bluuebunny/crossref_metadata_2025 huggingface dataset:
The forage and grain yield of cold-tolerant sorghum and maize as affected by time of planting in the highlands of Kenya.
Authors: Arkel H. van
Published: June 2020

In trials with sorghum and maize in the highlands of Kenya the effects of sowing date on the forage and grain yields were studied. Yields were regressed on sowing date in days after the start of the wet season, mean air temp. during the 1st 5 wk post-em. and sowing date index in a yield stability analysis. Grain yields varied more than total DM yields, indicating that correct sowing date was more important if crops were harvested for grain than for forage. Sorghum cv. E 1291 gave the highest grain yields and sorghum cv. E 6518 the highest DM yields under all conditions. The grain yield of E 1291 was less affected by delayed sowing than the grain yield of maize cv. H 613. In a dry yr delayed sowing was beneficial because it allowed a certain soil moisture reserve to be built up, but this beneficial effect disappeared if the duration of crop development exceeded the length of the wet season. If rainfall was heavy immediately after the dry season, delayed sowing had a pronounced negative effect on yields. Under such conditions DM yields decreased by 1.0 t/ha for each wk delay in sowing for both E 6518 and H 613; grain yields decreased by 0.41 t/ha wk and 0.47 t/ha wk for E 1291 and H 613, resp. All grain yields were positively correlated with av. mean air temp. and regression coeff. varied from 0.77 to 3.67 t/ deg C, but temp was confounded with rainfall and more work was needed to separate temp. and rainfall effects. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Relation between nutrition and fertility in pigs.
Authors: Hartog L.A. den , Kempen G.J.M. van
Published: June 2020

A review of experiments on the effect of energy and protein intake on fertility in gilts suggested that a high energy intake shortly before oestrus (flushing) increased ovulation rate. Although high energy intake gave more ovulations than low energy intake, embryonic mortality was greater. The most suitable sequence during rearing, flushing and early pregnancy seemed to be low, high and low energy, respectively. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Accumulation of heavy metals in the soil due to annual dressings with sewage sludge.
Authors: Hemkes O.J. , Kemp A. , Broekhoven L.W. van
Published: June 2020

In a long term field experiment 0, 6, 12 or 18 tonnes/ha/yr of sewage sludge (dry matter basis) were applied to permanent grassland. Sludge application markedly increased the contents of Cd, Pb, Zn, Cu, Ni, Cr, Mo, to a depth of 15-25 cm, but Co, Mn and Fe contents were increased only in the surface 5 cm of soil. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Methods for the recovery of nutrients and energy from swine manure. 1. Biogas.
Authors: Boersma L. , Gasper E. , Oldfield J.E. , Cheeke P.R.
Published: June 2020

The recovery of nutrients from pig manure (300 l/day discharged by 100 pigs) during digestion for biogas production amounted to 1435 kg N, 350 kg P and 490 kg K per year. When spread on the 15.26 ha of land required to grow the corn and soybean for the pig ration, each hectare would receive 94 kg N, 23 kg P and 32 kg K per year. The energy value of the recovered fertilizer represents 4.4% of the total energy input of the pig production system. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The analysis of volatile N-nitrosamines in the rumen fluid of cows.
Authors: Broekhoven L.W. van , Davies J.A.R.
Published: June 2020

For 1 week 2 nonlactating Friesian cows were given hay with potassium nitrate 80 mg/kg bodyweight daily. Then nitrate 120 mg/kg was given into the rumen and rumen fluid was sampled every 15 min for the next 165 min. Greatest concentrations of nitrate, 3.9 and 2.9 mmol/litre in each cow, were present after 90 to 105 min. Dimethylnitrosamine was the only volatile N-nitrosamine found. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Reproductive traits in primiparous sows in relation to feeding level.
Authors: Hartog L.A. den , Steen H.A.M. van der
Published: June 2020

To estimate the effect of plane of nutrition and induction of oestrus with 400 IU of pregnant mare serum and 200 IU of human chorion gonadotropin, 113 primiparous Dutch Landrace sows were given 4 or 2.5 kg feed daily from weaning to oestrus. The feed included maize 12, barley 18, soya bean oilmeal 15, wheat bran 15, cassava pellets 13, maize gluten feed 5, lucerne meal 8, citrus pulp 5.5, molasses 5, animal protein 1.1%, minerals and vitamins. The number of sows in oestrus within 21 days of weaning was 69 (61%). Within 7 days of induction of oestrus on day 21, 41 sows were in oestrus (36%). On day 21, 37 (65%) of the better-fed sows were in oestrus and 32 (53%) of the poorer-fed group. The interval from weaning to spontaneous oestrus was 9.1 and 8.2 days, respectively, and ovulation rate 15.2 and 14.8. Size of the sexual organs was not affected by feeding level. Rate of gain of sows during the interval from weaning to oestrus was influenced by feeding level: +4.1 kg and -2.3 kg, respectively, for the sows in oestrus within 21 days of weaning. Sows with induced oestrus shed significantly more ova than did sows in which oestrus was not induced (21.7 and 15.0, respectively). Loss of weight, loss of heart girth, and loss of backfat thickness during previous lactation (absolute and relative) did not differ for sows with or without induction, but was higher for sows with a spontaneous oestrus between 10 and 21 days after weaning than for sows with an oestrus within 10 days after weaning. Ovulation rate was not affected by weight at weaning or at oestrus, weight loss during lactation, gain during the interval from weaning to oestrus or size of the preceeding litter at birth. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Evaluation of a screening technique for manganese toxicity in relation to leaf manganese distribution and interaction with silicon.
Authors: Blatt C.R. , Diest A. van
Published: June 2020

