/day decreased NH3 emission (by 5 and 26% in L96 and S96, respectively). During the last testing period, just before removal of the cows, NH3 emission from the compartment with the S12 variant was 30-35 g NH3/h (10 cows). After removal of the cows this level decreased to 3-17 g NH3/h (average: 8.7 g NH3/h). Covering the openings through which the slurry collected by the scraper system was dropped in the pit, reduced emission to 4-10 g NH3/h (average: 5.5 g NH3/h). However, covering only decreased NH3 emission when the inside temperature was higher that outside. Urease activity at\less than or =\10 and approximately 20 degrees C was 0 and 0.04 g NH3/msuperscript 2 per h, respectively. Up to a urease activity of about 2 g NH3/msuperscript 2 per h, NH3 emission increased with increasing urease activity. At higher levels of urease activity the amount of urea on the floor surface or the rate of volatilization of NH3 from a urine puddle or from the slurry pit to the inside air limited the NH3 emission. It is concluded that the slope of the floor had more impact on reducing ammonia emission than increasing the scraping frequency. Solid floors without a slope may not decrease ammonia emission compared with slatted floors.
Comparison of sampling methods for animal manure
Authors: Derikx P.J.L. , Ogink N.W.M. , Hoeksma P.
Published: June 2020

Currently available and recently developed sampling methods for slurry and solid manure were tested for bias and reproducibility in the determination of total phosphorus and nitrogen content of samples. Sampling methods were based on techniques in which samples were taken either during loading from the hose or from the transport vehicle after loading. Most methods were unbiased. New sampling methods for slurry from the hose were substantially more reproducible than existing methods. For practical reasons, the mechanization of sampling is desirable, and to minimize the influence of human activity on sample quality, the automation of sampling is advisable.
Response of silage maize to placement of cattle slurry
Authors: Schroder J.J. , Ten Holte L. , Brouwer G.
Published: June 2020

In field trials in 1993-94 on sandy soils at 2 sites in the Netherlands, cattle slurry was applied by injection into slots 25 cm apart (standard injection) or 75 cm apart (banded injection). Subsequently, maize cv. Melody or Mandigo was sown at a row spacing of 75 cm parallel to the slots, either at random lateral positions in the standard injection treatment or 10 cm from the injection slots of the banded injection treatment. All treatments, including a control without slurry, were combined with 0 or 20-31 kg/ha of subsurface banded P starter fertilizer. Dry matter yields of silage maize were on average reduced by 8% when standard injection of slurry was not supplemented with P. However, the yield reduction was only 2% when slurry was banded.
Yield losses of white cabbage caused by competition with clovers grown as cover crop
Authors: Lotz L.A.P. , Groeneveld R.M.W. , Theunissen J. , Van Den Broek R.C.F.M.
Published: June 2020

The use of intercropping as an integrated pest management (IPM) tool to reduce population densities of pests of field grown vegetables, and the growth and yields of cabbage and clover cover crops grown in the Netherlands, were investigated. In the first 2 experiments, the clover (Trifolium repens cv. Pertina or T. subterraneum cv. Geraldton) crop significantly reduced pest damage of fresh market cabbage cv. Minicole. The associated yield losses due to competition with the cover crop were 15-24%. In other experiments designed to investigate these yield losses in cabbage for storage (cv. Slawdena), the losses were 18-43%. The decrease in weight/head was reduced by decreasing the row distance from 0.75 to 0.50 m, although yield losses were still high. Delaying the sowing of the clover crop, or transplanting the cabbage into a rotary cultivated strip in the clover stand instead of transplanting in the clover stand itself, did not reduce yield losses. It is suggested that intercropping with clover as an IPM tool is not suitable at present for cabbage crops in the Netherlands.
Yields of millet between shelterbelts in semi-arid northern Nigeria, with a traditional and a scientific method of determining sowing date, and at two levels of organic manuring
Authors: Onyewotu L.O.Z. , Stigter C.J. , Oladipo E.O. , Owonubi J.J.
Published: June 2020

