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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    Effect of application timing and grass height on the nitrogen fertilizer replacement value of cattle slurry applied with a trailing-shoe application system
    Lalor, S.T.J. ; Schroder, J.J. ; Lantinga, E.A. ; Schulte, R.P.O. - \ 2014
    Grass and Forage Science 69 (2014)3. - ISSN 0142-5242 - p. 488 - 501.
    ammonia-emission - soil compaction - animal slurry - pig slurry - manure - volatilization - yield - reduction - herbage
    This study investigated the effect of using a trailing-shoe system to apply cattle slurry, under different conditions of grass height (low [LG]: freshly cut sward [4–5 cm height] vs. high [HG]: application delayed by 7–19 d and applied to taller grass sward [4–11 cm] height) and month of application (June vs. April), on the nitrogen fertilizer replacement value (NFRV) and apparent N recovery (ANRS) of cattle slurry applied to grassland. NFRV was calculated using two methods: (i) NFRVN based on the apparent recovery of slurry-N relative to that of mineral-N fertilizer; and (ii) NFRVDM based on DM yield. The effect of applying slurry into HG swards, relative to LG swards, decreased the DM yield by 0·47 t ha-1 (P = 0·001), N uptake by 5 kg ha-1 (P = 0·05), ANRS by 0·05 kg kg-1 (P = 0·036), NFRVN by 0·05 kg kg-1 (P = 0·090) and NFRVDM by 0·11 kg kg-1 (P <0·001). It was concluded that the main factor causing these decreases with HG, compared with LG applications, was wheel damage affecting subsequent N uptake and growth of the taller grass sward.
    Effects of sheep breed and soybean meal supplementation on rumen environment and degradation kinetics
    Lourenco, A. ; Cone, J.W. ; Fontes, P. ; Dias-Da-Silva, A. - \ 2013
    NJAS Wageningen Journal of Life Sciences 64-65 (2013). - ISSN 1573-5214 - p. 77 - 85.
    voluntary food-intake - low-quality roughage - bos-indicus cattle - dry-matter - nitrogen supplementation - apparent digestibility - merino sheep - digestion - herbage - protein
    The aim of this study was to evaluate if the in vivo digestibility and intake differences, observed in previous studies, between Ile-de-France (IF) and Churra-da-Terra-Quente (CTQ) sheep breeds, were due to rumen environment and degradability differences. The intake, digestibility, rumen environment and degradability and urinary allantoin-nitrogen excretion were evaluated in 8 adult cannulated ewes (4 CTQ and 4 IF ewes). The animals were fed ad libitum hay – with and without a soybean meal supplementation (150 g/kg ingested hay, dry matter basis). The organic matter intake per kg of body weight was higher (P <0.05) and the NDF and hay organic matter digestibility was lower in CTQ ewes (P <0.05), irrespective of supplementation. The rumen pH remained above 6.35 in all treatments, and the difference between the breeds was not biologically relevant. The ammonia nitrogen rumen content and the urinary allantoin-nitrogen excretion were similar (P > 0.05), whether the breeds where fed hay or hay supplemented with soybean meal. The volatile fatty acid concentrations in the rumen were similar (P > 0.05) for both genotypes. There was no breed effect (P > 0.05) on the rumen protozoa population, although supplementation increased its number (P <0.001). As a result of the absence of differences in rumen content characteristics, there were no differences between the breeds (P > 0.05) on rumen in sacco degradation results. Thus, the effective rumen degradation was lower in the CTQ breed, when its inherit lower outflow rate was used to calculate it. This study suggests that the native CTQ breed and the IF breed exhibit similar rumen conditions for the microbial degradation of fibrous feeds. Thus the higher intake and lower digestibility of the CTQ breed can only result from its inherit faster flow through the gastrointestinal tract
    Pathways for improving the nitrogen efficiency of grazing bovines
    Hoekstra, N.J. - \ 2007
    Wageningen University. Promotor(en): Paul Struik, co-promotor(en): Egbert Lantinga; R.P.O. Schulte. - [S.l.] : S.n. - ISBN 9789085047834 - 159
    bovidae - stikstof - begrazing - lolium perenne - diervoeding - koeien - grasbestand - graslandbeheer - plantensamenstelling - chemische samenstelling - gebruiksefficiëntie - bovidae - nitrogen - grazing - lolium perenne - animal nutrition - cows - herbage - grassland management - plant composition - chemical composition - use efficiency
