Home About us Contact
|
Home About us Contact | ||
|
|
||
Tillage
Kinds of Tillage Terms modified by Tillage Selected AbstractsTillage affects the activity-density, absolute density, and feeding damage of the pea leaf weevil in spring peaENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2010Timothy D. Hatten Abstract Conversion from conventional-tillage (CT) to no-tillage (NT) agriculture can affect pests and beneficial organisms in various ways. NT has been shown to reduce the relative abundance and feeding damage of pea leaf weevil (PLW), Sitona lineatus L. (Coleoptera: Curculionidae) in spring pea, especially during the early-season colonization period in the Palouse region of northwest Idaho. Pitfall traps were used to quantify tillage effects on activity-density of PLW in field experiments conducted during 2001 and 2002. As capture rate of pitfall traps for PLW might be influenced by effects of tillage treatment, two mark-recapture studies were employed to compare trapping rates in NT and CT spring pea during 2003. Also in 2003, direct sampling was used to estimate PLW densities during the colonization period, and to assess PLW feeding damage on pea. PLW activity-density was significantly lower in NT relative to CT during the early colonization period (May) of 2001 and 2002, and during the late colonization period (June) of 2002. Activity-density was not different between treatments during the early emergence (July) or late emergence (August) periods in either year of the study. Trap capture rates did not differ between tillage systems in the mark-recapture studies, suggesting that pitfall trapping provided unbiased estimates of PLW relative abundances. PLW absolute densities and feeding damage were significantly lower in NT than in CT. These results indicate that NT provides a pest suppression benefit in spring pea. [source] Impact of Soil Tillage and Crop Rotation on Barley (Hordeum vulgare) and Weeds in a Semi-arid EnvironmentJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2004H. Z. Ghosheh Abstract Experiments were conducted to evaluate the effect of mouldboard- or chisel-ploughing and rotations on barley crops and associated weeds in a semi-arid location. Two primary soil tillage operations and eight crop rotation-tillage operation combinations were evaluated over two successive seasons. Drought conditions prevailed (<152 mm annual precipitation) and affected the measured parameters. Barley grown in mouldboard-ploughed plots had higher biomass compared with chisel-ploughed plots. Barley grain yield was greater in mouldboard-ploughed plots in a fallow-fallow-barley rotation. Weed species densities varied between tillage systems and rotations. Density of Hordeum marinum, for example, was high in fallow-barley-fallow in chisel-ploughed plots, and was high under more continuous fallow in mouldboard-ploughed plots. Similar variations were also observed in weed fresh weights and in numbers of seed produced. The results describe the productivity of barley under extremely dry conditions, where an advantage for mouldboard ploughing was observed. The results also indicate the complexity of weed communities in their response towards different tillage-rotation combinations. [source] Stabilization mechanisms of organic matter in four temperate soils: Development and application of a conceptual model,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2008Margit von Lützow Abstract Based on recent findings in the literature, we developed a process-oriented conceptual model that integrates all three process groups of organic matter (OM) stabilization in soils namely (1) selective preservation of recalcitrant compounds, (2) spatial inaccessibility to decomposer organisms, and (3) interactions of OM with minerals and metal ions. The model concept relates the diverse stabilization mechanisms to active, intermediate, and passive pools. The formation of the passive pool is regarded as hierarchical structured co-action of various processes that are active under specific pedogenetic conditions. To evaluate the model, we used data of pool sizes and turnover times of soil OM fractions from horizons of two acid forest and two agricultural soils. Selective preservation of recalcitrant compounds is relevant in the active pool and particularly in soil horizons with high C contents. Biogenic aggregation preserves OM in the intermediate pool and is limited to topsoil horizons. Spatial inaccessibility due to the occlusion of OM in clay microstructures and due to the formation of hydrophobic surfaces stabilizes OM in the passive pool. If present, charcoal contributes to the passive pool mainly in topsoil horizons. The importance of organo-mineral interactions for OM stabilization in the passive pool is well-known and increases with soil depth. Hydrophobicity is particularly relevant in acid soils and in soils with considerable inputs of charcoal. We conclude that the stabilization potentials of soils are site- and horizon-specific. Furthermore, management affects key stabilization mechanisms. Tillage increases the importance of