bluuebunny/crossref_metadata_2025 huggingface dataset:
Amino acid requirements of pigs. 3. Requirement for apparent digestible threonine of pigs in different stages of growth.
Authors: Lenis N.P. , Diepen J.T.M. van
Published: June 2020

Individual and group housed crossbred pigs 45 to 105 kg and 65 to 95 kg in experiments 1 and 2, respectively, were given basal diets with L-threonine 0.6, 1.2 and 1.8 g/kg. Positive and negative control diets contained total threonine 5.7 and 4.5 g/kg, respectively. To prevent other amino acids being limiting, the negative control diet was supplemented with lysine, methionine, tryptophan, isoleucine, histidine and valine. The positive control diet was supplemented with lysine and methionine. The requirement for total threonine of growing-finishing pigs for maximum growth performance was about 5.6 g/kg in a diet containing net energy 9.4 MJ/kg. This figure corresponds with about 4.7 g/kg apparent faecal digestible threonine and 4.3 apparent ileal digestible threonine. There was no difference between the growing and the finishing pigs. The requirement for ileal digestible threonine, relative to ileal digestible lysine requirement, was about 64%. It is concluded that dietary protein can be reduced by 2 percentage units without any adverse effect on growth performance, if limiting amino acids are sufficiently supplemented. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effects of gibberellic acids on time of maturity and on yield and quality of cauliflower.
Authors: Booij R.
Published: June 2020

Gibberellic acid (GA4+7) was applied to cauliflower crops of the cultivars Delira and Elgon, grown in spring and summer of the years 1984, 1985 and 1986. Observations were made on the timing of the end of the juvenile phase and of curd initiation, the final number of leaves and the total length of growing period. In most crops the period between transplanting and harvest was shortened when GA4+7 was applied twice after the end of juvenility at a concentration of 80 mg/litre. The extent of shortening of the growing period increased with increasing difference between the number of leaves initiated at the time of application and the final number of leaves of the untreated crop. GA4+7 reduced the final number of leaves. Quality of the curds was unaffected by the treatment in most harvests, but the bracting incidence was reduced. In crops of cv. Delira with a low final number of leaves, size and quality of the curds was reduced. The results are discussed in relation to harvest planning of cauliflower. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Dried beet pulp, pressed beet pulp and maize silage as substitutes for concentrates in dairy cow rations. 2. Feed intake, fermentation pattern and ruminal degradation characteristics.
Authors: Visser H. de , Huisert H. , Ketelaar R.S.
Published: June 2020

In a 3 x 4 Latin square design with periods of 5 weeks rumen cannulated cows were fed on mixed diets supplemented with dried beet pulp (DP) pressed beet pulp (PP) and maize silage (M) at 15 kg DM and 25 kg DM (low, LL1 or high, HL1), respectively. Measurements were made of organic matter degradation (nylon bag) of diet ingredients, while during 48-h periods the pattern of intake, pH and osmolality, and concentration of volatile fatty acids (VFA), lactic acid (HL) and ammonia (NH3) were determined. The pH and concentration of the major VFA's were similar between treatments. The concentration of the branched chain fatty acids (BCFA), valerate and ammonia were significantly higher with M. The level of intake significantly influenced the pH, concentration of the major VFA's, 2-methyl-butyrate and valerate. The feed intake pattern differed between intake levels, but were similar between diets. Degradability of treatments were calculated from individual degradability measurements of diet ingredients. The undegradable fraction was highest for diet M. The water-soluble fraction was lowest for treatment DP, and the rate of degradation (kd) was lowest for treatment M. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Cadmium uptake by lettuce varieties.
Authors: Florijn P.J. , Nelemans J.A. , Beusichem M.L. van
Published: June 2020

The uptake of Cd by lettuce cultivars was studied in soil and water culture experiments (16 and 8 cultivars, respectively). In the soil experiment, sandy soils from both a Cd-contaminated and a non-contaminated area of the Netherlands were used; the water culture experiment included 3 Cd levels (0, 0.03 and 0.1 mg/litre). Fresh and dry yields of shoots and roots were hardly affected by Cd in either of the experiments. The lettuce cultivars showed a close similarity in shoot Cd concentration, ranging from 8.23 to 10.72 micro g/g DW for the Cd-contaminated soil and from 3.96 to 8.83 micro g/g DW in the water culture at the highest Cd level tested. These results contradict published data on a large genotypic variation in Cd concentration in lettuce [see John, M. K. et al, Environmental Pollution (1976) 10, 163-173]. Based on the narrow range in shoot (and root) Cd concentration between cultivars, it is concluded that it is unwarranted to use lettuce as a pilot plant in comparative physiological investigations on Cd uptake and distribution. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The relation between flower initiation and sink strength of stems and tubers of Jerusalem artichoke.
Authors: Meijer W.J.M. , Mathijssen E.W.J.M.
Published: June 2020