Eucalyptus camaldulensis shelterbelts positively influenced yields of millet (Pennisetum glaucum) planted close to the belts. Only smaller distances between shelterbelts than used in semiarid Nigeria, certainly
Sustainable land use in the Sudano-Sahelian zone of Mali: exploring economically viable options using multiple goal linear programming
Authors: Bakker E.J. , Hengsdijk H. , Sissoko K.
Published: June 2020

Technical options in crop and animal husbandry to reduce soil nutrient mining and other forms of natural resource degradation in the Sudano-Sahelian zone should be economically attractive, if they are to be adopted. A model is presented in which agronomic and economic information and goals are combined to explore possibilities for agro-ecologically sustainable and economically viable land use in three different climatic regions in Mali and for a situation of non-degraded soils. The time frame of the study is to the year 2010. For each region, an agro-ecologically sustainable land use system (a combination of crop, livestock and pasture production systems) that maximizes income of the agricultural sector and satisfies self sufficiency targets is identified. Special attention is given to the use of chemical fertilizer in crop activities. It is shown that use of chemical fertilizer is an important element of sustainable and economically viable land use, especially in higher rainfall regions. Population size has a marked effect on optimal land use systems in the regions, but self sufficiency is not endangered even if the population is 50% higher than estimated for 2010. It is argued that results should not be used to simulate the actual situation or future developments, but to define priorities for agricultural development in the Sudano-Sahelian region.
Heavy-metal balances of agro-ecosystems in the Netherlands
Authors: Moolenaar S.W. , Lexmond T.M.
Published: June 2020

Heavy-metal flows (Cd, Cu, Pb, and Zn) of arable, dairy and mixed farming systems in the Netherlands were studied, and farm-gate and field-scale balances calculated. On the field-scale, static and dynamic balances were distinguished. By determining the characteristic metal flows, it became possible to differentiate between farming systems and to select the most viable options for sustainable heavy-metal management. Crop rotation, and choice of fertilizers, clearly influenced the heavy-metal balance of arable farming systems. In dairy farming systems, the role of feed management was very important, but the effects on the heavy-metal balance were not always straightforward. Mixed farming systems compared favourably with specialized (arable or dairy) farming systems with regard to heavy-metal accumulation. Due to the internal cycling of feedstuff and manure, lower inputs were required and therefore the import of heavy-metal containing raw materials and products was minimized. Uncertainties related to the calculation of heavy-metal balances are discussed.
Effect of different degraded protein balances (OEB) on the performance of beef bulls and on digestibility and rumen fermentation in sheep
Authors: Fiems L.O. , Cottyn B.G. , Boucque C.V. , Vanacker J.M. , De Campeneere S.
Published: June 2020

A total of 125 non-double-muscled Belgian Blue finishing bulls (liveweight range 375-620 kg) were used to investigate the effect of different levels of degraded protein balance in the rumen (OEB) -2, -7, -16 and -22 g/kg DM on animal performance, with the dietary content of true protein digested in the small intestine (DVE) fixed at 80 g/kg. Lower OEB levels significantly reduced daily liveweight gain from 1.57 to 1.39 kg during the first 84 days of the experiment, but not during the subsequent part. For the whole experiment, daily liveweight gain decreased from 1.40 to 1.32 kg but the difference was not significant. Intake of DM, DVE and NE for finishing was not modified by OEB level, while CP intake was reduced and OEB deficit was increased. An OEB level of -22 g/kg DM resulted in a significantly unfavourable conversion of DM and NE during the initial months (11.3 and 11.5% compared with OEB = -2 g/kg DM, respectively). For the total period the conversion of DM and NE was still less favourable, but the differences were not significant. There was a nominal decrease in cold carcass weight and dressing percentage when OEB level decreased, but the effect was not significant. The effect of different OEB levels on digestibility and rumen fermentation was investigated in a separate experiment with wethers. Apparent protein digestibility was reduced from 74.2 to 68.9% when OEB level decreased. Rumen pH and concentrations and molar percentages of volatile fatty acids were not altered by OEB level. Ammonia concentration was only reduced by a lower OEB level at 7 h after feeding. Because of a nominal reduction in daily liveweight gain, feed efficiency, carcass weight, dressing percentage and carcass conformation with decreasing OEB level, it is advisable not to feed less than -16 g OEB/kg DM in diets with 80 g DVE/kg DM to Belgian Blue non-double-muscled finishing bulls from 375 kg onwards. This tolerable OEB deficit is larger than proposed to avoid protein overfeeding.
Crop management and anthracnose development in caraway (Carum carvi L.)
Authors: Evenhuis A. , Verdam B. , Wander J.G.N.
Published: June 2020