organo-mineral interactions for OM stabilization, and in Ap horizons with high microbial activity and C turnover, organo-mineral interactions can contribute to OM stabilization in the intermediate pool. The application of our model showed that we need a better understanding of processes causing spatial inaccessibility of OM to decomposers in the passive pool. [source] Weed species shifts in glyphosate-resistant cropsPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 4 2008Micheal DK Owen Abstract The adoption of glyphosate-based crop production systems has been one of the most important revolutions in the history of agriculture. Changes in weed communities owing to species that do not respond to current glyphosate-based management tactics are rapidly increasing. Clearly, glyphosate-resistant crops (GRCs) do not influence weeds any more than non-transgenic crops. For most crops, the trait itself is essentially benign in the environment. Rather, the weed control tactics imposed by growers create the ecological selection pressure that ultimately changes the weed communities. This is seen in the adoption of conservation tillage and weed management programs that focus on one herbicide mode of action and have hastened several important weed population shifts. Tillage (disturbance) is one of the primary factors that affect changes in weed communities. The intense selection pressure from herbicide use will result in the evolution of herbicide-resistant weed biotypes or shifts in the relative prominence of one weed species in the weed community. Changes in weed communities are inevitable and an intrinsic consequence of growing crops over time. The glyphosate-based weed management tactics used in GRCs impose the selection pressure that supports weed population shifts. Examples of weed population shifts in GRCs include common waterhemp [Amaranthus tuberculatus (Moq ex DC) JD Sauer], horseweed (Conyza canadensis L), giant ragweed (Ambrosia trifida L) and other relatively new weed problems. Growers have handled these weed population shifts with varying success depending on the crop. Copyright © 2008 Society of Chemical Industry [source] Factors That Affect the Adoption Decision of Conservation Tillage in the Prairie Region of CanadaCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2008Kelly A. Davey The adoption of conservation tillage technology since the 1970s has been one of the most remarkable changes in the production of crops on the Canadian Prairies. The decision whether to adopt conservation tillage technology or not requires the producer to go through a thorough decision-making process. In Canada, there has been little economic research on the question of what farm, regional, and environmental characteristics affect the adoption decision. Using 1991, 1996, and 2001 Census of Agriculture data together with other data sources we estimate a probit model explaining the adoption decision. We find that important variables include farm size, proximity to a research station, type of soil, and weather conditions. La pratique du semis direct depuis les années 1970 constitue l'un des changements les plus notables de la production des cultures dans les Prairies canadiennes. Avant de décider d'adopter ou non cette pratique, le producteur doit s'engager dans un processus rigoureux de prise de décisions. Au Canada, peu d'études économiques se sont penchées sur les caractéristiques agricoles, régionales et environnementales qui influencent la décision d'adopter ou non. Au moyen des données tirées du Recensement de l'agriculture de 1991, 1996 et 2001, combinées à d'autres sources de données, nous avons estimé un modèle probit pour expliquer la décision d'adopter ou non. Nous avons estimé que les variables importantes incluent la taille de l'exploitation, la proximité d'une station de recherche, le type de sol et les conditions météorologiques. [source] Evaluation of the SWEEP model during high winds on the Columbia Plateau ,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2009G. Feng Abstract A standalone version of the Wind Erosion Prediction System (WEPS) erosion submodel, the Single-event Wind Erosion Evaluation Program (SWEEP), was released in 2007. A limited number of studies exist that have evaluated SWEEP in simulating soil loss subject to different tillage systems under high winds. The objective of this study was to test SWEEP under contrasting tillage systems employed during the summer fallow phase of a winter wheat,summer fallow rotation within eastern Washington. Soil and PM10 (particulate matter ,10 µm in diameter) loss and soil and crop residue characteristics were measured in adjacent fields managed using conventional and undercutter tillage during summer fallow in 2005 and 2006. While differences in soil surface conditions resulted in measured differences in soil and PM10 loss between the tillage treatments, SWEEP failed to simulate any difference in soil or PM10 loss between conventional and undercutter tillage. In fact, the model simulated zero erosion for all high wind events observed over the two years. The reason for