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Fertiliser Application (fertiliser + application)
Selected AbstractsDual isotope and isotopomer ratios of N2O emitted from a temperate grassland soil after fertiliser applicationRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2003R. Bol The N2O and N2 fluxes emitted from a temperate UK grassland soil after fertiliser application (equivalent to 25 and 75,kg N ha,1) were simultaneously measured, using a new automated soil incubation system, which replaces soil atmosphere (N2 dominated) with a He+O2 mixture. Dual isotope and isotopomer ratios of the emitted N2O were also determined. Total N2O and N2 fluxes were significantly lower (P,<,0.001) in the control (0,kg N) than in the 25 and 75,kg N treatments. The total N2O flux was significantly higher (P,<,0.001) in the 75,kg N than in the 25,kg N treatment. The general patterns of N2O and N2 fluxes were similar for both fertiliser treatments. The total gaseous N loss in the control treatment was nearly all N2, whereas in the fertiliser treatment more N2O than N2 was emitted from the soil. The ratio N2O/N2 fluxes as measured during the experiment suggested three phases in N2O production, in phase 1 nitrification > denitrification, in phase 2 denitrification,>,nitrification, and in phase 3 denitrification (and total denitrification),,,nitrification. Dual ,15N and ,18O isotope and isotopomer (,15N, and ,15N,) value ratios of emitted N2O also pointed towards an increasing dominance of the production of N2O by denitrification and total denitrification. The site preference value from the soil-emitted N2O was lower than the troposphere value. This confirmed that the enhanced troposphere N2O site preference could result from back injection of N2O from the stratosphere. The measurements of N2O/N2 flux ratio and the isotopic content of emitted N2O pointed, independently, to similar temporal trends in N2O production processes after fertiliser application to grassland soil. This confirmed that both measurements are suitable diagnostic tools to study the N2O production process in soils. Copyright © 2003 John Wiley & Sons, Ltd. [source] Physiological changes in soybean (Glycine max) Wuyin9 in response to N and P nutritionANNALS OF APPLIED BIOLOGY, Issue 3 2002YINBO GAN Summary Phosphorus deficiency is a very common problem in the acid soil of central China. Previous research has shown that starter N and N topdressing at the flowering stage (Rl) increased soybean (Glycine max) yield and N2 fixation (Gan et al, 1997, 2000). However, there is little information available concerning soybean response to P-fertiliser in soybean production in central China (Gan, 1999). A field experiment was conducted to investigate the response to P (0 kg P ha,1, 22 kg P ha,1, 44 kg P ha,1 before sowing) and N fertiliser application (N1: 0 kg N ha,1, N2: 25 kg N ha,1 before sowing, N3: N2 + 50 kg N ha,1 at the V2 stage and N4: N2 + 50 kg N ha,1 at the R1 stage) on growth, yield and N2 fixation of soybean. Both N and P fertiliser increased growth and seed yield of soybean (P < 0.01). Application of basal P fertiliser at 22 kg P ha,1 or 44 kg P ha,1 increased total N accumulation by 11% and 10% (P < 0.01) and seed yield by 12% and 13% (P < 0.01), respectively, compared to the zero P treatment. Although application of starter N at 25 kg N ha,1 had no positive effect on seed yield at any P level (P > 0.05), an application of a topdressing of 50 kg N ha,1 at the V2 or R1 stage increased total N accumulation by 11% and 14% (P < 0.01) and seed yield by 16% and 21% (P < 0.01), respectively, compared to the zero N treatment. Soybean plants were grown on sterilised Perlite in the greenhouse experiment to study the physiological response to different concentrations of phosphate (P1: 0 mM; P2: 0.05 mM; P3: 0.5 mM; P4:1.0 mN) and nitrate (N1: 0 mM with inoculation, N2: 20 mM with inoculation). The result confirmed that N and P nutrients both had positive effects on growth, nodulation and yield (P < 0.01). The relative importance of growth parameters that contributed to the larger biomass with N and P fertilisation was in decreasing order: (i) total leaf area, (ii) individual leaf area, (iii) shoot/root ratio, (iv) leaf area ratio and (v) specific leaf area. The yield increase at N and P supply was mainly associated with more seeds and a larger pod number per plant, which confirmed the result from the field experiment. [source] Dynamics of species-rich upland hay meadows over 15 years and their relation with agricultural management practicesAPPLIED VEGETATION SCIENCE, Issue 3 2007C.N.R. Critchley Stace (1997) Abstract Questions: Has the species-rich vegetation of upland hay meadows been maintained under low intensity management imposed by an agri-environment scheme? Is the target plant community re-establishing where it has been modified previously by intensive agricultural practices? What combinations of management practices and soil properties are associated with changes towards or away from the target community? Location: The Pennines, northern England, UK. Methods: A survey of 116 hay meadows in 1987 was repeated in 2002 by recording plant species in permanent quadrats. Changes in community variables (species richness, Ellenberg values, upland hay meadow community coefficients) were analysed in species-rich, modified species-rich and degraded grassland types. Redundancy Analysis and Generalised Linear Models were used to show the relationship between management practices and soil