Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Optimal leaf area indices in C3 and C4 mono‐ and dicotyledonous species at low and high nitrogen availability
    Anten, N.P.R. ; Schieving, F. ; Medina, E. ; Werger, M.J.A. ; Schuffelen, P. - \ 1995
    Physiologia Plantarum 95 (1995)4. - ISSN 0031-9317 - p. 541 - 550.
    C and C photosynthetic pathway - Canopy structure - dicotyledonous - leaf area index - monocotyledonous - nitrogen distribution - optimization

    From an analytical model it was shown that for a given total amount of nitrogen in the canopy, there exists an optimal leaf area index (LAI), and therefore an optimal average leaf introgen content, at which canopy photosynthesis is maximal. If the LAI is increased above this optimum, increased light interception will not compensate for reduction in photosynthetic capacity of the canopy resulting from reduced leaf nitrogen contents. It was further derived from the model that the value of the optimal LAI increases with the photosynthetic nitrogen use efficiency (PNUE) and decreases with the canopy extinction coefficient for light (KL) and incident photon flux density (PFD) at the top of the canopy. These hypotheses were tested on dense stands of species with different photosynthetic modes and different architectures. A garden experiment was carried out with the C4 monocot sorghum (Sorghum bicolor [L.] Moensch cv. Pioneer), the C3 monocot rice (Oryza sativa L. cv. Araure 4), the C4 dicot amaranth (Amaranthus cruentus L. cv. K113) and the C3 dicot soybean (Glycine max [L.] Merr. cv. Williams) at two levels of nitrogen availability. The C4 species had higher PNUEs than the C3 species while the dicots formed stands with higher extinction coefficients for light and had lower PNUEs than the monocots. The C4 and monocot species were found to have formed more leaf area per unit leaf nitrogen (i.e., had lower leaf nitrogen contents) than the C3 and dicot species, respectively. These results indicate that the PNUE and the extinction coefficient for light are important factors determining the amount of leaf area produced per unit nitrogen as was predicted by the model.

    Carboxylates and the uptake of ammonium by excised maize roots
    Breteler, H. - \ 1975
    Landbouwhogeschool Wageningen. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - ISBN 9789022005705 - 99
    assimilatie - experimenten - in vitro - maïs - stikstof - organische verbindingen - fosfor - plantenfysiologie - planten - zwavel - zea mays - assimilation - experiments - in vitro - maize - nitrogen - organic compounds - phosphorus - plant physiology - plants - sulfur - zea mays
    The effect of carboxylates (organic acid anions) on NH 4 uptake was studied by changing the carboxylate level of roots prior to uptake experi ments. Succinate was the most effective stimulator of ammonium uptake. The oxocarboxylates (α-oxoglutarate, oxaloacetate and pyruvate) and malate also promoted NH 4 entry. Preloading of roots with citrate, acetate, oxalate, glyoxylate or malonate reduced subsequent ammonium uptake. It is concluded that oxocarboxylates are important compounds in both the assimilation and the uptake process of ammonium. All carboxylates tested enhanced K uptake, but repressed NO 3 uptake, except citrate which increased nitrate absorption. Carboxylate stimulation of NH 4 entry showed metabolic as well as non-metabolic aspects.
    The ionic balance of the sugar-beet plant
    Egmond, F. van - \ 1975
    Landbouwhogeschool Wageningen. Promotor(en): A.C. Schuffelen, co-promotor(en): C.T. de Wit. - Wageningen : Pudoc - ISBN 9789022005484 - 70
    beta vulgaris - suikerbieten - plantkunde - beta vulgaris - sugarbeet - botany
    The ionic balance of the sugar-beet plant was studied by measuring dry weight and chemical composition of every leaf, the crown and the root during the growing season.

    The sugar-beet plant has an almost neutral uptake. The nitrate and sulphate reduction determines the amount of carboxylates in the plant. Accumulation of carboxylates prevents large changes of cell-pH because of the ion-uptake and ion-utilization processes.

    In every plant part the carboxylates are a quantitative measure of the amount of nitrate reduced. It is concluded that nitrate is mainly reduced in the leaves and to a small extent in the root.

    It is proved that for the sugar-beet plant, Cl can be used as an index element to calculate the supply of the various ions to the various plant parts. Redistribution of potassium, calcium, magnesium, phosphate and organic N is determined by comparing the actual and calculated amounts in the various plant parts. The redistribution of potassium from the old leaves to the root is counterbalanced by redistribution of divalents in the opposite direction. The redistribution of the divalents takes place from organs with a relatively small oxalate production towards organs with a relatively large oxalate production.

    In an appendix a rapid carboxylate determination is described.

    Aspects of potassium and magnesium uptake by oats.
    Schuffelen, A.C. - \ 1974
    Netherlands Journal of Agricultural Science 22 (1974)4. - ISSN 0028-2928 - p. 237 - 244.
    Oude en nieuwe bemestingsproblemen
    Schuffelen, A.C. - \ 1974
    Wageningen : Landbouwhogeschool - 30
    alternatieve landbouw - kunstmeststoffen - mest - biologische landbouw - plantenvoeding - bemesting - openbare redes - alternative farming - fertilizers - manures - organic farming - plant nutrition - fertilizer application - public speeches
    De opname van fluoride door de wortel en de gevolgen daarvan voor diverse gewassen, in het bijzonder fresia
    Roorda van Eysinga, J.P.N.L. - \ 1974
    Landbouwhogeschool Wageningen. Promotor(en): A.C. Schuffelen. - S.l. : s.n. - ISBN 9789022005200 - 83
    vloeistoffen (liquids) - absorptie - emissie - omloop - wortels - sierplanten - iridaceae - oogstschade - luchtverontreiniging - fluoride - liquids - absorption - emission - circulation - roots - ornamental plants - iridaceae - crop damage - air pollution - fluoride

    In a trial with pots, filled with peat, and the treatments 0N, 0P and 0K an unfavourable influence of triple superphosphate on freesias was observed. The crop showed scorching of the leaf margin, that turned out to be a symptom of fluorine excess. Especially monocotyle bulbous and cormous crops were susceptible to excess of fluoride from the substrate. In some trials a relation was found between the contents of fluorine in soil and in the crop, in others a relation between soil fluoride content and percentage of scorched leaf

    Over hundred samples of soils were collected in the Netherlands and analysed for total fluorine, 'labile' fluoride and water soluble fluoride.