A screening technique utilizing a flowing nutrient culture was used to evaluate 20 lettuce cultivars differing in the severity of the toxicity symptoms marginal yellowing and necrosis in older leaves. Growth, leaf and root Mn contents and toxicity ratings (1 = no symptoms to 5 = high toxicity) were recorded over six Mn and two Si concentrations. A test solution of 0.5-1.0 mg/l Mn produced consistent toxicity ratings and the ratings for tolerant and sensitive cultivars were similar to ratings for the same cultivars grown under glasshouse conditions. Total Mn content in leaves was not a useful index for Mn sensitivity. Increased Si resulted in a repression of toxicity symptoms and decreased shoot/root Mn ratios in 12 cultivars.
ADDITIONAL ABSTRACT: A screening technique was developed to evaluate lettuce cultivars for manganese tolerance in flowing nutrient culture. Considerable variation in the sensitivity of 20 cultivars was observed, as shown by visible symptoms. However there was no correlation between accumulation of Mn in leaves and roots and the degree of Mn tolerance. Increasing silicon in the solution repressed Mn toxicity symptoms, but had variable effects on the Mn content of leaves and roots. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The mentek disease of lowland rice in Indonesia.
Authors: Van de Goor G.A.W.
Published: June 2020

The factors which appear to influence the development of mentek disease in rice (the symptoms closely resemble those of potash deficiency in other cereals) are discussed.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of light intensity on the photoperiodical behaviour of the rice plant.
Authors: Worker Th.M.
Published: June 2020

The photoperiodic behaviour of two varieties of rice, Kameji and Nero di Vialone was compared in an experiment in 1952 in which the rice plants were grown in 12 hr. daylight only and in 12 hr. daylight plus 6 hr. light from a fluorescent tube with an intensity ranging from 1-80 foot-candles. The extension of the period sowing-to-earing caused by increasing intensity of the supplemental light was most notable over ranges of light-intensity of 1-2 and 1-10 foot-candles in the case of Nero di Vialone and Kameji, respectively. Increasing light-intensity from 2-80 foot-candles had no effect on the length of the period sowing-to-earing in the case of Nero di Vialone; in the case of Kameji there was a steady increase of the length of the period sowing-to-earing as the light intensity was increased from 10-80 foot-candles.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Research on varieties in connection with the Netherlands List of Varieties.
Authors: Groenewolt J.K.
Published: June 2020

With few exceptions, only seed of varieties appearing in the Netherlands List of Varieties is allowed to be marketed. An account is given of the procedure (including field trials) which is followed in determining which varieties of field crops (including forage crops and green manures) and herbage crops are suitable for including in the list.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
New instruments for agricultural research.
Authors: Thijssen H.A.C. , De Wit C.T. , Van Vollenhoven E. , Timmers H.J. , Admiraal L.
Published: June 2020

The following instruments have been developed and are briefly described: (a) mechanical ground-water-level recorder, (b) a resistance bridge for measuring soil- and water-salinity, soil moisture and soil temperature, (c) oscillating micropsychro-meter, (d) field apparatus for rapid determination of soil moisture.-W.J.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of crop management on yield formation in cereals. [German]
Authors: Fischbeck G.
Published: June 2020

Grain yield of winter wheat in a given yr varied between 3.19 and 5.85 t/ha and between 3.2 and 4.7 t in 2 sets of data compiled in 1969-79 and 1972-8, respectively. no single factor including soil type, cv., preceding crop or N application was responsible for the yield differences. Variance for yr X location was responsible for 50% of grain yield variation in a series of field trials; cv.-specific crop management was only important at high yield levels. Preventive application of fungicides against major diseases increased the av. grain yield of 16 wheat cv. by 1.38 t. From trials in 1976-80 with winter wheat and spring barley, the number of grains/m2 was the most important criteron differentiating yield between and within the crops. Correlation between grain number and yield decreased as yield increased but 1000-grain wt. compensated for this effect. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Nutrient absorption by pea plants during dinitrogen fixation. 2. Effects of ambient acidity and temperature.
Authors: Beusichem M.L. van
Published: June 2020

