Distribution by Scientific Domains
Distribution within Earth and Environmental Science

Kinds of Fertilizer

  • chemical fertilizer
  • inorganic fertilizer
  • mineral fertilizer
  • n fertilizer
  • nitrogen fertilizer
  • organic fertilizer
  • p fertilizer
  • phosphate fertilizer

  • Terms modified by Fertilizer

  • fertilizer addition
  • fertilizer application
  • fertilizer dose
  • fertilizer input
  • fertilizer management
  • fertilizer n
  • fertilizer nitrogen
  • fertilizer rate
  • fertilizer treatment
  • fertilizer use

  • Selected Abstracts


    Mitoshi YAMAGUCHI
    O11; O13; O41; Q18 The agricultural sector of Sri Lanka reacted sharply to the highly contentious policy reforms called Structural Adjustment Programs. We used a four-sector general equilibrium model under a growth accounting approach to find out the effect of the policy (exogenous) variable on the target (endogenous) variable. Here, we considered only the most important variables, and the overall results indicate that policy changes are favorable to overall agricultural development, although their effect on the domestic food sector is negative. The most serious negative determinant under the policy changes relates to fertilizer, and our study indicates that fertilizer prices considerably affect agricultural production; it especially has a negative effect on domestic food production. Second, this paper analyzes the impact of nonagricultural price, finding that it positively helped the development of overall agriculture. Third, agricultural exports increased under the new policy reforms and made large contributions to agricultural production. [source]

    Economy in water and fertilizer use in trickle fertigated potato,

    J.K. Chawla
    fertigation; économies d'eau; économies de fertilisant; irrigation à regime lent Abstract Fertilizer and water use in trickle fertigated potato using different fertilizer application rates, frequencies of application and wetted soil volumes were compared with a furrow irrigated and conventionally fertilized crop. Results indicate that water and fertilizer savings to the extent of 30 and 70% respectively with comparable yield levels were possible under the trickle fertigated crop as compared to the furrow irrigated crop of potatoes. Highest yield of 36.29 t ha,1 of fresh tubers was obtained under trickle irrigation as compared to 21.5 t ha,1 for the furrow irrigated crop. Copyright © 2001 John Wiley & Sons, Ltd. Usage de fertilisant et d'eau dans la pomme de terre fertiguée à régime lent utilisant différents cours d'applicage de fertilisant, fréquencies d'applicage et volumes de sol imbibé d'eau étaient comparés avec la récolte irriguée à sillon et fertilisé conventionnellement. Les résultants indiquent que des économies d'eau et de fertilisant jusqu'à 30 et 70 pour cent respectivement avec des niveaux de rendement comparables étaient possibles sous la récolte fertiguée à régime lent en comparaison de la récolte irriguée à sillon des pommes de terre. Le plus grand rendement de 36.29 t ha,1 de tubéreuses fraiches était obtenu sous l'irrigation à régime lent en comparaison de 21.5 t ha,1 pour la récolte irriguée à sillon. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Impact of Phosphorus from Dairy Manure and Commercial Fertilizer on Perennial Grass Forage Production

    E. A. Mikhailova
    Abstract Increased recovery and recycling of manure phosphorus (P) by crops on dairy farms is needed to minimize environmental problems. The main objective of this study was to compare P utilization by orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) from dairy manure or inorganic fertilizer. The study was conducted from 1994 to 2000 at the Cornell University Baker Farm, Willsboro, NY, on a somewhat poorly drained Kingsbury clay (very,fine, illitic, mesic Aeric Epiaqualfs). The design was a split-plot in a randomized complete block with two manure rates (16 800 and 33 600 kg ha,1) and one nitrogen (N) fertilizer rate (84 kg N ha,1 at spring greenup and 56 kg N ha,1 prior to each regrowth harvest) as the main plots and grass species as subplots replicated six times. Fertilizer P [Ca(H2PO4)2] was applied to the fertilizer treatment in 1995 and 1996 at 11 kg P ha,1 year,1. Orchardgrass P removal averaged 21 % higher than tall fescue P removal for the spring harvest, but orchardgrass averaged 24 % lower P removal than tall fescue removal for all regrowth harvests from 1995,99. Phosphorus herbage concentration in the fertilizer treatment was in the range of 1.9,2.7 g P kg,1 compared with 2.2,5.3 g P kg,1 in the manure treatments. Seasonal P removal ranged from as low as 9.2 kg P ha,1 to as high as 48.5 kg P ha,1. Morgan extractable soil P in the top 0,0.20 m remained high through 1999, with 29.1 kg P ha,1 at the highest manure rate in tall fescue compared with 8.4 kg P ha,1 measured in 1993 prior to the experiment. In 2000, soil P at the highest manure rate in tall fescue dropped to 10.1 kg P ha,1, following cessation of manure application in 1998. Intensively managed harvested orchardgrass and tall fescue have the potential to remove large quantities of manure P. [source]

    Fertilizer affects the behaviour and performance of Plutella xylostella on brassicas

