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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 27 (1991), S. 189-198 
    ISSN: 1573-0867
    Schlagwort(e): Winter wheat ; nitrogen ; uptake ; simulation ; model ; soil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Simulation of the nitrogen behavior in the soil and the nitrogen uptake by winter wheat was performed using the model ANIMO. As input for the model ANIMO simulations of the hydrological conditions in the soil crop ecosystem were executed with the model SWATRE. Compared with measured data the simulation of nitrogen uptake by the crop was satisfactory. The simulation of mineral nitrogen in the soil agreed reasonably well with measured data for one of the experiments used for the analysis. The agreement was less for experiments with additional fertilizer applications in May and June.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 27 (1991), S. 129-140 
    ISSN: 1573-0867
    Schlagwort(e): Douglas-fir ; nitrogen ; mineral cycling ; growth and yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Forest managers in the Pacific Northwest (PNW) use fertilization as a means to increase timber yields in managed stands. Information on the biological basis for nutrient amendments and stand growth responses to fertilization is required to effectively use fertilization as a silvicultural tool, and research programs in mineral cycling and forest nutrition have been underway in the region for about four decades. Most PNW Douglas-fir forest sites are nitrogen deficient. Mineral cycling research has shown high C/N ratios and low nitrification rates for soils in the region. Research and development projects in the Pacific Northwest have produced an information base that is used to select sites and stands for fertilization and to forecast growth after treatment. Much of the basis for operational fertilization programs in western Oregon and Washington comes from cooperative research programs; current activities for these programs are directed toward improving site-specific response information. Forest fertilization in the Pacific Northwest has become a silvicultural practice of major significance over the past two decades. Forest industry and government organizations managing forest lands in western Oregon and Washington apply nitrogen fertilizer to Douglas-fir stands over a range of soil and stand types (operational fertilization of other species is minor). About 50,000 to 55,000 ha are fertilized each year, and future programs will likely be of similar magnitude. Most current plans for management regimes including fertilization call for multiple applications.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 21 (1990), S. 167-170 
    ISSN: 1573-0867
    Schlagwort(e): Mo ; interaction ; soybean ; deficiency ; nitrogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Recent on-farm liming experiments showed that Mo deficiency in soybean [Glycine max (L.) Merr.] is widespread in northern Alabama. In contrast, a long-term, fertility-rotation experiment in the same area showed no response to Mo during 33 yr when Mo was added bienially to corn [Zea mays L.] in the rotation; however, soybean foliage had the chlorotic appearance of Mo deficiency. The objective of this study was to determine if Mo deficiency was being missed by comparing only two fertilizer treatments. Each rotation-fertilizer treatment plot was split into two, with one-half receiving MO at a 100 g ha−1 foliar rate after seedling emergence, while the other half received none. Yields were increased by Mo in 13 to 16 fertilizer treatments in 1985 and 15 out of 16 in 1986. Leaf-N concentrations and seed weight had comparable increased amounts by the Mo supplement. Without the Mo supplement, there was a response to lime but not to P, K, or a Mo-containing micronutrient mixture; with the Mo supplement, there was no response to liming, but a definite response to P and K (in addition to Mo). The lack of response to Mo when applied to corn in a 2-yr rotation over 33 yr led to the erroneous conclusion that these soils were not Mo deficient for soybean.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 22 (1990), S. 71-78 
    ISSN: 1573-0867
    Schlagwort(e): Boron ; critical level ; grain ; nitrogen ; nodulation ; nutrition ; toxicity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A two year field study on the effect of nitrogen N and boron B fertilization on the nodulation, mineral nutrition and grain yield of cowpea was carried out in the Nigerian savanna where fairly widespread B deficiency has been reported. Treatments consisted of four levels of N (0, 15, 30 and 60 kg/ha in 1986 and 0, 15, 30 and 45 kg/ha in 1987) and three levels of B (0, 1.5 and 3.0 kg/ha). Cowpea responded positively though nonsignificantly to N fertilization up to 30 kg N/ha. However, N had no effect on the N, P, K and B content of index leaves. Boron application consistently reduced grain yield. Like N, applied B had no effect on the N, P, K concentration of index leaves but increased B concentration highly significantly (P 〈 0.001). The critical level of B toxicity in index leaves was approximated to be 21pm under field condition. Application of N and B depressed nodulation.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 23 (1990), S. 97-103 
    ISSN: 1573-0867
    Schlagwort(e): Carbon ; mineralization ; nitrogen ; organic fertilizer ; temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The C and N mineralization characteristics of two organic N fertilizers were determined in a soil-less incubation system at three temperature regimes. Protox (derived from activated sewage sludge) initially degraded more rapidly by microbial action compared with dried blood. However, dried blood released more CO2-C and inorganic N towards the end of the incubation periods. The rate of microbial degradation increased with temperature. Mineralization characteristics of protein-based N sources are discussed in relation to organic N nutrition of vegetable crops.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 23 (1990), S. 105-112 
    ISSN: 1573-0867
    Schlagwort(e): Ammonium ; fertigation ; nitrate ; nitrogen ; trickle irrigation ; urea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The movement and transformations of ammonium-, urea- and nitrate-N in the wetted volume of soil below the trickle emitter was studied in a field experiment following the fertigation of N as ammonium sulphate, urea and calcium nitrate. Effects on soil pH in the wetted volume were also investigated. During a fertigation cycle (emitter rate 2lh−1) applied ammonium was concentrated in the surface 10 cm of soil immediately below the emitter and little lateral movement occurred. In contrast, because of their greater mobility in the soil, fertigated urea and nitrate were more evenly distributed down the soil profile below the emitter and had moved laterally in the profile to 15 cm radius from the emitter. The conversion of applied N to nitrate-N was more rapid when urea rather than ammonium-N was applied suggesting that the accumulation of large amounts of ammonium below the emitter in the ammonium sulphate treatment probably retarded nitrification. Following their conversion to nitrate-N, both fertigated ammonium sulphate and urea caused acidification in the wetted soil volume. Acidification was confined to the surface 20 cm of soil in the ammonium sulphate treatment, however because of its greater mobility, fertigation with urea (2lh−1) resulted in acidification occurring down to a depth of 40 cm. Such subsoil acidity is likely to be very difficult to ameliorate. Increasing the trickle discharge rate from 2lh−1 to 4lh−1 reduced the downward movement of urea and encouraged its lateral spread in the surface soil. As a consequence, acidification was confined to the surface (0–20 cm) soil.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 29 (1991), S. 133-138 
    ISSN: 1573-0867
    Schlagwort(e): Phaseolus vulgaris L. ; nitrogen fixation ; nitrogen ; yield components ; side-dress ; selection criteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract There is usually a positive yield response when N is applied to common bean plants grown on N-poor soils. Recommendations include application of some or all of the N at planting, but growth and yield responses to later applications are not well documented. From 50 to 60kg N ha−1 was applied at different growth stages to three bean lines during three years. All N treatments increased yield compared to the unfertilized control. Nitrogen applied during the vegetative stage produced higher seed yields than N applied at planting, flowering, during podfill or a split application. N applied at planting or during vegetative growth increased pod-set, while application at the vegetative and reproductive stages increased seed weight. Even though N application during the vegetative stage showed a negative effect on nodulation, there was a large shoot growth response. The lower yield from N applied at planting may have been caused by less shoot growth response as well as inhibited nodulation. Based on these results the best management system using N fertilizer was an application during vegetative growth. Further studies are needed to identify bean lines capable of high N2 fixation in the presence of N and to determine optimum amounts and timing of N application to maximize biological and economic yields.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 29 (1991), S. 249-260 
    ISSN: 1573-0867
    Schlagwort(e): Canola ; irrigation ; nitrogen ; nitrogen efficiency ; yield ; oil content ; water use
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Effects of N application and water supply on yield, oil content and N accumulation by canola, cultivar Marnoo, grown on a heavy clay soil in the Goulburn Murray Irrigation Region were investigated. Treatments were rainfed (Rf) or watered at a deficit of 50 mm (40–60 mm, I50) beginning in the spring. N treatments were 0, 50, 100 or 200 kg N ha−1 at sowing or as split applications of 20/80, and 50/50 kg N ha−1 at sowing and rosette, respectively. Yield (Yg) ranged from 170 to 520 g m−2. Irrigation and N increased yield in both years. Grain yields were increased by N application on the irrigated treatments when 100 or 200 kg N ha−1 was applied. Oil concentrations ranged from a maximum of 46.4% in treatment N0 to a minimum of 40.6% in treatment N200 and was inversely related to seed N concentration. Although fertilizer N decreased oil concentration, it increased the yield of oil. Nitrogen accumulation (Nb) limited yield of all treatments and was described by the equation, Yg = 806[1-EXP(−0.039*Nb)]. This implied a decrease in yield per unit of Nb at the higher rates of fertilizer addition with consequent increases in grain N concentration. The efficiency of water use in the production of grain (WUEg) and biomass (WUEb) were 7.5 and 23 kg ha−1 mm−1 respectively. Nitrogen additions increased WUEg and WUEb in both seasons. Maximum values of 8.9 (WUEg 1986) and 26.8 (WUEb 1987) were measured from treatment N200. These data suggest that the crops made efficient use of the applied water.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Biodegradation 14 (1991), S. 167-191 