the lack of simulated erosion is complex owing to the number of parameters and interaction of these parameters on erosion processes. A possible reason might be overestimation of the threshold friction velocity in SWEEP since friction velocity must exceed the threshold to initiate erosion. Although many input parameters are involved in the estimation of threshold velocity, internal empirical coefficients and equations may affect the simulation. Calibration methods might be useful in adjusting the internal coefficients and empirical equations. Additionally, the lack of uncertainty analysis is an important gap in providing reliable output from this model. Published in 2009 by John Wiley & Sons, Ltd. [source] Windblown dust influenced by conventional and undercutter tillage within the Columbia Plateau, USA,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2009B. S. Sharratt Abstract Exceedance of the US Environmental Protection Agency national ambient air quality standard for PM10 (particulate matter ,10 µm in aerodynamic diameter) within the Columbia Plateau region of the Pacific Northwest US is largely caused by wind erosion of agricultural lands managed in a winter wheat,summer fallow rotation. Land management practices, therefore, are sought that will reduce erosion and PM10 emissions during the summer fallow phase of the rotation. Horizontal soil flux and PM10 concentrations above adjacent field plots (>2 ha), with plots subject to conventional or undercutter tillage during summer fallow, were measured using creep and saltation/suspension collectors and PM10 samplers installed at various heights above the soil surface. After wheat harvest in 2004 and 2005, the plots were either disked (conventional) or undercut with wide sweeps (undercutter) the following spring and then periodically rodweeded prior to sowing wheat in late summer. Soil erosion from the fallow plots was measured during six sampling periods over two years; erosion or PM10 loss was not observed during two periods due to the presence of a crust on the soil surface. For the remaining sampling periods, total surface soil loss from conventional and undercutter tillage ranged from 3 to 40 g m,2 and 1 to 27 g m,2 while PM10 loss from conventional and undercutter tillage ranged from 0·2 to 5·0 g m,2 and 0·1 to 3·3 g m,2, respectively. Undercutter tillage resulted in a 15% to 65% reduction in soil loss and 30% to 70% reduction in PM10 loss as compared with conventional tillage at our field sites. Therefore, based on our results at two sites over two years, undercutter tillage appears to be an effective management practice to reduce dust emissions from agricultural land subject to a winter wheat,summer fallow rotation within the Columbia Plateau. Copyright © 2009 John Wiley & Sons, Ltd. [source] Flow energy and channel adjustments in rills developed in loamy sand and sandy loam soilsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2009Jovan R. Stefanovic Abstract The storms usually associated with rill development in nature are seldom prolonged, so development is often interrupted by interstorm disturbances, e.g. weathering or tillage. In laboratory simulated rainfall experiments, active rill development can be prolonged, and under these conditions typically passes through a period of intense incision, channel extension and bifurcation before reaching quasi-stable conditions in which little form change occurs. This paper presents laboratory experiments with coarse textured soils under simulated rainfall which show how channel adjustment processes contribute to the evolution of quasi-stability. Newly incised rills were stabilized for detailed study of links between rill configuration and flow energy. On a loamy sand, adjustment towards equilibrium occurred due to channel widening and meandering, whereas on a sandy loam, mobile knickpoints and chutes, pulsations in flow width and flow depth and changes in stream power and sediment discharge occurred as the channel adjusted towards equilibrium. The tendency of rill systems towards quasi-stability is shown by changes in stream power values which show short-lived minima. Differences in energy dissipation in stabilized rills indicate that minimization of energy dissipation was reached locally between knickpoints and at the downstream ends of rills. In the absence of energy gradients in knickpoints and chutes, stabilized rill sections tended toward equilibrium by establishing uniform energy expenditure. The study confirmed that energy dissipation increased with flow aspect ratio. In stabilized rills, flow acceleration reduced energy dissipation on the loamy sand but not on the sandy loam. On both soils flow deceleration tended to increase energy dissipation. Understanding how rill systems evolve towards stability is essential in order to predict how interruptions between storms may affect long-term rill dynamics. This is essential if event-based physical models are to become effective in predicting sediment transport on rilled hillslopes under changing weather and climatic conditions. Copyright © 2008 John Wiley and