    Livestock production has been identified as a major source of nitrogen (N) losses in agro-ecosystems. N excreted in dung and urine contributes to environmental N pollution either as ammonia and N oxides in air, or as nitrate in soil and ground water. Therefore, it is important to reduce N output through animal excretions by improving N utilisation by the animal. Bovine N utilisation can be increased substantially through changing the composition of the diet. In many parts of Europe, a large proportion of the bovine’s diet consists of grass taken up by grazing. Manipulating the nutritional composition of grazed grass poses a complex challenge, since it is hard to control the diet under grazing as this depends on grassland management and environmental factors. The objective of this research was to investigate the efficacy of grassland management tools for manipulating herbage quality and to assess the subsequent effect on the N efficiency of grazing cows. In the literature review, three pathways were identified through which more efficient N utilisation by grazing bovines can be achieved by manipulation of the chemical composition of the grass forage: 1) matching protein supply to animal requirements, 2) balancing and synchronising carbohydrate and N supply in the rumen, and 3) increasing the proportion of rumen undegradable protein (RUP). Under grazing conditions, grassland management tools, such as the length of the regrowth period, defoliation height, fertiliser N application rate, and growing high-sugar grass cultivars, are the main tools to manipulate herbage quality and subsequent bovine N efficiency. A field experiment was carried out to study the effect of those grassland management tools on the chemical composition of lamina and sheath material. These results were used to design a model for predicting the efficacy of herbage management tools for affecting the quality of herbage ingested by cattle under strip-grazing management. This model was validated and connected to the Cornell Net Carbohydrate and Protein System model in order to evaluate the effectiveness of a) the grassland management tools and b) the herbage quality pathways on the N utilisation of grazing dairy cows. Within the modelled scenario the concentration of crude protein (CP) in the ingested dry matter (DM) was the main factor affecting N utilisation. Model predictions indicated that herbage should be managed to achieve a CP concentration of 130−150 g / kg DM in order to maximise the efficiency of N utilisation for milk production and minimise the proportion of N excreted in urine. Both N application rate and rotation length were shown to be effective tools for affecting the CP concentration of the intake and subsequent cow N utilisation. However, there was no effect of the high-sugar cultivar and defoliation height on cow N utilisation. Assessment of the effectiveness of the three herbage quality pathways for improving bovine N utilisation resulted in the following conclusions: 1) N utilisation is strongly related to the daily N intake (g / day), however, this seems more connected to the N concentration of the ingested DM (g / kg DM), rather than the actual daily N intake. Therefore, the effect is more related to the balance between energy and N (pathway 2). 2) The balance between N and energy is the most important herbage quality factor for improving bovine N utilisation. In contrast, the synchronisation between the release of energy and N seems to have little effect. 3) The proportion of protein in the form of RUP is not much affected by the herbage management tools, and is therefore not an effective pathway for improving the N utilisation of grazing cows. It is recommended that the model will be extended to include a herbage yield and intake component. This would allow the model to be used to design herbage management systems to optimise N utilisation on a yearly basis.
    Chemical composition of lamina and sheath of Lolium perenne as affected by herbage management
    Hoekstra, N.J. ; Struik, P.C. ; Lantinga, E.A. ; Schulte, R.P.O. - \ 2007
    NJAS Wageningen Journal of Life Sciences 55 (2007)1. - ISSN 1573-5214 - p. 55 - 73.