Nutrient uptake and biological dinitrogen fixation were studied using effectively nodulated pea plants which had been grown hydroponically for 6 wk in nutrient sol. of pH 4.0, 5.5 or 7.0. The pH of the root medium was kept constant by automatic titration and the temp. maintained at 13 deg C throughout. Although the N content of the plants grown at pH 4.0 and 7.0 was lower in comparison with that of plants of the pH 5.5 treatment, no N deficiency symptoms were observed. About the same number of nodules was formed in each of the treatments but they were smallest in the pH 5.5 treatment. Nevertheless, the total amount of dinitrogen fixed/plant at pH 5.5 was larger than that at higher or lower acidity. This was due to a higher nitrogenase activity/unit of nodule wt., which could be ascertained by an in vivo acetylene reduction test. In all cases more nutritive cations than anions were absorbed resulting in net proton extrusion by the roots. Both cation and anion uptake and hence the extent of proton release were affected substantially by ambient acidity. Plants grown at pH 7.0 generated 2.3 times as much acidity as plants grown at pH 4.0. The symbiotic dinitrogen fixing process was repressed by raising the temp. to 25 deg which resulted in no DM production and proton release and accelerated the onset of maturation. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Seed viability of pigeon pea stored in two environments.
Authors: Rao N.K. , Maesen L.J.G. van der , Remanandan P.
Published: June 2020

Pigeonpea cv. ICP-1, -26, -2624, -6443 and -6997 were stored at 15-20 deg C and RH and compared with ambient room conditions at ICRISAT. After 4 yr in cool storage the viability of all cv. except ICP-6997 remained >92%. At room temp. ICP-6997 lost viability completely, ICP-2624 maintained 53% viability and ICP-26, -1 and -6443 germinated 44, 24 and 4%, resp. Plastic bottles were the best containers at ambient room temp. and in cool storage no difference was detected between them and paper and cloth bags. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Contamination of soil and street dust with lead and cadmium near a lead smelter at Arnhem, Netherlands.
Authors: Keizer M.G. , Hooghiemstra-Tielbeek M. , Haan F.A.M. de
Published: June 2020

An investigation was carried out into lead and cadmium pollution of soil and street dust in the vicinity of a secondary lead smelter in Arnhem, Netherlands. A significant correlation was found between the Pb content of the soil and the distance from the smelter. In the sampling area 1 km around the smelter the average Pb content was 370 mg/kg in the 0-5 cm soil layer and 256 mg/kg in the 5-20 cm soil layer. Mean Cd contents were 1.60 and 1.28 mg/kg, respectively. Correlation between the contents in both layers was low for Pb and high for Cd, owing to different solubilities of the metals. There was a weak relationship between the Pb and Cd contents of the soil, suggesting that only part of the metals originated from the same source. Mean heavy metal concentrations in street dust (fraction < 0.3 mm) were 761 mg Pb/kg and 3.81 mg Cd/kg. Correlation between both heavy metals in street dust was high, suggesting the same sources of pollution (mainly traffic). The most important sources of Pb and Cd pollution in the area were the lead smelter and traffic. (Abstract retrieved from CAB Abstracts by CABI’s permission)
New cultivation techniques for cashew (Anacardium occidentale L.).
Authors: Van Eijnatten C.L.M. , Abubaker A.S.
Published: June 2020

The cashew tree produces its fruits at the periphery of the canopy but experiments in Kenya showed that increasing planting distances from 6 to 15 m did not influence yields/ha although they led to increased yields/tree. Productivity can be much increased, however, by planting cashews in hedgerows 9 to 12 m apart with 2 to 3 m within rows and using a clonal cashew cv. It is estimated that for the first 5 years of a new plantation gross margins would be 459, 519, 2827 and 2244 sh/ha annually, respectively, for traditional growing without charcoal production, traditional growing with charcoal production (from prunings at rejuvenation or replacement), hedgerows at 9 m, and hedgerows at 12 m. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Further studies on the effect of fat supplementation of concentrates fed to lactating dairy cows. II. Total digestion and energy utilization.
Authors: Honing Y. van der , Tamminga S. , Wieman B.J. , Steg A. , Donselaar B. van , Gils L.G.M. van
Published: June 2020

For wether sheep given 300 g hay and 800 g concentrates the addition of fat (beef tallow:palm kernel oil 9:1) to concentrates at 7 or 12% tended to decrease crude fibre digestibility and increased crude fat digestibility. For 2 rumen-fistulated cows given concentrates containing 7% fat, or 12% fat free or adsorbed on carrier, and 2 cows with fistulae and reentrant duodenal cannulae given concentrates with 12% fat in rations with hay:concentrate 1:2, there were no significant differences between diets in the digestibility of any nutrient; fat digestibility was decreased at feed intakes above maintenance, particularly with the 12% fat concentrates. The use of a carrier in the 12% fat concentrates did not affect nutrient digestibilities for sheep or cows. Inclusion of fat in concentrates increased the metabolizability of sheep diets but there were no significant differences among cattle diets, although methane losses tended to decrease as fat content increased. Additional energy from fat tended to be retained rather than used for milk yield. ME utilization for milk, storage and maintenance was 61-62.5%, tending to be highest with the 12% adsorbed fat. [See DSA 45, 5398 for part I.] (Abstract retrieved from CAB Abstracts by CABI’s permission)
A laboratory silo permitting repeated sampling.
Authors: Spoelstra S.F.
Published: June 2020

A new type of laboratory silo for studying silage fermentation is described. Samples are taken manually from the silo using a glove mounted on the apparatus. Introduction of air during sampling is prevented by a sample lock. In a preliminary experiment, the accumulation and disappearance of nitrite in wilted perennial ryegrass ensiled in the laboratory silo was monitored and there was less variation in nitrite content than when the same grass was ensiled in 2-l flasks. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Developments in rural areas in relation with developments in land and water management research in the Netherlands. 2. Rural development plans and research.
Authors: Bijkerk C. , Oostrom C.G.J. Van
Published: June 2020