In a field experiment with a late cultivar (Violet de Rennes) the relation between flower initiation and the onset of redistribution of stem reserves and rapid tuber filling was studied. The treatments, which comprised long day (18-h photoperiod) treatment, application of the growth retardant triapenthenol at 3 kg/ha, transplanting or delayed planting, were designed to vary the duration of the vegetative plant stage or to alter the pattern of dry matter distribution. During the vegetative stage, tuber growth proceeded at a slow rate (about 20 kg ha-1 d-1) and inulin accumulated in the stems. With the plants that were kept vegetative by prolonging daylength, the tuber growth rate remained at that low level until final harvest. At the beginning of Sep. the plants in all other treatments showed flower initiation at the apices and thereafter tuber filling rates were much higher. From the similar growth rate per tuber, with crops differing considerably in tuber number per unit area, it is concluded that total tuber growth depends not on assimilate availability but on the storage capacity, i.e. the number of tubers or number of storage cells, and is therefore sink limited. Tuber number appeared to be linearly related to a cumulative temperature. The changes in relative sink strength of stems and tubers over the growth period are discussed as well as the metabolic costs and economic risks of the temporary inulin storage in the stems. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Transformation rate of methyl isothiocyanate and 1,3-dichloropropene in water-saturated sandy subsoils.
Authors: Boesten J.J.T.I. , Pas L.J.T. van der , Smelt J.H. , Leistra M.
Published: June 2020

The transformation rates of methyl isothiocyanate and 1,3-dichloropropene were studied in four water-saturated sandy subsoil materials collected between 2 and 4 m below the soil surface, using laboratory incubation systems at 10 degrees C. In three samples, transformation of methyl isothiocyanate was rapid (< 10% remaining after 30 days), whereas in the fourth, a half-life of ~ 35 days was found. In the transformation of the (Z)- and (E)-isomers of 1,3-dichloropropene in the same materials, half-lives between 16 and 64 days were found. Incubation in systems where the subsoil materials had been exposed unintentionally to temperatures up to 30 degrees C before adding the compounds, resulted in much lower transformation rates for methyl isothiocyanate (half-lives ranging from 150 to 570 days) and in only slightly lower rates for (Z)- and (E)-1,3-dichloropropene (half-lives ranging from 38 to 76 days). (Abstract retrieved from CAB Abstracts by CABI’s permission)
Uptake of nutrients by lettuce on NFT with controlled composition of the nutrient solution.
Authors: Heinen M. , Jager A. de , Niers H.
Published: June 2020

An automatically-controlled recirculating NFT system was developed, consisting of a growth unit and a measuring and control unit. It is described together with some basic growth and uptake models. Results are presented of a preliminary experiment with the lettuce cultivar Sitonia (using manual control and nutrient dosage). The % DM in the heads decreased from 6.86 (week 1, 20 June 1988) to 3.89 (week 5, 25 July). The shoot:root ratio increased from 0.50 (week 1) to 6.47 (week 6). The time courses of DW increase and cumulative uptake of macronutrients were well described by exponential equations. The cumulative uptake determined from the loss of nutrients from the nutrient solution exceeded that determined from plant analysis. Cumulative uptake as a function of cumulative daily radiation was well described by a logistic equation. Some constant plant uptake ratios between micro- and macronutrients were observed: Cl uptake was related to that of N, K, P or Mg, and B uptake to that of K. DW as a function of transpiration was also well described by a logistic model, with an average DM production of 3.1 g/litre transpired; a logistic model also expressed transpiration as a function of radiation, with an average transpiration output of 5.8 litres/unit (kJ/cmsuperscript 2) increase in radiation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Determination of soil permeability in situ.
Authors: Timmers H.J.
Published: June 2020

The theory of non-stationary flow has, been applied to the movement of water in the upper layers of the Pleistocene terrace on the western side of the river IJssel. A Fourier analysis of the movement of the water levels in the river and in several wells permitted calculation of the ratio of permeability to the storage coefficient of the soil. Assuming that the storage coefficient was o. I0 and the average thickness of the aquifer was I5 m, the average permeability was calculated to be 53 m/day. The discharge of water from the soil (0.8 cu m/day) can be calculated without knowing the thickness of the aquifer. The method can be used to calculate the amount of water needed for irrigation and the amount of water percolating from the hinterland to the river. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Tillage in relation to rainfall intensity and infiltration capacity of soils.
Authors: Van Duin R.H.A.
Published: June 2020