    The pH of the soil was found to be an important factor regulating fluoride uptake and leaf scorch. Evaporation probably is the cause that other factors, such as electrolyte concentration of the soil, the season, the temperature of soil and air, the occurence of diseases, are of influence on leaf scorch while foliar fluorine is not clearly changed.

    Effect of nitrogen dressings on growth and development of sugar-beet
    Houba, V.J.G. - \ 1973
    Wageningen University. Promotor(en): A.C. Schuffelen; L.J.P. Kupers. - Wageningen : Pudoc - ISBN 9789022004357 - 65
    beta vulgaris - chemische analyse - chemische samenstelling - groei - stikstof - planten - suikerbieten - oogsttoename - oogstverliezen - opbrengsten - blootstelling - milieuafbraak - kinetica - metabolisme - ecotoxicologie - beta vulgaris - chemical analysis - chemical composition - growth - nitrogen - plants - sugarbeet - yield increases - yield losses - yields - exposure - environmental degradation - kinetics - metabolism - ecotoxicology

    The growth and development of sugar-beet with different nitrogen dressings was studied by measurement of leaf area and of dry weight and chemical composition (inorganic cations and anions) of several plant parts during the growth season.

    For a correct interpretation of the data, the losses in dry weight, leaf area and minerals due to leaf fall could not be ignored and were therefore estimated. The losses were calculated to be 4-5 tons dry matter . ha -1and 3-4 m 2leaf area . m -2soil area depending on the amount of nitrogen dressed. The losses of N, H 2 PO 4 and K were 90-140, 5-13 and 80-105 kg . ha -1, respectively.

    When the losses were included in the harvest data, other growth and uptake figures were obtained than when these losses were ignored. With no deficiency, instead of three growth stages, only two stages appeared in the distribution curve.

    Furthermore a hypothesis was developed which could explain the differences in dry weight, chemical composition and leaf area of the succeeding laminae of a sugar-beet plant. It was suggested that the laminae formed first stayed small due to competition for the produced minerals within the plant. Maximum leaf area and weight was found for the 10th to l5th leaf. Later formed laminae stayed small due to the shortage of light, minerals, water and time.

    Stikstofvoeding, bodembehandeling en stikstofbemesting bij vruchtbomen (appel, peer)
    Delver, P. - \ 1973
    Landbouwhogeschool Wageningen. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - ISBN 9789022004326 - 187
    appels - kunstmeststoffen - mest - stikstof - stikstofmeststoffen - peren - plantenvoeding - bodem - apples - fertilizers - manures - nitrogen - nitrogen fertilizers - pears - plant nutrition - soil

    Due to the increased use of dwarfing rootstocks and fertilizer experiments dressings increased from 90-120 kg N/ha in 1958 to 170-270 kg in 1965. In deciding on the quantity of nitrogen dressing its interacting effects on growth and fruit production as well as the influence of soil, weather and undergrowth were studied. Some of the experiments were carried out in pots, the others in the field.

    The discussions cover the availability of nitrogen in the soil and the nitrogen requirements of the trees, especially in relation to competition with a full grass cover and grass strips. The system with grass strips and mulched bare tree strips is considered a case of fertilizer placement since the soil under the grass strip is extremely low in nitrogen during the greater part of the season.

    Molybdenum uptake by beets in Dutch soils
    Henkens, C.H. - \ 1972
    Landbouwhogeschool Wageningen. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - ISBN 9789022003947 - 54
    voedingsstoffentekorten - chlorose - beta vulgaris - suikerbieten - sporenelementen - chelaten - bodemchemie - planten - chemische analyse - nederland - molybdeen - milieuafbraak - bodem-plant relaties - nutrient deficiencies - chlorosis - beta vulgaris - sugarbeet - trace elements - chelates - soil chemistry - plants - chemical analysis - netherlands - molybdenum - environmental degradation - soil plant relationships

    In the Netherlands a soil may induce Mo-deficiency symptoms in beet if it contains more than 1 or 2% iron; whether such deficiency did occur depended primarily on pH, but particle size and kind of iron also played a role: αFe 2 O 3 and αFeOOH sharply reduced Mo content of the plant; γFe 2 O 3 had only little effect. When no molybdenum was supplied, three groups of soils could be distinguished by the interaction Mo X P: soils where P almost completely prevented Mo deficiency; soils where P aggravated deficiency; and soils where P dressing hardly affected response to Mo. Steaming soils influenced Mo content of the plant. The effect of adding Mo differed when it was supplied before from when it was supplied after steaming. Applying Mo before steaming reduced its availability but after steaming increased it. Application of manganese sulphate reduced Mo content of the plant to a degree depending on the amount of available Mo in soil. Beet could take up Mo as a cation, the cation was less effective within the plant. A scheme summarizes processes affecting the availability of Mo in Dutch soils.

    Fertilizer requirements of cacao (Theobroma cacao L.) in South-Western Nigeria
    Wessel, M. - \ 1971
    Wageningen University. Promotor(en): A.C. Schuffelen. - Amsterdam : Koninklijk Instituut Voor de Tropen - 104
    plantenvoeding - kunstmeststoffen - mest - theobroma cacao - cacao - bodemkunde - plantkunde - nigeria - plant nutrition - fertilizers - manures - theobroma cacao - cocoa - soil science - botany - nigeria

    The studies reported on were conducted in the period 1961-1970 when the author was employed by the Cocoa Research Institute of Nigeria at Ibadan, formerly a sub-station of the West African Cocoa Research Institute.