The relationship between improvement plans for rural areas in the Netherlands and agricultural research is discussed. This research is briefly reviewed, under the headings water management (including water supply, drainage, evaporation, geohydrology and water quality), soil technology (including tillage requirements, subsidence, and soil physical properties in urban areas) and land layout (including agricultural, rural recreational, ecological and urban uses). (Abstract retrieved from CAB Abstracts by CABI’s permission)
Distribution of dry matter and nitrogen between the different plant parts in intact and depodded soyabean plants after flowering.
Authors: Alberda T. , Boer J.M. W-de
Published: June 2020

Soyabeans were grown in nutrient sol. in a controlled environment. 50% developed normally but the rest were depodded once a wk. During 9 wk of seed development, growth of roots, shoots, leaves and pods as well as their total percentage N was monitored by weekly harvests. In the normal plants, only the pods continued to increase in dry wt. after the 2nd harvest and the wt. of the other plant parts remained nearly constant. N in roots and stems decreased slightly during pod filling and N in the leaves decreased considerably. Increase in N in the pods was relatively greater than the increase in total dry wt. The amount of N taken up from the nutrient sol. and that redistributed between plant parts was calculated. In the depodded plants, DM continued to accumulate in all plant parts throughout the experiment including the detached pods. The amount of N also increased in all plant parts. N uptake/unit DM produced was about the same for both groups of plants. The results are discussed in relation to the hypothesis that in leguminous plants the fixation or uptake of N by the roots cannot cope with the demand of the developing pods so that the necessary withdrawal from other plants parts, especially the leaves, causes the plants to die prematurely. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Displacement of lead from polluted top soil by treatment with HCl or FeCl₃.
Authors: Hooghiemstra-Tielbeek M. , Keizer M.G. , Haan F.A.M. de
Published: June 2020

In batch, column and lysimeter experiments the addition of HCl or FeCl3 to a soil heavily polluted with lead markedly reduced the soil pH and resulted in the dissolution of lead. The amount of lead dissolved from the soil was strongly correlated with the pH of the system: at pH 2.5, 45-65% of the total lead in the soil was extracted in batch experiments. In the lysimeter experiment 77% and 66% of the total lead was displaced from the 0-10 cm soil layer by HCl and FeCl3, respectively. The displaced lead was fixed in the 10-30 cm soil layer. No lead was detected in the effluent. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Requirement of fattening pigs for gross and digestible lysine in feeds with easily and poorly digestible protein.
Authors: Borggreve G.J. , Veen W.A.G.
Published: June 2020

In a feeding trial with 96 barrows and gilts and based on a 2 x 3 experimental design, feeds containing poorly digestible protein sources were compared with feeds containing easily digestible protein sources, at lysine levels of 6.9, 7.5 and 8.1 g/kg. In the liveweight range from 30 to 70 kg daily rate of gain on both types of diet was higher with more lysine. From 30 to 110 kg, rate of gain was proportional to lysine content only for the diet with poorly digestible protein. Requirement for gross lysine seemed to be 7.0 to 7.5 g/kg for feed with easily digestible protein and at least 7.9 g/kg for that with poorly digestible protein. In a digestibility trial with pigs weighing about 30 kg, apparent digestibility of feeds with lowest and highest lysine levels was determined. Digestibility coefficient of crude protein was 7 to 12 units lower than figures given in the CVB table (Central Bureau on Livestock Feeding in the Netherlands). Digestibility coefficients for lysine were only marginally lower than for crude protein. On the basis of digestibility coefficients determined for lysine, it was possible to calculate the requirement for digestible lysine for the pigs used in the feeding trial. Results showed 5.3 to 5.7 g/kg for the diet containing easily digestible protein, and at least 5.6 g/kg for that with poorly digestible protein. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Relationships between soil albedos and soil and air temperatures.
Authors: Stigter C.J. , Mjungu Y.B. , Lutege P.B.M. , Waryoba J.M. , Othieno C.O. , Mwampaja A.R.
Published: June 2020

Relationships are derived between near-interface soil and air temperatures and the albedos and temperatures of the interface under low evaporation conditions. Simple theoretical approximations of these relationships are established for nearly identical soil conditions with different albedos. A demonstration experiment is discussed which proves that this theory is valid at the surface of plastic-covered dry soil. Field temperatures for bare and black plastic-covered relatively dry soil in Kenya at 7.5 cm depth are also in good agreement with the theory. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Shading: a traditional method of microclimate manipulation.
Authors: Stigter C.J.
Published: June 2020

Microclimate management and manipulation are among the methods which have traditionally been employed on small plots in low-input agriculture. Methods employed by smallholders to shade soil, seedlings, plants and crops to protect them from environmental stresses and to improve their yield capacity are described. Specific examples collected from Tanzanian practice, including maize, millet, wheat, potatoes and sunflowers grown under trees, are described as evidence of the use of shading methods in traditional farming. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of energy intake of gilts on the supply of metabolizable energy and protein deposition.
Authors: Hartog L.A. den , Verstegen M.W.A.
Published: June 2020