    afsnijhoogte - grasbestand - voedergewassen - lolium perenne - hergroei - rotaties - chemische samenstelling - graslandbeheer - voedingswaarde - lignine - totale hoeveelheid droge stof - koolhydraten - stikstof - vezelgehalte - bloeiwijzen - cutting height - herbage - fodder crops - lolium perenne - regrowth - rotations - chemical composition - grassland management - nutritive value - lignin - total solids - carbohydrates - nitrogen - fibre content - inflorescences - water-soluble carbohydrate - neutral detergent fiber - dairy-cows - nitrogen application - nutritive-value - ryegrass varieties - animal nutrition - milk-production - rumen function - l. cultivars
    The quality of grass in terms of form and relative amounts of energy and protein affects both animal production per unit of intake and nitrogen (N) utilization. Quality can be manipulated by herbage management and choice of cultivar. The effects of N application rate (0, 90 or 390 kg N ha¿1 year¿1), duration of regrowth period (2¿3, 4¿5, or 6¿7 weeks), and cutting height (8 or 12 cm) on the mass fractions of nitrogen (N), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and ash in lamina and sheath material of a high-sugar (Aberdart) and a low-sugar (Respect) perennial ryegrass (Lolium perenne) cultivar, were studied in a factorial field experiment during four seasons in 2002 and 2003. Expressing NDF and ADF mass fractions in g per kg WSC-free dry matter (DM) increased the consistency of treatment effects. The high-sugar cultivar had generally higher WSC mass fractions than the low-sugar cultivar, especially during the late season. Moreover, the relative difference in WSC mass fraction between the two cultivars tended to be higher for the lamina material than for the sheath material, which suggests that the high-sugar trait may be more important under grazing conditions, when lamina forms the bulk of the intake, than under mowing regimes. Longer regrowth periods and lower N application rates increased WSC mass fractions and decreased N mass fractions; interactions between regrowth period and N application rate were highly significant. The mass fractions of NDF and ADF were much less influenced. The NDF mass fraction in terms of g per kg WSC-free DM tended to be higher at lower N application rates and at longer regrowth periods. The effect of cutting height on herbage chemical composition was unclear. In conclusion, high-sugar cultivars, N application rate and length of the regrowth period are important tools for manipulating herbage quality.
    Interpretation of results from on-farm experiments: manure-nitrogen recovery on grassland as affected by manure quality and application technique. 1. An agronomic analysis
    Groot, J.C.J. ; Ploeg, J.D. van der; Verhoeven, F.P.M. ; Lantinga, E.A. - \ 2007
    NJAS Wageningen Journal of Life Sciences 54 (2007)3. - ISSN 1573-5214 - p. 235 - 254.
    melkveehouderij - mest - graslandbeheer - stikstofmeststoffen - organisch bodemmateriaal - stabiliteit - agronomische kenmerken - bemesting - dairy farming - manures - grassland management - nitrogen fertilizers - soil organic matter - stability - agronomic characteristics - fertilizer application - cattle slurry - dairy farms - ammonia volatilization - soil - netherlands - management - efficiency - reduction - herbage - performance
    In a 5-year field experiment, a comparison was made between the manure application practices of two adjacent dairy farms in the north of the Netherlands. Grassland management systems at Drogeham and Harkema contrasted in manure application technique (surface application versus shallow injection, respectively), quality of applied manure (slurry + MX: slurry with Euromestmix® clay mineral additive versus regular slurry), and some relevant site characteristics (high versus low soil organic matter content and soil moisture supply). Effects of manure types and application techniques, and treatment of the soil with a micro-organism supplement, were tested in a factorial experiment at the two sites, two blocks per site, one with and one without additional application of 157 kg N ha¿1 year¿1 inorganic fertilizer. Apparent N recovery was higher after shallow injection than after surface application. For plots receiving no additional inorganic fertilizer, this difference was largest for slurry + MX applied at site Harkema, since this slurry¿site combination resulted in the highest observed average apparent N recovery following shallow injection (47%) and the lowest N recovery following surface application (20%). For plots receiving additional inorganic fertilizer N the contrasts between treatments were less pronounced. Year effects on N uptake and dry matter production could be related to cumulative temperature and precipitation surplus over the growing season. A simple comparison between the grassland management systems was carried out based on the response curves derived from the experiment. This demonstrated that the grassland system where slurry was applied by shallow injection is not necessarily the lowest in actual amount of N not accounted for (i.e., potentially lost). The efficiency of the Harkema system strongly depended on high N recovery, but showed high potential losses in some years and a high herbage crude protein content in other years, due to the low DM production capacity. On the other hand, the Drogeham system was tuned to high DM production and was characterized by higher system stability, as reflected by more stable relationships between DM production and N not accounted for and herbage crude protein content. These differences between the systems were probably to a large extent caused by differences in water balance and soil organic matter content
