Vorfruchtwirkurigen unterschiedlicher Rotationsbrachen auf Winterweizen     

W. Opitz  Von Boberfeld J. Jasper 《Journal of Agronomy and Crop Science》1994,173(2):125-134

Effects of rotational fallows (‘set-aside land’) on subsequent winter wheat. The aim of the present study was to investigate the effects of different fallow treatment on subsequent winter wheat. The field trials included rotational fallows planted with Trifolium repens, Festuca rubra and Lolium perenne sown under winter barley compared to complete fallow and natural fallow without seed application and fallows planted with Trifolium pratense, Festuca rubra and Dactylis glomerata sown under winter wheat. After ploughing up the fallow vegetation, winter wheat was planted for 2 succeeding years at two levels of N-fertilization. Herbicides and fungicides were not applied. The following criteria were investigated: biomass-production, N-uptake, yield, weed infestation, nitrate and water content of the soil. In autumn, after ploughing up the fallow vegetation, the nitrate content of the soil (0—150 cm) increased by up to 210 kg NO₃-N/ha after complete fallow, by up to 60 kg NO₃-N/ha after natural fallow and by up to 75 and 130 kg NO₃-N/ha after fallows cropped with Trifolium repens and Trifolium pratense, respectively. Low nitrate levels of 20—27 kg NO₃-N/ha were observed after fallows planted with grass. N-immobilization caused by ploughing up grass fallows continued until the first harvest of the subsequent winter wheat. In the second year of winter-wheat, no differences of N-mineralization dependent on the previous fallow crop occurred, except in the case complete fallow which showed lower N-mineralization. It can be concluded that fallows cropped with grass lead to a higher nitrogen fertilizer requirement m the succeeding crops. Festuca rubra was able to form dense swards in strong competition with weeds and to decrease the abundance of Alopecurus myosuroides and Apera spíca-venti in subsequent winter wheat, while natural fallow and fallow planted with Trifolium repens and Lolium perenne caused epidemical increases in grass-weed density. Preceding crop effects on grain yield of the winter wheat showed a close relation to N-supply and were compensated by mineral N-fertilization. After natural fallow and fallow covered with Trifolinm repens, yield reductions due to grass-weed competition occurred. Undersown Festuca rubra seems to possess a special suitabihty for cultivation in routional fallows. It establishes itself strongly under different cover crops and is able to form dense swards in strong competition with weeds. Grass-weed density in the succeeding crops will be reduced and nitrate leaching will still be prevented after ploughing up the fallow vegetation. N-fertilization of the subsequent crops must be carried out under considerations of higher N-requirements which is probably not entirely due to a stronger N-immobilization.  相似文献   

Venus Thermosphere: In situ Composition Measurements, the Temperature Profile, and the Homopause Altitude     

VON Zahn U  Krankowsky D  Mauersberger K  Nier AO  Hunten DM 《Science (New York, N.Y.)》1979,203(4382):768-770

The neutral mass spectrometer on board the Pioneer Venus multiprobe bus measured composition and structral parameters of the dayside Venus upper atmosphere on 9 December 1978. Carbon dioxide and helium number densities were 6 x 10(6) and 5 x 10(6) per cubic centimeter, respectively, at an altitude of 150 kilometers. The mixing ratios of both argon-36 and argon-40 were approximately 80 parts per million at an altitude of 135 kilometers. The exospheric temperature from 160 to 170 kilometers was 285 +/- 10 K. The helium homopause was found at an altitude of about 137 kilometers.  相似文献   

Karlheinz richter zum 65. geburtstag     

Wilhelm Opitz Von Boberfeld 《Archives of Agronomy and Soil Science》2013,59(3):237-239

Studies were carried out on spatio-temporal variations of arbuscular mycorrhizal (AM) fungi associated with Carica papaya L. growing in two different geographic localities in Goa, India – Western Ghats and coastal area, differing in soil characteristics and plantation status. The study recorded considerable variation in root colonization, spore density and distribution of AM fungi in the selected sites. The mean total root colonization was at a maximum in the month of July, while spore density was highest in April. The study recorded a total 33 species of AM fungi. Western Ghats recorded a relatively higher diversity of AM fungi compared to coastal area. Species richness of AM fungi was at a maximum in April and coincided with maximum mean spore density. Edaphic as well as climatic factors influenced the AM fungal parameters. The study recorded the existence of seasonality in AM fungi.  相似文献   