Two trials with 16 gilts of 35 kg and 16 gilts of 64 kg were made. Rations were prepared by mixing two basal feeds in different ratios. Four different energy levels were used in which energy was expressed as multiples of maintenance (M) requirement (treatments: 1 = 2.8 to 3.0 M; 2 = 2.4 to 2.6 M; 3 = 2.1 to 2.2 M; 4 = 1.8 to 1.9 M). Digestibility of energy was not influenced by treatment (mean 83.5%). Feed components (except protein) were better digested in pigs at a larger weight (e.g., energy 3.2 and crude fibre 5.7 percentage units). Rations of weight class 2 were based on a different ratio of the basal feeds than the rations of weight class 1. Metabolizable energy content of the ration was similar for the four diets (mean 12.4 kJ/g). After correcting for differences in feed composition the metabolizability tended to be slightly depressed at the high levels of energy intake. Protein gain was determined for each gilt. Protein and fat gains were calculated from the rate of gain and daily energy intake at the same amount of digestible protein intake. Protein gain was reduced at a level of energy intake below 2.5 M. Fat gain was influenced more by feeding level than protein gain. Fat gain was diminished when energy intake was reduced. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Vegetative propagation of Nidularium fulgens Lem. in vitro.
Authors: Pierik R.L.M. , Steegmans H.H.M.
Published: June 2020

Shoot tips were isolated and placed on solid agar media (half strength Murashige and Skoog macroelements, 3% sucrose, vitamins, 1 mg l-1 BA and 0.1 mg l-1 NAA). After one month, shoots which had begun to grow were transferred to liquid media (composition as above but with no agar and BA reduced to 0.3 mg l-1). After 12 weeks about 5 axillary shoots per explant were produced. Subsequent planting of these shoots in soil achieved almost 100% rooting. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The influence of the degradability of concentrate protein in the rumen and of the lysine content of the concentrate on growth and feed efficiency in early-weaned calves.
Authors: Veen W.A.G. , Vahl H.A.
Published: June 2020

In two feeding trials involving 96 rearing calves each and based on a 2 x 3 factorial design, a comparison was made between concentrates containing rapidly and slowly rumen-degradable protein and among concentrates with lysine 6, 7 and 8 g/kg or 7, 8 and 9 g/kg. In a third trial involving 84 animals, 2 feeds containing rapidly and slowly degradable protein were compared. Calves were weaned at 6 weeks and remained in the trial an additional 5 to 6 weeks. Concentrates were fed freely from 21 days old and in 2 trials after weaning the calves were fed according to a plan based on body weight. Hay or prewilted grass silage was given freely. Difference in protein degradability between feeds with rapidly degradable protein and those with slowly degradable protein was 28 and 36% in the second and third trials. Treatments involving concentrates with slowly degradable protein resulted in a higher daily weight gain. Feed efficiency was usually improved. Increase in lysine content of the concentrate from 6 to 8 g/kg or from 7 to 9 g/kg resulted in a significant linear rise in daily weight gain and a linear rise in feed efficiency. In 2 of the 3 trials intake of roughage (1 x prewilted grass silage, 1 x hay) was positively affected by presence in the concentrate of slowly degradable protein. Lysine content of the concentrate had no effect on roughage intake. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Prospects for grassland utilization in Eastern Europe.
Authors: Dijk G. van , Hoogervorst N.
Published: June 2020

The influence of agricultural, economic and political aspects on grassland production are described and discussed and reasons to account for the lower economic importance of grassland in Eastern than in Western Europe are given. The input of grassland to food production, its production and utilization, the ecological suitability of the area for grassland production, its place in the general structure of agricultural production and in particular in relation to the agricultural policy of Eastern Europe is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Consequences of clustering in parasite-host relations of the cereal aphid Sitobion avenae: a simulation study.
Authors: Rabbinge R. , Kroon A.G. , Driessen H.P.J.M.
Published: June 2020

The quantitative effects of the patchy distribution of Sitobion avenae on its relationship with the parasite Aphidius rhopalosiphi were studied using a simulation model. The model computations were compared with field data obtained in the Netherlands. Various hypotheses on the parasite-host relationship were tested. The functional response and aggregation of the parasites showed that clustering increases the effect of parasites on the population development of S. avenae, but the parasite does not prevent population upsurge even when it shows clear aggregation to host clusters. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Simulation of the production pattern of rape-seed on the basis of a field experiment.
Authors: Backx M. , Duivenvoorden J. van , Goudriaan J.
Published: June 2020

A simulation model, an extension of SUCROS, for growth and development of rape (Brassica napus) seed on the basis of laboratory and field measurements gave a final seed yield of 2.9 t/ha. Light interception by the inflorescence caused a reduction of 4, 8 and 5% in total DM yield, stem wt. and seed wt., resp. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of energy intake on development and reproduction of gilts.
Authors: Hartog L.A. den
Published: June 2020