    Proceedings of the Frontis workshop on fresh herbage for dairy cattle : the key to a sustainable food chain
    Elgersma, A. ; Dijkstra, J. ; Tamminga, S. - \ 2006
    Dordrecht : Springer (Wageningen UR Frontis series vol. 18) - ISBN 9781402054518
    melkvee - grasbestand - begrazing - soortenrijkdom - lolium perenne - voeropname - voedingsstoffen - voedersupplementen - graslandbeheer - stikstofmetabolisme - lipiden - melkkwaliteit - diervoeding - duurzaamheid (sustainability) - dairy cattle - herbage - grazing - species richness - lolium perenne - feed intake - nutrients - feed supplements - grassland management - nitrogen metabolism - lipids - milk quality - animal nutrition - sustainability
    Product quality and a sustainable food chain of ruminant products are largely determined by animal nutrition, in which forage is the major feed source. Forages and grasslands play a unique role in agriculture because they contribute through animals to our food supply and to the abatement of environmental problems. Interest in grassland management and grass utilization for dairy production in temperate and subtropical regions has recently led to considerable research efforts. In the past this research often emphasized on plant and animal aspects separately. However, the interrelationship between pasture and the grazing ruminant is a dynamic, two-way process. Many people are not aware of these complex relations, and scientists often focus on either soil-plant interactions, plant production, animal nutrition, animal production or product quality issues. This book contains the contributions of researchers and experts in the field of grassland management and grass utilization. Chapters are arranged in an order that allows progressive development within the food chain, moving from the big picture to basic principles of grassland management and effects on herbage quality, intake and nutrient flows.
    Imaging Spectroscopy for On-Farm Measurement of Grassland Yield and Quality
    Schut, A.G.T. ; Heijden, G.W.A.M. van der; Hoving, I.E. ; Stienezen, M.W.J. ; Evert, F.K. van; Meuleman, J. - \ 2006
    Agronomy Journal 98 (2006)5. - ISSN 0002-1962 - p. 1318 - 1325.
    infrared reflectance spectroscopy - chemical-composition - calibration transfer - management - regression - chemistry - herbage - models - litter - swards
    Grassland management has a large influence on the operating cost and environmental impact of dairy farms and requires accurate, detailed, and timely information about the yield and quality of grass. Our objective was to evaluate imaging spectroscopy as a means to obtain accurate, detailed, and rapid measurements of grass yield and quality. The work consisted of three steps. In the first step, a new mobile measurement system comprising several hyperspectral sensors was constructed and calibrated on measurements collected in six field experiments in the Netherlands in 2 yr. A partial least squares regression model was used to fit parameters derived from hyperspectral images to values of DM (dry matter) yield and quality obtained through destructive sampling. Leave-k-out cross validation showed relative errors of prediction of 8 to 22% (167¿477 kg DM ha¿1 absolute) for DM yield, 21% (0.07 absolute) for the fraction of clover in DM, 6 to 12% for nutrient concentration, 15 to 16% for sugar concentration, and 3 to 5% for feeding values. In the second step, the measurement system was used to predict grassland yield and quality on fields from two farms. In the third step, the absence of calibration data for a specific date was simulated with a leave-harvest-out procedure. Predictions of absolute values were strongly biased due to system instability. Prediction of relative values was good, with a mean absolute error of 183 kg ha¿1 for DM yield. The instability of the measurement system requires that duosampling must be used for prediction of absolute values.
    Improving the quality of perennial ryegrass (Lolium perenne L.) for dairy cows by selecting for fast clearing and/or degradable neutral detergent fiber
    Taweel, H.Z. ; Tas, B.M. ; Smit, H.J. ; Elgersma, A. ; Dijkstra, J. ; Tamminga, S. - \ 2005
    Livestock Production Science 96 (2005)2-3. - ISSN 0301-6226 - p. 239 - 248.