    In the first three chapters information is given on the cacao industry and on the climate and soils in general and cacao soils in particular of the main cacao growing area of South-Western Nigeria. In the next chapter (4) a study on soil moisture is presented. In view of the long dry season the soil moisture relationships are the main factor determining the suitability of the soil for cacao. This chapter is followed by one on soil phosphorus which was found to be the main nutritional factor limiting yield as shown by the results of the fertilizer trials reported in chapter 6.

    The results of an investigation on whether soil and leaf analysis can be used to assess the nutrient requirements of cacao are given in chapter 7. In the last chapter the results of the preceding chapters are summarized and discussed.

    Analytical methods and sampling procedures are given in appendix I while some analyses of variance are given in appendix II. Most of the statistical analyses were carried out by the Statistics Department of Rothamsted Experimental Station, England.

    Intermitterende voeding bij tarwe
    Slangen, J.H.G. - \ 1971
    Landbouwhogeschool Wageningen. Promotor(en): A.C. Schuffelen. - Wageningen : Centrum voor Landbouwpublikaties en Landbouwdocumentatie - ISBN 9789022003664 - 130
    plantenvoeding - kunstmeststoffen - mest - triticum aestivum - tarwe - hexaploïdie - plantkunde - oogsttoename - oogstverliezen - opbrengsten - plant nutrition - fertilizers - manures - triticum aestivum - wheat - hexaploidy - botany - yield increases - yield losses - yields

    The influence of intermittent nutrition on dry-matter production, on contents (meq/kg) and amounts (meq per plant) of inorganic nutrients was studied in water and soil cultures with wheat as a test crop.

    From the results of this study notably from chapters 9 and 12 it is clear that differences between the techniques of water (2.1.1) and soil cultures (2.2.1) do not lead to essential differences in growth and development of wheat plants. Supplying nutrients at a constant level (water culture) brings about a different way of ripening (4.3) and no losses of dry matter from plant parts (fig. 8). But the character of a normal seed-bearing annual is the same as in soil culture where the store of nutrients decreases during growth. This holds for main shoots and tillers (with and without ears); the number of the latter increases in water culture as long as nutrients, especially nitrogen, are supplied and conditions such as light and temperature are favourable for growth (Aspinall 1961, 1963; section 4.2).

    According to Dilz (1964) data of dry matter and N uptake from pot and field trials are only comparable if based on dry matter of plants grown with these techniques and not on number of plants, weight or soil surface (per pot or per field plot). In this pot trial with soil the average of 2.5 culms per plant is in agreement with the number normally (Brouwer, 1970) found for spring wheat in the field. When inner plants of the pot bear less tillers than outer plants (light side) this is called the 'side effect' (Dilz, 1964). Water culture plants with very pronounced tillering show this effect but in soil culture with 10 plants per pot of which 6 to 7 are outer plants the effect is of none importance. New tillers with or without few and small grains only develop with low (105 mg N per pot) dressings before sowing and suppletion of nitrogen at a very late stage of development (10.2.2.1 treatments 112 and 113). This situation is normally not found in the field because of light shortage.

    Values of main shoots from water and soil cultures as well as from field trials are similar. Therefore these main shoots must be to some degree independent from the tillers. Young tillers need the leaves and root system of their parents to get carbohydrates, water and nutrients. But in wheat plants at the stage of shooting Quinlan & Sagar (1962) found no transport of 14C from main shoot to tillers or in the opposite direction. This was verified by Williams (1964) with timothy. From this stage on the conclusion of independence of main shoots and tillers, seems reasonable. By comparing only main shoots the influence of treatments 0N, 0K, split application of nitrogen and potassium on numbers of tillers (Chapter 5, 10.2.2. 1, Fig. 33, Table 24) is excluded.

    With the technique of water culture used in these trials it is not possible to distinguish between roots of main shoots and tillers. In soil culture a part of the older roots is lost by cleaning them (Fig. 29). Therefore the balance of uptake, assimilation and excretion of nutrients will be incomplete although the amounts of nutrients in the roots of older plants are far less than in the aerial parts.

    The influence of intermittent nutrition in water cultures and split application of N, K and N + K in soil culture on chemical composition of main shoots of young wheat plants is summarized in Fig. 51 by the relationship N-org. vs. C-A (= organic anions). According to Dijkshoorn et al. (1969) with rye grass, uptake and reduction of NO, in aerial parts (leaves) results in production of organic nitrogen and an equivalent amount of organic anions (carboxylates) from which a part is translocated to the roots for maintaining the process of cation and anion uptake by decarboxylation and exchange of H +and HCO3-. The main shoots of wheat (and according to Fig. 11 the same holds for the tillers) grown under optimum conditions (as supposed for water culture) retain, in the period of 35 to 49 days after emergence (Fig. 10) nearly 1000 meq of carboxylates per kg of dry matter. This content decreases gradually in older plants (Fig. 10).

    Usually for cereals excess uptake of anions, especially nitrate, results in an alkaline effect in the growth medium (in the water culture this was corrected by refreshing the solutions (Table 2) twice a week) and in a store of nitrate (and sulphate) in the plant. The difference between the N-org. and C-A relationship for water culture (Figs. 51 and 26, treatment NPK) and soil culture (Figs. 51 and 49, treatment 130, i.e. 840 mg N and 400 mg K 2 O per pot before sowing) can be explained by the difference in N source. In water culture all nitrogen was given as NO 3 , in the soil NH 4 NO 3 was used and from an incubation trial it was evident that NH 4 was available for uptake at least untill day 60 after emergence. Uptake of NH 4 ions suppresses the uptake of metallic cations and positive charge of NH4+is eliminated without production of organic anions (C-A). This results in, relative to the water culture, a high N-org. content and a low C-A content as expressed in Fig. 51. Withdrawal of nitrogen (waterculture) or low dressings of nitrogen (soil culture) lead to a relative decrease of N-org. against C-A production; the latter, according to Dijkshoorn et al. (1969), proceeds slowly in the roots by using HCO3-. In soil culture (Fig. 49) there is the same process but because of mineralisation of nitrogen the transition is smoother than in water culture (Fig. 26) from which nitrate is withdrawn and replaced by chloride (treatment 0 and 0N).