    Joanna T. Staley
    Abstract 1,Foliar nitrogen concentration, which can be manipulated in crop plants by fertilizer supply, has long been recognized as a major factor in phytophagous insect abundance and performance. More recently, the type of fertilizer supplied has been shown to influence the abundance of some herbivore species. The diamondback moth Plutella xylostella is a global pest of Brassica crops. Although it has been the subject of numerous studies on host-plant resistance and pest control, few studies have addressed the effect of abiotic factors, such as nutrient supply, on its performance and behaviour. 2,We assessed oviposition preference, larval feeding preference and larval performance of P. xylostella on two cultivars of Brassica oleracea. Plants were grown using two fertilizer types, John Innes fertilizer and an organic animal manure, at high and low concentrations. 3,Plutella xylostella laid more eggs on cultivar Derby Day than Drago. Derby Day was also the cultivar on which larval performance was maximized. However, differences in larval performance between cultivars were only found when plants were grown in compost with John Innes fertilizer, and not when fertilized with animal manure. 4,Foliar nitrogen concentration was greater in plants grown in high fertilizer treatments but did not differ between cultivars. The concentrations of three glucosinolate compounds (glucoiberin, sinigrin and glucobrassicin) were greater in the high fertilizer treatments. Glucosinolate concentrations were higher in the Drago than the Derby Day cultivar. 5,These results are discussed in relation to the preference-performance hypothesis, and the assessment of plant resistance differences between cultivars using different types of fertilizer. [source]

    Establishing native plants on newly-constructed and older-reclaimed sites along West Virginia highways

    J.G. Skousen
    Abstract Many state highway departments in the USA must use native plants for revegetating roadsides. We conducted two field studies in West Virginia to assess native plant establishment under two different conditions. On newly-constructed sites, native species were seeded alone or combined with non-native species. On older roadsides, native species were seeded in disturbed existing vegetation. In the first study, we used four seed mixtures comprised of seeds of native and non-native species, and two N-P-K fertilizer treatments at three newly-constructed sites. Native, warm-season grasses were slow to establish and only contributed 25 per cent cover in some plots after three years. Indiangrass (Sorghastrum nutans [L.] Nash), big bluestem (Andropogon gerardii Vitman), Brown-Eyed Susan (Rudbeckia triloba L.), and wild senna (Cassia hebecarpa Fernald) were the only seeded native species found. Fertilizer at 150,kg,ha,1 of 10-20-10 showed little influence on increasing plant cover. In the second study, we disturbed three different-aged established stands of vegetation composed of tall fescue (Festuca arundinacea Screb.) and crownvetch (Coronilla varia L.) by mowing, herbicide, or tillage, and native plants were seeded with and without fertilizer. Native cover was <10 per cent in all plots during the first year, but greatly increased by the second year to as much as 45 per cent in tilled plots, indicating that disturbance was necessary for natives to become important contributors within 2 years. Only switchgrass (Panicum virgatum L.), little bluestem (Andropogon scoparius Vitman), partridge pea (Chamaecrista fasciculate Michx.), and Brown-Eyed Susan were observed in plots. Fertilizer at 300,kg,ha,1 of 10-20-10 did not increase native plant cover on these sites. Based on our results, introducing or increasing the cover of native species along roadsides requires (1) reducing competition from non-native species, and (2) longer time periods for these slower-establishing species to be observed. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Revegetation Methods for High-Elevation Roadsides at Bryce Canyon National Park, Utah

    S. L. Petersen
    Abstract Establishment of native plant populations on disturbed roadsides was investigated at Bryce Canyon National Park (BCNP) in relation to several revegetation and seedbed preparation techniques. In 1994, the BCNP Rim Road (2,683,2,770 m elevation) was reconstructed resulting in a 23.8-ha roadside disturbance. Revegetation comparisons included the influence of fertilizer on plant establishment and development, the success of indigenous versus commercial seed, seedling response to microsites, methods of erosion control, and shrub transplant growth and survival. Plant density, cover, and biomass were measured 1, 2, and 4 years after revegetation implementation (1995,1998). Seeded native grass cover and density were the highest on plots fertilized with nitrogen and phosphorus, but by the fourth growing season, differences between fertilized and unfertilized plots were minimal. Fertilizers may facilitate more rapid establishment of seeded grasses following disturbance, increasing soil cover and soil stability on steep and unstable slopes. However the benefit of increased soil nutrients favored few of the desired species resulting in lower species richness over time compared to unfertilized sites. Elymus trachycaulus (slender wheatgrass) plants raised from indigenous seed had higher density and cover than those from a commercial seed source 2 and 4 years after sowing. Indigenous materials may exhibit slow establishment immediately following seeding, but they will likely persist during extreme climatic conditions such as cold temperatures and relatively short growing seasons. Seeded grasses established better near stones and logs than on adjacent open microsites, suggesting that a roughened seedbed created before seeding can significantly enhance plant establishment. After two growing seasons, total grass cover between various erosion-control treatments was similar indicating that a variety of erosion reduction techniques can be utilized to reduce erosion. Finally shrub transplants showed minimal differential response to fertilizers, water-absorbing gels, and soil type. Simply planting and watering transplants was sufficient for the greatest plant survival and growth. [source]

    Fertilizers, Pills, and Magnetic Strips: The Fate of Public Education in America , By Gene V. Glass

    Alex Posecznick
    No abstract is available for this article. [source]

    Corporate socially responsible (CSR) practices in the context of Greek industry

    Dr Constantina Bichta
    This paper sets out to describe the level of corporate environmental responsibility of the Greek industrial sector. While the level of corporate socially responsible behaviour has been widely explored in the context of Northern European industry, the theoretical work surrounding the level of CSR practices of Greek industry is underdeveloped. A qualitative study was designed to increase awareness about the level of environmental responsibility of two Greek firms, which represented the chemical/fertilizer and metal sectors. The empirical findings suggest that a number of factors, both internal and external, determine the level of environmental policy and performance of the two companies. The environmental policy of the companies appears also to relate to the sector of operation. The paper concludes that the Greek business actor should look at his workforce in order to accelerate the environmental activities of the organization. With regard to the theory of CSR, it is argued that the development of a model of CSR is aided by the study and identification of factors that support and/or undermine the socially responsible behaviour of the European corporate sector. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment. [source]