    feed-intake - nitrogen - digestion - protein - lignin - diet - digestibility - nutrition - herbage - time
    Neutral detergent fiber (NDF) fractional clearance rate (Kcl) and fractional degradation rate (kd) of six varieties of perennial ryegrass were measured to examine the possibility of selecting for varieties with fast degradable NDF. The experiment was conducted in 2000 and repeated in 2001. In each year, six multiparous rumen-cannulated dairy cows were stall-fed with six varieties of perennial ryegrass during three 2-week periods, using a double 3 × 3 Latin square design. The NDF fractional clearance rate (KclNDF) and the acid detergent lignin fractional clearance rate (KclADL) were estimated using two consecutive rumen evacuations, separated by a 12-h period of feed deprivation assuming a first-order kinetics. The NDF fractional degradation rate (kdNDF) was calculated based on the assumption that NDF fractional passage rate (kpNDF) was equal to KclADL. The KclNDF of the different grass varieties was in the range of 5 to 6%/h. The kdNDF was lower than reported in situ values and ranged from 2 to 3%/h. The KclNDF and kdNDF were not significantly different among grass varieties in both years. The difference between the fastest disappearing and degrading variety and the slowest one was less than 1%/h. This may indicate that within perennial ryegrass varieties, there is a narrow range of improvement with regard to clearance and degradation rates
    Perennial ryegrass for dairy cows: effects of cultivar on herbage intake during grazing
    Smit, H.J. - \ 2005
    Wageningen University. Promotor(en): Seerp Tamminga, co-promotor(en): Anjo Elgersma. - [S.l.] : S.n. - ISBN 9789085042150 - 138
    melkkoeien - lolium perenne - cultivars - grasveld - grasbestand - voeropname - begrazing - voedingsvoorkeuren - rundveevoeding - dairy cows - lolium perenne - cultivars - grass sward - herbage - feed intake - grazing - feeding preferences - cattle feeding
    Keywords:Perennial ryegrass, Lolium perenne , sward morphology, sward cutting, n-alkanes, herbage intake, selection, preference.

    Perennial ryegrass ( Lolium perenne L.) is the most important species for feeding dairy cows. The majority of the farmers in the Netherlands graze their dairy cows during summer. During grazing, the limited herbage intake is the main limitation of the dairy cows' production. This study examined opportunities for grass breeders to influence the quality of perennial ryegrass cultivars to improve the herbage intake of dairy cows.

    Six cultivars of perennial ryegrass (Abergold, Respect, Agri, Herbie, Barezane,Barnhem) were intensively studied during two years (2000 and 2001) between June and September. There were differences between the cultivars for important characteristics influencing herbage intake, e.g. herbage yield, sward surface height and density. Furthermore, differences between cultivars were found for the proportions and the biomass of leaf, stem and pseudostem in the sward. The sward cutting and the n-alkanes technique, both methods to determine the herbage intake by grazing dairy cows, were compared with an average that was calculated from the milk production and the live weight of the dairy cows. The sward cutting technique gave very variable results that varied largely per cow and year, and did not match with the expected calculated intake. The n-alkanes method gave less variable results that were more related to the expected calculated intake values. Within the n-alkanes method, the ratio C 32 :C 33 gave the best results.

    The effects of perennial ryegrass cultivars on the intake of grazing dairy cows were examined. In 2002 and 2003, cows grazed each of the four cultivars during four 2-week periods. Herbage intake was estimated using the C 32 :C 33 -alkanes method. In 2002, a clear difference was found between the cultivars, but in the second year no differences were found. A higher herbage intake was related with a higher mass of herbage and green leaf, a higher sward surface height, a lower infestation rate of the crown rust fungi anda lowerlignin content in the herbage. The cultivars differed too little in the other quality parameters to induce effects in the cow. The aspects of selection and preference were examined in an experiment with the six earlier described cultivars. The experiment was conducted in three 4-day periods in spring, summer and autumn. Herbage intake was measured using the sward cutting method. The dairy cows very consistently preferred cultivars with a high water soluble carbohydrates concentration, a high digestibility, a low cell wall concentration and a low ash concentration. It was concluded that in the selection process the chemical quality of the herbage plays an important role.
    Potential of imaging spectroscopy as tool for pasture management
    Schut, A.G.T. ; Lokhorst, C. ; Hendriks, M.M.W.B. ; Kornet, J.G. ; Kasper, G.J. - \ 2005
    Grass and Forage Science 60 (2005)1. - ISSN 0142-5242 - p. 34 - 45.