    Uptake, distribution and redistribution in older (from flowering on) main shoots of wheat are also in good agreement for water and soil culture. The order of mobility K>N = P>Mg>Ca>Cl is the same for both. This mobility is, as regards translocation (redistribution), connected with uptake and dry-matter production for young plants as represented in Fig. 27 (Chapter 9) for water culture and in Fig. 50 (Chapter 12) for soil culture. Potassium is supposed to be the most mobile nutrient in this cereal because of the fast uptake of this element relative to dry-matter production in young shoots (Figs. 27 and 50) and because from the older plant part is retranslocated to the root medium. (Fig. 45). Nitrogen and phosphorus are only redistributed within the shoots; P from stalks only, N from leaves and stalks. In water culture (Fig. 13) 65 % of both nutrients are found in the ears and 15 to 20% in leaves and stalks of main wheat shoots. In soil culture (Fig. 40) these values for nitrogen were 85, 10 and 5 % for ears, leaves and stalks respectively. Dilz (1964) found in field trials with wheat and oats, 75 % of total nitrogen in the grains (for chaff (= ear minus grain) 10 % of total nitrogen can be used) The amounts of Mg, Ca and Cl increase in all parts of the plant until the end of the growth period, for these elements no net losses are found; more Mg than Ca is found in the ear (grains) so that Mg is probably more mobile. By decomposition of proteins in older plants some sulphur is stored as SO 4 in leaves. The amounts of Na in aerial parts of wheat (also in water culture with 1 meq Na per liter) are very low, especially if compared with K; in roots the contents are higher but still to low to influence (C-A) contents.

    Uptake and distribution of nutrients are generally determined by the qualitative and quantitative supply in the growth medium, the selection of the uptake mechanism and the translocation from one plant part to another. An example of different N source (NH 4 or NO 3 ) was already given. But also in a system with SO 4 or Cl as anions (Marschner & Ossenberg-Neuhaus, 1970) differences in amounts taken up and mobility influence (C-A) content and the distribution in the different plant parts.

    As was seen in Table 9 Na is taken up by roots in large amounts. However the small amounts found in aerial parts of wheat, points to a selectivity in the transport system for Na. As opposed to Na, K is taken up by cereals in large quantities and is transported easily.

    With water culture the continuous uptake of nutrients leads to stores so that changes in supply of nutrients (e.g. K) during short intervals do not influence development and growth of plants and only have a small effect on distribution. If, as in older plants, transpiration is important changes in uptake and distribution can be found. With split application of K (Section 11.3.2, Fig. 45) in soil culture, Ca in leaves and ears (transpiring parts) was higher than in stalks. In water culture replacing K by Ca (treatment 0K, section 6.3.2, Table 16) the same is found for potassium. These results can be explained by exchange of ions in the transport system (Isermann, 1969, 1970) and translocation of the exchanged ions to transpiring parts. The amount of Ca does not seem to influence the quality of grain of cereals.

    By split application of nitrogen (in this pot trial (Fig. 6) suppletion of N on day 34, 62 and 90 after emergence i.e. at tillering, earing and flowering), the effect on yielddetermining factors (Fig. 38, 10.2.2.1 till 10.2.2.4) is the same as under field conditions (Coic, 1956; de Jong, 1969). Nitrogen applied during tillering and shooting has the most important influence on the number of culms whereas nitrogen dressed at earing and their flowering gives more grains per ear and a higher (1000) grain weight. Yet none of the treatments with split application of nitrogen outyielded (10.2.2.4) the dressing of 840 mg N per pot before sowing (treatment 130). Related to this, soils with low level of available soil nitrogen give a remarkable effect on grain yield (Dilz, 1964). In field trials (de Jong, 1969) no close correlation was found between yields of the untreated plots (controls) and the effect of nitrogen (dressings in one or split application and expressed as yields of grains resp. straw) was found. To be able to forecast the effect of split application of N on different soil types as was tried by de Jong (1969), it would be better to use the uptake of nitrogen (kg/ha) either by grain or straw or both instead of dry-matter production (kg/ha of grains and straw) because in humid areas nitrogen is the most important factor for determining yield.

    Soil fertility in the Great Konya Basin, Turkey
    Janssen, B.H. - \ 1970
    Wageningen University. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - ISBN 9789022003299 - 113
    akkerbouw - kunstmeststoffen - veldgewassen - horizonten - landevaluatie - mest - stikstof - fosfor - plantenvoeding - bodem - bodemvruchtbaarheid - bodemkunde - bodemgeschiktheid - bodemkarteringen - turkije - arable farming - fertilizers - field crops - horizons - land evaluation - manures - nitrogen - phosphorus - plant nutrition - soil - soil fertility - soil science - soil suitability - soil surveys - turkey

    Soil fertility was studied in the Great Konya Basin, as part of the study carried out by the Department of Tropical Soil Science of the Agricultural University at Wageningen.

    The purpose was to find the agricultural value of the soils, to learn about the main factors governing soil fertility, and to work out regional fertilizer recommendations for winter wheat, the main crop in dry farming.

    The study was in the field, greenhouse and laboratory. Because of results already available from Turkish scientists, only nitrogen and phosphorus were examined.

    In 1966-7 and 1967-8 a total of about thirty trial fields were laid out on the most important soils suitable for crops, mainly Terrace, Bajada, and Marl soils. The trials were carried out on farmers' fields in the common wheat-fallow rotation. As rainfall is low (about 300 mm per year), the land is fallowed each alternate year to conserve moisture for the next crop. To study the significance of this fallow year, the course of soil moisture content was observed during the trial years.