A reduction of leaf wetness duration was positively correlated (r2 = 0.71; P < 0.001) with a decrease in severity of anthracnose of caraway, caused by the fungus Mycocentrospora acerina. Lodging and higher plant density prolonged leaf wetness duration. Disease incidence and severity of anthracnose were reduced by crop management activities minimizing leaf wetness duration. Reduction of nitrogen levels reduced the risk of anthracnose development in spring and biennial caraway. Decreasing the sowing rate from 8 to 4 kg/ha resulted in a lower disease severity and an increase of seed yield in spring caraway, but not in biennial caraway. In biennial caraway disease severity decreased with wider row spacing. A damage threshold between 6% and 12% disease severity is proposed. Positive financial results of crop management activities are indicated.
Design of farming systems for low input conditions: principles and implications based on scenario studies with feed allocation in livestock production
Authors: Schiere J.B. , De Wit J. , Steenstra F.A. , Van Keulen H.
Published: June 2020

This study addresses the issue of designing farming systems for low input conditions. By focusing on the problem of feed (resource) allocation in livestock systems it provides clues for the design of alternative agricultural systems and systems in general. Linear programming (LP) is used to examine system behaviour under conditions of varying feed resource qualities, for individual animal production levels that range from 0.75 to 3.00 times maintenance. Milk yield, animal numbers and amounts of feed offered or refused are measures of system performance in two hypothetical cases representative for actual farming systems. Case 1 considers available feed as one aggregated resource, with an average nutritive value ranging from that of straw to that of high quality forage. It establishes the individual animal output level that is required to achieve maximum total system output from a given feed resource. In Case 2, animals of different production levels are allowed to select between two feed resources that, through proper definition of the their proportions on offer, on average represent the same feed quality scale as in Case 1. The possibility of selection, however, allows the nutritive value of the actual intake to differ from the average nutritive value of feed offered. Better feed and higher (potential) individual animal output tend to increase total system output in terms of milk, by reducing the number of animals. Nevertheless, the term 'damning objective' is introduced to express that high targets for subsystem output reduces total system output if subsystem requirements exceed resource availability. Moreover, heterogeneity of (feed) resources can increase system output by using more production units with lower individual output. The results are tested against farmers' practice and situations reported in literature. Implications for the design of sustainable systems and further research are discussed.
Measuring soil water content and evaporation by the neutron scattering method.
Authors: Holmes J.W.
Published: June 2020

The calibration curve used for converting field measurements of counting rate into water-content values was obtained in principle from neutron transport theory, using the "Fermi age" treatment of the slowing down of fast neutrons. Measurements were made at vertical intervals of 30 cm at depths of 30-180 cm at different dates over 5 months. Measurements were not made between o and 30 cm depth as experiment showed that the size of the sampling volume scanned by the neutrons resulted in errors at water contents below about 0.13 g/cc. Water-content profile curves were constructed, and evaporation obtained by measuring the areas between curves and adding the figures for precipitation in the same period. A graph of the accumulative evaporation is presented, the evaporation as calculated by Penman's method being also shown. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Radiation intensity and transpiration.
Authors: Brouwer R.
Published: June 2020

Stomatal aperture quickly increased with light intensity to a maximum and then decreased until the stomata closed. Transpiration was optimal at a weak light intensity and then the curve fell quite sharply, increasing again rectilinearly at higher intensities, the latter increase being due to cuticular transpiration. Analysis of the curved part representing stomatal transpiration suggested that the relative humidity within the leaf was
The actual evapotranspiration as a function of the potential evapotranspiration and the soil moisture tension.
Authors: Makkink G.F. , Van Heemst H.D.J.
Published: June 2020