Zum Einfluß von Untersaaten zur Begrünung von Ackerbrachen auf die Vegetationsentwicklung und die Nitratdynamik     

W. Opitz  Von Boberfeld U. Schultheiss 《Journal of Agronomy and Crop Science》1994,172(1):52-61

The influence of undersown green manure crops for fallows – set-aside land – in view of vegetation-development and the dynamic of nitrate
In view of the establishment of rotational fallows - set-aside land - as well as the bridging of the vegetation-free winter period the suitability of different undersown grasses and legumes m winter cereals was investigated in field trials. Festuca rubra developed well in winter barley and winter wheat. The success of the cultivation of Lolium perenne, Trifolium pratense and Trifolium repens in winter cereals is uncertain because of the risk of light and water deficiences. Dactylis glomerata caused an negative influence on the yield of the cover crop. During the fallow period only low levels of nitrate could be found in the soil. Under fallow tilled repeatedly complete fallow- a nitrate accumulation could be observed during the fallow period. After ploughing up the fallow vegetation, nitrate concentrations - depth 0–150 cm – increased to 60 kg NO₃-N · ha^-1 after the natural fallow without seeding, between 60 and 130 kg NO₃-N · ha^-1 after Trifolium and between 160 and 210 kg NO₃-N · ha^-1 after complete fallow. Lowest nitrate levels were observed from the grass-sites. Undersown Festuca rubra seems to be the best choice in order to compete with weeds, to form a dense sod and to prevent nitrate leaching. In general a seed rate of 8 kg · ha^-1 can be recommended.  相似文献   

Zum Einfluβ interspezifischer Konkurrenz in einer Kleegrasmischung auf die Futterqualität     

W. Opitz  von Boberfeld B. Biskupek 《Journal of Agronomy and Crop Science》1995,175(5):355-364

The Influence of Interspecific Competition in a Grass-clover Mixture on Nutritional Value
In a field experiment, the influence of interspecific competition on the nutritional value of different species in a grass-clover mixture was studied. The species were Trifolium pratense and Dactylis glomerata or Lolittm multiflorum , respectively. N-fertilization was varied in two steps (20 and 70 kg N ha^-1 cut^-1). The swards were cut four times a year, and each species was harvested separately. The content of net energy (NEL), crude protein (CP), water-soluble carbohydrates (WSC) and minerals in each species were determined. The NEL content of the species was only slightly influenced by mixed cropping. The CP concent of the grasses was higher in mixtures with Trifolium pratense than in monocultures. The WSC content of the grasses decreased with an increasing ratio of Trifolium pratense in the mixtures. This was due to a higher N-supply in the grasses in mixtures compared with monocultures on the one hand, and shading by Trifolium pratense on the other. In a few cases, the WSC content of Trifolium pratense was reduced by mixed cropping with the grasses. The mineral content of three species was clearly influenced by interspecific competition. The extent and the direction of the changes were different in the particular cuts and depended on the growing conditions and yield ratios of the species in the different mixtures. The results show that interspecific competition has an influence on the nutritional value of the species in a grass-clover mixture.  相似文献   

Residues of atrazine, simazine, linuron and diuron after repeated annual applications in a peach orchard     