    Bioremediation of 6 % [w/w] Diesel-Contaminated Mainland Soil in Singapore: Comparison of Different Biostimulation and Bioaugmentation Treatments

    M. Mathew
    Abstract The efficacy of indigenous microorganisms to degrade diesel oil in contaminated mainland sites in Singapore was investigated. A semi-scale trial was made by spiking topsoil with 6,% [w/w] of diesel oil. The results indicated that in the presence of NPK commercial (Rosasol®) fertilizer a 53,% reduction in contaminant concentration was recorded after 60,days compared to untreated controls while the addition of a mixture of urea and K2HPO4 effected a 48,% reduction in the Total Recoverable Petroleum Hydrocarbons. A commercial culture and an enriched/isolated microbial association proved to be the least effective with 25 and 9,% reductions, respectively. The results confirmed the bioremediation potential of indigenous microorganisms for diesel-oil contaminated mainland soil. Identification of the persistent compounds was done and perceived as a tool in decision-making on strategies for speeding up of the degradation process to achieve clean-up standards in shorter remediation periods. [source]

    The role of Variovorax and other Comamonadaceae in sulfur transformations by microbial wheat rhizosphere communities exposed to different sulfur fertilization regimes

    Achim Schmalenberger
    Summary Sulfonates are a key component of the sulfur present in agricultural soils. Their mobilization as part of the soil sulfur cycle is mediated by rhizobacteria, and involves the oxidoreductase AsfA. In this study, the effect of fertilization regime on rhizosphere bacterial asfA distribution was examined at the Broadbalk long-term wheat experiment, Rothamsted, UK, which was established in 1843, and has included a sulfur-free treatment since 2001. Direct isolation of desulfonating rhizobacteria from the wheat rhizospheres led to the identification of several Variovorax and Polaromonas strains, all of which contained the asfA gene. Rhizosphere DNA was isolated from wheat rhizospheres in plots fertilized with inorganic fertilizer with and without sulfur, with farmyard manure or from unfertilized plots. Genetic profiling of 16S rRNA gene fragments [denaturing gradient gel electrophoresis (DGGE)] from the wheat rhizospheres revealed that the level of inorganic sulfate in the inorganic fertilizer was correlated with changes in the general bacterial community structure and the betaproteobacterial community structure in particular. Community analysis at the functional gene level (asfA) showed that 40% of clones in asfAB clone libraries were affiliated to the genus Variovorax. Analysis of asfAB -based terminal restriction fragment length polymorphism (T-RFLP) fingerprints showed considerable differences between sulfate-free treatments and those where sulfate was applied. The results suggest the occurrence of desulfonating bacterial communities that are specific to the fertilization regime chosen and that arylsulfonates play an important role in rhizobacterial sulfur nutrition. [source]

    Abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea communities of an alkaline sandy loam

    Ju-pei Shen
    Summary The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities under different long-term (17 years) fertilization practices were investigated using real-time polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE). A sandy loam with pH (H2O) ranging from 8.3 to 8.7 was sampled in years 2006 and 2007, including seven fertilization treatments of control without fertilizers (CK), those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): NP, NK, PK and NPK, half chemical fertilizers NPK plus half organic manure (1/2OMN) and organic manure (OM). The highest bacterial amoA gene copy numbers were found in those treatments receiving N fertilizer. The archaeal amoA gene copy numbers ranging from 1.54 × 107 to 4.25 × 107 per gram of dry soil were significantly higher than those of bacterial amoA genes, ranging from 1.24 × 105 to 2.79 × 106 per gram of dry soil, which indicated a potential role of AOA in nitrification. Ammonia-oxidizing bacteria abundance had significant correlations with soil pH and potential nitrification rates. Denaturing gradient gel electrophoresis patterns revealed that the fertilization resulted in an obvious change of the AOB community, while no significant change of the AOA community was observed among different treatments. Phylogenetic analysis showed a dominance of Nitrosospira -like sequences, while three bands were affiliated with the Nitrosomonas genus. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). These results suggest that long-term fertilization had a significant impact on AOB abundance and composition, while minimal on AOA in the alkaline soil. [source]

    Effect of N-fertilization, plant genotype and environmental conditions on nifH gene pools in roots of rice

    Zhiyuan Tan
    Summary Terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR-amplified nitrogenase gene (nifH) fragments is a rapid technique for profiling of diazotrophic microbial communities without the necessity of cultures for study. Here, we examined the impact of N-fertilization, plant genotype and environmental conditions on diazotrophic microbial populations in association with roots of rice (Oryza species) by T-RFLP community profiling and found marked effects on the composition of the microbial community. We found a rapid change of the diazotrophic population structure within 15 days after application of nitrogen fertilizer and a strong effect of environmental conditions and plant genotype. Control experiments revealed that phylogenetically distantly related nifH genes were proportionately amplified, and that signal strength reflected the relative abundance of nifH genes in the sample within a 10-fold range of template concentrations. These results clearly demonstrated that our T-RFLP method was suitable to reflect compositional differences in the diazotrophic community in a semiquantitative manner and that the diazotrophic rhizosphere communities of rice are not static but presumably rather highly dynamic. [source]

    Identification of optimal poultry litter biorefinery location in Alabama through minimization of feedstock transportation cost