    infrared reflectance spectroscopy - grass swards - chemical-composition - nitrogen - herbage - mass - deficiency - regression - quality - nirs
    The use of imaging spectroscopy to predict the herbage mass of dry matter (DM), DM content of herbage and crude fibre, ash, total sugars and mineral (N, P, K, S, Ca, Mg, Mn, Zn and Fe) concentrations was evaluated. The experimental system used measured reflectance between 404 and 1650 nm at high spatial (0·281·45 mm2) and spectral resolution. Data from two experiments with Lolium perenne L. mini-swards were used where the degree of sward damage or N-fertilizer application varied. Regression models were calibrated and validated and the potential reduction in prediction error with multiple observations was estimated. The mean prediction errors for DM mass, DM content and N, total sugars, ash and crude fibre concentrations were 235268 kg ha1, 9·616·8 g kg1, 2·43·4 g kg DM1, 16·227·7 g kg DM1, 5·86·5 g kg DM1 and 8·410·4 g kg DM1 respectively. The predictions for concentrations of P, K, S and Mg allowed identification of deficiency levels, in contrast to the concentrations of Na, Zn, Mn and Ca which could not be predicted with adequate precision. Prediction errors of DM mass may be maximally reduced to 95142 kg ha1 with 25 replicate measurements per field. It is concluded that imaging spectroscopy can provide an accurate means for assessment of DM mass of standing grass herbage. Predictions of macronutrient content and feeding value were satisfactory. The methodology requires further evaluation under field conditions.
    Gevoelige bodem koesteren
    Klein Swormink, B. ; Livestock Research, - \ 2004
    Oogstplus. Rundveehouderij 17 (2004)20. - p. 15 - 15.
    melkveehouderij - melkveebedrijven - biologische landbouw - graslanden - weiden - graslandbeheer - plantenvoeding - toedieningswijzen - toedieningshoeveelheden - mestgiften - opbrengsten - gewasopbrengst - klavers - grasbestand - bemesting - dairy farming - dairy farms - organic farming - grasslands - pastures - grassland management - plant nutrition - application methods - application rates - dressings - yields - crop yield - clovers - herbage - fertilizer application
    Graslandbeheer en bemesting op het biologische melkveebedrijf van Durk Oosterhof in Drachten (Fr). Alle percelen, op leemachtig zand, worden maximaal benut voor de productie van grasklaver. Op het bedrijf is, in het kader van het Bioveem-project, onderzoek gedaan naar de effectiviteit van dierlijke mest bij verschillende manieren van toedienen (sleepvoetbemester, zodenbemester, bovengronds). Daaruit bleek dat berijden van het land van invloed is op de grasopbrengst; de sleepslangmethode kwam nog als beste uit de bus. Een lagere mestgift kan toch leiden tot een acceptabele opbrengst, mits er voldoende fosfaat en kali in de bodem zit
    Hyperspectral remote sensing of tropical grass quality and quantity
    Mutanga, O. - \ 2004
    Wageningen University. Promotor(en): Andrew Skidmore; Herbert Prins, co-promotor(en): H.G.J. Huizing. - Enschede : ITC - ISBN 9789058089816 - 196
    tropische graslanden - kwaliteitscontroles - kwantiteitscontrole - remote sensing - spectroscopie - spectraalanalyse - zuid-afrika - grasbestand - tropical grasslands - quality controls - quantity controls - remote sensing - spectroscopy - spectral analysis - south africa - herbage
    Resource distribution is a fundamental factor governing the movement and distribution of herbivores. Specifically, the quality (foliar concentration of nitrogen, phosphorous, calcium, magnesium, potassium and sodium) and quantity (biomass) of vegetation are important factors. In this regard, the development of techniques that can model the distribution of vegetation quality and quantity are critical for an improved understanding of wildlife distribution as well as facilitating an optimal management of wildlife resources. The advent of hyperspectral remote sensing has offered unprecedented opportunities to accomplish this task.

    This study aimed to investigate the potential of hyperspectral remote sensing in estimating biomass of tropical grass at full canopy cover (a task that could not be achieved using broad band satellite images) and to predict and map the quality of tropical grasses at canopy level. Our approach was to investigate the potential of hyperspectral remote sensing at three levels of investigation - laboratory level, field level and airborne platform level.