680 Dutch Landrace gilts were fed diets containing 3.0, 2.5, 2.1 or 1.8 times the metabolizable energy required for maintenance for 26 wk beginning at 12 wk of age. Gilts not showing oestrus by 38 wk of age were hormonally induced. The number of gilts showing spontaneous oestrus, embryo survival rate, number of liveborn piglets per litter, av. piglet birth weight and homogeneity of the litter (standard deviation of birth weight within a litter) were not affected by energy intake. The number of liveborn piglets per 100 gilts in the litters conceived to insemination at the 1st spontaneous oestrus was 386, 399, 437 and 438 for the 4 diets resp.; when data for hormonally induced gilts were included, the corresponding values were 485, 486, 599 and 579, indicating that in terms of reproductive performance, when the diet contains adequate protein, there is no need to supply more than 2.1 times the metabolizable energy required for maintenance. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Comparative investigation into the effect of fertigation and of broadcast fertilization on the yield and nitrate content of lettuce (Lactuca sativa L.).
Authors: Bakker M.J. , Slangen J.H.G. , Glas W.
Published: June 2020

Three [unnamed] cultivars were grown successively during March to May, June to July, and July to August 1983 on a sandy soil. For each of these field experiments the treatments were: no N application, and fertilization with various amounts of ammonium nitrate, either as split applications via irrigation water or as a single broadcast application. Fertigation increased the availability and uptake of N and increased the nitrate content of the crop compared with broadcast fertilization. A second-degree polynomial model fitted the fertilization:NO3-content data. In the first cropping, yield was significantly higher when N was applied by fertigation compared with broadcast application, but in the following croppings there was no significant difference. However, it is suggested that the yield difference in the first cropping may be related to the very wet spring conditions (a 56 mm rain surplus compared with 105 and 116 mm deficits in the following two experiments) when leaching of NO3 from the upper soil layer would be expected. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The formation of volatile N-nitrosamines in laboratory-scale grass and maize silages.
Authors: Broekhoven L.W. van , Davies J.A.R.
Published: June 2020

Fresh grass and maize samples from experimental fields with different fertilizer regimes were ensiled in the laboratory in glass preserving jars. The resulting silages were analysed for the presence of volatile N-nitrosamines with a Thermal Energy Analyzer. In the grass silages, up to 4 micro g N-nitrosodimethylamine (NDMA)/kg was found. In the maize silages no NDMA was found above the limit of detection (0.2 micro g/kg). (Abstract retrieved from CAB Abstracts by CABI’s permission)
Apple growing potentials in Europe. 2. Flowering dates.
Authors: Kronenberg H.G.
Published: June 2020

A method of calculating flowering dates of apple in Europe is presented, based on dates of fulfilment of the cold requirement, temperature sums and minimum temperature per month. Calculated and reported dates were compared. With the exception of the most southern part of the growing area an acceptable agreement was found. Differences between both values were less than 5 days in 65% of the cases, which is less than 2.5-5% of the duration of the period that apples are hanging on the trees. [For part 1 see Horticultural Abstracts 50, 2376.] (Abstract retrieved from CAB Abstracts by CABI’s permission)
A stochastic model for the simulation of management decisions in dairy herds, with special reference to reproductive performance.
Authors: Dijkhuizen A.A. , Hibma S. , Renkema J.A.
Published: June 2020

A 15 year simulation was carried out in order to test a model for dairy cattle culling. Provisional results indicate that decreasing max. allowed calving interval from 520 to 360 days decreases herd income due to adverse effects on herd life. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The health condition of the Dutch forests in 1984.
Authors: Boer W.M.J. den , Tweel P.A. van den
Published: June 2020

A nationwide survey of forest health in 1984 showed that 1.5% of all trees were dying, 8% were sick and 40% showed signs of reduced vitality (premature leaf-fall, etc.). Only 43.5% of conifers were healthy compared with 67% of broadleaves. Forests in most coastal regions and in the extreme NE were still over 90% healthy. Results suggest that air pollution is a more likely cause of the decline than drought, pests or fungal diseases, and furthermore that NH3 pollution from intensive livestock rearing may be partly involved. Since 1982 Diplodia pinea has appeared as a secondary pathogen of declining stands. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Estimation of blood (plasma) volume in sheep with Evans blue and bromsulphalein.
Authors: Waversveld J. van , Bruchem J. van
Published: June 2020

Tests in a wether fitted with a jugular catheter showed that, after application of correction factors calculated by multiple regression analysis, blood volume could be measured with Evans Blue and blood plasma volume with bromsulphalein. Mean haematocrit value corresponded to 28% of the blood volume and 22.8% of the blood plasma volume. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Influence of nitrogen on sown and ratooned upland kangkong (Ipomoea aquatica Forsk.) at two planting densities.
Authors: Linnemann A.R. , Louwen J.M. , Straver G.H.M.B. , Westphal E.
Published: June 2020

Kangkong cv. Large Leaf was grown in a glasshouse at 2 densities (20 or 44 plants/msuperscript 2) and at 4 rates of N as calcium ammonium nitrate. The crop was either ratooned (5 crops) or cut and resown (3 crops) starting 6 weeks after sowing. Increasing the rate of N application from 100 kg/ha to 250, 500 and 750 kg/ha increased the total at 18 weeks by 3.8, 5.1 and 6.1 kg/msuperscript 2, respectively, and increased the crop nitrate content from 599 mg/kg fresh weight at 100 kg/ha to 3812 mg/kg at 750 kg/ha; stems had a higher nitrate content than leaves. The high plant density gave a 3 kg/msuperscript 2 greater yield than the low density, and ratooning gave a 5 kg/msuperscript 2 greater yield than the resowing method. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Dry matter production and nitrogen utilization in cropping systems with grass, lucerne and maize. 1. Comparison of crop characteristics, growth and production.
Authors: Sibma L. , Spiertz J.H.J.
Published: June 2020