Starting from Darcy's law, the rate of infiltration of water into homogeneous and layered soils is given. At field capacity the rate of infiltration approaches that of percolation. The influence of an upper layer of high permeability on infiltration rate of the subsoil is small; loosening the surface layer increases infiltration capacity until it is saturated and further infiltration is limited by the percolation rate of the subsoil at field capacity. Stagnation of water at the soil surface during periods of high rainfall intensity may be prevented by cultivation. A graph shows maximum rainfall surplus to be dependent on percolation rate. Cultivating soil in view of infiltration capacity is not important if the percolation rate of the subsoil is >1.5 cm/hr, since corresponding high rainfall intensities occur in summer when soil is not bare and potential evapo-transpiration is high. With low percolation rate and a potential storage capacity of the upper layer X'p = 0.25, a depth of 11-22 cm of the upper layer is sufficient to store the maximum surplus rain in Holland even during extreme wet periods. The total storage capacity of subsoil is only limiting with small depths or very low values of potential storage capacity. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Apparent digestible phosphorus in the feeding of pigs in relation to availability, requirement and environment. 2. The requirement of digestible phosphorus for piglets, growing-finishing pigs and breeding sows.
Authors: Jongbloed A.W. , Everts H.
Published: June 2020

Digestible phosphorus requirement for maintenance, growth, foetal growth and milk production of pigs was estimated using a factorial design. Digestible P requirements for piglets from 10 to 20 kg, growing pigs from 30 to 50 kg, finishing pigs from 50 kg onwards, pregnant and lactating sows were 3.6, 2.3, 2.0, 2.2 and 2.9 g P/kg feed, respectively. Large differences in recommendations of the P requirements exist between those reported in the literature and calculated data presented. Those for piglets in the literature were higher. For sows further information concerning the P requirement in different phases of pregnancy and lactation is required to allow a more precise estimation of the P requirement. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Effect of grassland management on N mineralization potential, microbial biomass and N yield in the following year.
Authors: Hassink J.
Published: June 2020

The effect of mowing or grazing and mineral fertilizer level on N mineralization potential and microbial biomass N (N flush) was studied in 1988 on a sandy soil and a sedimentary calcareous silty loam (loam) in the Netherlands. On the loam the residual effect of the treatments on N yield and herbage dry matter accumulation in the following year was also studied. The different management practices were started in 1985 on the sandy soil and in 1986 on the loam. The amount of microbial biomass N was larger under grazing than under mowing. The increase in the amount of microbial biomass N due to grazing was larger for the loam than for the sandy soil. The N-mineralization rate was higher under grazing than under mowing. The difference in N-mineralization rates between grazed and mown fields was 20-30 % in April for both soils, but increased considerably in the sandy soil during the growing season. It was estimated that the difference in N-mineralization between mown and grazed plots under field conditions was 110 and 40 kg N/ha per year in the sandy soil and the loam, respectively. Thus the optimum N fertilizer application rate should be considerably lower under grazing conditions than under mowing conditions, especially on sandy soil. Fertilizer level had no effect on the amount of microbial biomass and rates of N-mineralization. Both grazing compared to mowing and increasing N fertilizer levels above 550 kg N/ha per year affected the N yield and dry matter accumulation in the following year (= residual effects) on the loam. These effects were greater for N yield than for dry matter accumulation. The residual effect of previous fertilizer input was probably caused by the presence of different amounts of N in roots and stubble. The residual effect on N yield under grazing exceeded that under mowing by 28%. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Weather indices of agricultural production in the Netherlands 1948-1989. 2. Grassland.
Authors: Oskam A.J. , Reinhard A.J.
Published: June 2020

Three models for deriving weather indices for grassland production are described and were applied over the 1948-64 period. The meteorological and agronomic models, but not the trend model, could also be used to calculate weather indices outside this period. The results of the 3 methods differed considerably. The meteorological model was most suitable for calculating a weather index for a long period. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A methodic way to more sustainable farming systems.
Authors: Vereijken P.
Published: June 2020

A methodic pathway is suggested for the definition, elaboration, evaluation and introduction of farming systems based on an 'integrated' or an 'ecosystem-oriented' vision, both considered more sustainable than a 'world-market-oriented' vision. The objectives of these three basic types of systems are defined in measurable terms with respect to the major social values or interests supported or adversely influenced by agriculture. For each type of system, a strategy is assessed through which the objectives can be achieved while avoiding conflict. Arable farming is taken as an example of the elaboration, evaluation and introduction of integrated and ecosystem-oriented systems. The paper discusses how prototype systems can be developed on an experimental farm, evaluated by a pilot group of farmers and dispersed on a large scale. For the short term it is recommended to focus research and policy on integrated farming systems, as an urgently needed compromise between socioeconomic and socio-ecological interests. For the long term, the development of ecosystem-oriented farming systems is recommended as a means of solving the agricultural crisis in a more comprehensive and sustainable way. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Region-wise development of prototypes of integrated arable farming and outdoor horticulture.
Authors: Wijnands F.G. , Vereijken P.
Published: June 2020

In the Netherlands integrated arable farming systems (IFS) are being developed at three regional experimental farms, with region-specific crop rotations and cropping systems. Most pesticide and fertilizer inputs appear to be replaceable by non-chemical methods and organic manure, with economic results similar to conventional systems. The targeted reductions in pesticide use in the Netherlands' Multi-Year Crop Protection Plan for the year 2000 can already clearly be met. Further improvements of the prototype systems are considered. Recently started farming systems research for outdoor horticulture is briefly discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Evaluation and introduction of integrated arable farming in practice.
Authors: Wijnands F.G.
Published: June 2020