Sons, Ltd. [source] Aeolian dust dynamics in agricultural land areas in Lower Saxony, GermanyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2001Dirk Goossens Abstract The dynamics of fine aeolian dust emitted from agricultural land was investigated over 15 months near Grönheim, Lower Saxony, Germany. The following aspects were studied: airborne dust concentration, the ratio of mineral versus organic dust, the vertical distribution of the particles in the atmosphere, horizontal and vertically integrated horizontal dust flux, vertical dust flux, dust deposition at ground level, grain-size distribution of the mineral dust component, and vertical distribution of organic matter in the dust. Standard meteorological parameters (wind speed and direction, precipitation) were measured as well. Dust activity in Grönheim is high in spring (March,May) and autumn (October,November) and low to very low during the rest of the year. There is a strong relationship between the periods of tillage and the intensity of dust activity. Also, there is high dust activity during wind erosion events. For the year 1999, dust emission due to tillage was 6·6 times higher than dust emission due to wind erosion. A dust transport of 15·8 ton km,1 a,1 was calculated for the first 10 m of the atmosphere in 1999. Total dust transport (in the entire mixing layer) was estimated between 16 and 20 ton km,1 a,1. About 25,30 per cent of this dust is mineral dust, emitted from the fields during tillage or during wind erosion events. In spring and autumn there is a strong vertical stratification in the airborne sediment, with much (coarse) dust in the lower air layers and significantly less (and finer) dust at higher altitudes. In summer and winter, when there is no local dust production, there is no stratification: equal amounts of dust are transported at all heights. The stratification in spring and autumn is exclusively caused by the mineral part of the dust. The organic particles are much better mixed in the atmosphere because of their lower density. Copyright © 2001 John Wiley & Sons, Ltd. [source] Effects of agricultural diversification on the abundance, distribution, and pest control potential of spiders: a reviewENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2000Keith Sunderland Abstract A review of the literature showed that spider abundance was increased by diversification in 63% of studies. A comparison of diversification modes showed that spider abundance in the crop was increased in 33% of studies by ,aggregated diversification' (e.g. intercropping and non-crop strips) and in 80% of studies by ,interspersed diversification' (e.g., undersowing, partial weediness, mulching and reduced tillage). It is suggested that spiders tend to remain in diversified patches and that extending the diversification throughout the whole crop (as in interspersed diversification) offers the best prospects for improving pest control. There is little evidence that spiders walk in significant numbers into fields from uncultivated field edges, but diversification at the landscape level serves to foster large multi-species regional populations of spiders which are valuable as a source of aerial immigrants into newly planted crops. There are very few manipulative field studies where the impact of spiders on pests has been measured in diversified crops compared with undiversified controls. It is encouraging, however, that in those few studies an increased spider density resulted in improved pest control. Future work needs are identified. [source] Quantifying the relationship between soil organic carbon and soil physical properties using shrinkage modellingEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2009P. Boivin Summary Changes in soil organic carbon (SOC) may strongly affect soil structure and soil physical properties, which in turn may have feedback effects on the soil microbial activity and SOC dynamics. Such interactions are still not quantitatively described and accounted for in SOC dynamics modelling. The objective of this study was to test the hypothesis that soil shrinkage curve (ShC) analysis allows the establishment of close relationships between soil physical properties and SOC. We sampled a rice-cropped vertisol, a cambisol under conventional tillage and no-tillage and a restored cambisol. Soil samples were analysed for clay and SOC content, bulk volume, hydro-structural stability and plasma and structural pore volumes changes on the full water content range using ShC analysis. Although the soils behaved differently according to their constituents and history, changes in SOC linearly affected most of the soil physical properties, with stronger effects than changes in clay content. The observed effects of increasing SOC, such as increasing hydro-structural stability, specific bulk volume and water retention, agreed well with previously reported results. However, using ShC measurement and modelling allowed the observation of all these different effects simultaneously for small changes in SOC, and in a single measurement. Moreover, the relation between