Lysimeter observations with a clay and a peat soil indicated that the actual evapotranspiration of grassland falls below the potential evapotranspiration while the soil is still drying, the fall being less for peat than for clay. The rate of reduction depends on the moisture tension of the soil and on the intensity of the potential evapotranspiration. The real evapotranspiration may keep up with the potential evapotranspiration of a definite intensity; the wetter the soil, the higher the intensity at which reduction begins to occur. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Calculation of the steady flow of ground water in vertical cross sections.
Authors: Ernst L.F.
Published: June 2020

The useful formulae for the relationship between rainfall and hydraulic head are only valid for symmetrical, one-layer problems. By introducing horizontal, vertical and radial resistances in the soil profile, it was possible to obtain solutions to problems of groundwater movement in systems with only one water table under asymmetrical conditions and in soil profiles consisting of layers with widely different permeabilities. In this way the groundwater flow can be calculated from a number of linear equations. Owing to the constant resistances, in some simple cases a linear relationship is found between hydraulic head and rainfall or runoff. In a compound drainage system (ditches and tile drains, rivers and secondary watercourses) the relationship is represented by a broken straight line. A similar, nonlinear, relationship is found in a thin aquifer with an elliptic phreatic surface. An important feature of the method is the characterization of open watercourses by a single value: the radial resistance.-Author's summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Problems of development in Ceylon.
Authors: Van Beukering J.A.
Published: June 2020

A description is given of the structure of native agriculture and of the necessary measures for its development. Rice cultivation, in particular, is described. Increasing the size of holdings and the extension of irrigation and dry farming into the dry zone are discussed.-J.F.C. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Aspects of consolidation of farms in some European countries.
Authors: Maris R.
Published: June 2020

By land consolidation is meant measures to improve the external productive factors of agriculture. Consolidation programmes in Bavaria, Switzerland, France, the Netherlands and Sweden are compared. The present degree of fragmentation of holdings is discussed by comparing numbers of fields per farm and the average distance from field to farmstead in each country.-J.F.C. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The determination of pasture yield.
Authors: Bosch S.
Published: June 2020

The determination of gross yield, directly measured, and of net yield, indirectly calculated, are described and compared. In estimating gross yield, methods independent of farm use, in which fenced-off sections or cages are used, are compared with those dependent on farm use, in which strips are harvested before grazing. The amount of pasture grazed is determined from yields of mown plots before and after grazing by the use of a simple formula which agrees closely with Linehan's logarithmic formula. In calculating the net yield of starch equivalent from grazing time, use is made of Geith's norms for maintenance, production and growth. By using factors which allow for the very variable losses, according to methods of grazing and conservation, net yields can be converted to gross yields of starch equivalent. Fields can be directly compared by the use of standard methods and allowance made for different amounts of N fertilization.-J.F.C. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On the variations in contents and in inter-relations of minerals in dandelion (Taraxacum officinale Weber) and pasture grass.
Authors: Van der Kley F.K.
Published: June 2020

Dandelion is high in Cl and Cu and in the usual cations, but poor in P and S. Consequently, its base-forming capacity is higher than that of grass [spp. not stated]. As an aid to balanced animal nutrition, its presence in a sward is considered to have some value.-- J.F.C. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of ventilation capacity on weight losses in ventilated potato stores.
Authors: Ophuis B.G.
Published: June 2020

The ventilation capacity required for cooling potatoes depends on the climate and is best determined by practical experiments. Increasing the quantity of air forced through per hour results in little or no increase in evaporation. Hence with a large ventilation capacity shrinkage is not higher than with a small ventilation capacity. The ventilation capacity recommended for potato stores in the Netherlands is 100 cu. m. air per hour per cu. m. potatoes. Under Dutch climatic conditions it is thus possible to obtain a storage temperature corresponding to the minimum outside temperature averaged per 10-day periods. Up to April these temperatures are low enough to prevent sprouting. In ventilated potato stores the loss of weight in immature harvested potatoes is 3-5% during the first month after harvesting, and one-half to a maximum of two-thirds % per month in the succeeding period. Ripe lifted potatoes have a weight loss of 1-3% in the first month and one-half to two-thirds % per month thereafter.-From author's summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some observations on the relation between transpiration and soil moisture.
Authors: Bierhuizen J.F.
Published: June 2020