    In the greenhouse, short-term trials (3 weeks) were used. A technique was developed, by which young wheat plants could take up nutrients simultaneously from the studied soil and from a nutrient solution (Fig. 11). If a nutrient is omitted in the solution, plants can take up that nutrient from the soil only. The availability of that nutrient in the soil is indicated by the 'sufficiency quotient', the ratio between the relative growth rates of plants on deficient and complete solutions (S QN and S QP for nitrogen and phosphorus, respectively).

    In the laboratory, several physical and chemical soil characteristics were determined; also grain and straw samples from the field trials were chemically analysed.

    Wheat yields of the field trials ranged from 300 to 3000 kg grain per ha. The response to fertilizers varied with precipitation and soil unit. There was a reasonable relation between crop data in May (height and growth stage) and final dry-matter production in July.

    The yield factors moisture, nitrogen and phosphorus were studied in more detail.

    The amount of water stored in soil at sowing proved to depend mainly on precipitation in the preceeding fallow period and slightly on soil unit. There Was a clear connexion between the amount of stored water and maximum dry-matter production. Because of differences in spring rainfall, the relation was not the same for 1967 as for 1968. Between transpiration and maximum dry-matter production, a linear relation was found; it was used to calculate transpiration from each field, so quantifying moisture supply.

    The different characteristics for nitrogen status in soil, namely organic nitrogen, nitrate nitrogen and SQN , corresponded well with each other. Yield increase with nitrogen fertilizer, nitrogen content of grain and nitrogen withdrawal from soil depended on soil nitrogen and on moisture supply. If grain nitrogen exceeded 2.0-2.2%, there was no yield increase with nitrogen fertilizer. Nitrogen recovery, the percentage of applied nitrogen absorbed by the crop, varied from 0 to 30%.

    The results of soil phosphorus determinations by P-Olsen did not correspond with SQP . Both parameters, as well as phosphorus content in the crop, indicated a very poor phosphorus status of all soils. The interrelations between soil, crop, and fertilizer phosphorus were complex and were governed by moisture conditions. Phosphorus withdrawal from soil was low, did not depend on soil properties and was determined almost entirely by moisture supply. Phosphorus recovery, low for all soils, was lowest on Marl soils, probably because of the fine texture and the high content of carbonate.

    On some fields, soil slaking, profile depth and slope were factors influencing yield.

    Yield increments from the factors moisture, nitrogen and phosphorus were effected mainly by increased tillering. The greater number of tillers could cause moisture shortage later in the season to become more severe, and could sometimes cause decrease of seed set and of 1000-grain weight. Phosphorus did not much change the grain/straw relation; longer culms were associated with more grains per ear.

    Differences in productivity and in response to fertilizers between the soil units could be ascribed to differences in content of organic matter and in moisture supply. Since those factors have been included partly directly, partly indirectly in many units of de Meester's soil map, a fertilizer recommendation map could be drawn. For recommendations, the profit- maximizing combinations of nitrogen and phosphorus were determined by an algebraic and a graphical method. For the algebraic method, regression equations were used that had been calculated for the statistical analysis of field results. The graphical method was based on the construction of 'maps' with iso-profit lines. On these 'maps' the optimum combination of fertilizers as well as financial consequences of non-optimum rates, can easily be found.

    Appendix I gives details of the developed technique of greenhouse trials, discusses the course of relative growth rate and its consequences for the determination of S QN and SQP and shows that reference soils are needed.

    IAEA/FAO international training course on the use of radioisotopes and radiation in soil and plant nutrition studies, 10 August - 25 September 1970
    Zeeuw, D. de; Schuffelen, A.C. - \ 1970
    Wageningen : ITAL - 450
    landbouw - bodemkunde - plantenvoeding - kunstmeststoffen - mest - toepassingen - isotopen - straling - radioactiviteit - tracer technieken - tracers - metabolisme - kernfysica - moleculaire fysica - agriculture - soil science - plant nutrition - fertilizers - manures - applications - isotopes - radiation - radioactivity - tracer techniques - tracers - metabolism - nuclear physics - molecular physics
    Nitrogen, salinity, substrates and growth of gloxinia and chrysanthemum
    Arnold Bik, R.A. - \ 1970
    Wageningen University. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc, Centre for Agricultural Publishing and Documentation - ISBN 9789022002964 - 89
    asteraceae - gesneriaceae - sierplanten - asteraceae - gesneriaceae - ornamental plants

    The study was on the harmful effect of salinity on N utilization in the flower crops gloxinia (a salt-sensitive mesophytic semi-shade plant) and chrysanthemum (a salt- tolerant sun plant). For solid substrates (trials 2 and 3) the specific conductivity of the saturation extract (EC. in mmho per cm at 25°C) was used as measure of salinity (Richards et al., 1954). In water culture (Trial 1), the specific conductivity of the nutrient solution (EC in mmho per cm at 25 °C) was used. The specific conductivity of the substrate also indicated osmotic suction S s .

    In solid substrates, the availability of water is dependent not only on S s but also on the matric suction S m . To eliminate the influence of S m , attempts were made to keep it constant.

    In Trial 1, the yield of dry matter was studied at 4 nitrate concentrations and with 4 EC e values, the latter obtained by adding NaCl. Increases in EC e depressed yield increment per unit nitrogen. This reduction in N effect, being much larger for gloxinia than for chrysanthemum, represented a decrease in N utilization, attributable to a disturbance in nitrogen metabolism at rising suction tension ( S l or DPD) in the leaf (Barnette & Naylor, 1966). This rise in S l with EC of the medium could be deduced from a decrease in percentage transpiration. Brouwer (1963) has shown that S l increases with NaCl concentration.