    ISSN: 1572-9729
    Schlagwort(e): leaf longevity ; nitrogen ; nutrient use efficiency ; phosphorus ; requirement ; retranslocation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Aboveground nitrogen (N) and phosphorus (P) requirement, retranslocation and use efficiency were determined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobes L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. Annual aboveground N and P requirements (kg/ha/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. Nitrogen and P retranslocation from current foliage ranged from 81 and 72%, respectively, for European larch, whereas red pine retranslocated the smallest amount of N (13%) and Norway spruce retranslocated the smallest amount of P (18%). In three evergreen species, uptake accounted for 72 to 74% of annual N requirement whereas for two deciduous species retranslocation accounted for 76 to 77% of the annual N requirement. Nitrogen and P use (ANPP/uptake) was more efficient in deciduous species than evergreen species. The results from this common garden experiment demonstrate that differences in N and P cycling among species may result from intrinsic characteristics (e.g. leaf longevity) rather than environmental conditions.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Biodegradation 14 (1991), S. 209-224 
    ISSN: 1572-9729
    Schlagwort(e): ground water ; hydrology ; nitrogen ; mass balance ; nutrient retention ; swamp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Ground water inputs and outputs of N were studied for a small ground water discharge swamp situated in a headwater drainage basin in southern Ontario, Canada. Darcy's equation with data for piezometers was used to measure inputs of shallow local ground water at the swamp margin and deep regional ground water beneath the swamp. Ground water flux was also quantified by measuring ground water discharge to the outlet stream draining the swamp in combination with a chemical mixing model to separate shallow and deep ground water components based on chloride differences. Estimates of shallow ground water flux determined by these two approaches agreed closely however, the piezometer data seriously underestimated the deep ground water input to the swamp. An average ground water input-output budget of total N (TN) total organic nitrogen (TON) ammonium (NH4 +-N) and nitrate (NO3 --N) was estimated for stream base flow periods which occurred on an average of 328 days each year during 1986–1990. Approximately 90% of the annual NO3 --N input was contributed by shallow ground water at the swamp margin. Deep ground water represented about 65% of the total ground water input and a similar proportion of TON and NH4 +-N inputs. Annual ground water NO3 --N inputs and outputs were similar whereas NH4 +-N retention was 4 kg ha-1 representing about 68% of annual ground water input. Annual TON inputs in ground water exceeded outputs by 7.7 kg ha (27%). The capacity of the swamp to regulate ground water N fluxes was influenced by the N chemistry of ground water inputs and the hydrologic pathways of transport within the swamp.
    Materialart: Digitale Medien
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  • 11
    ISSN: 1573-5036
    Schlagwort(e): disturbance ; fertilizer ; nitrogen ; nutrient enrichment ; phosphorus ; secondary succession ; species richness
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Effects of annual additions of mineral N and P (100 kg ha−1) on plant species composition and annual aboveground net primary production (ANPP) were investigated during the first three years following disturbance in a semi-arid ecosystem. Additions of N reduced richness of perennial plant species during years 2 and 3, while P reduced the number of perennial species only in year 3. From year 1 to year 2, annual and biennial species richness declined in all treatments while ANPP of annual species increased greatly. Added N increased ANPP of annual species while it decreased ANPP of most perennial species relative to the unfertilized control treatment. Community similarities were higher for the control and native vegetation than for other pairs of treatments using both species presence and plant production data. Nitrogen additions have retarded but not completely arrested secondary succession in this system.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1573-5036
    Schlagwort(e): eucalypt ; foliar analysis ; legume ; nitrogen ; phosphorus ; plant nutrients ; plant analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The sensitivity of tissue nutrient concentrations to changes in plant age and the supply of P and N was compared between leaves and associated twigs in two forest species. In a young regrowth stand, tissues were sampled on three occasions from the mid-crown position of karri (Eucalyptus diversicolor F. Muell.) and Bossiaea laidlawiana Tovey and Morris, a major understorey legume. Leaves and twigs were also sampled from young plants of B. laidlawiana growing in a mature eucalypt stand to which P treatments had been applied. Nitrogen application increased N concentrations in twigs of karri and B. laidlawiana, but not in leaves. Phosphorus application increased P concentrations in both leaves and twigs of karri but the average increases were proportionally greater in twigs (65%) than in leaves (36%). Over the sampling period, P concentrations in leaves declined, while those in twigs were relatively stable. In B. laidlawiana, P supply also had a larger effect on P concentrations in twigs than in leaves. Addition of 200 kg P ha−1 increased average P concentrations in twigs by 109% in the regrowth stand and by 215% in the mature stand while the corresponding increases in leaves were only 11% and 27%. Concentrations of other nutrients in both species were also affected by N and P application, the most notable being a decline in the concentrations of the minor nutrients, Zn and Cu, with increased P supply. The increased N concentrations in twigs of karri, and the increased P concentrations in tissues of both species, were associated with responses of karri to added N and P, and of B. laidlawiana to added P. This indicates that tissue concentrations of N and P were generally below critical concentrations where N and P were not applied. The results show that for these species twigs may be a better tissue than leaves for diagnosing deficiencies or predicting N and P requirements. The ratio of P concentrations in twigs to P concentrations in leaves also increased with added P. It is suggested that this ratio may be a useful index if it reduces the variability caused by sampling position within the crown or genetic differences between plants.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 123 (1990), S. 67-71 
    ISSN: 1573-5036
    Schlagwort(e): Dalbergia sissoo ; fertilization ; nitrification ; nitrogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The influence of added ammonium, phosphorus, potassium, and gypsum on net nitrogen mineralization was studied in soil beneath a six-year-old plantation of the N2-fixing tree Dalbergia sissoo in Pakistan. Soil with and without amendments was placed in polyethylene bags and incubated, buried in the soil, for 30 days. After that time the soil was analyzed and net ammonium and nitrate production and net nitrogen mineralization were calculated. The addition of ammonium stimulated nitrification indicating that the process was substrate limited. The inhibition of nitrification by Nitrapyrin showed that the process is autotrophic in these soils. Gypsum addition lowered soil pH from 8.0 to 7.2 and significantly stimulated ammonification, nitrification and net nitrogen mineralization. The addition of potassium more than tripled the soil K:Na ratio. Net ammonium and nitrate production and net nitrogen mineralization all increased in this treatment. The addition of phosphorus had no significant effect on soil nitrogen dynamics.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 127 (1990), S. 213-218 
    ISSN: 1573-5036
    Schlagwort(e): dry matter yield ; nickel ; nitrogen ; nutrient concentration ; wheat roots ; wheat tops
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A glasshouse experiment was conducted to study the effect of Ni on the growth and nutrients concentration in wheat (Triticum aestivum Cv. WH 291) in the presence and absence of applied N as urea. Responses to N application were observed up to 120 μg N g−1 soil. No response to Ni was observed in the dry matter yield of wheat tops (leaves + stem) in the absence of applied N while in the presence of applied N, significant yield increases were obtained at 12.5μg Ni g−1 soil. Nickel was not toxic to wheat up to 50μg Ni g−1 soil in the presence of 120μg N g−1 soil. Nitrogen and Ni concentration in wheat tops and roots increased with increasing levels of applied N and Ni, respectively. Applied Ni had an antagonistic effect on N concentration. Similarly, N reduced the Ni concentration in the wheat tissues. Positive growth responses to Ni were associated with 22 and 15μg Ni g−1 in wheat tops, in the presence of applied N at 60 and 120μg N g−1 soil, while Ni toxicity was associated with 63, 92.5 and 112.5μg Ni g−1 in wheat tops, in the absence and presence of applied N at 60 and 120μg N g−1 soil, respectively.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 128 (1990), S. 21-30 
    ISSN: 1573-5036
    Schlagwort(e): allocation ; clearcut ; mineralization ; nitrogen ; prescribed fire
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Past and current work on biological processes related to nitrogen fluxes and cycling in natural and disturbed Mediterranean forest sites are discussed. In natural conditions, the main point reviewed is mineral nitrogen availability in the soil, and particularly the process of mineralization (ammonification, nitrification) in the field as well as nitrogen uptake by Pinus pinea. Some aspects of nitrogen translocation within the trees are also considered. Perturbation of the nitrogen status, and especially nitrogen mineralization, as a result of manipulation of forest sites are discussed by comparing both a holm oak coppice with a clearcut and a Pinus halepensis woodland before and after prescribed fire.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1573-5036
    Schlagwort(e): Fusarium oxysporum ; nitrogen ; peas ; phosphorus ; potassium ; Pythium vexans ; Rhizoctonia solani ; root-rots
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In field peas the application of nitrogen plus phosphorus, phosphorus plus potassium or nitrogen plus phosphorus plus potassium were effective in reducing severity of root rot caused by Rhizoctonia solani and with the combination of nitrogen plus phosphorus plus potassium in the case of Fusarium oxysporum. The fertilizers tested did not reduce disease caused by Pythium vexans or a combination of all pathogens.