A four-year project to evaluate and introduce integrated arable farming systems (IFS) in practice is presented. The project comprises the testing of IFS prototypes that have been developed at experimental farms by a group of pilot farms and the introduction of IFS in the farming community, mainly by the establishment of a network of study groups. To support these main activities, training programmes and courses are organized for advisers, teachers and farmers. Preliminary results of the pilot farms show perspectives of IFS to considerably reduce pesticide and nutrient inputs under varying farm and management conditions. A broader adoption of IFS seems until now more hampered by social than technological causes, notably by the lack of motivation and cooperation of extensionists and farmers. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Towards integrated pig production in the Netherlands.
Authors: Hartog L.A. den
Published: June 2020

The intensive production of pigs requires attention to the effects of the production on the environment (slurry production, mineral excretion and ammonia volatilization), the quality of the product, the health and welfare of pigs, and the working circumstances of the farmer. An integrated approach to these items is necessary to achieve sustainable, safe and economic production. The constraints of integrated pork production and possible solutions are described. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Liver selenium analysis in cows with a fast method of neutron activation reveals deficiency areas in the Netherlands
Authors: Binnerts W.T. , Das H.A. , Viets T.C.
Published: June 2020

A total of 230, 100-g freeze-dried liver samples from the caudal lobe of cows from 13 slaughterhouses in the Netherlands were analysed by irradiating with neutrons in a high flux generator for 5 s followed by measurement of the short-lived isotope 77mSe in a rigid time sequence, under fully automated conditions. Liver Se ranged from 0.16 to 1.82 mg/kg DM and did not appear to relate to geography. 3% of the livers contained Se less than 0.25 mg/kg DM, which is considered critical for development of Se deficiency. Another 20% with less than 0.4 mg/kg DM was considered borderline Se deficiency. There was no evidence of Se toxicity. Liver Se positively correlated with liver copper, which may be obtained via feed, but not with liver zinc. It was concluded that animals at risk to Se deficiency are those not fed on concentrates, particularly heifers suffering from retained placentas at delivery. The feeding of Se fortified feeds is recommended.
Ammonia treatment of wheat straw. 2? Efficiency of microbial protein synthesis, rumen microbial protein pool size and turnover, and small intestinal protein digestion in sheep
Authors: Oosting S.J. , Viets T.C. , Lammers-Wienhoven S.C.W. , Van Bruchem J.
Published: June 2020

Ammonia-treated wheat straw (AWS) was compared with untreated wheat straw (UWS) and untreated wheat straw supplemented with urea (SWS) in an experiment with 6 wether sheep. Microbial protein synthesis increased after ammonia treatment due to the higher intake of rumen degradable organic matter (OM). The efficiency of microbial protein synthesis was low for all diets, averaging 22.1 g N/kg apparently rumen degradable OM and was not significantly affected by ammonia treatment. Estimates of microbial protein synthesis based on diaminopimelic acid or the amino acid profile methods did not differ significantly. The pool of microbial DM (average, 151 g) and N (12 g) in the rumen and the proportion of rumen microorganisms associated with the fluid phase (average, 36%) were not affected by diet, but the clearance rate (%/h) of microorganisms tended (P
Moisture content of cereals at harvesting time by comparing microclimate values and standard weather data
Authors: Atzema A.J.
Published: June 2020

The moisture content of wheat and barley together with the weather elements were measured at 3 different experimental sites in the Netherlands in 1990-91. The difference in the dew point temperature in the screen[house] and in the field was small. However, the differences between air temperature in the screen and those at different heights in wheat and in barley stands were considerable. In daytime the surface temperature of barley was higher than that of wheat under the same weather conditions as a result of a higher absorbtion coefficient. Both for wheat and barley, the maximum difference between the calculated moisture content was 0.5%, using the air temperature at 1.5 m height from the nearest standard weather station and the surface temperature of the spikes. Barley had a greater daily cycle in the moisture content of the grains than wheat as a result of a high equilibrium moisture content during the night and a low one in daytime.
Low external input sustainable agriculture: expectations and realities
Authors: Kessler J.J. , Moolhuijzen M.
Published: June 2020