    Our results showed that, at full canopy cover, tropical grass biomass is more accurately estimated by vegetation indices based on narrow wavelengths located in the red edge than the standard NDVI. At laboratory level, we could discriminate between different foliar nitrogen treatments using high-resolution spectra measured at canopy level. We also showed that there was a shift of the red edge position to longer wavelengths with an increase in nitrogen concentration. The laboratory experiment permitted the extension of the developed techniques to the field level. Using continuum-removed absorption features calculated from field spectra, we could reliably predict the quality (N, K, P, Ca, Mg, Na) of in situ grass measured in the Kruger National Park, South Africa. We also showed a strong interaction between species type and biochemical concentration in effecting spectral reflectance. This provided a basis for the algorithms to use in mapping foliar biochemicals in a mixed species environment using airborne hyperspectral image. Therefore the techniques developed for accomplishing the final stage (airborne platform level) were largely built upon the laboratory and field observations. The new integrated approach, involving the red edge position, continuum-removed absorption features as well as a neural network was applied to map foliar nitrogen concentration in the Kruger National Park, South Africa.

    Overall, the study has shown the potential of hyperspectral remote sensing to predict the quality as well as the quantity of tropical grasses. The result is important for wildlife habitat modelling.

    Explorative research into quality of slurry manure from dairy farms with different feeding strategies
    Reijs, J.W. ; Meijer, W.H. ; Bakker, E.J. ; Lantinga, E.A. - \ 2003
    Netherlands Journal of Agricultural Science 51 (2003)1-2. - ISSN 0028-2928 - p. 67 - 89.
    rundveemest - rundveedrijfmest - stikstof - diervoedering - grasbestand - fytotoxiciteit - grassen - klavers - biotesten - melkveehouderij - cattle manure - cattle slurry - nitrogen - animal feeding - herbage - phytotoxicity - grasses - clovers - bioassays - dairy farming - cress lepidium-sativum - seed-germination - sewage-sludge - cattle feces - growth - mineralization - decomposition - netherlands - deterrents
    To assess cattle slurry manure quality in relation to feeding strategy, a field experiment and a bio-assay were carried out with slurries from four dairy farming systems that used diets differing in protein content and digestibility. Several quality aspects were evaluated. In the field experiment the effects of slurry manure type on herbage rejection by grazing heifers and herbage yield on undisturbed plots under cages were studied for a grass monoculture and a grass/clover mixture. The bio-assay, consisting of a cress (Lepidium sativum L.) seed germination test, was used to study differences in phytotoxicity between the slurry types. After five weeks of undisturbed growth at equal amounts of applied inorganic nitrogen (N), the herbage yields differed statistically for the different slurries. This was probably due to immobilization of N in the case of the two slurries from farming systems in which straw was fed and used as bedding material. Herbage rejection by grazing animals was significantly shown for all slurry types and was significantly and positively correlated with the NH3/NH4 +-N content of the slurry. The slurries showed large differences in phytotoxicity to seeds and seedlings in the bio-assay. Ammonia and electric conductivity appeared to be the most important slurry parameters with inhibiting effects. The slurries with a high C/N ratio showed lowest phytotoxicity. Phytotoxicity in the cress seed germination test did not account for reduced herbage yields in the field experiment. On the contrary, when the slurries were ranked according to their phytotoxicity the order was the same as the ranking on the basis of undisturbed herbage yield. It was concluded that there is a need for other laboratory tests that show greater resemblance with what is observed in the field to assess slurry quality.
    Engels raaigras: een stimulans voor de melkveehouderij in Litouwen
    Wouters, B. ; Schukking, S. - \ 2002
    Praktijkkompas. Rundvee 16 (2002)3. - ISSN 1570-8586 - p. 14 - 15.
    melkveehouderij - agrarische bedrijfsvoering - melkveebedrijven - demonstratiebedrijven, landbouw - melkproductie - melkopbrengst - diervoedering - veevoeding - rundveevoeding - voedergewassen - voederplanten - grassen - grasbestand - graslandbeheer - graslandverbetering - weiden - lolium perenne - litouwen - landen van de europese unie - lidmaatschap - dairy farming - farm management - dairy farms - demonstration farms - milk production - milk yield - animal feeding - livestock feeding - cattle feeding - fodder crops - fodder plants - grasses - herbage - grassland management - grassland improvement - pastures - lolium perenne - lithuania - european union countries - membership
    Met steun vanuit Nederland is op zeven praktijkbedrijven de bedrijfsvoering verbeterd. De introductie van Engels raaigras droeg daar sterk aan bij.