    Materialart: Digitale Medien
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  • 17
    ISSN: 1573-5036
    Schlagwort(e): ammonia volatilization ; denitrification ; grazing ; model ; nitrate leaching ; nitrogen ; simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The model simulates the cycling of N in grassland systems grazed by beef cattle and predicts the annual amount of N in liveweight gain, and the amounts lost through ammonia volatilization, denitrification and leaching, on the basis of fertilizer application and soil and site characteristics. It aims to provide a better understanding of the way in which these various factors interact in their influence on N transformations. The model has been programmed to run on IBM-compatible personal computers and responds rapidly to changes in input parameters. The model has been constructed from the average annual amounts of N passing through various components of the N cycle in ten field systems grazed by beef cattle. The amounts were either measured directly or were calculated from empirical sub-models, assuming a balance between inputs to, and outputs from the soil inorganic N pool. The model is given wide applicability through the inclusion of a mineralization sub-model which is sensitive to soil texture, sward age, previous cropping history, and climatic zone. Another important sub-model determines the partitioning of soil inorganic N to either plant uptake or the processes of loss: the proportion partitioned to plant uptake decreases as the total amount of soil inorganic N increases. Outputs from the model indicate that fertilizer N has a strong influence on ammonia volatilization, denitrification and leaching at a given site but that, over a range of sites with a given rate of fertilizer N, total loss and the proportions lost by the three processes are greatly influenced by the amount of N mineralized by the soil. The model indicates how fertilizer N should be matched with mineralization to limit gaseous and leaching losses and to achieve optimum efficiency of N use in grazing systems.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 125 (1990), S. 19-27 
    ISSN: 1573-5036
    Schlagwort(e): amino acid ; deficiency ; essentiality ; malate ; micronutrient ; nickel ; nitrogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Barley (Hordeum vulgare L. cv. ‘Onda’) plants were grown in nutrient solutions supplied either 0 (no Ni added), 0.6, or 1.0 μM NiSO4. Plants supplied 0 μM Ni developed Ni deficiency symptoms; Ni deficiency resulted in the disruption of nitrogen metabolism, and affected the concentration of malate and various inorganic anions in roots, shoots, and grain of barley. The concentrations of 10 of the 11 soluble amino acids determined were 50–200% higher in 30-day-old shoots of plants supplied inadequate Ni levels than in shoots of Ni-supplied plants. The total concentration of all amino acids determined was higher in roots and grain of Ni-deficient plants. Concentrations of NO3 - and Cl- were also higher in Ni-deficient barley shoots than in Ni-sufficient barley shoots. In contrast, the concentration of alanine in shoots of Ni-deficient barley was reduced to one-third of the concentration in Ni-sufficient plants. The shoot concentrations of malate and SO4 2- were also depressed under Ni-deficient conditions. Total nitrogen concentration in grain, but not in shoots, of Ni-deficient plants was significantly increased over that found in Ni-adequate plants. Nickel deficiency results in marked disruptions of N metabolism, malate and amino acid concentrations in barley. These results are discussed in view of the possible roles of Ni in plants.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 125 (1990), S. 119-128 
    ISSN: 1573-5036
    Schlagwort(e): ammonia ; application method ; application rate ; environment ; grassland ; nitrogen ; slurry ; volatilization ; wind speed
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Three experiments were conducted to examine the influence of slurry application rate, wind speed and applying slurry in narrow bands on ammonia (NH3) volatilization from cattle slurry surface-applied to grassland. The experiments were conducted in the field using a system of small wind tunnels to measure NH3 loss. There was an inverse relationship between slurry application rate and the proportion of NH4 +-N volatilized. From slurry applied at 20, 40, 60, 80, 100 and 120 m3 ha-1, the respective proportions of NH4 +-N lost by NH3 volatization in 6 days were 60, 56, 49, 40, 44 and 44%. The negative relationship was most pronounced in the first 24 hours after application when 57–77% of the total loss for 6 days occurred. Wind speed had a positive effect on NH3 volatilization, although the effect was small in relation to the total loss; increasing the wind speed from 0.5 to 3.0 m s-1 increased the total 5 day loss by a factor of 0.29. The effect of wind speed was also most pronounced in the first 24 hours when much of the NH3 loss took place. The effect of reducing the surface area of the applied slurry was examined by comparing NH3 volatilization from slurry broadcast across plots with that applied in narrow bands. Although the rate of NH3 volatilization was considerably smaller from the banded application immediately after the slurry was applied, the difference between the treatments progressively narrowed until 2 days after application, after which a higher rate was maintained from the banded slurry. After 5 days the total loss from the banded application was 83% of that from broadcast slurry.
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 125 (1990), S. 109-117 
    ISSN: 1573-5036
    Schlagwort(e): ammonia ; environment ; grassland ; mechanical separation ; nitrogen ; slurry ; volatilization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Three experiments were conducted using a system of small wind tunnels to measure ammonia (NH3) volatilization from cattle slurry after surface application to land. In each experiment slurry was applied at a rate equivalent to 80 m3 ha-1, providing the equivalent of approximately 100 kg NH4 +-N ha-1. The first experiment compared NH3 volatilization from the liquid fraction obtained by mechanical separation of slurry with that from unseparated slurry. The total NH3 loss over six days from unseparated and separated slurry were very similar, being 38 and 35% respectively of the NH4 +-N applied. For the first five hours, the rate of NH3 loss was higher from the unseparated slurry, thereafter it was consistently lower. In the second experiment, slurry was ponded in a tray to examine whether impeded infiltration or changes in the NH4 + concentration or overall pH of the slurry influenced the rapid decline in rate soon after application that is characteristic of NH3 volatilization from animal slurries applied to land. It appeared, however, that other factors such as resistance to diffusion within the slurry and/or at the slurry surface were mostly responsible for the rapid decline in rate. In the third experiment, in which NH3 volatilization was measured from slurry applied to grassland or bare soil, the total loss from slurry applied to grassland was approximately 1.5 times that from slurry applied to bare soil.