Low External Input Sustainable Agriculture (LEISA) is receiving increased attention, both as a sustainable alternative to Green Revolution-like strategies making intensive use of external inputs, and as a strategy of sustainable agriculture in resource-poor environments where no or very few external inputs are used. The evaluation of LEISA field-experiences in the Philippines and in Ghana shows that the potential of LEISA to improve ecological and/or socioeconomic sustainability depends on site-specific factors in the first place. In areas with a high production potential, LEISA can simultaneously improve ecological sustainability and farmers' socioeconomic conditions by reduced use of external inputs. In areas with a low production potential, LEISA can stabilize and restore the carrying capacity, but generally has limited potential to improve socioeconomic conditions for growing populations, and an increased production may also result from a further depletion of natural resources, and by a limited number of farmers. Other factors that can influence the potential and the applicability of LEISA are the production dip and the rehabilitation period involved, high labour requirements, land ownership aspects, gender issues, constraints to implement a participatory technology development approach, macroeconomic aspects, government influences and information dissemination. Together with the site-specific conditions, these aspects should be considered in planning and evaluation of LEISA techniques.
Oestrogen receptors in endometrial cytosol of gilts on days 10-13 of oestrous cycle and pregnancy
Authors: Van Der Meulen J. , Helmond F.A. , Oudenaarden C.P.J.
Published: June 2020

Cytosolic oestrogen receptors (ER(c)) were determined with a Dextran-coated charcoal assay and Scatchard plot analysis in endometrial tissue of non-pregnant and pregnant gilts on Days 10-13 after standing oestrus. The Kd of the ER(c) was 0.40 +/- 0.04 nM (mean +/- SEM) and was not affected by day or reproductive state. The endometrial ER(c) concentration was affected by day and reproductive state (P
Risk management in crop production and fertilizer use with uncertain rainfall; how many eggs in which baskets?
Authors: Van Noordwijk M. , Dijksterhuis G.H. , Van Keulen H.
Published: June 2020

Model results are analysed for risk management options for sorghum production with a range of N fertilizer rates on three soils of a toposequence in three climatic zones in Burkina Faso. The three levels of analysis are: (a) quantifying the probability distribution of physical and economic yield for a range of fertilizer levels and soil types; (b) quantifying the possible variance reduction by soil heterogeneity or by a combination of soils and N rates; (c) developing a procedure for selecting 'meaningful diversity' of soil and N fertilizer combinations.
Photothermal response of sympodium development and flowering in potato (Solanum tuberosum L.) under controlled conditions
Authors: Almekinders C.J.M. , Struik P.C.
Published: June 2020

In two phytotron experiments with different potato cultivars (experiment 1: cv. Atzimba and Van Gogh; experiment 2: cv. Spunta and Desiree), a study was made of the effects of temperature (15-27 degrees C) and photoperiod (long day, LD, or short day, SD) on sympodial development and shoot, leaf and flower production. In experiment 1, data on the entire shoot were collected, whereas in experiment 2 only leaf and flower production of the main and secondary stems were measured. In experiment 1, increasing the temperature in both SD and LD treatments, and increasing the photoperiod at 15 degrees C increased the number of lateral shoots, and the numbers of inflorescences and leaves of the sympodium and of the entire shoot. In experiment 2, the number of flower primordia and survival of flower primordia of individual inflorescences increased with the photoperiod and with temperature up to 23 degrees. At 27 degrees, flower development was suppressed. Total leaf and flower production per plant were largely a function of lateral shoot production. Increasing temperature and photoperiod increased the number of leaves of individual shoots in most treatments. However, the effects on leaf and flower production of individual shoots were relatively small, except for the effect of a temperature increase from 23 to 27 degrees in experiment 2. The photoperiodic response of the time till flowering of individual shoots was facultative SD or daylength-neutral, depending on the cultivar and stem position.
In vitro estimation of rumen fermentable organic matter using rumen fluid and a cell free preparation of rumen fluid
Authors: Cone J.W. , Van Gelder A.H. , Veerman E.T. , Van Vuuren A.M.
Published: June 2020

The amount of microbial protein leaving the rumen is considered as a function of the amount of rumen-fermentable organic matter (FOM) in the rumen. FOM can be calculated using tables, or estimated by in situ incubation, but both methods have some drawbacks. In vitro methods were therefore developed to estimate FOM, using fresh rumen fluid or a cell-free preparation of rumen fluid. Results were compared with the in situ method and a method using chemical feed composition. The in vitro methods gave a good prediction of the in situ estimation of FOM for the majority of feeds. For some feeds rich in starch or fat, the correlation was poor. Because no in vivo data of FOM were available, it could not be determined whether the in vitro or in situ methods gave false results. However, arguments suggest that the in situ method is not suitable for some feeds.
Farmers' knowledge and management of spatial soil and crop growth variability in Niger, West Africa
Authors: Lamers J.P.A. , Feil P.R.
Published: June 2020