    Burak Aksoy
    Abstract The estimated amount of poultry litter produced annually in Alabama is more than 1,250,000 tons. This large amount results in significant litter management challenges. Currently, poultry producers are facing many regulatory issues and challenges with respect to environmental impacts of litter management. Commercialization and implementation of environmentally benign biorefinery technologies have the potential to generate electric power (including on-site power) and heat as well as transportation fuels, hydrogen, valuable chemicals, and fertilizer from poultry litter economically while addressing environmental problems caused by traditional disposal practices. In this study, poultry litter generated annually in northern and southern Alabama was documented on the basis of published literature, and transportation cost of poultry litter is minimized for both north and south Alabama by the selection of the best large-scale biorefining facility location and optimal feedstock allocation using mathematical optimization techniques. The available portion of the existing poultry litter feedstock for a large scale biorefinery is found to be an important factor in determining transportation cost. Transportation cost increases several fold as the local feedstock availability for biorefining reduces from 100 to 50%. Optimum facility locations for both north and south Alabama were found within a 10 mile radius for three different poultry litter feedstock availabilities. © 2008 American Institute of Chemical Engineers Environ Prog, 2008 [source]

    Uptake and transport of roxarsone and its metabolites in water spinach as affected by phosphate supply

    Lixian Yao
    Abstract Roxarsone (ROX) is widely used as a feed additive in intensive animal production. While an animal is fed with ROX, the As compounds in the manure primarily occur as ROX and its metabolites, including arsenate (As[V]), arsenite (As[III]), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). Animal manure is commonly land applied with phosphorous fertilizers in China. A pot experiment was conducted to investigate the phytoavailability of ROX, As(V), As(III), MMA, and DMA in water spinach (Ipomoea aquatica), with the soil amended with 0, 0.25, 0.50, 1.0, and 2.0,g PO4/kg, respectively, plus 2% (w/w manure/soil) chicken manure (CM) bearing ROX and its metabolites. The results indicate that this species of water spinach cannot accumulate ROX and MMA at detectable levels, but As(V), As(III), and DMA were present in all plant samples. Increased phosphorous decreased the shoot As(V) and As(III) in water spinach but did not affect the root As(V). The shoot DMA and root As(III) and DMA were decreased/increased and then increased/decreased by elevated phosphorous. The total phosphorous content (P) in plant tissue did not correlate with the total As or the three As species in tissues. Arsenate, As(III), and DMA were more easily accumulated in the roots, and phosphate considerably inhibited their upward transport. Dimethylarsinic acid had higher transport efficiency than As(V) and As(III), but As(III) was dominant in tissues. Conclusively, phosphate had multiple effects on the accumulation and transport of ROX metabolites, which depended on their levels. However, proper utilization of phosphate fertilizer can decrease the accumulation of ROX metabolites in water spinach when treated with CM containing ROX and its metabolites. Environ. Toxicol. Chem. 2010;29:947,951. © 2009 SETAC [source]

    The effect of pH and ionic strength on the sorption of sulfachloropyridazine, tylosin, and oxytetracycline to soil

    Thomas L. ter Laak
    Abstract Antimicrobial agents are the most heavily used pharmaceuticals in intensive husbandry. Their usual discharge pathway is application to agricultural land as constituents of animal manure, which is used as fertilizer. Many of these compounds undergo pH-dependent speciation and, therefore, might occur as charged species in the soil environment. Hence, pH and ionic strength of the soil suspension can affect the sorption behavior of these compounds to soil. Consequently, the soil sorption of three antimicrobial agents,sulfachloropyridazine (SCP), tylosin (TYL), and oxytetracycline (OTC),was investigated. Their respective sorption coefficients in two agricultural soils ranged from 1.5 to 1,800 L/kg. Sorption coefficients were greater under acidic conditions. Addition of an electrolyte to the solution led to decreased sorption of TYL and OTC by a factor of 3 to 20, but it did not influence the sorption of SCP. This behavior was analyzed by accounting for the pH-dependent speciation of TYL and OTC and considering the presence of OTC-calcium complexes. It appears that the decreased sorption of TYL and OTC with increasing ionic strength results from competition of the electrolyte cations with the positively charged TYL species and the positively charged OTC complexes. A model linking sorbate speciation with species-specific sorption coefficients can describe the pH dependence of the apparent sorption coefficients. This modeling approach is proposed for implementation in the assessment of sorption of ionizable compounds. [source]

    Influence of developmental stage on sensitivity to ammonium nitrate of aquatic stages of amphibians

    Manuel E. Ortiz-Santaliestra
    Abstract In static renewal experiments, we studied how developmental stage influences the effect of ammonium nitrate on embryonic and larval stages of anuran amphibians. The observed lethal effects caused by ammonium nitrate increased with both concentration and duration of exposure. Significant differences were observed in sensitivity to ammonium nitrate as a function of developmental stage in Discoglossus galganoi, Pelobates cultripes, and Bufo calamita. In D. galganoi and P. cultripes, younger individuals displayed greater acute effects from the chemical fertilizer compared with older individuals. For example, 100% of P. cultripes hatchlings died after 4 d of exposure to a nominal concentration of 225.8 mg N-NO3NH4/L, whereas less than 40% of individuals from older larval stages died when exposed to this concentration. A delay of 4 d in the beginning of the exposure to the chemical was enough to cause significant differences in sensitivity. Bufo calamita showed a higher sensitivity in later larval stages after 12 d of exposure. Hyla meridionalis and B. calamita were less sensitive than the other two species. Peak ammonium nitrate concentrations usually occur when amphibians are breeding and, thus, when the most sensitive aquatic stage is in the water. The developmental stage of the test animals should be considered when evaluating the risk of ammonium nitrate to amphibians. [source]

    The Prestige oil spill.