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  • 21
    ISSN: 1573-5036
    Schlagwort(e): calcium ; copper ; desert ; ground water ; iron ; magnesium ; manganese ; nitrogen ; phosphorus ; Prosopis glandulosa ; rooting patterns ; sodium ; symbiotic nitrogen fixation ; trace metals ; water table ; water use efficiency ; zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Mesquite plants (Prosopis glandulosa var. Torreyana) were grown in 2-m long columns 20 cm in diameter, and provided with a constant, stable ground water source 10 cm above the sealed base of the column. Ground water contained 0, 1 or 5 mM nitrate, or a mixed salt solution (1.4, 2.8, or 5.6 dS m-1) with the ionic ratios of ground water found in a field stand of Prosopis at Harper's Well (2.8 dS m-1). Water uptake in the highly salinized columns began to decrease relative to low salt columns when soil salinity probes 30 cm above the column base read approximately 28 dS m-1, a potential threshold for mesquite salt tolerance. Prosopis growth increased with increasing nitrate, and decreased with increasing salinity. Water use efficiency was little affected by treatment, averaging approximately 2 g dry matter L-1 water used. Most fine roots were recovered from a zone about 25 cm above the ground water surface where water content and aeration appeared to be optimal for root growth. Root-shoot ratio was little affected by nitrate, but increased slightly with increasing salinity. Plant tissue P concentrations tended to increase with increasing salinity and decrease with increasing N, approaching potentially deficient foliage concentrations at 5 mM nitrate. The whole-plant leaf samples increased in sodium concentration both with added salt and with added nitrate. Foliar manganese concentrations increased with increasing salt in the absence of nitrate. Concentrations of sodium in leaves were low (〈10 g kg-1), considering the high salt concentrations in the ground water. Prosopis appears to exclude sodium very effectively, especially from its younger leaves. Although Prosopis is highly salt tolerant, the degree to which it utilizes soil nitrate in place of biologically fixed N may lower its salinity tolerance and affect its nutrient relations in phreatic environments.
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  • 22
    ISSN: 1573-5036
    Schlagwort(e): grassland ; leaching ; leaf litter ; macro-organic matter ; mineralization ; nitrogen ; ploughing ; roots ; stubble
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The amounts of organic matter in the stubble, litter, root and soil macro-organic matter fractions of two swards of perennial ryegrass that had received normal applications of either fertilizer or cattle urine were, on average for the four fractions, about 3000, 500, 11,500 and 8,800 kg ha−1. The swards had been established 8 or 15 years previously and each was sampled at intervals over a period of about one year. The amounts of N contained in the four fractions were, on average, 68, 12, 249 and 240 kg ha−1, a total of 569 kg N ha−1. With other swards, increasing rates of application of fertilizer N were found to have little effect on the amounts of organic matter in stubble and roots. Concentrations of N in the organic matter of the stubble and roots, however, increased significantly with increasing rate of fertilizer application, though, with stubble, moderate rates of application had little effect. Assessments based on these data, together with other published information, indicate that the amount of N mineralized from the combined stubble, litter, root and macro-organic matter fractions during the first year after ploughing may range from about 40 kg to at least 360 kg N ha−1 depending on the age of the sward and its recent management. The amount mineralized is likely to increase with age of sward, with increasing rate of fertilizer N and with utilisation by grazing rather than cutting.
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 123 (1990), S. 155-159 
    ISSN: 1573-5036
    Schlagwort(e): cultivars ; nitrogen ; roots ; tropic climate ; Zea mays L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Due to the high price of fertilizer the input of N for grain maize production must be kept low in many parts of the world. Low input cultivars have been suggested to meet this requirement. Screening of a group of tropical cultivars revealed two high input, two low input and two intermediate cultivars with regard to N utilization. One of the causes of an interaction between genotype and N fertilization might be differences in root morphology. Screening for such differences at an early seedling stage would facilitate the selection for low input varieties. This hypothesis was tested by growing seedlings of the six varieties at different levels of N until the fourth leaf stage. There was no significant interaction between genotypes and N supply. At low and medium N supply, the total seedling biomass was the same but at low N a higher proportion of dry weight was found in the roots. Total biomass was reduced at high N. Low input and intermediate cultivars had higher shoot and root dry weights than did high input cultivars but no significant differences in root surface area were found. Root surface area was greatest at low N. Number and total length of seminal roots were significantly lower for high input varieties which, in combination with a relatively high root surface area, points to an intensive root type.
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 124 (1990), S. 33-37 
    ISSN: 1573-5036
    Schlagwort(e): leaf area ; nitrogen ; mineral nutrition ; phosphorus ; photoperiod ; Triticum ; wheat ; spikelet initiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effects of N and P on the number of spikelets of spring wheat (Triticum aestivum L.), grown in nutrient solution, were studied under 8 h and 16 h photoperiods. The effect of P was apparent only at a high rate of N supply and the effects of N were increased significantly at a high rate of P supply. Increasing N supply increased the number of spikelets due to a promotion of the rate of spikelet initiation. It also increased the leaf-blade area and the dry matter weight of the plants at the stage of terminal spikelet initiation. These effects of N were much greater under the short photoperiod than under the long photoperiod. The practical significance of these findings for winter-grown wheat in temperate regions is pointed out.
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 128 (1990), S. 97-101 
    ISSN: 1573-5036
    Schlagwort(e): calcium ; magnesium ; nitrogen ; nitrogen saturation ; Norway spruce ; nutritional imbalance ; Picea abies ; soil solution ; sulphur/nitrogen ratio ; tree nutrition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Differences in nitrogen cycling and in the nutrition of trees are significantly coupled to the levels of nitrogen input and to the nitrate levels in the soil solution. Relatively high nitrogen supply can cause unbalanced nutrition on sites which contain either low or moderate amounts of other nutrients. This is indicated by low cation/nitrogen ratios in foliage and also by the S/N ratio falling temporarily below 0.030.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 133 (1991), S. 17-30 
    ISSN: 1573-5036
    Schlagwort(e): fertilisers ; foliage analysis ; growth studies ; Lotus ; Lupinus ; nitrogen ; nutrients ; phosphorus ; Trifolium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The phosphorus (P) responses of seven temperate perennial pasture legumes and two species of lupins were compared in a field trial over a range of nine P rates, from 0 to 800 kg ha-1. The two lupins produced more than 5 t ha-1 of dry matter in the absence of added P and showed no response to the fertiliser. In contrast, the pasture legumes initially failed to grow without added P and responded to applications of between 200 and 800 kg ha-1. At the higher rates of P, dry matter production of the pasture legumes was equivalent to that of the lupins. In the first 2 years of the trial; the most productive pasture legume species at the higher rates of added P were also the most productive at the lower rates. Phosphorus requirements for 90% of maximum yield varied greatly between species, but were closely related to maximum yield. Thus species with low P requirements for maximum yield were not necessarily P-efficient species. In the third and subsequent years of the trial Lotus corniculatus performed better than the other pasture legumes at the lower rates of added P. In contrast to other studies Lotus pedunculatus showed no ability to outyield Trifolium repens at low rates of P. Critical P concentrations of the pasture species for the late spring-early summer period declined in the order Trifolium repens (0.34%) 〉 Lotus pedunculatus (0.30%) 〉 Triofolium pratense (0.28%) 〉 Trifolium hybridum (0.27%) 〉 Trifolium ambiguum (0.26%) 〉 Lotus corniculatus (0.23%). Mineralisable nitrogen (N) levels were determined in soils under three species in the 7th year of the trial. At the lowest rates of added P, mineralisable N levels were much higher under Lupinus polyphyllus than under Trifolium repens or Lotus corniculatus. With increasing P rate, levels under the latter species increased, and at 100 kg P ha-1 were equivalent to those under the lupin with no added P.
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  • 27
    ISSN: 1573-5095
    Schlagwort(e): actinorhizae ; fertilization ; Frankia ; nitrogen ; nodulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract To determine if inoculation increases nodulation and yield of bare-root red alder (Alnus rubra Bong.), fumigated nursery plots were treated with inoculum and ammonium sulfate (28 kg N ha−1) in a factorial experiment. Inoculum was alder soil with 100 infective units of Frankia g−1. Seedlings were evaluated for nodulation at age 10 wk and when lifted, at age 9 mo. Inoculation produced earlier and more extensive nodulation and increased seedling root collar diameter, height, and dry weight. Fertilization decreased seedling height, but did not decrease nodulation. No interaction of fertilization with inoculation was found. Inoculated unfertilized plots had the highest yield of packable seedlings (257 m−2), and uninoculated fertilized seedlings had the lowest yield (126 m−2).