DM production and crop characteristics of Medicago sativa were studied in comparison with Lolium perenne and maize under temperate conditions and various N applications. Annual DM yields of M. sativa ranged from 13.4 to 18.1 t/ha and were comparable to those of L. perenne and maize. However, the digestibility of M. sativa was lower than that of L. perenne cut for silage and that of maize. Despite significant differences in leaf:stem ratio, specific leaf area and LAI, full light interception was achieved with the same amount of DM for L. perenne and M. sativa. After defoliation by cutting, the time taken to regenerate a closed crop canopy did not differ. DM losses of M. sativa by root and shoot senescence were measured. The decline in tap root number was compensated for by the number of shoots per tap root. It was concluded that the yield potential of M. sativa could be improved by breeding for earlier cv. with a good persistence of roots and shoots. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Dry matter production and nitrogen utilization in cropping systems with grass, lucerne and maize. 2. Nitrogen yield and utilization.
Authors: Spiertz J.H.J. , Sibma L.
Published: June 2020

The N yield and the N use efficiency were studied in a 3-year experiment with various cropping systems of Lolium perenne, Medicago sativa and maize. N yields of L. perenne and maize were about 450 and 200 kg/ha, resp. N yields of M. sativa ranged from about 400 to 600 kg/ha depending on crop age and weather conditions. N fixation rates of M. sativa were assessed in 1982 and ranged from 107 to 507 kg/ha for high (450 kg N/ha) and no N fertilization, resp. The after-effects of 1-, 2- and 3-year crops of L. perenne, M. sativa and maize on the DM and N yields of a test crop of maize were measured. Depending on the age of the preceding L. perenne crop, annually supplied with 450 kg N/ha, the N after-effects ranged from 120 to 175 kg/ha. The after-effect of a previous cropping with M. sativa was independent of the N dressing and ranged from 140 to 175 kg/ha. For comparison, the after-effect of a preceding maize crop ranged from 90 to 110 kg/ha. Mineral soil N reserves were determined in spring and autumn. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Differences between genotypes of tomato (Lycopersicon esculentum Mill.) in foliar contents of total phosphorus, total nitrogen and nitrate nitrogen, under low light intensity and low night temperatures.
Authors: Dijk S.J. van de
Published: June 2020

Six tomato genotypes were grown in pots of fertilized soil under low light intensity (24 W/msuperscript 2), a day temperature of 19 degrees C and night temperatures of 14 degrees , 10 degrees or 6 degrees C. Significant differences between genotypes in nutrient contents of the leaves were established. For all the nutrients studied, contents were highest under the 19 degrees C/6 degrees C regime. Irrespective of temperature, Eurocross BB, Baby, Stupicke Polni and IVT line 2 had the highest P contents, while IVT line 2, Baby and Stupicke Polni had the highest contents of total N, nitrate N and reduced N. Differences were greatest for nitrate N, with Stupicke Polni being especially noted for its high contents under all 3 temperature regimes. Plant development was not limited in any of the genotypes or treatments by uptake and translocation of P and N, nor by the rate of nitrate reduction. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A decimal code for the development stages of maize and its relation to accumulated heat units.
Authors: Groot J.J.R. , Kropff M.J. , Vossen F.J.H. , Spitters C.J.T. , Rabbinge R.
Published: June 2020

A detailed phenological scale for maize was developed for use under W. European conditions. Primary and secondary growth stages were distinguished and characterized with a decimal code. Growth stages were easily recognizable in the field. Development codes were related to an ontogenetic time expressed in accumulated temp. by using detailed phenological observations from 2 field experiments. An approx. linear relationship was found between accumulated temp. and development codes with a discontinuity around anthesis. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Geogenesis and pedogenesis of well drained brown soils on the youngest Late Weichselian Meuse terrace in North Limburg, Netherlands.
Authors: Jongmans A.G. , Miedema R.
Published: June 2020

The Meuse terraces of Late Weichselian and Holocene age can be subdivided into 4 levels. The youngest Late Weichselian terrace occurs partly along and close to the present-day Meuse. On recent soil maps the well drained brown soils, occupying the highest positions of this terrace level, have been indicated as Plaggepts. This implies the presence of a plaggen epipedon of more than 50 cm thick. Three characteristic soil profiles were studied macromorphologically and micromorphologically and samples were analysed for particle size distribution and selected chemical properties. It is concluded that the brown top-soils are due to periodic Holocene sedimentation followed by homogenization. The sandy loam and finer-textured Late Weichselian subsoils have a clear argillic horizon. These soils should be classified as Alfisols (Luvisols) rather than Plaggepts. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Changes in blood acid-base characteristics, haemoglobin and lactate concentrations due to increasing moderate stress in pigs.
Authors: Wal P.G. van der , Engel B. , Essen G. van , Hulshof H.G.
Published: June 2020