    There was a practically linear negative relationship between yield and EC. After extrapolating EC to zero, the nitrogen curves coincided into one typical yield curve. Therefore the osmotic factor seemed dominant.

    The large influence of NaCI on ionic balance in the plant showed that specific ion effects could not be neglected. Notable specific effects were for the cations, the antagonism of Na +to uptake of K +, Ca 2+and Mg 2+, and for the anions the antagonism of Cl -to NO3-. The organic salts (C-A) decreased appreciably with rising Cl -concentrations in the medium.

    The two plants deviated in pattern of ion uptake. Chrysanthemum selectively absorbed K +, and could to some degree control the entry of ions. Gloxinia showed no selectivity and could not prevent the entry of ions. This difference must partly account for the difference in salt tolerance between the species. Certainly some investigators (Bernstein & Ayers, 1953; Sutcliffe, 1962) looked upon selective uptake of K +, as an indication of a species' salt tolerance.

    Since salinity depresses water balance of plant through S s , salt tolerance must also depend on the genetically determined osmotic characteristics of the plant. According to Slatyer (1963) the osmotic pressure of mesophytic shade plants (e.g. gloxinia), is about 5 bar, for most crop plants (e.g. tomato and chrysanthemum) between 10 and 20 bar, and for halophytes (e.g. Atriplex nummularia ) even 72 bar.

    In Trial 2, on a solid substrate, the nitrogen effect was depressed by four different types of salt, as by NaCl in Trial 1. The depression seemed to be almost proportional to the increase in EC e caused by addition of salt. Only K 2 SO 4 depressed yield of gloxinia more than could be explained by the increase in EC e caused by addition of the salt. As in Trial 1, the depression of the N effect by any salt could be attributed to a decreased N utilization.

    The almost linear negative relationship between yield and EC e was clearly influenced by the N rate. At optimum N rate, the reduction in yield by EC e was much larger than at the lowest N rate. In assessing damage by salinity, the nitrogen status of the crop must be considered. Specific ion effects could be detected by correction for EC e . K 2 SO 4 exerted the largest specific harmful effect on growth of gloxinia. Chrysanthemum, which was usually much less affected by specific salt injury, suffered mostly from the specific effect of Na 2 SO 4 . Extremely important for the ionic balance in the plant was the increase in proportion of N as NH4+with N rate (here given as ammonium nitrate). NH4+competes strongly with other cations but according to van Tuil (1965) contributes much less than NO3-to the content of organic salts. Increases in NH4+in the substrate with N rate therefore accounted for the decreases in organic salts in almost all series.

    For gloxinia, K +, competed markedly with uptake of Ca 2+, for K 2 SO 4 even more so than for KCl. The specific harmfulness of K 2 SO 4 for growth was therefore essentially a Ca 2+deficiency induced by K +, and SO42-together.

    The specific harmfulness of Na 2 SO 4 for chrysanthemum can be ascribed to a decrease in K +, in the plant by competition from NH4+and Na +together.

    The difference between species in pattern of ion uptake in Trial 1 was confirmed. Gloxinia seemed to have a high Ca 2+requirement but unlike chrysanthemum's selectivity for K +, could not absorb Ca 2+selectively. According to van den Berg (1952) the salt tolerance of a crop is often associated with a specific Ca 2+requirement. The results of Trial 2 support this opinion.

    In Trial 3, the influence of different substrates proved to be based entirely on the inverse proportionality between moisture capacity and EC e .

    The shape of the pF curve and the daily water loss by transpiration indicate that, despite of attempts to standardize the moisture level, the influence of matric suction S m was considerable in the clay-peat substrates of chrysanthemum, although it had been eliminated in the sand-peat substrates of gloxinia.

    The increase in N effect with increasing peat content of the substrates proved to be an EC e effect, as did also the lower negative effect of NaCl or of excess N with increasing peat content. These results also explained the significant interaction between nitrogen and substrate, reported elsewhere for gloxinia and cyclamen (Arnold Bik, 1962). The relationship between yield and EC e were almost independent of substrate. The usefulness of EC e as a criterion of salinity in trials with different substrates was thus confirmed.

    For gloxinia, the curves of N rate against yield for each of substrate-NaCl series coincided into one typical yield curve when EC e was adjusted to zero. Therefore at uniform pF and with adequate aeration the substrate effect is actually an EC e effect so long as the substrate components do not exert any particular effect such as fixation of K +.

    Plant composition again showed that the form of N (NH4+or NO3-) and, by its influence on nitrification, the CaCO 3 content of the substrate governed the ionic balance of the plant. In gloxinia total cations and total inorganic anions in the plant both decreased with increasing peat content, in accordance with the lower concentrations in the substrate. In chrysanthemum, this relationship was confused by the influence of the clay component of the substrate.

    Trial 3 suggests that the effect of salinity was more an osmotic effect than a specific ion effect.

    Practical measures for growers are suggested (Chap. 6) to minimize the harmfulness of salinity on the N effect and on the vegetative growth of pot plants and other ornamentals.

    Foliar diagnosis, nutrition and yield stability of black pepper (Piper nigrum L.) in Sarawak
    Waard, P.W.F. de - \ 1969
    Wageningen University. Promotor(en): A.C. Schuffelen. - Amsterdam : Koninklijk Instituut Voor de Tropen - 149
    piper nigrum - maleisië - sarawak - borneo - piper nigrum - malaysia - sarawak - borneo

    Until 1942 cultivation of pepper P. nigrum L. in Sarawak produced relatively small but regular yields. High demands after 1945 and restricted use of "burnt earth" compelled farmers to abandon the application of this traditional fertilizer. Instead, "fool proof" manufactured fertilizers of mainly organic origin were successfully applied in massive volumes and large yields were obtained. In 1954 and following years a sharp fall in price induced a decline in production, in part owing to much reduced applications of fertilizer. As a result the economic crop cycle of some 16 years was limited to some 1-3 years; the bulk of the total yield was obtained in the first year of production.