A household survey conducted in the Sahel, combined with an extensive literature search of baseline studies, complemented on-station research on spatial soil and crop growth variability from a farmers viewpoint. Farmers explained spatial variability in crop growth in terms of differences in soil types, soil fertility and degradation, as well as their cultivation and management practices. Farmers counteract spatial crop growth variability by within-field fallow; kraaling; spot applications of manure, crop residues and household waste; by intentionally moving their settlements; and by exploiting the micro-environmental differences around specific tree and shrub species. However, these strategies also enforce the spatial crop growth variability. The accuracy of farmers' comprehensive knowledge of agriculture, soil, animal husbandry and agro-forestry was confirmed by compartmentalized on-farm and on-station studies conducted in the same region, although explanations of farmers and researchers were not always the same. Farmers are aware of soil fertility management technologies, either coming from outside or developed within the farming community, but are often unable to translate these into action on a large scale. This is due to insufficient resources and socioeconomic, as well as institutional, constraints such as cattle ownership, land tenure, labour requirements and prices of inputs. Implications for agricultural research and technology generation are discussed.
The effect of nitrogen and the method of application on the yield of cauliflower
Authors: Everaarts A.P. , De Moel C.P.
Published: June 2020

The effects of nitrogen on cauliflower yields were studied over a period of 3 seasons at several locations. The cultivar used was Fremont in some cases and Plana in others. Different amounts of N fertilizer were applied at planting and were broadcast or band placed. Another treatment consisted of a split application. The number of plants harvested was not consistently influenced by the amount of N or the method of application. N application influenced the size of the marketable curd. At high yields, band placement had no advantage over broadcast application with regard to increasing the yield or reducing the amount of fertilizer supplied. Split application did not increase the yield and sometimes even decreased the yield. The best correlation between yield and N availability was found when the mineral nitrogen (Nmin) in the soil layer 0-60 cm at planting was taken into account. N fertilizer application was optimal when it produced an Nmin value of 224 kg/ha.
Dynamics of change of leaf attributes of Brussels sprouts in response to switches between high and low supply of nitrogen
Authors: Vos J. , Biemond H. , Struik P.C.
Published: June 2020

In a greenhouse pot experiment with Brussels sprouts grown in sand, 4 treatments were compared: a control without N limitation, a continuously N-deficient control and 2 treatments with a switch from the high to the low supply or vice versa. All treatments received nutrient solution at 9 dates during the experiment. The high-N and low-N controls received 1.96 and 0.56 g/application, respectively. In the high-low treatment the switch from the higher to the lower application rate took place 57 days after planting (DAP) and in the low high treatment the reverse switch took place 85 DAP; these 2 treatments received the same total amount of N. Plant N concentrations changed rapidly upon changes in N supply regime. When the supply rate was increased, N concentration increased in leaves that had completed their expansion. Changes in leaf growth started about 15 days after the switch in N regime. Leaves that were expanding at the switch responded by increase in area when N supply increased without a change in mass, i.e. specific leaf area increased. Leaf areas and specific leaf area of expanding leaves decreased when the N supply became smaller. The control of leaf size during initiation and expansion is discussed.
The effect of nitrogen and the method of application on nitrogen uptake of cauliflower and on nitrogen in crop residues and soil at harvest
Authors: Everaarts A.P. , De Moel C.P. , Van Noordwijk M.
Published: June 2020

The effects of the method and rate of nitrogen application on the efficiency of nitrogen utilization by cauliflower were studied during 2 seasons and at 4 locations. Maximum nitrogen uptake by the crop was ~310 kg/ha. Uptake of nitrogen was influenced neither by the method of application (band placement vs. broadcast) nor by splitting the applications (twice vs. once). The utilization efficiency decreased with increasing nitrogen rates. Independent of the amount of nitrogen applied, ~50% of the nitrogen taken up in the above-ground plant parts was removed from the field with the product. The amount of soil mineral nitrogen at harvest increased with an increase in nitrogen applied, but was not significantly influenced by band placement. With broadcast application, more nitrogen was sometimes found between the rows as compared to in the row. With band placement at the highest fertilizer rate, considerably more nitrogen was found where the fertilizer had been placed. The 'loss' of nitrogen from the crop/soil system during cultivation increased with increased availability of nitrogen. At the optimum application of nitrogen fertilizer ~100-120 kg/ha of nitrogen remained in crop residues and ~50-80 kg/ha in the soil (0-60 cm). Practical implications for the reduction of loss of nitrogen from crop and soil after harvest are discussed.
Effects of light intensity on growth, anatomy and forage quality of two tropical grasses (Brachiaria brizantha and Panicum maximum var. trichoglume)
Authors: Deinum B. , Sulastri R.D. , Zeinab M.H.J. , Maassen A.
Published: June 2020

Effects of light intensity on growth, histology and anatomy, and nutritive value were studied in seedlings of two shade tolerant species: Brachiaria brizantha and Panicum maximum var. trichoglume. They were studied under greenhouse conditions in pots with sandy soil and sufficient N and cut after a growth period of 8 weeks. High light intensity stimulated growth, tillering and yield per tiller and increased stem proportion. It greatly increased number of sclerenchyma cells, their wall thickness in all organs and the content of cell wall constituents. High light intensity also reduced concentrations of total N, NO3-N and ash appreciably. It reduced digestibility of cell wall constituents in leaf blades but increased it in leaf sheaths and stem, especially in Panicum. Variation in sclerenchyma tissue could be associated with variation in percentage of cell wall constituents, but not with variation in cell wall digestibility. The result of these effects of light intensity on composition of organs was a higher digestibility of organic matter of the whole crop at lower light intensity. Brachiaria was more tolerant to shade than Panicum with regard to growth, N-concentration and digestibility, but it accumulated more nitrate. It was suggested that light intensity may affect forage quality little under low nitrogen supply in the tropics, but effects may be larger at ample nitrogen supply. Individual species may partly divert from this general pattern.
Improving the efficiency of greenhouse climate control: an optimal control approach
Authors: Van Henten E.J. , Bontsema J. , Van Straten G.
Published: June 2020