properties and change in species composition and community variables. Results: Few sites contained the species-rich grassland type, and here forb richness declined. In the modified species-rich type, total and grass species richness increased but Ellenberg N-values also increased. Total and grass species richness increased in the degraded type and the community coefficient increased. Management was weakly related to change in species composition but showed clear relationships with the community variables. Re-establishment of the target species-rich community was more likely with late cutting, in the absence of cattle or prolonged spring grazing, and at lower soil nutrient status. Conclusion: The species-rich community was not maintained but some reversion occurred in degraded grassland. Inorganic fertiliser application and intensive spring grazing should be avoided and cutting delayed until late July. [source] Nitrogen concentrations in soil solution and surface run-off on irrigated vineyards in AustraliaAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2 2009K. BARLOW Abstract Background and Aims:, Water and nutrients exported from vineyards through surface and subsurface pathways have the potential to adversely affect water quality downstream. This project aimed to improve the scientific understanding of the pathways and quantity of Nitrogen (N) leaking from Australian vineyards. Methods and Results:, Seasonal water balance and N in soil solution was monitored in one Rutherglen Shiraz and six Riverina Chardonnay vineyards. Surface run-off was monitored in one vineyard in each wine region. Six vineyards were planted 2 years prior and one Riverina vineyard 10 years prior to study commencement. Two vineyards, one drip and one flood irrigated, were selected on each of the three main soil groups of the Riverina, the Rutherglen vineyard was drip irrigated. The annual risk of leaching extended up to 205 days, the average N (nitrate + nitrite) concentrations in soil solution (1 m) ranged from 0.64 to 82 mg N/L and surface run-off from 0.0 to 0.3 kg N/ha. Conclusions:, The soil N concentration combined with the number of days in which drainage was likely, highlights the potential risk for N export by subsurface pathways, while surface run-off was insignificant. Higher soil N concentrations and fertiliser application increased the risk of N exported beyond the rootzone. Significance of the Study:, N fertiliser inputs could be reduced without affecting vine performance, since several vineyards monitored were above the recommended petiole N concentrations at flowering. This would decrease production costs and reduce the risk of N leaching out of the soil profile to water tables or waterways. [source] Sources and bioavailability of phosphorus fractions in freshwaters: a British perspectiveBIOLOGICAL REVIEWS, Issue 1 2001C. S. REYNOLDS ABSTRACT This paper seeks a perspective on the forms of phosphorus which promote aquatic eutrophication, with the particular quest of establishing their sources. A short background traces the development of understanding of nutrient enrichment and the suppositions about the relative contributions of agriculture, sewage and detergent residues. Most aquatic systems, and their primary producers, are naturally deficient in biologically-available phosphorus. Aquatic plants have evolved very efficient phosphorus uptake mechanisms. The biomass responses to an increase in the supply of phosphorus are stoichiometrically predictable. The most bioavailable forms of phosphorus are in solution, as orthophosphate ions, or are readily soluble or elutable from loose combinations. Ready bioavailability coincides well with what is measurable as molybdate-reactive (MRP) or soluble-reactive phosphorus (SRP). Most other forms, including phosphates of the alkaline earth metals, aluminium and iron are scarcely available at all. Orthophosphate ions sorbed to metal oxides and hydroxides are normally not biologically available either, except through weak dissociation (,desorption'). The production of alkaline phosphatase provides organisms with an additional mechanism for accelerating the sequestration of phosphate from organic compounds. Bioavailable phosphate is liberated when redox- or alkali-sensitive metal hydroxides dissolve but these processes are minor contributors to the biological responses to nutrient enrichment. Most of the familiar eutrophication is attributable to the widespread application of secondary sewage treatment methods to the wastes emanating from a burgeoning and increasingly urbanised human population. The use of polyphosphate-based detergents, now in decline, has contributed to the problem. In aquatic systems, the additional phosphorus raises the biological supportive capacity, sometimes to the capacity of the next limiting factor (carbon, light, hydraulic retention or of another nutrient). At high orthophosphate loadings, the straight stoichiometric yield relationship between biomass yield and phosphorus availability is lost. Movements of phosphorus and its recycling within aquatic systems do not prevent the slow gravitation of phosphorus to the bottom substrata. The phosphorus retentivity of sediments depends upon their chemical composition. While oxide-hydroxide binding capacity in the surface sediments persists, they act as a sink for phosphorus and a control on further cycling. Iron-rich and clay-rich sediments perform best in these conditions; calcareous sediments least so. Eutrophication may lead to the