    Abstract In vitro biodegradation of the Prestige heavy fuel oil has been carried out using two microbial consortia obtained by enrichment in different substrates to simulate its environmental fate and potential utility for bioremediation. Different conditions, such as incubation time (i.e., 20 or 40 d), oil weathering, and addition of an oleophilic fertilizer (S200), were evaluated. Weathering slowed down the degradation of the fuel oil, probably because of the loss of lower and more labile components, but the addition of S200 enhanced significantly the extension of the biodegradation. n -Alkanes, alkylcyclohexanes, alkylbenzenes, and the two- to three-ring polycyclic aromatic hydrocarbons (PAHs) were degraded in 20 or 40 d of incubation of the original oil, whereas the biodegradation efficiency decreased for higher PAHs and with the increase of alkylation. Molecular markers were degraded according to the following sequence: Acyclic isoprenoids < diasteranes < C27 -steranes < ,,-steranes < homohopanes < monoaromatic steranes < triaromatic steranes. Isomeric selectivity was observed within the C1 - and C2 -phenanthrenes, dibenzothiophenes, pyrenes, and chrysenes, providing source and weathering indices for the characterization of the heavy oil spill. Acyclic isoprenoids, C27 -steranes, C1 - and C2 -naphthalenes, phenanthrenes, and dibenzothiophenes were degraded completely when S200 was used. The ratios of the C2 - and C3 -alkyl homologues of fluoranthene/pyrene and chrysene/benzo[a]anthracene are proposed as source ratios in moderately degraded oils. The 4-methylpyrene and 3-methylchrysene were refractory enough to serve as conserved internal markers in assessing the degradation of the aromatic fraction in a manner similar to that of hopane, as used for the aliphatic fraction. [source]

    Amino acid 15N in long-term bare fallow soils: influence of annual N fertilizer and manure applications

    R. Bol
    Summary Long-term dynamics of amino acids (AAs), from a bare fallow soil experiment (established in 1928 at INRA-Versailles, France), were examined in unamended control (Con) plots and plots treated with ammonium sulphate (Amsul), ammonium nitrate (Amnit), sodium nitrate (Nanit) or with animal manure (Man). Topsoil (0,25 cm) from 1929, 1963 and 1997 was analysed for C, N and 15N content and distribution of 18 amino acids recovered after acid hydrolysis with 6 m HCl. With time, soil N, C and AA content were reduced in Con, Amsul, Amnit and Nanit, but increased in Man. However, the absolute N loss was 3,11 times larger in Man than Nanit, Amsul, Amnit and Con, due to the much higher N annual inputs applied to Man. From 1929 to 1997 in Con, Amsul, Amnit and Nanit the whole soil and non-hydrolysable-N pool ,15N increased associated with the loss of N (indicative of Rayleigh 15N/14N fractionation). No ,15N change from 1929 to 1997 was found in the hydrolysable AA-N (HAN) pool. Fertilizer N inputs aided stabilization of soil AA-N, as AA half-life in the mineral N fertilizer treatments increased from 34 years in 1963 to 50 years in 1997. The ,15N values of alanine and leucine reflected both source input and 15N/14N fractionation effects in soils. The ,15N increase of ornithine (,6,) was similar to the whole soil. The ,15N change of phenylalanine in Con (decrease of 7,) was related to its proportional loss since 1929, whereas for Amsul, Amnit, Nanit and Man it was associated with isotope effects caused by the fertilizer inputs. However, the soil ,15N value of most individual amino acids (IAAs) did not significantly change over nearly 70 years, even with mineral or organic N inputs. We conclude for these bare fallow systems that: (i) ,15N changes in the whole soil and non-hydrolysable AA pool were solely driven by microbial processes and not by the nature of fertilizer inputs, and (ii) without plant inputs, the ,15N of the HAN pool and (most) IAAs may reflect the influence of plant,soil interactions from the previous (arable cropping) rather than present (fallow) land use on these soil ,15N values. [source]

    Total and soluble fluorine concentrations in relation to properties of soils in New Zealand

    P. Loganathan
    Summary Soil fluorine (F) concentrations continue to increase in agricultural soils receiving regular applications of phosphatic fertilizer. Continued accumulation of soil F poses a risk to grazing ruminants and may pose a future risk to groundwater quality. This paper examines the range of total F (Ft) concentrations and forms of soluble F species and their relationship to selected soil properties in New Zealand agricultural soils. The Ft and soluble F (soil F extracted with water (Fwater) and 0.01 m KCl (FKCl)) concentrations in 27 soil samples (0,75 mm depth) taken from predominantly pasture sites in the North and South Islands of New Zealand were much less than those reported in the literature for sites contaminated with F from industry. The Ft concentrations ranged from 212 to 617 µg F g,1 soil. The F-toxicity risk to grazing animals in farms at these sites through soil ingestion is small at present, but farms with very large Ft concentrations (i.e. > 500 µg F g,1) need to adopt suitable grazing and fertilizer management practices to avoid future F-toxicity risk. The Ft concentration had very strong positive correlations with both total soil P and total soil Cd concentrations, reflecting the link between P fertilizer use and F accumulation in the soils. It also had significant positive correlations with organic matter and amorphous Al oxides contents, indicating that F is strongly bound to Al polymers adsorbed to organic matter and amorphous Al oxides. The Fwater and FKCl concentrations and free F, ion concentrations in water (F,water) and 0.01 m KCl (F,KCl) extracts were generally two and three orders of magnitude, respectively, less than the Ft concentrations and were much less than the concentrations considered phytotoxic. The Fwater and FKCl concentrations were positively related to soil organic matter content and negatively related to soil pH. Regression models relating Fwater and FKCl concentrations to soil organic matter content and soil pH suggest that F can be very soluble in extremely acidic soils (pH(water) < 4.9) with large organic matter contents and therefore F potentially may contaminate groundwater if these soils are also coarse-textured and the water table is shallow. [source]