A method to improve the efficiency of greenhouse climate control based on the framework of optimal control theory is described. By exploiting a dynamic model of the greenhouse crop production process, information on auction price, operating costs of the climate conditioning equipment and outdoor climate conditions, the optimal greenhouse climate control scheme balances basic costs against revenues for operating the equipment. In a greenhouse experiment (using lettuces) the behaviour of conventional greenhouse climate control by the grower was measured. Then, in simulation experiments, optimal control strategies were calculated for the same conditions (outdoor climate, auction price, energy price). The results support the conclusion that a considerable improvement in the efficiency of greenhouse climate management is possible. This improvement may well exceed 15%.
Potential of solubility, enzymatic methods and NIRS to predict in situ rumen escape protein
Authors: De Boever J.L. , Cottyn B.G. , Vanacker J.M. , Boucque C.V.
Published: June 2020

The percentage of feed protein escaping rumen degradation was measured by the in situ method (%EPsitu) for 29 compound feeds, untreated and formaldehyde-treated soyabean meal and 12 forages: 3 grass silages, 2 maize silages, fresh grass, grass hay, fodder beets, fresh potatoes, ensiled beet pulp, chopped ear-maize silage and brewers' grains. Loss of particles through bag pores was determined by the difference between the washable fraction (W) and the fraction soluble in borate-phosphate buffer at pH 6.7 (S). W - S was most pronounced for compound feeds (on average 14.4 percentage units), for brewers' grains and maize silages. A correction of %EPsitu, assuming that W - S degrades like the potentially degradable fraction, was not appropriate. Solubility in borate-phosphate buffer after 1 h, enzymic degradability by protease from Streptomyces griseus or ficin after 1, 6 and 24 h and near infrared reflectance spectroscopy (NIRS) (for compound feeds alone) were examined as a routine method to predict %EPsitu. With the buffer and S. griseus the effect of pH (6.7 vs. 8.0) and at pH 8.0 the effect of amount of substrate (500-mg sample vs. 20 mg N) were tested. With ficin, 500-mg samples were incubated at pH 6.7. Predictions were better when compound feeds and forages were considered separately. However, the best in vitro method was different for the 2 feed categories, being solubility in buffer for the compound feeds and enzymic degradation of a constant amount of protein with S. griseus at pH 8.0 for forages. NIRS showed potential to predict %EPsitu of compound feeds, but needs more reference samples. The Dutch feed tables appeared more accurate than the best in vitro method for compound feeds, but was too inaccurate for some forages like fodder beets, maize silage and ear-maize silage.
Farm decision making under risk and uncertainty
Authors: Backus G.B.C. , Eidman V.R. , Dijkhuizen A.A.
Published: June 2020

Relevant portions of the risk literature are reviewed, relating them to observed behaviour in farm decision-making. Relevant topics for applied agricultural risk research are proposed. The concept of decision making under risk and uncertainty is discussed by reviewing the theory of Subjective Expected Utility and its limitations. Subjective Expected Utility theory is the major framework for thinking systematically through complex issues of decision. Limitations of Subjective Expected Utility theory were that its application to unique decisions is doubtful, that it does not contribute to difficulties in determining the available decision alternatives, and that it is cast in a timeless setting, making the theoretic framework to a very limited extent helpful to solve real world decision problems. Most empirical studies indicate that farmers are risk neutral to slightly risk averse. It is doubtful whether decision makers could be classified according to their risk preferences. A presented overview of applied risk responses reveals much attention for diversification of the enterprise and of production practices, maintaining reserves, and farm expansion. Research reports on observed problems in farm decision making behaviour are lacking. Proposed topics for agricultural risk research include the assessment of the need for a strategic change, the creation of databases to determine both the (co)variances of input and output prices, the effectiveness of various kinds of decision support for different decision problems, and methods for applied scenario analysis to deal with long-run risk.
Factors changing farmers' willingness to grow trees in Gunung Kidul (Java, Indonesia)
Authors: Filius A.M.
Published: June 2020