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 10 (1990), S. 67-79 
    ISSN: 1573-515X
    Schlagwort(e): deserts ; ecosystem ; nitrogen ; nutrient cycling ; soils ; southwestern United States
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract A lower limit for nitrogen loss from desert ecosystems in the southwestern United States was estimated by comparing nitrogen inputs to the amount of nitrogen stored in desert soils and vegetation. Atmospheric input of nitrogen for the last 10 000 years was conservatively estimated to be 2.99 kg N/m2. The amount of nitrogen stored in desert soils was calculated to be 0.604 kg N/m3 using extant data from 212 profiles located in Arizona, California, Nevada, and Utah. The average amount of nitrogen stored in desert vegetation is approximately 0.036 kg N/m2. Desert conditions have existed in the southwestern United States throughout the last 10 000 years. Under such conditions, vertical leaching of nitrogen below a depth of 1 m is small (ca. 0.028 kg N/m2 over 10 000 years) and streamflow losses of nitrogen from the desert landscape are negligible. Thus, the discrepancy found between nitrogen input and storage represents the amount of nitrogen lost to the atmosphere during the last 10 000 years. Loss of nitrogen to the atmosphere was calculated to be 2.32 kg N/m2, which is 77% of the atmospheric inputs. Processes resulting in nitrogen loss to the atmosphere from desert ecosystems include wind erosion, ammonia volatilization, nitrification, and denitrification. Our analysis cannot assess the relative importance of these processes, but each is worthy of future research efforts.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 11 (1990), S. 1-22 
    ISSN: 1573-515X
    Schlagwort(e): disturbance ; ecosystems ; forests ; indirect interactions ; landscape ecology ; Minnesota ; nitrogen ; nutrient cycling ; path analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Path analysis was used to determine the importance of long-term disturbance regime and the relative importances of correlations among vegetation patterns, disturbance history, and nitrogen (N) mineralization in old-growth forests of northwestern Minnesota. Leaf biomass (estimated by allometric equations), fire history (from fire scars on Pinus resinosa trees), and N mineralization rates (estimated from incubationsin situ) were determined from sample plots dominated by Betula papyrifera, Populus tremuloides, andP. grandidentata a mixture ofAcer saccharumandTilia americana, or Quercus borealis andOstrya virginiana. Results showed that topographic and soil-moisture controls on N mineralization, vegetation patterns, and disturbance are substantially stronger than is suggested by direct correlation. Indirect interactions among ecosystem variables played in important role. These interactions probably include the tendency for species that cycle large amounts of N to colonize more mesic sites that burned rarely in the past. Soil moisture was correlated both directly with N mineralization and indirectly, through its effects on vegetation pattern, and thus, litter quality. Although disturbance regime also depended on topography, the strengths of relationships between disturbance regime and other variables were relatively weak. These dependencies suggested that long-term fire regime is probably more a consequence than a cause for vegetation and fertility patterns. Topography, through its effects on soil moisture and microclimate, is an overriding influence on ecosystem properties, which in turn influence fire regime.
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 10 (1990), S. 105-141 
    ISSN: 1573-515X
    Schlagwort(e): cumulative ; flow ; GIS ; landscape ; lead ; nitrogen ; phosphorus ; suspended solids ; watershed ; wetlands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis—St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived from historical aerial photos. These watershed variables were then reduced to eight principal components which explained 86% of the variance. Relationships between stream water quality variables and the three wetland-related principal components were explored through stepwise multiple regression analysis. The proximity of wetlands to the sampling station was related to principal component two, which was associated with decreased annual concentrations of inorganic suspended solids, fecal coliform, nitrates, specific conductivity, flow-weighted NH4 flow-weighted total P, and a decreased proportion of phosphorus in dissolved form(p 〈 0.05). Wetland extent was related to decreased specific conductivity, chloride, and lead concentrations. The wetland-related principal components were also associated with the seasonal export of organic matter, organic nitrogen, and orthophosphate. Relationships between water quality and wetlands components were different for time-weighted averages as compared to flow-weighted averages. This suggests that wetlands were more effective in removing suspended solids, total phosphorus, and ammonia during high flow periods but were more effective in removing nitrates during low flow periods.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 11 (1990), S. 23-43 
    ISSN: 1573-515X
    Schlagwort(e): acid precipitation ; ammonium ; mass balance ; nitrate ; nitrogen ; retention
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The relative contribution of HN03 to precipitation acidity in eastern Canada has increased in recent years leading to some concern that the relative importance of NO− 3 deposition in acidification of terrestrial and aquatic ecosystems may increase. To gauge the extent of this impact, annual mass balances for N0− 3 and NH+ 4 were calculated for several forested catchments and lakes in Ontario. Retention of NH+ 4 (R NH4) by forested catchments was consistently high compared to retention of NO3 − (R NO3) which was highly variable. Retention of inorganic nitrogen was influenced by catchment grade and areal water discharge. In lakes, the reciprocals of retention of N0− 3 and NH+ 4 were linearly related to the ratio of lake mean depth to water residence time (z/τ; equal to areal water discharge), and retention did not appear to be a function of degree of acidification of the lakes. Net N consumption-based acidification of lakes, defined as the ratio of annual NH; mass to N0− 3 mass consumption, was negatively correlated with /τ and N consumption-related acidification was most likely to occur when − was 〈 1.5 m yr−1. If retention mechanisms are unaffected by changes in deposition, changes in deposition will still result in changes in surface water concentrations although the changes will be of similar proportions. Therefore, ‘NO− 3 saturation’ should not be defined by concentrations alone, but should be defined as decreasing long-term, average NO− 3 retention in streams and lakes in response to long-term increases in NO− 3 deposition. Analysis o f survey data will be facilitated by grouping lakes and catchments according to similar characteristics.
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 12 (1991), S. 129-134 
    ISSN: 1573-515X
    Schlagwort(e): biomass burning ; forest soils ; nitrogen ; sulphur
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The proportion of total sulphur lost during combustion (600 °C) of Douglas-fir (Pseudotsuga menziesii) foliage is reduced from〉 90% to 65–70% as the SO4-S concentration increases from 10% to 45–50% of the total S content. Foliar SO4-S content is decreased by improvement of plant nitrogen status, suggesting that alterations to soil N availability may influence S transfer to the atmosphere during biomass burning.
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 15 (1991), S. 21-46 
    ISSN: 1573-515X
    Schlagwort(e): denitrification ; forest ; nitrification ; nitrogen ; nitrogen mineralization ; N20 ; proton budget ; The Netherlands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Within a long-term research project studying the biogeochemical budget of an oak-beech forest ecosystem in the eastern part of the Netherlands, the nitrogen transformations and solute fluxes were determined in order to trace the fate of atmospherically deposited NH4 + and to determine the contribution of nitrogen transformations to soil acidification. The oak-beech forest studied received an annual input of nitrogen via throughfall and stemflow of 45 kg N ha−1 yr−1, mainly as NH4 +, whereas 8 kg N ha−1 yr−1 was taken up by the canopy. Due to the specific hydrological regime resulting in periodically occurring high groundwater levels, denitrification was found to be the dominant output flux (35 kg N ha−1 yr−1). N20 emmission rate measurements indicated that 57% of this gaseous nitrogen loss (20 kg N ha−1 yr−1) was as N2O. The forest lost an annual amount of 11 kg N ha−1 yr−1 via streamwater output, mainly as N03 −. Despite the acid conditions, high nitrification rates were measured. Nitrification occurred mainly in the litter layer and in the organic rich part of the mineral soil and was found to be closely correlated with soil temperature. The large amount of NH4 + deposited on the forest floor via atmospheric deposition and produced by mineralization was to a large extent nitrified in the litter layer. Almost no NH4 + reached the subsurface soil horizons. The N03 − was retained, taken up or transformed mainly in the mineral soil. A small amount of N03 − (9 kg N ha−1 yr−1) was removed from the system in streamwater output. A relatively small amount of nitrogen was measured in the soil water as Dissolved Organic Nitrogen. On the basis of these data the proton budget of the system was calculated using two different approaches. In both cases net proton production rates were high in the vegetation and in the litter layer of the forest ecosystem. Nitrogen transformations induced a net proton production rate of 2.4 kmol ha−1 yr−1 in the soil compartment.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 12 (1991), S. 135-148 
    ISSN: 1573-515X
    Schlagwort(e): fens ; management ; nitrogen ; phosphorus ; productivity ; vegetation ; wetlands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract A fertilization experiment was carried out in 3 mesotrophic fens to investigate whether plant growth in these systems is controlled by the availability of N, P or K. The fens are located in an area with high N inputs from precipitation. They are annually mown in the summer to prevent succession to woodland. Above-ground plant biomass increased significantly upon N fertilization in the two “mid”-succession fens studied. In the “late”-succession fen that had been mown for at least 60 years, however, plant biomass increased significantly upon P fertilization. The mowing regime depletes the P pool in the soil, while it keeps N inputs and outputs in balance. A long-term shift occurs from limitation of plant production by N toward limitation by P. Hence, mowing is a suitable management tool to conserve the mesothrophic character of the fens.