    Preferential phosphorus leaching from an irrigated grassland soil

    G. S. Toor
    Summary Intact lysimeters (50 cm diameter, 70 cm deep) of silt loam soil under permanent grassland were used to investigate preferential transport of phosphorus (P) by leaching immediately after application of dairy effluent. Four treatments that received mineral P fertilizer alone (superphosphate at 45 kg P ha,1 year,1) or in combination with effluent (at , 40,80 kg P ha,1 year,1) over 2 years were monitored. Losses of total P from the combined P fertilizer and effluent treatments were 1.6,2.3 kg ha,1 (60% of overall loss) during eight drainage events following effluent application. The rest of the P lost (40% of overall loss) occurred during 43 drainage events following a significant rainfall or irrigation compared with 0.30 kg ha,1 from mineral P fertilizer alone. Reactive forms of P (mainly dissolved reactive P: 38,76%) were the dominant fractions in effluent compared with unreactive P forms (mainly particulate unreactive P: 15,56%). In contrast, in leachate following effluent application, particulate unreactive P was the major fraction (71,79%) compared with dissolved reactive P (1,7%). The results were corroborated by 31P nuclear magnetic resonance analysis, which showed that inorganic orthophosphate was the predominant P fraction present in the effluent (86%), while orthophosphate monoesters and diesters together comprised up to 88% of P in leachate. This shows that unreactive P forms were selectively transported through soil because of their greater mobility as monoesters (labile monoester P and inositol hexakisphosphate) and diesters. The short-term strategies for reducing loss of P after application of dairy effluent application should involve increasing the residence time of applied effluent in the soil profile. This can be achieved by applying effluent frequently in small amounts. [source]

    Cadmium leaching from some New Zealand pasture soils

    C. W. Gray
    Summary Cadmium (Cd) inputs and losses from agricultural soils are of great importance because of the potential adverse effects Cd can pose to food quality, soil health and the environment in general. One important pathway for Cd losses from soil systems is by leaching. We investigated loss of Cd from a range of contrasting New Zealand pasture soils that had received Cd predominantly from repeated applications of phosphate fertilizer. Annual leaching losses of Cd ranged between 0.27 and 0.86 g ha,l, which are less than most losses recorded elsewhere. These losses equate to between 5 and 15% of the Cd added to soil through a typical annual application of single superphosphate, which in New Zealand contains on average 280 mg Cd kg,1 P. It appears that Cd added to soil from phosphate fertilizer is fairly immobile and Cd tends to accumulate in the topsoil. The pH of the leachate and the total volume of drainage to some extent control the amount of Cd leached. Additional factors, such as the soil sorption capacity, are also important in controlling Cd movement in these pasture soils. The prediction of the amount of Cd leached using the measured concentrations of Cd in the soil solution and rainfall data resulted in an overestimation of Cd losses. Cadmium concentrations in drainage water are substantially less than the current maximum acceptable value of 3 µg l,1 for drinking water in New Zealand set by the Ministry of Health. [source]

    Analysis of phosphorus in two humic acid fractions of intensively cropped lowland rice soils by 31P-NMR

    N. Mahieu
    Summary The organic forms of phosphorus in the soil appear to be changing as rice growing intensifies and the soil is flooded for longer in tropical Asia. To examine these changes, we extracted the labile mobile humic acid (MHA) and more recalcitrant calcium humate (CaHA) fractions from soils supporting long-term field trials in the Philippines and analysed them by solution 31P-nuclear magnetic resonance (NMR) spectroscopy. Diester P and sugar-diester P accumulated moderately with increasing intensity of irrigated rice cropping, reaching a combined 42% of all MHA-P for a triple-cropped irrigated field compared with 28% for fully aerated fields growing dryland crops. The mono- to diester P ratio decreased by 43% for the MHA and CaHA from the aerated fields to the triple-cropped field. Smaller effects on forms of P were noted for the rates and type of N, P and K fertilizer and site effects. The effects of treatment and site were more noticeable in the MHA than in the CaHA. The proportions in the NMR spectra were tightly correlated with visible light absorption, concentrations of organic free radicals and H, and 15N-NMR spectral proportions, which indicate the degree of humification. The MHA and CaHA accounted for only 0.6,8.3% and 0.9,5.7%, respectively, of total P; most of the P is inorganic. [source]

    Soilscape and land-use evolution related to drift sand movements since the bronze age in Eastern Jutland, Denmark

    Jari Hinsch Mikkelsen
    Quarry faces several kilometers long in the Glesborg area in Denmark show that Bronze Age farmers used a sustainable land-use system. Despite nutrient-poor soils, the Glesborg area was under a rotation system in which cropland alternated with grassland. Soil fertility was improved by the addition of household waste and probably also by locally obtained inorganic fertilizer. The soil surface was very stable, and local drift sand movement was limited. Toward the end of the Bronze Age, the landscape changed dramatically with the arrival of overwhelming amounts of drift sand, and farmsteads were abandoned. Subsequent land use on these poor fine sandy soils was no longer capable of maintaining a stable soil surface, and frequent erosion/sedimentation events of more local importance took place. The post-Bronze Age landscape may have been mainly a shifting mosaic of heathland with some temporary arable fields and deflation/accumulation areas. This landscape persisted up to about 200 years ago, when afforestation programs started. © 2007 Wiley Periodicals, Inc. [source]