Farmers' willingness to grow trees depends on many factors, and if governments or other organizations want farmers to grow more trees, these factors need to be understood. This article describes the expansion of the tree component in farming systems in recent decades in the Gunung Kidul district of Java. This trend is then explained with elements of the induced innovation model of agricultural development, viz. resource endowment, demand for products and institutional aspects. An increase in the productivity of staple crops seems to have been an important factor permitting farmers to plant trees. Another factor related to resource endowment that induced farmers to grow trees is the response to declining soil productivity as a result of erosion. The Indonesian government's trade and pricing policy for certain tree products has supported the favourable market trend for these products, and has induced farmers to plant fruit and fodder trees in particular. Improvement of the (physical) infrastructure has demonstrably encouraged tree growing. Examples are given of technological change in tree growing that result from farmers' own innovation as well as from research done by various organizations.
Nitrous oxide emission from dairy farming systems in the Netherlands
Authors: Velthof G.L. , Oenema O.
Published: June 2020

A large part of the nitrogen (N) input in dairy farming systems in the Netherlands is lost from the system via N leaching and volatilization of gaseous N compounds, including the greenhouse gas nitrous oxide (N2O). The aim of the present study was to quantify N2O emission from dairy farming systems in the Netherlands, using a whole-farm approach. A total of 14 N2O sources was identified and emission factors were derived for each of these using the literature. Figures are presented for the amounts of N2O produced/kg herbage N produced (ranging from 4 to 89 g N2O-N kg-1 herbage N), depending on soil type and grassland management. Using Monte Carlo simulations, variations in mean total N2O emissions from the different sources were calculated for 3 model dairy farming systems differing in nutrient management. These different farming systems were chosen to assess the effect of improved nutrient management on total N2O emission. The total direct annual N2O emissions ranged from 15.4 +or-9.4 kg N2O-N/ha for the average dairy farming system in the 1980s to 5.3 +or-2.6 kg N2O-N/ha for a prototype of an economically feasible farming system with acceptable nutrient emissions. Leaching-derived, grazing-derived and fertilizer-derived N2O emissions were the major N2O sources on dairy farming systems. The total direct N2O emissions accounted for 3.2 to 4.6% of the N surplus on the dairy farming systems, suggesting that only a small amount of N was lost as N2O. Total N2O emissions from dairy farming systems in the Netherlands were 13.7+or-5.1 Gg N/year, which is about 35% of the estimated total N2O emission in the Netherlands. It is concluded that improvement of nutrient management of dairy farming systems will significantly decrease the N2O emissions from these systems, and thus the total N2O emission in the Netherlands.
From natural forest to tree crops, co-domestication of forests and tree species, an overview
Authors: Wiersum K.F.
Published: June 2020

The process of domestication of tree crops has only been given limited attention. This process starts with the protection of natural forests and ends with the cultivation of domesticated tree crops. In this evolutionary process three types of human-influenced forest environments may be distinguished: (1) conserved forests, (2) modified forests, and (3) transformed forests. During the process of domestication an increasing input of human energy per unit of exploited forest takes place. Accordingly three phases in the domestication of forests may be distinguished: (1) an acculturalization phase in which social measures aimed at controlling the utilization of valuable tree species or patches of forests are implemented, (2) a phase of manipulation of wild tree species in which the socially-oriented management practices are enhanced with measures aimed at enhancing the (re)productive potential of valued species, and (3) a phase of cultivation of genetically modified tree crops. As a result of the co-domestication of forests and trees various types of forests and/or tree cultivation systems can be distinguished. So far more attention has been given to understanding the characteristics of the early and end phases than to the various intermediate phases represented by indigenous forest management and agroforestry systems. These are characterized by a modification of the highly diverse natural forest ecosystems to a state in which the biodiversity has been somewhat reduced, but in which a larger proportion of useful resources are present. Such systems provide interesting examples of the wide range of options for managing forest resources with varying degrees of biodiversity and productive values.
Extraction of non-timber forest products from tropical rain forests. Does diversity come at a price?
Authors: Boot R.G.A.
Published: June 2020

Tropical rain forests are rich in plant and animal species. The sustainable extraction of non-timber forest products has been advocated as a strategy to best conserve this diversity. However, the development and implementation of such exploitation systems, which aim to reconcile conservation and economic development, are still hampered by the lack of information on the biological sustainability of these systems, the impact of these exploitation systems on the biological diversity and the insufficient knowledge of the role of forest products in the household economy of forest dependent people and hence their prospects for economic development. Whether the exploitation of non-timber forest products from tropical rain forests is sustainable or not is still open to question, but data presently available on the biological, social and economic aspects of these extraction systems point at an interesting question: does diversity come at a price? Namely, low density of conspecifics, and thus products, and hence low productivity for those involved in the collection of forest resources. The paper will further discuss whether domestication of forest species provides an alternative for some of these species. Species are part of a complex ecosystem and their functioning is partly depended on the presence of other species in the system. The attributes of the species which have to be taken into account in order to make domestication of forest species successful are considered. Finally, the paper returns to the question of how to reconcile conservation and use of tropical rain forests. It will present a case for domesticating the forest instead of the species or, in other words, changing the forest composition without changing its structure and functioning, and maintaining acceptable levels of biodiversity.