    Gras lagekostenbedrijf nog geen topkwaliteit
    Wouters, B. ; Remmelink, G. - \ 2002
    Praktijkkompas. Rundvee 16 (2002)1. - ISSN 1570-8586 - p. 16 - 17.
    grassen - graskuilvoer - graslanden - kuilvoer - graslanden, conditie - graslandbeheer - ruwvoer (forage) - ruwvoer (roughage) - veevoeder - voederwaardering - grasbestand - rundveevoeding - melkveebedrijven - proefbedrijven - groenvoer - groenvoeders - kwaliteit - proefboerderijen - grasses - grass silage - grasslands - silage - grassland condition - grassland management - forage - roughage - fodder - feed evaluation - herbage - cattle feeding - dairy farms - pilot farms - green feed - green fodders - quality - experimental farms
    Op het lagekostenbedrijf is de melkproductie uit ruwvoer hoog bij de beperkte krachtvoergift. Dit zou nog hoger kunnen zijn bij een betere graskwaliteit.
    Veranderingen in de kruidlaag in bosreservaten
    Dort, K.W. van; Bouwma, L.M. ; Broekmeyer, M.E.A. ; Koop, H.G.J.M. - \ 1999
    De Levende Natuur 100 (1999)5. - ISSN 0024-1520 - p. 154 - 157.
    bossen - bosbouw - bosecologie - planten - grondvegetatie - grondbedekking - grasbestand - onderlaag - plantensuccessie - plantengemeenschappen - soortendiversiteit - botanische samenstelling - zandgronden - forests - forestry - forest ecology - plants - ground vegetation - ground cover - herbage - understorey - plant succession - plant communities - species diversity - botanical composition - sandy soils
    Algemene waargenomen trends in de ontwikkeling van de kruidlaag in bossen op voedselarme zandgronden. In de natuurlijke bosdynamiek spelen licht en voedingstoestand een belangrijke sturende rol
    Eerste opname van de ondergroei in het Meetnet Bosvitaliteit
    Dobben, H.F. van; Vocks, M.J.M.R. ; Bouwma, I.M. - \ 1997
    Wageningen : IBN-DLO (IBN - rapport 321) - 29
    bosbouw - grondbedekking - grasbestand - mossen - korstmossen - milieu - verontreiniging - monitoring - achteruitgang, bossen - levensvatbaarheid - nederland - onderlaag - forestry - ground cover - herbage - mosses - lichens - environment - pollution - monitoring - forest decline - viability - netherlands - understorey
    Influence des arbres agroforestiers sur le sol et la strate herbacée du Sud du Sahel : étude particuliere du phosphore
    Radersma, S. - \ 1996
    Wageningen : AB-DLO (Rapports PSS 26) - 106
    bosbouw - bomen - agroforestry - grondbedekking - grasbestand - bodemvorming - planten - bodemprofielen - bodem - fosfor - onderlaag - forestry - trees - agroforestry - ground cover - herbage - soil formation - plants - soil profiles - soil - phosphorus - understorey
    Het vochtgehalte in de strooisellaag onder verschillende vegetaties in twee grove-dennenopstanden
    Clerkx, A.P.P.M. ; Hees, A.F.M. van - \ 1993
    Wageningen : IBN (IBN - rapport 040) - 34
    bosbouw - bodemwater - permeabiliteit - absorptie - hygroscopiciteit - bosstrooisel - strooisel - grondbedekking - grasbestand - bomen - pinus sylvestris - nederland - onderlaag - utrecht - forestry - soil water - permeability - absorption - hygroscopicity - forest litter - litter (plant) - ground cover - herbage - trees - netherlands - understorey
    Effects of acidification, liming and fertilization on the undergrowth of a pine forest stand in central Sweden
    Dobben, H.F. van; Dirkse, G.M. ; Braak, C.J.F. ter - \ 1992
    Wageningen : IBN-DLO (RIN report 92/21) - 26
    bosbouw - bomen - bosschade - zure regen - grondbedekking - grasbestand - kalk - gips - krijtkalk - atmosfeer - luchtverontreiniging - chemicaliën - zweden - onderlaag - bosopstanden - bemesting - forestry - trees - forest damage - acid rain - ground cover - herbage - lime - gypsum - chalk - atmosphere - air pollution - chemicals - sweden - understorey - forest stands - fertilizer application
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