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  • 35
    ISSN: 1573-515X
    Schlagwort(e): atmospheric deposition ; nitrogen ; nutrient cycling ; spruce decline ; subalpine spruce-fir
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Nitrogen inputs, fluxes, internal generation and consumption, and outputs were monitored in a subalpine spruce-fir forest at approximately 1000-m elevation on Whiteface Mountain in the Adirondacks of New York, USA. Nitrogen in precipitation, cloudwater and dry deposition was collected on an event basis and quantified as an input. Throughfall, stemflow, litterfall and soil water were measured to determine fluxes within the forest. Nitrogen mineralization in the forest floor was estimated to determine internal sources of available N. Lower mineral horizon soil water was used to estimate output from the ecosystem. Vegetation and soil N pools were determined. During four years of continuous monitoring, an average of 16 kg N ha−1 yr−1 was delivered to the forest canopy as precipitation, cloudwater and dry deposition from the atmosphere. Approximately 30% of the input was retained by the canopy. Canopy retention is likely the result of both foliar uptake and immobilization by bark, foliage and microorganisms. Approximately 40 kg of N was made available within the forest floor from mineralization of organic matter. Virtually all the available ammonium (mineralized plus input from throughfall) is utilized in the forest floor, either by microorganisms or through uptake by vegetation. The most abundant N component of soil water solutions leaving the system was nitrate. Net ecosystem fluxes indicate accumulation of both ammonium and nitrate. There is a small net loss of organic N from the ecosystem. Some nitrate leaves the bottom of the B horizon throughout the year. Comparisons with other temperate coniferous sites and examination of the ecosystem N mass balance indicate that N use efficiency is less at our site, which suggests that the site is not severely limited by N.
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  • 36
    ISSN: 1573-515X
    Schlagwort(e): nitrogen ; snow ; flux
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Increased emissions of nitrogen compounds to the atmosphere by human activities have been well documented. However, in order to better quantify these anthropogenic emissions, better knowledge of natural emissions rates must be known. In addition, variation in natural emissions through time should be documented. In this note we present data collected and/or analyzed by us for NO3 − in recent snow from remote regions of the world. We also summarize existing data sets from other remote regions. This is done to establish a better understanding of NO3 − deposition rates in these regions as well as to add more information to our global understanding of NO3 − deposition.
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 9 (1990), S. 117-134 
    ISSN: 1573-515X
    Schlagwort(e): nitrogen ; Mediterranean ; natural versus anthropogenic atmospheric nitrogen ; atmospheric input ; riverine input ; marine ecosystems ; primary production
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Bulk inorganic nitrogen deposition was monitored over a period of 3 years at the Bavella Pass (Corsica, France). Annual fluxes range between 126 and 150μmol.m−2.d-−1, increasing slightly with annual rainfall. Natural background average concentrations of rain water and associated fluxes were estimated from a classification of rain events into ‘natural’ (Oceanic and Saharan), polluted and composite. Long range transport of incoming polluted air masses increases the atmospheric wet nitrogen input by at least a factor of 1.6 in this Mediterranean area. Extrapolation of atmospheric dissolved inorganic nitrogen input to the Western Mediterranean leads to fluxes of 80 to l00μmol.m−2.d-−1. This atmospheric input is in the same order of magnitude as the inorganic nitrogen riverine input. As a consequence, the nitrogen budget for the Mediterranean has had to be reassessed. Atmospheric wet inorganic nitrogen input is of noticeable importance to marine Mediterranean ecosystems, representing on average 10 to 25% of new production in the Western Basin, with values of up to 60% in oligotrophic zones.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 28 (1991), S. 179-184 
    ISSN: 1573-0867
    Schlagwort(e): Ammonium sulphate ; leaching ; nitrogen ; potassium nitrate ; urea ; lowland rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Application of 120 kg urea-N ha−1 to lowland rice grown in a highly percolating soil in 10 equal split doses at weekly intervals rather than in 3 equal split doses at 7, 21 and 42 days after transplanting did not significantly increase rice grain yield and N uptake. Results suggest that leaching losses of N were not substantial. In lysimeters planted with rice, leaching losses of N as urea, NH 4 + , and NO 3 - beyond 30 cm depth of a sandy loam soil for 60 days were about 6% of the total urea-N and 3% of the total ammonium sulphate-N applied in three equal split doses. Application of urea even in a single dose at transplanting did not result in more N leaching losses (13%) compared to those observed from potassium nitrate (38%) applied in three split doses. Nitrogen contained in potassium nitrate was readily leached during the first week of its application. More N was lost from the first dose of N applied at transplanting than from the second or third dose. Data pertaining to yield, N uptake and per cent N recovery by rice revealed that the performance of different fertilizer treatments was inversely related to susceptibility of N to leaching.
    Materialart: Digitale Medien
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 22 (1990), S. 29-35 
    ISSN: 1573-0867
    Schlagwort(e): Zinc ; nitrogen ; interaction ; limed ; unlimed
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A green house experiment was conducted to study the interaction effect of Zn and N in wheat (S-308). Zinc was applied as ZnSO4.7H2O at 0, 5, 10 and 20 mg per kg, and nitrogen as urea at 0, 75 and 150 mg per kg. In the absence of added N and lime 5 mg Zn per kg increased the grain, straw and root weight, but the application of either N (75 and 150 mg per kg) or lime (4000 mg CaCO3 per kg), 10 mg Zn per kg responded significantly. However, when N and lime were added together, 20 mg Zn per kg increased the grain, straw and root weight significantly. Irrespective of Zn and N, the grain, straw and root weights were higher in limed that in unlimed soils. The application of N increased the Zn concentration in wheat tops and roots in unlimed soils, and decreased it in limed soils. However, because of an increase in wheat yield, the uptake of Zn by wheat tops and roots also increased with N application both in limed and unlimed soils. The addition of Zn to 10 mg per kg, increased the N concentration in the absence of N, but in the presence of N, the addition of Zn to 20 mg per kg decreased the N concentration in wheat tops and roots. The applied Zn to 10 mg per kg in unlimed soils and to 20 mg per kg in limed soils increased the N uptake by wheat tops and roots, respectively. The Zn concentration was higher in absence of lime than in its presence while a reverse trend was true for N concentration.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 21 (1990), S. 133-140 
    ISSN: 1573-0867
    Schlagwort(e): Potatoes ; nitrogen ; foliar sprays ; urea ; 15N
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effect of the timing of N fertilizer application on the uptake and partitioning of N within the crop and the yield of tubers has been studied in two experiments. In 1985 either none, 8 or 12 g N m−2 was applied and in 1986 none, 12 or 18 g N m−2. Fertilizer N was applied either at planting, around the time of tuber initiation or half at planting and the remainder in four foliar sprays of urea during tuber bulking.15N-labelled fertilizer was applied to measure the recovery of fertilizer N in the crops. There was an apparent pre-emergence loss of nitrate from the soil when N was applied at planting in 1986, thereby reducing the efficiency of fertilizer use. Applying the N at tuber initiation delayed and reduced the accumulation of N in the canopy compared with crops receiving all their fertilizer at planting. Foliar sprays of urea slightly increased both tuber yields and tuber N contents when compared to a single application at planting. The proportion of the fertilizer N recovered in the crop was little affected by the rate of N application, but a greater proportion of foliar-applied N was recovered than N broadcast at planting, due partly to pre-emergence losses of nitrate in 1986. It is suggested that late applications of N was foliar sprays can be of benefit to crops with a long growing season and reduce environmental losses of N.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 21 (1990), S. 171-177 
    ISSN: 1573-0867
    Schlagwort(e): Bermudagrass ; nitrogen ; model ; nutrient uptake ; forages
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Equations were developed to estimate concentration of nitrogen for bermudagrass forage [Cynodon dactylon, (L.) Pers.] as related to applied nitrogen level and harvest interval. Data from six field studies were used in the analysis. Estimates of N concentration in forage obtained with these equations agreed with data from other studies with fertilizer and waste application to bermudagrass (correlation coefficient of 0.94). Concentration of nitrogen decreased linearly with harvest interval (up to 6 weeks) and increased exponentially with nitrogen level. These equations should provide relevant information for crop production and environmental quality.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 27 (1991), S. 87-93 
    ISSN: 1573-0867
    Schlagwort(e): Volume increment ; Norway spruce ; liming ; nitrogen ; phosphorus ; fertilization ; precipitation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The amount, fluctuation and duration of increment response to fertilization (liming) in three regions of southwestern Germany is described. After liming, additional yield increases slowly while after N-fertilization, there is a rapid yield increase. A long-lasting high response was found to a combination of liming, P- and N-fertilization. This response was regionally different and was influenced by climatic conditions during the years after fertilization.