    An initial survey on leaf symptoms and die-back indicated unbalanced and inadequate mineral nutrition of the crop. The current system induced severe deterioration of plant appearance in the period of monsoon rains, which coincide with berry expansion. During this time no fertilizers are applied as a rule.

    A method has been worked out to diagnose the nutritional demands of N, P, K, Ca and Mg by chemical foliar analysis. Major aspects involved in the establishment of a sampling procedure were systematically studied. The effect on chemical concentrations was investigated of the portion of the vine, the presence of fruit, the branch, the age of the leaf, the presence of the petiole, leaf size, leaf thickness, sunshine, different stems on a plant, location of fertilizer dressings and the number of leaves to be sampled per vine. Similarly, the influence of the mode of cleaning of the leaves, of the drying temperature on loss of N and the effect of length of storage on the content of N were studied.

    Studies on the error of bulk sampling and the effect of appropriate stratification of the different leaves in the canopy on the reduction of this error showed that suitable division into strata reduced the number of vines to be included in a bulk sample up to 16 times as compared with random sampling, assuming the same degree of precision. Furthermore the inclusion Of 4 appropriately stratified leaves from each of 60-70 vines in each bulk sample obtained from homogeneous areas, would represent chemical concentrations with a precision of 10% of the population mean (P = 0.05) irrespective of physiological condition.

    Data on seasonal variation indicated declining levels of N and K within the monsoon; this was accompanied by gradually rising levels of leaf P and leaf Ca. Leaf Mg tended towards constancy. Bivariate ratios showed, on most occasions, a regular relationship with time, but constant values were observed only occasionally.

    A sand experiment on deficiencies of nutrients showed characteristic discolourations due to nutrient shortage. Concurring foliar concentrations and ratios associated with full nutrients, partial or complete deficiency of a single element allowed tentative registration of normal, fair, critical and deficient threshold values in the leaves for each element (table 18). Single and multiple deficiencies could be recognized by using an appropriate grouping of concentrations and their ratios. Application of these values to random field data showed a satisfactory power of discrimination. The ratio values gave a good indication of the order of importance in the case of multiple deficiencies.

    The influence was studied of dressings of NPK fertilizers on leaf concentrations and ratios. It was observed that increasing dressings of N, P, and K were directly reflected in risising concentrations of leaf N, leaf Pand leaf K, respectively. Simultaneously, N- P "antagonism" and "antagonism" between bases was also operative. Apparently, considered balancing of applications of different fertilizers is essential. The ratios between elements gave some indication of priorities of different dressings. It was also observed that under the influence of the very heavy, early applications leaf concentrations of N, K and Mg fall to deficiency levels. This indicates that the distribution in time also requires adjustment.

    The development of physiological exhaustion could be attributed to an inadequate net supply of N, K and Mg to the leaves during translocation processes of nutrients in the period of fruit development. Stability of yield at a high level of production can be maintained by preventing development of nutrient shortages and ensuring fair to normal concentrations of N, P, K, Ca and Mg in the leaves throughout the year. Threshold values, independently obtained from field vines corroborate the tentative values for the normal levels found in the pot experiment. The latter may therefore be considered as fundamentally correct. Rather complicated interactions of "antagonisms" and "synergisms" may become operative if foliar levels fall below these normal levels. The data have also shown convincingly that the values for log N/P can be used as a satisfactory control for abundance of flowers at a specific potential for flowering.

    Finally, the agricultural implications of these findings are discussed in Ch. 10. The data allowed a plausible interpretation of crop behaviour and crop performance under the traditional system of cultivation before 1942 and that in the period after 1945. By integrating the leaf data of this work with information concerning factors affecting the supply of nutrients to the plant, it was shown that foliar diagnosis furnished a suitable foundation to devise an appropriate fertilizer policy for pepper.

    Sound absorption at the soil surface
    Janse, A.R.P. - \ 1969
    Wageningen University. Promotor(en): C.W. Kosten; A.C. Schuffelen. - Wageningen : [s.n.] - ISBN 9789022001790 - 215
    bodemstructuur - bodemdeeltjes - grondanalyse - geluidsleer - vibratie - geluiden - bodemlucht - reflectie - resonantie - meting - onderzoek - bodemkunde - bodemfysica - grondmechanica - wetenschappelijk onderzoek - wetenschap - soil structure - aggregates - soil analysis - acoustics - vibration - sounds - soil air - reflection - resonance - measurement - research - soil science - soil physics - soil mechanics - scientific research - science
    The properties of a soil structure may be examined in various manners. As well as a study of the stability, a knowledge of the geometry of the volume of air filled pores is often needed. The most common measurements, like those of porosity and flow resistance to gases do not permit a detailed description of this pore volume. Since wave phenomena are characterized by three independent variables, viz. frequency, amplitude and phase, with frequency chosen freely, the measurement of acoustical characteristics of the air in the soil offers new opportunities. Also a determination of the acoustical properties of a porous material is non-destructive.

    In chapter 1, a description is given of an interferometric method of measurement following the derivation of the wave equation. The propagation velocity of sound in air and the specific mass of air are the important physical quantities. The change in these quantities is studied from variations in the experimental conditions, such as temperature and humidity. Next the principles of the propagation of sound in porous materials are presented. For a sample of thickness l and having a rigid backing, the specific acoustic impedance Z at the free surface is given by Z = W m coth(γ m l), where γ m is the propagation constant for acoustical waves in the sample and W m is the specific acoustic wave impedance. Z, W m and γ m are complex quantities. Z may be measured in an interferometer and W m and γ m characterize the sample material. γ m and W m considered as functions of frequency give more information on pore geometry than may be obtained from static measurements. The loci of the function in two types of a complex plane is studied. Finally the behaviour of this function in the complex planes is shown with some examples.

    Chapter 2 contains a discussion of the measuring equipment used and of the calibration of the measuring set-up. After a discussion of the measuring techniques, the sources of error are evaluated.