    Laurence Becker
    ABSTRACT. Pressured by structural adjustment loan conditions, Côte d'Ivoire reduced state support for rice production and processing during the 1990s. In this article we examine how various actors in the rice commodity chain adapted to the macroeconomic reforms. Following a brief history of the rice sector, we present the results of fieldwork based on interviews conducted in 2002 of farmers, millers, traders, and workers in the state extension service and nongovernmental organizations. We found that, in the absence of state supports for farmers, private millers became the focal point of regional producer-processor rice networks. The four networks identified became the sole source of domestic commercial rice when the state removed subsidies for fertilizer and modern seeds, privatized extension, and liberalized prices and imports. To increase their role in the national rice supply, the rice networks may need support through microlending and a focus on niche markets. [source]

    Soil organic carbon contents in long-term experimental grassland plots in the UK (Palace Leas and Park Grass) have not changed consistently in recent decades

    Abstract A recent report of widespread declines in soil organic C (SOC) in the UK over the 10,25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0,27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha,1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6,31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2,10%, but in the other three it had increased by 4,8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha,1, while the gains ranged from 4 to 7 t C ha,1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t -tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [source]

    Contribution of N2O to the greenhouse gas balance of first-generation biofuels

    Abstract In this study, we analyze the impact of fertilizer- and manure-induced N2O emissions due to energy crop production on the reduction of greenhouse gas (GHG) emissions when conventional transportation fuels are replaced by first-generation biofuels (also taking account of other GHG emissions during the entire life cycle). We calculate the nitrous oxide (N2O) emissions by applying a statistical model that uses spatial data on climate and soil. For the land use that is assumed to be replaced by energy crop production (the ,reference land-use system'), we explore a variety of options, the most important of which are cropland for food production, grassland, and natural vegetation. Calculations are also done in the case that emissions due to energy crop production are fully additional and thus no reference is considered. The results are combined with data on other emissions due to biofuels production that are derived from existing studies, resulting in total GHG emission reduction potentials for major biofuels compared with conventional fuels. The results show that N2O emissions can have an important impact on the overall GHG balance of biofuels, though there are large uncertainties. The most important ones are those in the statistical model and the GHG emissions not related to land use. Ethanol produced from sugar cane and sugar beet are relatively robust GHG savers: these biofuels change the GHG emissions by ,103% to ,60% (sugar cane) and ,58% to ,17% (sugar beet), compared with conventional transportation fuels and depending on the reference land-use system that is considered. The use of diesel from palm fruit also results in a relatively constant and substantial change of the GHG emissions by ,75% to ,39%. For corn and wheat ethanol, the figures are ,38% to 11% and ,107% to 53%, respectively. Rapeseed diesel changes the GHG emissions by ,81% to 72% and soybean diesel by ,111% to 44%. Optimized crop management, which involves the use of state-of-the-art agricultural technologies combined with an optimized fertilization regime and the use of nitrification inhibitors, can reduce N2O emissions substantially and change the GHG emissions by up to ,135 percent points (pp) compared with conventional management. However, the uncertainties in the statistical N2O emission model and in the data on non-land-use GHG emissions due to biofuels production are large; they can change the GHG emission reduction by between ,152 and 87 pp. [source]

    Nutrient constraints to tropical agroecosystem productivity in long-term degrading soils

    GLOBAL CHANGE BIOLOGY, Issue 12 2008
    Abstract Soil degradation is one of the most serious threats to sustainable crop production in many tropical agroecosystems where extensification rather than intensification of agriculture has occurred. In the highlands of western Kenya, we investigated soil nitrogen (N) and phosphorus (P) constraints to maize productivity across a cultivation chronosequence in which land-use history ranged from recent conversion from primary forest to 100 years in continuous cropping. Nutrient treatments included a range of N and P fertilizer rates applied separately and in combination. Maize productivity without fertilizer was used as a proxy measure for indigenous soil fertility (ISF). Soil pools of mineral nitrogen, strongly bound P and plant-available P decreased by 82%, 31% and 36%, and P adsorption capacity increased by 51% after 100 years of continuous cultivation. For the long rainy season (LR), grain yield without fertilizer declined rapidly as cultivation age increased from 0 to 25 years and then gradually declined to a yield of 1.6 Mg ha,1, which was maintained as time under cultivation increased from 60 to 100 years. LR grain yield in the old conversions was only 24% of the average young conversion grain yield (6.4 Mg ha,1). Application of either N or P alone significantly increased grain yield in both the LR and short rainy (SR) seasons, but only application of 120 kg N ha,1 on the old conversion increased yield by >1 Mg ha,1. In both SR and LR, there was a greater average yield increment response to N and P when applied together (ranging from 1 to 3.8 Mg ha,1 for the LR), with the greatest responses on the old conversions. The benefit,cost ratio (BCR) for applying 120 kg N ha,1 alone was <1 except on the old conversions, while BCRs were>1 for applying 25 kg P ha,1 alone at all levels of conversion for both seasons. Application of both N (120 kg N ha,1) and P (25 kg P ha,1) on the old conversions resulted in the greatest BCRs. This study clearly indicates that maize productivity responses to N and P fertilizer are significantly affected by the age of cultivation and its influence on ISF, but that loss of productivity can be restored rapidly when these limiting nutrients are applied. Management strategies should consider ISF and economic factors to determine optimal N and P input requirements for achieving and sustaining profitable crop production on degraded soils. [source]