Transpiration rates of Phaseolus vulgaris were measured in pot experiments, at different soil moisture levels and light intensities. Transpiration increased with available moisture, becoming nearly constant at the higher levels. At the highest light intensity transpiration increased with available moisture content to a maximum at 16% moisture, but then showed a slight decrease; it is suggested that this effect is a result of O2 deficiency at high moisture levels.-Inst. Land Water Management Res., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Observations on the flowering and fructification of the groundnut, Arachis hypogaea. 2.
Authors: Bolhuis G.G.
Published: June 2020

Flowers produced by bunch-type groundnut plants of the variety Schwarz 21, grown in pots, were counted and then removed to prevent fruitsetting. The plants continued to flower throughout their life-span, and the number of flowers produced per plant often exceeded 1500, compared with 60-80 in plants which were allowed to set fruit. The life of these plants could be prolonged to more than 12 months by preventing fruit-setting.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On the classification and genesis of soils, derived from andesitic volcanic material under a monsoon climate.
Authors: Hong T.K. , Van Schuylenborgh J.
Published: June 2020

The Lawu volcano was sampled from an altitude of 500-3, 300 m and investigated morphologically, mineralogically and chemically. The soil organic matter was analysed in respect of its C, H, O and N content. Comparison of soils in a monsoon climate with those formed in a wet climate showed that the process of laterization proceeded to higher altitudes in a monsoon climate. It seems possible to recognize the following belts: a zone from 3, 300 to 2, 500 m altitude with brown podzolic soils, 2, 000-1, 400 m with brown forest soils, 1, 400-1, 000 m with latosolic brown forest soils and 1, 000-300 m with brown and reddish-brown latosolic soils. Organic acid was a more important soil-forming factor than CO2 at altitudes > 1, 000 m and under a monsoon climate. An explanation is proposed for the curious trends of C/N ratios of the soil and organic matter and for the trends in the clay's molar Al2O3/Fe2O3 ratios.-From authors' summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Observations on the flowering and fructification of the groundnut, Arachis hypogaea. 3.
Authors: Bolhuis G.G.
Published: June 2020

Removal of flowers from Schwarz 21 groundnuts caused a marked increase and a marked periodicity in the intensity of flowering. Treated plants began to show a difference in flowering pattern after 10 days. In normal plants, 7-8 days elapsed between flowering and fruiting. It is suggested that inhibition of flowering occurs in normal groundnut plants before fruiting begins, possibly as early as at fertilization. [See Abs. 730.]-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Rubber growing in Brazil in view of the difficulties caused by South American leaf blight (Dothidella ulei).
Authors: Tollenaar D.
Published: June 2020

In an attempt to avoid blight infection, blight-resistant crowns were top-budded on high-yielding Eastern clones; this method, however, proved impracticable, because the crown buddings used depressed the yields of the Eastern panel clones, and there was also a high percentage of failures after transplanting. Results were more satisfactory with single-budded trees, when the highest-yielding resistant clones were used. In establishing rubber plantations in Brazil the author recommends that material be chosen from highly resistant clones (of relatively unknown performance), from high-yielding Eastern clones which are tolerant, or from seedlings of selfed PB86 and AV1301, both of which show some leaf blight resistance. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A study on the effect of a massive prophylactic dose of vitamins A and D on the neonatal dairy calf.
Authors: Weits J. , King J.M. , Warner R.G.
Published: June 2020