P. B. MARRIAGE  W. J. SAIDAK  F. G. VON  STRYK 《Weed Research》1975,15(6):373-379

Annual applications of the herbicides atrazine, simazine, linuron and diuron at 45 kg/ha were made to the same plots for 9 consecutive years from 1963 to 1971 in a peach (Prunus persica (L.) Batsch.) orchard located on sandy loam soil near Harrow, Ontario. Soil samples from these plots were collected in late October for the last 3 years (1969–1971) and trees were cut down in December, 1969. Herbicide residues were determined by bioassays based on the fresh and dry weight of oats (Avena sativa L.) and in one year results were confirmed by chemical analysis. Significant accumulation of herbicides was not observed. The maximum residue levels measured in October over the 3 years of sampling were 7′3 kg/ha for diuron, 3–8 kg/ha for linuron, 1–6 kg/ha for simazine and 04 kg/ha for atrazine in the top 15 cm of the soil profile. Simazine and atrazine showed a rapid decrease in amount after treatment but diuron and linuron were degraded more slowly. Measurable residues of all herbicides were confined to the upper 15 cm of the soil profile and the majority of herbicide remained in the 0–5-cm soil layer. Oats were planted in the orchard plots from 1972 to 1974 to follow the disappearance of the herbicides. All herbicides caused highly significant yield decreases in 1972, atrazine causing the least (38%) and diuron the greatest (86%) reductions. Diuron reduced the yield of oats in 1973 and caused a highly significant decrease in the weight of young oat plants in 1974.  相似文献   

Accumulation of Secondary Metabolites Formed by Field Fungi in Autumn-Saved Herbage     

P. Golinski  W. Opitz von Boberfeld  M. Kostecki  Z. Kaczmarek  P. K. Golinski 《Journal of Agronomy and Crop Science》2006,192(5):344-351

Taking into consideration the fact that in recent years weather conditions were sufficient to feed cattle on pasture until late autumn or early winter, an experiment was carried out during the years 2000 and 2003 on a low input pasture to show the effect of the pre‐utilization date (June, July, August) and the harvest date in the autumn/winter period (November, December, January) on the accumulation of the following secondary metabolites formed by fungi: ergosterol (ERG), ochratoxin A (OA) and zearalenone (ZEA) in the autumn‐saved herbage. The highest levels of concentration of these metabolites were 470.3, 1.63 and 34.9 ng g^?1 respectively. Lower ERG levels were influenced by later pre‐utilization, which is a logical consequence of the shorter period of time for field toxigenic fungi development. Pre‐utilization in August is strongly recommended as the concentration of ochratoxin A (OA) in the autumn‐saved herbage in January was the lowest (not much changed in comparison with earlier harvest). Later harvest was also affected by higher ZEA concentrations in the analysed samples, which indicates that, under conditions of prolonged pasture utilization, field toxigenic fungi (producing ZEA) increased their population and had proper weather conditions stimulating the biosynthesis of the toxin. The later suggests that the final harvest of autumn‐saved herbage should be made rather in December than in January. Higher levels of humidity influenced higher concentrations of ERG and ZEA in the autumn‐saved herbage.  相似文献   

Effects of Nitrogen Fertilization and Date of Utilization on the Quality and Yield of Tall Fescue in Winter   总被引：1，自引：0，他引：1  

D. Wolf  W. Opitz von Boberfeld 《Journal of Agronomy and Crop Science》2003,189(1):47-53

There is no information available on the influence of nitrogen (N) fertilization on autumn‐accumulated forage under Central European conditions. In this context, the metabolizable energy and the degree of fungal infection have never been examined before. In this study, the effects of the amount of N fertilizer (0, 50, 100 and 150 kg N ha^?1), the date of N application (July and August) and the date of winter harvest (December, January and February) on the quality and dry matter (DM) yield of Festuca arundinacea stands in winter were investigated. DM yield, the metabolizable energy and digestibility of organic matter (= in vitro rumen fermentation technique), crude protein, ADL (acid detergent lignin), and for the first time ergosterol were determined. Disregarding the 0 variant, no interactions of any relevance were present. DM yield, crude protein and values of ADL increased with increasing amounts of N, but the concentration of energy decreased. The late N application resulted mostly in lower DM yields but kept the forage physiologically younger, which brought about higher levels of metabolizable energy and lower concentrations of ADL. With later date of harvest, losses of mass and quality occurred. The degree of fungal infection rose as the amount of N fertilizer increased. Three years of investigation under different weather conditions, including interactions with the effects of N fertilization, provide a good base for generalization.  相似文献   

THE SOYBEAN CROP IN THE UNITED STATES     

VON Struve AW 《Science (New York, N.Y.)》1941,93(2404):86-87

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THE DEMAND FOR SCIENCE BOOKS     

VON Struve AW 《Science (New York, N.Y.)》1941,93(2416):375-376

  相似文献