SOC changes and physical properties could be quantified. ShC analysis may, therefore, be used to account for the effect of changes in SOC on soil physical properties. [source] Effect of residual vanadyl ions on the spectroscopic analysis of humic acids: a multivariate approachEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2008E. H. Novotny Summary In a study of the vanadyl (VO2+)-humic acids system, the residual vanadyl ion suppressed fluorescence and specific electron paramagnetic resonance (EPR) and NMR signals. In the case of NMR, the proton rotating frame relaxation times (T1,H) indicate that this suppression is due to an inefficient H-C cross polarization, which is a consequence of a shortening of T1,H. Principal components analysis (PCA) facilitated the isolation of the effect of the VO2+ ion and indicated that the organic free radical signal was due to at least two paramagnetic centres and that the VO2+ ion preferentially suppressed the species whose electronic density is delocalized over O atoms (greater g -factor). Additionally, the newly obtained variables (principal components , PC) indicated that, as the result of the more intense tillage a relative increase occurred in the accumulation of: (i) recalcitrant structures; (ii) lignin and long-chain alkyl structures; and (iii) organic free radicals with smaller g -factors. [source] Long-term effects of crop rotation and fertilization on soil organic matter compositionEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2007M. Kaiser Summary Long-term effects of crop rotation and fertilization are mostly observed with respect to the amount of soil organic matter (SOM) and measured in terms of soil organic carbon (SOC). In this paper, we analyze the SOM composition of samples from long-term agricultural field experiments at sandy and clayey sites that include complex crop rotations and farm-yard manure applications. The organic matter (OM) composition of the soil samples, OM(Soil), and that of sequentially extracted water, OM(W), and sodium pyrophosphate, OM(PY), soluble fractions was analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The fraction OM(PY) represented between 13 and 34% of SOC, about 10 times that of OM(W). Site specific differences in OM(Soil) composition were larger than those between crop rotations and fertilizer applications. The smaller C=O group content in FTIR spectra of OM(W) compared with OM(PY) suggests that analysis of the more stable OM(PY) fraction is preferable over OM(W) or OM(Soil) for identifying long-term effects, the OM(Soil) and OM(W) fractions and the content of CH groups being less indicative. Farm-yard manure application leads to a more similar content of C=O groups in OM(PY) between crop rotations and fertilizer plots at both sites. Short-term effects from soil tillage or potato harvesting on composition of OM require further studies. [source] Factors controlling aggregation in a minimum and a conventionally tilled undulating fieldEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2007S. De Gryze Summary Wind and water erosion induce breakdown of soil aggregates and loss of soil organic matter. Whereas most of the relations between aggregation and its driving factors have been established on a plot scale, these relations might be very different within an undulating landscape where both erosion (by wind or water) and deposition occur. The aim of this study was to investigate to what degree spatial patterns in soil variables influence spatial patterns in aggregation under different tillage intensities. We studied an agricultural field of about 3 ha in the silty region of Belgium. The site was split into a conventional tillage (CT) and a minimum tillage (MT) system. Within the field, 396 geo-referenced surface soil samples (0,5 cm) were taken and analyzed for organic matter content, quantity of aggregates and a number of other soil properties. Under CT, 28.5% of the total sample variation was explained by the occurrence of depositional areas, 20.8% by the amount of soil organic matter, and 13.8% by the presence of a clay-rich B horizon which surfaced due to progressive water and tillage erosion. Regression analysis revealed that 27% of the variation in the quantity of macroaggregates (>0.25 mm) was accounted for by these three factors. Under MT, 27.1% of the total sample variation was related to the surface cover of Tertiary sand, 22.6% to the amount of soil organic matter, and 13% to erodibility. These three factors explained 53% of the variation in the quantity of macroaggregates. In the CT system, the correlation between grass- or maize- carbon and the quantity of macroaggregates was strongly linked to erodibility, while this was not the case in the MT system. We concluded that at this site, macroaggregation is dominated by landscape-scale processes (such as water or tillage erosion) rather than determined by the commonly considered local variables (such as small variations in texture or organic matter content). [source] The historic man-made soils of the Generalife garden (La