Blood samples were collected by indwelling ear vein catheter from pigs (100 kg body weight) at rest and at different stages of increasing moderate stress. The stress increased from being forced to stand to fixation by maxillary sling alone and combined with stimulation with an electric goad. Stress caused significant decreases in blood pH, base excess and, at lower levels of significance, standard bicarbonate, while pCO2 and lactate increased significantly. Respiration rate was not affected. It is concluded that stress caused a combined respiratory and metabolic acidosis, although both components of the acidosis might originate from changes in muscle metabolism. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The effect of compaction of the arable layer in sandy soils on the growth of maize for silage. 1. Critical matric water potentials in relation to soil aeration and mechanical impedance.
Authors: Boone F.R. , Werf H.M.G. van der , Kroesbergen B. , Hag B.A. ten , Boers A.
Published: June 2020

A new approach in defining the range of soil structure for optimal maize production is proposed. The effect of different degrees of compaction of ploughed sandy soils on soil aeration and mechanical impedance and on root and shoot growth of maize was tested in 5 model field experiments in the eastern Netherlands. In this first paper the effects on soil aeration and penetration resistance are described. The narrower the range of matric water potentials which allow unimpeded root growth, the greater the potential risks for plant growth and the greater the need for a controlled supply of water. Soil structures which substantially impede root growth even at the most favourable water potential are classified as dangerous. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Phytopathology at the Wageningen Agricultural University.
Authors: Zadoks J.C.
Published: June 2020

Contributions of the Dep. to phytopathology are described, including ecology of soil-borne fungi, epidemiology, phytopharmacy and physiology of host-parasite interactions. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Quantitative root ecology as element of soil fertility theory.
Authors: Noordwijk M. van , Willigen P. de
Published: June 2020

Nutrient use efficiency with special reference to the soil/plant system, soil fertility theory relating to fertilizers, plant nutrition, soil properties and root ecology and aspects of quantitative root ecology are considered and an approach to modelling the relation of root ecology to soil fertility theory is outlined. (Abstract retrieved from CAB Abstracts by CABI’s permission)
The concept of carrying capacity and land-use.
Authors: Geerling C. , Bie S. de
Published: June 2020

Land use is far from sustained in large parts of the Third World. Ecosystems and sociological systems are degraded as a result of resource depletion. Restoring the equilibrium between exploitation and the availability of resources is a matter of economic and ecological survival for both man and nature in these systems. The concept of carrying capacity lends itself to analysis of actual and potential land use which in turn makes it possible to identify the development potential and the limiting factors which may be alleviated by inputs in order to reduce degradation and raise productivity. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Some recent developements and approaches in soil protection research.
Authors: Haan F.A.M. de , Keizer M.G. , Lexmond T.M. , Reimsdjik W.H. van , Zee S.E.A.T.M. van der
Published: June 2020

Evaluation of soil quality occupies a key position in investigations of soil protection. When quality is related to soil pollution, contaminant behaviour in the soil system is important. An important aspect is contaminent mobility, both with respect to its transport to other environmental compartments and to its uptake by organisms. Behaviour of compounds in soil is governed by a large number of variables which can be compound-related and soil-related. Compound speciation and factors affecting 'bio-availability' are briefly reviewed and attention given to problems associated with heterogeneity. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Developments in the control of growing conditions in Dutch glasshouse horticulture.
Authors: Kooistra E.
Published: June 2020

A short review and discussion on recent advances in greenhouse heating and ventilation, energy saving, growing on artificial substrates, and automated management information systems. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Naturally occurring carcinogens and modulating factors in food of plant origin.
Authors: Jongen W.M.F. , Dorgelo F.O.
Published: June 2020

The current state of knowledge concerning the process of carcinogenesis, including the role of initiators and promoters is discussed, and foods of plant origin which contain naturally occurring carcinogens and mutagens are highlighted. Carcinogens and promoters, anticarcinogens and endogenous formation of mutagens and carcinogens are also covered. The mutagenic activity in some foods of plant origin is tabulated and the role of plant breeding in introducing or deleting the carcinogenic or anticarcinogenic properties in these foods is discussed. It is suggested that future research will focus on tumour promotion. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Meat production in West African Dwarf goats.
Authors: Montsma G.
Published: June 2020

A summary is given of work on flocks of West African Dwarf goats at Wageningen, the University of Ife (Nigeria) and a village in Nigeria. It was concluded that these goats are suitable for meat production under low and high levels of feeding and management. Under intensive management, daily gain averaged 80 g (0.3-0.4% of mature body weight), and the number of weaned kids produced per [female] per yr 2.56. Goats fed only roughage gained 43 g per day. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Factors affecting head formation of iceberg lettuce (Lactuca sativa L.).
Authors: Maaswinkel R.H.M. , Welles G.W.H.
Published: June 2020

In a series of greenhouse experiments (winter and spring, 1980-85), significant differences in frequency of (undesirable) open head formation were detected among 6 cultivars. Starlina, Aubade, Cristallo and Kellys showed 18-38% open heads, whereas Sonia and Marbello had