exhaustion of sediment P-binding capacity. Non-sorbed phosphate is readily recyclable if primary producers have access to it. Recycling is most rapid in shallow waters (where sediment disturbance, by flow, by wind action and through bioturbation, is frequent) and least in deep ventilated sediments. The contributions of phosphorus from catchments are assessed. The slow rate of weathering of (mostly apatitic) minerals, the role of chemical binding in soils and the incorporation and retentivity by forested terrestrial ecosystems each contribute to the minimisation of phosphorus leakage to drainage waters. Palaeolimnological and experimental evidence confirms that clearance of land and ploughing its surface weakens the phosphorus retentivity of catchments. The phosphorus transferred from arable land to drainage remains dominated by sorbed fractions which are scarcely bioavailable. Some forms of intensive market gardening or concentrated stock rearing may mobilise phosphates to drainage but it is deduced that drainage from agricultural land is not commonly a major source of readily bioavailable phosphorus in water. Careful budgeting of the phosphates in run-off from over-fertilised soils may nevertheless show that a proportionately small loss of bioavailable phosphorus can still be highly significant in promoting aquatic plant production. The bioavailable-phosphorus (BAP) load achieving the OECD threshold of lake eutrophy (35 mg P m,3) is calculated to be equivalent to a terrestrial loss rate of approximately 17.5 kg BAP km,2 year,1), or only 1,2% of a typical fertiliser application. The output is shown to be comparable with the P yield from secondary treatment of the sewage produced by a resident population of 30,44 persons km,2. With tertiary treatment, the equivalence is with approximately 200 persons km,2. [source] Long-term influence of manure and mineral nitrogen applications on plant and soil 15N and 13C values from the Broadbalk Wheat Experiment,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2008Mehmet Senbayram The Broadbalk Wheat Experiment at Rothamsted Research in the UK provides a unique opportunity to investigate the long-term impacts of environmental change and agronomic practices on plants and soils. We examined the influence of manure and mineral fertiliser applications on temporal trends in the stable N (15N) and C (13C) isotopes of wheat collected during 1968,1979 and 1996,2005, and of soil collected in 1966 and 2000. The soil ,15N values in 1966 and 2000 were higher in manure than the mineral N supplied soil; the latter had similar or higher ,15N values than non-fertilised soil. The straw ,15N values significantly decreased in all N treatments during 1968 to 1979, but not for 1996,2005. The straw ,15N values decreased under the highest mineral N supply (192,kg,N,ha,1,year,1) by 3, from 1968 to 1979. Mineral N supply significantly increased to straw ,13C values in dry years, but not in wet years. Significant correlations existed between wheat straw ,13C values with cumulative rainfall (March to June). The cultivar Hereward (grown 1996,2005) was less affected by changes in environmental conditions (i.e. water stress and fertiliser regime) than Cappelle Desprez (1968,1979). We conclude that, in addition to fertiliser type and application rates, water stress and, importantly, plant variety influenced plant ,13C and ,15N values. Hence, water stress and differential variety response should be considered in plant studies using plant ,13C and ,15N trends to delineate past or recent environmental or agronomic changes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Biological and environmental factors controlling root dynamics and function: effects of root ageing and soil moistureAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2010L.H. COMAS Abstract Understanding factors controlling root dynamics and functioning can lead to more efficient and profitable vineyard management. However, our current understanding of root dynamics and their regulation by plant and environmental factors is limited, particularly under field conditions. This paper presents current understanding of grape root dynamics, highlighting studies using minirhizotron cameras, which directly assess root dynamics, and experiments on roots of known age, which link root phenology and function. Data summarised here show timing of grape root production varies widely among different regions, as well as among rootstocks and canopy management systems in the same region. Timing of production can be responsive to differences in soil moisture. Lifespan of grape roots, however, appears less affected by soil moisture because of nocturnal hydraulic redistribution. Root function, such as capacity for P and N uptake, declines rapidly with root age. Differences in timing and spatial distribution of root production can effect above-ground growth and vineyard water-use efficiency. Improving our understanding of when roots grow and are functionally active in agricultural systems can lead to improved water and fertiliser applications, and more precise vineyard management. Because both environmental and biological factors affect root dynamics, simple predictions of timing of root production or standing populations with shoot development are unlikely to be achieved. However, with multi-year data on root dynamics, and environmental and biological factors, regionally specific models of root populations and their functioning may be possible to develop. [source] | |||||||||||||