Alhambra, Granada, Spain)EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2007R. Delgado Summary We studied the soils of the Patio de la Acequia garden of the Generalife, a palatial villa forming part of La Alhambra, a World Heritage Site in Granada, Spain. This garden, which is estimated to be around 700 years old, is the oldest historical garden in the Western World. The soils are man-made cumulimollihumic-calcaric (hypereutric, anthric) Regosols. Noteworthy amongst the main pedogenic processes, in relation to the human activities of cultivation, irrigation and tillage, are horizonation, melanization (the contents of organic carbon varied between 0.59% and 8.87%, and those of P205 extracted with citric acid between 723 mg kg,1 and 7333 mg kg,1, with maximae in the Ap horizons) and structure formation. The soil fabric, studied at the ultramicroscopic level using scanning electron microscopy, is of laminar and partition-walls' type in the lower horizons, depending on the microped zones. The partition-walls' fabrics found are different to those of the possible pre-existing sedimentary fabrics. These are numerous lithological discontinuities and at least two burials, leading us to deduce that there have been two main stages of filling with materials in the formation of these soils. The first is Arabic-Medieval (13th century), when the garden was created, its surface being some 50 cm below the level of the paved area of the present patio. In the deeper parts, the materials employed in the fill are similar to the in situ soils of the zone, unaffected by the buildings. The second stage is Christian (15th century to the present day). During this period the Medieval garden was gradually buried under a layer of materials from the nearby soils and/or sediments mixed with manure until the surface was only just below the level of the paved area of the patio. In this work we discuss the difficult classification of these relatively little studied soils. In spite of their being clearly related to human activity, they are not classified as Anthrosols in the FAO system (1998) because soil materials cannot be classified as anthropopedogenic or as anthropogeomorphic. [source] Soil moisture, carbon and nitrogen dynamics following incorporation and surface application of labelled crop residues in soil columnsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2006F. Coppens Summary One way to increase the amount of carbon sequestered in agricultural land is to convert conventional tillage into no-tillage systems. This greatly affects the location of crop residues in soil. To investigate the impact of the location of residues on soil physical and biological properties and how the interactions between those properties influence the fate of carbon and nitrogen in soil, we did a laboratory experiment with repacked soil in columns. Doubly labelled 13C15N oilseed rape residues were incorporated in the 0,10 cm layer or left on the soil surface. The columns were incubated for 9 weeks at 20°C and were submitted to three cycles of drying and wetting, each of them induced by a rain simulator. The location of the residues affected the water dynamics and the distribution of C and N in the soil, which in turn influenced microbial activity and the decomposition rate of the added residues. After 9 weeks of'incubation, 18.4 ± 1.5% of the surface applied residue-C and 54.7 ± 1.3% of the incorporated residue-C was mineralized. We observed a nitrate accumulation of 10.7 mg N kg,1 with residues at the soil surface, 3.6 mg N kg,1 with incorporated residues and 6.3 mg N kg,1 without addition of fresh organic matter, which entailed net N mineralization in soil under mulch and immobilization of N with residue incorporation compared with the control soil. We concluded that application of oilseed rape residues at the soil surface increased the storage of fresh organic C in soil in the short term, compared with the incorporation treatment, but increased the risk of nitrate leaching. [source] Aggregate-occluded black carbon in soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2006S. Brodowski Summary The great stability of black carbon (BC) in soils may not be solely attributable to its refractory structure but also to poor accessibility when physically enveloped by soil particles. Our aim was to elucidate the intensity of physical entrapment of BC within soil aggregates. For this purpose, the A horizon of a forest, and of a grassland soil, and of three soils under tillage, were sampled at the experimental station Rotthalmünster, Germany. Black carbon was assessed in water-stable aggregates and aggregate-density fractions using benzene polycarboxylic acids as specific markers. The greatest BC concentrations made up 7.2% of organic carbon and were found in the < 53 ,m fraction. The smallest BC concentrations occurred in the large macroaggregate fractions (> 2 mm). This pattern has been sustained even after tillage. The C-normalized BC concentrations were significantly greater (P < 0.05) in the occluded particulate organic matter (OPOM) fractions than in the free particulate organic matter (FPOM) and