    Chapter 3 deals with the propagation of waves in porous materials. Independent determination of W m and γ m proves impossible for soil samples. A method for this, described in the literature, is rejected on the grounds of inadequate accuracy. An alternative approach is followed: the material is described by a mathematical model and the parameters in the model are considered as the characteristic quantities for pore geometry. The models assume comparatively simple geometries and may be considered an extension of the work of previous authors. In addition a new projection plane for the determination of γ m and W m by a graphical method is discussed. Use of the plane is confined to cases where the sample thickness may be varied. Also, formulas are derived with which the acoustical properties of prismatic of structures soils can be studied. Finally, the applicability of scale rules and the possibility of an electric- acoustical equivalent network are examined for the sample material. Neither approach seems promising.

    Chapter 4 starts with a discussion of the problems to be expected on the com parison of calculated and measured curves for Z. Somes series of measurements are discussed. The mathematical models selected yield a reasonably good relation ship between the theoretical and measured values. A short critical discussion is given on the feasibility of an extension of the mathematical model.

    In conclusion a brief discussion is devoted to measurements on layers whose solid phases can no longer be considered as rigid, such as layers of mulch and straw. Some results obtained with straw are dealt with.

    Analyse van de bodemvruchtbaarheid volgens de proefplekkenmethode bij een meerjarig tuinbouwgewas, de aardbei op zandgrond
    Boon, J. van der - \ 1967
    Wageningen University. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - ISBN 9789022001523 - 213
    bodemvruchtbaarheid - fragaria - aardbeien - tuinbouw - grondanalyse - bemonsteren - plantenvoeding - noord-brabant - soil fertility - fragaria - strawberries - horticulture - soil analysis - sampling - plant nutrition - noord-brabant
    The study had two purposes: to test the feasibility of the stratified randomplot method in a perennial market-garden crop; to gain a better insight into the ecological requirements of the strawberry, particularly to improve the use of fertilizers. Already known soil factors could be more closely put onto a quantitative basis for their effect on yield, for instance winter and summer watertable, humus content, pH, P, K and Mg status of the top soil and thickness of humic layer. Farmyard manure was clearly beneficial. The harmfulness of diseases came out more clearly than expected. Wind shelter was necessary to obtain a good crop. Close study of the crop and soil can show previously unknown factors, as here with Cu for the strawberry.

    But in the main it cannot be said that the plot method was a complete success for a perennial crop. Many influences could hardly be distinguished. In particular it was not possible to distinguish correlative soil complexes representing soil types which could be described from the profile and which could be of use in forecasting yield.

    Growth changes of plants following the removal of nutritional stresses
    Bouma, D. - \ 1965
    Wageningen University. Promotor(en): A.C. Schuffelen. - Oosterbeek : Viking - 98
    groei - gewassen - plantenvoeding - voedingsstoffen - kunstmeststoffen - mest - groeistadia - gewassen, groeifasen - metabolisme - assimilatie - chemische analyse - blootstelling - milieuafbraak - kinetica - ecotoxicologie - growth - crops - plant nutrition - nutrients - fertilizers - manures - growth stages - crop growth stage - metabolism - assimilation - chemical analysis - exposure - environmental degradation - kinetics - ecotoxicology
    Differential changes in leaf area of plants were used to assess the fertility status of soils. For this method subterranean clover plants were raised in solutions with different levels of nutrients and transferred either into complete solutions or to solutions lacking one of the elements. Response of plants to addition of nutrients was measured by the increase in leaf area over a 7-day period after transfer. In field experiments quantitative relationships were investigated between differences in leaf area as measured by application of the above technique and responses of clover yields to fertilizers containing P or S. Highly significant correlation coefficients were found for both elements.

    The uptake of these nutrients during the experiment seemed to be related to their functions in the metabolism of the plant. During the first 3 days of recovery from P stress, the uptake and translocation of P into the aerial parts of the plant were rapid. Between the 3rd and the 7th day a redistribution of P into newly developed leaves took place and only a little P was taken up from the solution. On the contrary the uptake of S continued during the whole experimental period, which fact suggested, that S compounds in solution were more accessible to meet demands for new growth than S present in other plant parts.

    Organic salts in plants in relation to nutrition and growth
    Tuil, H.D.W. van - \ 1965
    Wageningen University. Promotor(en): A.C. Schuffelen. - Wageningen : Pudoc - 83
    plantkunde - planten - embryologie - organische verbindingen - bosbouw - bomen - plantenvoeding - voedingsstoffen - lolium - beta vulgaris - suikerbieten - waterrelaties - wortels - bodem - botany - plants - embryology - organic compounds - forestry - trees - plant nutrition - nutrients - lolium - beta vulgaris - sugarbeet - water relations - roots - soil
    Nutrient elements applied to the soil not only give crop production but cause certain interactions with chemical constituents of the plant. Studies on four different plants, perennial ryegrass, sugar-beet, poplar and birch, demonstrated that regardless of difference in natural environment, each plant needed an optimum organic salt content as a condition to achieve optimum growth.

    The total amount of organic salts present in tissue and the relative proportion of the individual organic salts could easily be influenced by application of certain nutrient elements. The total organic salt content required for optimum growth was about 1000 m-equiv. per kg dry matter for herbage of perennial ryegrass, 3500 m-equiv. in young leaves of sugar-beet plants, 1100 m-equiv. in poplar leaves and 550 m-equiv. in birch leaves.

    The uptake of ammonium nitrogen led to decrease of organic salt content in plant tissue. This is probably not due to utilization of nitrogen in a plant but to competition between other cations and ammonium during nutrient uptake.

    Kunstmest voor voedsel
    Schuffelen, A.C. - \ 1965
    Wageningen : Unknown Publisher - 15
    kunstmeststoffen - ontwikkelingslanden - openbare redes - fertilizers - developing countries - public speeches
    Rede Wageningen
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