In a pilot experiment 3 newborn calves were given 250, 000 I.U. vitamin D and 500, 000 I.U. vitamin A, as Duphasol A + D3 (Philips-Roxane), and had 6 litres whole milk daily for 16 days. Blood was then sampled and Ca, P and phosphatase were estimated; the calves were killed and tissues were examined histologically. Both blood and tissues were normal. In a repeat experiment at Cornell, 13 calves were given 250, 000 I.U. vitamin D and 500, 000 I.U. vitamin A or twice these amounts in the same compound before they were 14 days old. Blood samples taken before, and 2 and 14 days after, the vitamins were given were normal in respect of Ca, P and phosphatase. Histological examination of kidney and other tissues of 11 of the calves gave no evidence of lesions due to excess of these vitamins.-J. Quarterman. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Agriculture in economically underdeveloped countries, especially in equatorial and subtropical regions.
Authors: Terra G.J.A.
Published: June 2020

The causes of low productivity in tropical and subtropical agriculture are discussed.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Evapotranspiration problems in Iraq.
Authors: Stork C.
Published: June 2020

The actual net irrigation requirement of the inundated, irrigated and drained plots (at Dujailah Experimental Station) was compared with results of empirical and theoretical methods based on climatic conditions. Penman's formula generally agreed with the empirical results whereas Blaney and Criddle's equation and Thornthwaite's formula were of limited use. Only evaporation from pans was used; the Piche evaporimeter and the Livingstone atmo-meter were unsuited to conditions in Iraq. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The prevention of microbiological deterioration of Jute potato-bags during storage.
Authors: Hueck H.J. , Ophuis B.G. , Hesen J.C.
Published: June 2020

Rot-proofing treatments at the Central Lab. T.N.O., Delft [cf. 38, 59], ensured better protection of bags buried in soil than bags containing potatoes stored at 5 degrees C. for 4 months. Application of D.D.M. (2, 2'-methylene bis (4-chlorophenol) compound)+Cu-fixation [cf. 38, 146] was most effective but the most expensive, while Cu-8-oxyquinolinolate, tributyltin, D.D.M. alone, and cuprammonium (the cheapest of all) were creditable. On the other hand, Cu-naphthenate and lauryl-pentachlorophenol are not recommended, the latter affecting the taste of the stored potatoes. Freshly impregnated bags should not be used, since potatoes may be damaged by the volatile solvents of the fungicides. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Placement of a compound (N.P.K.) fertilizer compared with straight fertilizers.
Authors: Prummel J.
Published: June 2020

The effect of a completely water-soluble compound fertilizer 12-10-18 on oats (600 and 1, 000 kg/ha) and potatoes (900 and 1, 600 kg/ha) was compared with that of equivalent rates of straight fertilizers (NH4NO3-limestone or (NH4)2SO4 with double super and K2SO4); both treatments were applied by broadcasting and by banding at 3 cm to the side and 3 cm below the oat seed and 7 cm to the side of the potato seed. Best yields resulted from placement of the compound fertilizer and the effects of broadcasting the compound fertilizer were slightly better than those of banding the straight fertilizers. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of nitrogen fertilisation and certain other factors on the chemical composition of apple leaf.
Authors: Van der Boon J.
Published: June 2020

Nitrolime (100-310 kg/ha N) was applied in spring to 10-year-old trees growing in a medium-heavy river ridge soil; 80 kg P2O5 and 200 kg K2O were also applied each year. In all but the first year more foliage and shoots occurred after the 310 kg than after lighter N treatments. Increasing N treatments were accompanied by increasing Mg and N and decreasing K, P and Ca contents in the leaves. (Abstract retrieved from CAB Abstracts by CABI’s permission)
On the classification and genesis of soils developed over acid volcanic material under humid tropical conditions. II.
Authors: Tan K.H. , Van Schuylenborgh J.
Published: June 2020

The formation of zonal soils on rhyolitic and daciiic tuffs is discussed, and profiles are described of seven zonal soils (distributed over four belts with podzols at 1500-2000 m, podzol-brown podzolic iniergrades at 1100-1500 m, brown podzolic soils at 1100-500 m, red-yellow podzolic soils at 500 m and less) and four intrazonal soils formed on andesitic-dacitic tuffs at low altitudes. Andosols, humic gley soils and grey hydromorphic soils are distinguished according to drainage impedance. (Abstract retrieved from CAB Abstracts by CABI’s permission)