    Climate- and crop-responsive emission factors significantly alter estimates of current and future nitrous oxide emissions from fertilizer use

    Helen C. Flynn
    Abstract The current Intergovernmental Panel on Climate Change (IPCC) default methodology (tier 1) for calculating nitrous oxide (N2O) emissions from nitrogen applied to agricultural soils takes no account of either crop type or climatic conditions. As a result, the methodology omits factors that are crucial in determining current emissions, and has no mechanism to assess the potential impact of future climate and land-use change. Scotland is used as a case study to illustrate the development of a new methodology, which retains the simple structure of the IPCC tier 1 methodology, but incorporates crop- and climate-dependent emission factors (EFs). It also includes a factor to account for the effect of soil compaction because of trampling by grazing animals. These factors are based on recent field studies in Scotland and elsewhere in the UK. Under current conditions, the new methodology produces significantly higher estimates of annual N2O emissions than the IPCC default methodology, almost entirely because of the increased contribution of grazed pasture. Total emissions from applied fertilizer and N deposited by grazing animals are estimated at 10 662 t N2O-N yr,1 using the newly derived EFs, as opposed to 6 796 t N2O-N yr,1 using the IPCC default EFs. On a spatial basis, emission levels are closer to those calculated using field observations and detailed soil modelling than to estimates made using the IPCC default methodology. This can be illustrated by parts of the western Ayrshire basin, which have previously been calculated to emit 8,9 kg N2O-N ha,1 yr,1 and are estimated here as 6.25,8.75 kg N2O-N ha,1 yr,1, while the IPCC default methodology gives a maximum emission level of only 3.75 kg N2O-N ha,1 yr,1 for the whole area. The new methodology is also applied in conjunction with scenarios for future climate- and land-use patterns, to assess how these emissions may change in the future. The results suggest that by 2080, Scottish N2O emissions may increase by up to 14%, depending on the climate scenario, if fertilizer and land management practices remain unchanged. Reductions in agricultural land use, however, have the potential to mitigate these increases and, depending on the replacement land use, may even reduce emissions to below current levels. [source]

    Ten years of free-air CO2 enrichment altered the mobilization of N from soil in Lolium perenne L. swards

    Manuel K. Schneider
    Abstract Effects of free-air carbon dioxide enrichment (FACE, 60 Pa pCO2) on plant growth as compared with ambient pCO2 (36 Pa) were studied in swards of Lolium perenne L. (perennial ryegrass) at two levels of N fertilization (14 and 56 g m,2 a,1) from 1993 to 2002. The objectives were to determine how plant growth responded to the availability of C and N in the long term and how the supply of N to the plant from the two sources of N in the soil, soil organic matter (SOM) and mineral fertilizer, varied over time. In three field experiments, 15N-labelled fertilizer was used to distinguish the sources of available N. In 1993, harvestable biomass under elevated pCO2 was 7% higher than under ambient pCO2. This relative pCO2 response increased to 32% in 2002 at high N, but remained low at low N. Between 1993 and 2002, the proportions and amounts of N in harvestable biomass derived from SOM (excluding remobilized fertilizer) were, at high N, increasingly higher at elevated pCO2 than at ambient pCO2. Two factorial experiments confirmed that at high N, but not at low N, a higher proportion of N in harvestable biomass was derived from soil (including remobilized fertilizer) following 7 and 9 years of elevated pCO2, when compared with ambient pCO2. It is suggested that N availability in the soil initially limited the pCO2 response of harvestable biomass. At high N, the limitation of plant growth decreased over time as a result of the stimulated mobilization of N from soil, especially from SOM. Consequently, harvestable biomass increasingly responded to elevated pCO2. The underlying mechanisms which contributed to the increased mobilization of N from SOM under elevated pCO2 are discussed. This study demonstrated that there are feedback mechanisms in the soil which are only revealed during long-term field experiments. Such investigations are thus, a prerequisite for understanding the responses of ecosystems to elevated pCO2 and N supply. [source]

    Nitrate leaching from cut grassland as affected by the substitution of slurry with nitrogen mineral fertilizer on two soil types

    GRASS & FORAGE SCIENCE, Issue 1 2010
    J. J. Schröder
    Abstract A field experiment was conducted to find out whether there is any difference in risk of N leaching to groundwater when cattle slurry and/or mineral fertilizer-N was applied to cut grassland. The experiment was carried out over two consecutive years on two sites (one with a relatively wet sandy soil and one with a relatively dry sandy soil). Treatments were mineral fertilizer-N at annual rates of 0,510 kg N ha,1 year,1 and combinations of sod-injected cattle slurry (85, 170, 250 and 335 kg N ha,1 year,1) and mineral fertilizer-N (289, 238, 190 and 139 kg N ha,1 year,1). Yield responses indicated that in the short run, 0·44,0·88 (average 0·60) of the slurry-N was as available as mineral fertilizer-N. The total N input from mineral fertilizer and slurry was a worse predictor of nitrate leaching ( 0·11) than the N surplus (i.e. the difference between total N input and harvested N) ( 0·60). The effective N surplus, based on the difference between the summed inputs of the plant-available N and harvested N, proved to be the best indicator of leaching ( 0·86). Annual N application rates of up to 340 kg plant-available N ha,1 complied with the target nitrate concentration in groundwater of 11·3 mg N L,1 set by the European Union in both years on the wet sandy soil, whereas on the dry sandy soil none of the treatments did. [source]