    Materialart: Digitale Medien
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Biodegradation 10 (1990), S. 309-328 
    ISSN: 1572-9729
    Schlagwort(e): estuaries ; groundwater ; nitrogen ; nitrogen cycle ; nitrogen loading
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract We examined the importance of nitrogen inputs from groundwater and runoff in a small coastal marine cove on Cape Cod, MA, USA. We evaluated groundwater inputs by three different methods: a water budget, assuming discharge equals recharge; direct measurements of discharge using bell jars; and a budget of water and salt at the mouth of the Cove over several tidal cycles. The lowest estimates were obtained by using a water budget and the highest estimates were obtained using a budget of water and salt at the Cove mouth. Overall there was more than a five fold difference in the freshwater inputs calculated by using these methods. Nitrogen in groundwater appears to be largely derived from on site septic systems. Average nitrate concentrations were highest in the region where building density was greatest. Nitrate in groundwater appeared to behave conservatively in sandy sediments where groundwater flow rates were high (〉 11/m2/h), indicating that denitrification was not substantially reducing external nitrogen loading to the Cove. Nitrogen inputs from groundwater were approximately 300 mmol-N/m3/y of Cove water. Road runoff contributed an additional 60 mmol/m3/y. Total nitrogen inputs from groundwater and road runoff to this cove were similar in magnitude to river dominated estuaries in urbanized areas in the United States.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Plant growth regulation 10 (1991), S. 185-195 
    ISSN: 1573-5087
    Schlagwort(e): mustard ; Brassica juncea ; nitrogen ; chlormequat chrloride ; seed oil ; seed yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The growth of mustard was increased significantly when treated with up to 80 kg N ha−1 (N80). Spraying with (2-chloroethyl) trimethylammoniumchloride (chlormequat chloride) increased seed yield and seed protein content. Spraying nitrogen fertilized plots with chlormequat chloride, increased leaf area, leaf area ratio, leaf area duration, number of siliquae plant−1, number of seeds siliqua−1 and length of siliqua. Reducing, non-reducing and total sugars in the leaves at 80 days after sowing were also affected significantly. Chlorophyll ‘a’, ‘b’ and total chlorophyll were little affected. The number of siliquae plant−1 was highly correlated with seed yield in both the seasons of experimentation. The correlation coefficient value (γ) was 0.586 in 1982/83 and 0.912 in 1983/84. The total accumulation of nutrients, i.e. nitrogen, phosphorus and potassium in seed and straw was significantly affected by N80 × chlormequat chloride interaction.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 45
    ISSN: 1573-5087
    Schlagwort(e): Lemna gibba ; cytokinins ; isopentenyladenosine ; zeatinriboside ; abscisic acid ; nitrogen ; phosphorus ; relative growth rate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The relationship between endogenous cytokinin content and relative growth rate (RGR) was studied in cultures of Lemna gibba L. G3 supplied with daily doses of mineral nutrients that were increased exponentially over time. At the optimal level of nutrient supply the RGR was 30–35% day-1. The RGR was regulated by adjusting the rate of nitrogen supply, or it was restricted by addition of 0.5 μM abscisic acid (ABA). Another approach used to investigate the specific roles of nitrogen (N) and phosphorus (P), was to transfer optimally growing plants to media without N or P but otherwise complete. The plants were harvested at regular intervals for determination of the RGR and levels of cytokinins of the isopentenyladenosine (iPA) and zeatinriboside (ZR) types with an enzyme-linked immunosorbent assay (ELISA). Levels of both iPA- and ZR-type cytokinins decreased when nitrogen was applied to cultures in growth limiting amounts. The cytokinin levels decreased more rapidly than the RGR when either N or P was lacking in the medium, suggesting an early influence of nutrient availability on cytokinin levels which in turn may induce adaptive response by the plant. RGR retardation induced by ABA did not affect cytokinin levels during the first 4 days of the treatment, and the later effects were small. The experiments gave no indication that ABA is involved in the adaptation response of Lemna plants to nutritional stress.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 128 (1990), S. 115-126 
    ISSN: 1573-5036
    Schlagwort(e): ammonium ; mineralization ; nitrate ; nitrification ; nitrogen ; roots ; tomato
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Tomato root growth and distribution were related to inorganic nitrogen (N) availability and turnover to determine 1) if roots were located in soil zones where N supply was highest, and 2) whether roots effectively depleted soil N so that losses of inorganic N were minimized. Tomatoes were direct-seeded in an unfertilized field in Central California. A trench profile/monolith sampling method was used. Concentrations of nitrate (NO3 -) exceeded those of ammonium (NH4 +) several fold, and differences were greater at the soil surface (0–15 cm) than at lower depths (45–60 cm or 90–120 cm). Ammonium and NO3 - levels peaked in April before planting, as did mineralizable N and nitrification potential. Soon afterwards, NO3 - concentrations decreased, especially in the lower part of the profile, most likely as a result of leaching after application of irrigation water. Nitrogen pool sizes and rates of microbial processes declined gradually through the summer. Tomato plants utilized only a small percentage of the inorganic N available in the large volume of soil explored by their deep root systems; maximum daily uptake was approximately 3% of the soil pool. Root distribution, except for the zone around the taproot, was uniformly sparse (ca. 0.15 mg dry wt g-1 soil or 0.5 cm g-1 soil) throughout the soil profile regardless of depth, distance from the plant stem, or distance from the irrigation furrow. It bore no relation to N availability. Poor root development, especially in the N-rich top layer of soil, could explain low fertilizer N use by tomatoes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 128 (1990), S. 241-247 
    ISSN: 1573-5036
    Schlagwort(e): anaerobic soils ; bacterial flush ; mineralisation ; nitrification ; nitrogen ; restoration ; soil perfusion ; soluble carbon ; stockpiles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Topsoil stockpiled for 4 years resulted in an accumulation of NH4-N at depths of 1m or more in mound, as measured by an ammonia gas-sensing electrode. When leached with water these soils were also found to contain high concentrations of dissolved organic C below 1m. Both NH4-N and DOC were products of microbial mineralisation of soil organic matter that accumulated under anaerobic conditions. When these soils were restored a flush of decomposition took place, fuelled by labile organic matter and soluble nitrogen. Stockpiled soil which underwent an ammonium-rich perfusion regime in the laboratory indicated that in-mound soils rapidly attained greater nitrification potential than surface mound soils and also had greater potential for further mineralisation of organic matter to NH4-N. This further production was seen as a contribution from the bacterial flush, stimulated by the large labile-C pool already present. As the bulk of stored soil was anaerobic, restored soils were seen as potentially wasteful of their N-reserves; the fate of nitrogen and soluble carbon compounds in restored soils is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 129 (1990), S. 219-225 
    ISSN: 1573-5036
    Schlagwort(e): drying ; grassland ; heating ; microbial biomass ; mineralization ; nitrogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A dwarf bamboo-type grassland soil (Thick High-humic Andosol) was nitrogen-limited for grass despite the presence of a considerable amount of microbial biomass N. By either treatments of air-drying and subsequent heating, the content of mineral N in the soil was increased by 3.7 g N and 11.7 g N m-2, respectively, after a 55-day incubation period. The efficiency of mineralized N for growth of orchardgrass was compared with nitrate-N added just before cultivation. The dry matter content of the grass increased from 81.7 g (control) to 169 g and to 337 g m-2 in the dried and in the heated soils, respectively, when N application was omitted. Of the mineral N released by air-drying and heating of the soil, 84% and 77% were absorbed by the grass, and 30% and 20% was assumed to be derived from microbial biomass, respectively. In contrast the grass apparently absorbed 54–56% of the 5 g nitrate-N m-2 added to the control and the air-dried soils. It was also noted that fungal biomass N had decreased by 1.5–1.9 g m-2 in the control soil after addition of 10 g nitrate-N m-2.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    ISSN: 1573-5036
    Schlagwort(e): nitrogen ; pasture ; phosphorus ; plant ; P fertility status ; season ; soil ; temporal variations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Temporal variations in plant production, plant P and some soil P (and N) pools were followed over 21 months in two New Zealand pasture soils of widely different P fertility status. Plant growth rates, and herbage composition at the high-fertility site, were closely linked to soil water use, with growth rates falling when soil water deficits exceeded 60 mm. Herbage P concentrations reflected P fertility, and varied with season, being generally higher in winter and lower in summer. A similar temporal pattern was also observed for labile organic P (NaHCO3-extractable P0) in both soils. In the low-fertility soil in spring, net mineralization was especially strong, but from early winter net immobilization occurred. Surprisingly, Olsen P also changed temporally in the high-fertility soil. The microbial biomass remained fairly constant throughout the year, whereas the P content of the biomass varied seasonally. Although microbial biomass was not a useful index of soil fertility, highest microbial P0 contents coincided with periods of maximum labile P0 mineralization, when herbage production was also at a peak. Net N-mineralization in the low-fertility soil, in contrast to the high-fertility soil, was low but varied seasonally, under standardised incubation conditions. Soil P and N dynamics were apparently synchronised in the low-fertility soil through soil microbial processes, with mineral N being negatively correlated with microbial P0 in samples collected two months later. The results of this investigation suggest that the demands of rapid and sustained pasture growth in spring and early summer can best be met by maximising the build-up of organic matter during the preceding autumn and winter. This practice could help to alleviate the common problem of feed shortage in North Island hill country pastures in late winter-early spring.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 50
    ISSN: 1573-5036
    Schlagwort(e): ammonium ; nitrogen ; Pseudotsuga menziesii ; rhizosphere pH ; sand culture ; shoot/root ratio ; specific root length (SRL) ; toxicity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Ammonium sulphate is a major component of the air pollutants deposited on forests in the Netherlands. Different amounts of NH4 + were added to Douglas-fir seedlings grown in tall containers of sand, to study the influence of high concentrations of NH4 + in the soil on the development of fine roots and the effects of nitrogen uptake on rhizosphere pH. At the end of this eight-month experiment part of the ammonium appeared to have nitrified into nitrate. High doses of ammonium negatively affected root length and root length per unit of dry matter (specific root length). Although Douglas fir shows a preferential ammonium uptake in nutrient solutions the increases in the pH of the rhizosphere in this experiment indicate that nitrogen was mostly taken up as nitrate. When the ammonium concentration in the soil is low, it cannot be taken up readily because of its low mobility in soil. Shoot growth was stimulated by high availability of nitrogen. The possible effects of high doses of ammonium on long-term forest vitality are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 132 (1991), S. 293-296 
    ISSN: 1573-5036
    Schlagwort(e): boron ; nitrogen ; nitrate reductase activity ; phosphorus sorghum ; water soluble sugar
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A foliar spray of boron (1 g borax litre-1) at the reproductive stage of sorghum varieties (PC 23, PC 9, PC 6 and HC 136), generally, increased the phosphorus content (24.5 per cent) and water soluble sugars (13.3 per cent) of seed coatings. The nitrogen content of a sorghum crop grown in a boron deficient soil improved only slightly (4.5 per cent) in spite of an elevated nitrate reductase activity (19.5 per cent). Such effects of boron seem to be associated with an increase in seed yield (14 per cent) and an improvement in the germination energy index. The magnitude of response was greater in variety HC 136 than the others.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 135 (1991), S. 197-203 
    ISSN: 1573-5036
    Schlagwort(e): fertilization ; nitrogen ; kohlrabi ; root growth ; rooting depth ; spinach
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract N fertilizer recommendatons are based on the Nmin content in the useable soil layer. However, for spinach, information from the literature differs for both depth of useable soil layer and N fertilizer recommendations. The objectives of these experiments were to study the importance of different soil zones for N supply to spinach and to kohlrabi, and to examine the relationship between N supply in the useable soil layer and yield of spinach. Field experiments with both crops showed that about 80% of total root length was in the upper 0–15 cm soil layer and less than 5% below 30 cm. Spinach roots were present in the 15–30 cm layer only during the last 2 weeks before harvest, whereas kohlrabi roots penetrated this layer already 4 weeks before harvest. Placement of NO3 below 30 cm depth did not influence root distribution. The top layer contributed about 80% to total N uptake for both crops. The 15–30 cm soil layer can maximally contribute 40–50 kg N ha-1. It is concluded that N fertilizer recommendations for both crops should be based on the Nmin content of the 0–30 cm soil layer. Maximum yield of spinach (300 dt f.m. ha-1) was obtained at 150 kg N supply ha-1. The nitrate residue was 50 kg N ha-1 at 0–30 cm in this treatment. It is argued that the nitrate residues at harvest could be decreased by delaying the harvest for a few days, at slightly suboptimal N supply.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 138 (1991), S. 123-132 
    ISSN: 1573-5036
    Schlagwort(e): Alnus glutinosa ; carbon ; cold temperate climate ; lignin ; mesh bags ; nitrogen ; Orthic ; Sombric Brunisol ; plantation ; Populus ; root decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The decomposition of the roots (0–2 mm, 2–5 mm and 5–10 mm) of black alder (Alnus glutinosa (L.) Gaertn.) and hybrid poplar (Populus nigra L. X Populus trichocarpa Torr & Gray) was followed over a 462-day period in pure and mixed plantings in southern Quebec. Small roots of alder had the highest initial concentrations of nitrogen and lignin, and lost 9 and 10% less mass than medium and large roots, respectively. Large roots of poplar had the highest lignin-to-nitrogen ratio and showed the smallest loss of mass over the total incubation period. Slow root decomposition of black alder and hybrid poplar was characterized by a greater proportion of initial root nitrogen immobilized per unit of carbon respired. Lignin concentration in roots of alder and poplar increased rapidly at the beginning of the incubation. Our results suggest that high levels of nitrogen in roots of alder could contribute in slowing the rate of decomposition by allowing the formation of nitrogen-lignin derivatives and low levels of nitrogen in roots of poplar may limit the growth of microorganisms and the rate of root decomposition. A multiple regression was developed using initial nitrogen, lignin concentration and the ratio of lignin to nitrogen to produce an index of the rate of root decomposition. The correlation between the index values and the percentage of residual root mass was significant (r=0.98, p〈0.01).
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 10 (1990), S. 1-28 
    ISSN: 1573-515X
    Schlagwort(e): boreal forest ; decomposition ; litter quality ; nitrogen ; productivity ; soil temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract A model of boreal forest dynamics was adapted to examine the factors controlling carbon and nitrogen cycling in the boreal forests of interior Alaska. Empirical relationships were used to simulate decomposition and nitrogen availability as a function of either substrate quality, the soil thermal regime, or their interactive effects. Test comparisons included black spruce forests growing on permafrost soils and black spruce, birch, and white spruce forests growing on permafrost-free soils. For each forest, simulated above-ground tree biomass, basal area, density, litterfall, moss biomass, and forest floor mass, turnover, thickness, and nitrogen concentration were compared to observed data. No one decay equation simulated forests entirely consistent with observed data, but over the range of upland forest types in interior Alaska, the equation that combined the effects of litter quality and the soil thermal regime simulated forests that were most consistent with observed data. For black spruce growing on permafrost soils, long-term simulated forest dynamics in the absence of fire resulted in unproductive forests with a thick forest floor and low nitrogen mineralization. Fires were an important means to interrupt this sequence and to restart forest succession.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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