the mineral fractions. This enrichment of BC compared with organic carbon in the OPOM fractions amounted to factors of 1.5,2.7. Hence, BC was embedded within microaggregates in preference to other organic carbon compounds. Only 2.5,3.5% of BC was located in the OPOM fraction < 1.6 g cm,3, but 22,24% in the OPOM fraction with a density of 1.6,2.0 g cm,3. This suggests that BC possibly acted as a binding agent or was selectively enriched during decomposition of protected SOM, or both. Physical inclusion, particularly within microaggregates, could therefore contribute to the long mean-residence times of soil-inherent BC. [source] Potential agronomic options for energy-efficient sugar beet-based bioethanol production in northern JapanGCB BIOENERGY, Issue 3 2009NOBUHISA KOGA Abstract Sugar beet (Beta vulgaris L. subsp. vulgaris) is deemed to be one of the most promising bioethanol feedstock crops in northern Japan. To establish viable sugar beet-based bioethanol production systems, energy-efficient protocols in sugar beet cultivation are being intensively sought. On this basis, the effects of alternative agronomic practices for sugar beet production on total energy inputs (from fuels and agricultural materials during cultivation and transportation) and ethanol yields (estimated from sugar yields) were assessed in terms of (i) direct drilling, (ii) reduced tillage (no moldboard plowing), (iii) no-fungicide application, (iv) using a high-yielding beet genotype, (v) delayed harvesting and (vi) root+crown harvesting. Compared with the conventional sugar beet production system used in the Tokachi region of Hokkaido, northern Japan, which makes use of transplants, direct drilling and no-fungicide application contributed to reduced energy inputs from raising seedlings and fungicides, respectively, but sugar (or ethanol) yields were also reduced by these practices, to a greater equivalent extent than the reductions in energy inputs. Consequently, direct drilling (6.84 MJ L,1) and no-fungicide application (7.78 MJ L,1) worsened the energy efficiency (total energy inputs to produce 1 L of ethanol), compared with conventional sugar beet production practices (5.82 MJ L,1). Sugar yields under conventional plow-based tillage and reduced tillage practices were similar, but total energy inputs were reduced as a result of reduced fuel consumption from not plowing. Hence, reduced tillage showed improved energy efficiency (5.36 MJ L,1). The energy efficiency was also improved by using a high-yielding genotype (5.23 MJ L,1) and root+crown harvesting (5.21 MJ L,1). For these practices, no major changes in total energy inputs were noted, but sugar yields were consistently increased. Neither total energy inputs nor ethanol yields were affected by extending the vegetative growing period by delaying harvesting. [source] Redistribution of archaeological assemblages in plowzonesGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2008Marta Navazo Archaeological surface surveys have located open-air sites on cropland in the Sierra de Atapuerca (Burgos, Spain). To what degree agricultural disturbances have impacted archaeological site integrity is poorly defined and may greatly affect interpretations of prehistoric land use. This paper presents the results of three experiments concerned with the effects of tillage on artifact distribution, focusing specifically on lateral and vertical artifact displacement. We demonstrate highly variable horizontal displacement of artifacts by plowing and overall downward movement of lithic materials within the soil. This results in an expansion of site boundaries and reduction of surface artifact density, yielding a biased and unrepresentative picture of past human activity. More experimental studies are needed to better define agricultural disturbances to surface archaeological assemblages. © 2008 Wiley Periodicals, Inc. [source] Soil greenhouse gas fluxes and global warming potential in four high-yielding maize systemsGLOBAL CHANGE BIOLOGY, Issue 9 2007M. A. A. ADVIENTO-BORBE Abstract Crop intensification is often thought to increase greenhouse gas (GHG) emissions, but studies in which crop management is optimized to exploit crop yield potential are rare. We conducted a field study in eastern Nebraska, USA to quantify GHG emissions, changes in soil organic carbon (SOC) and the net global warming potential (GWP) in four irrigated systems: continuous maize with recommended best management practices (CC-rec) or intensive management (CC-int) and maize,soybean rotation with recommended (CS-rec) or intensive management (CS-int). Grain yields of maize and soybean were generally within 80,100% of the estimated site yield potential. Large soil surface carbon dioxide (CO2) fluxes were mostly associated with rapid crop growth, high temperature and high soil water content. Within each crop rotation, soil CO2 efflux under intensive management was not consistently higher than with recommended management. Owing to differences in residue inputs, SOC increased in the two continuous maize systems, but decreased in CS-rec or remained unchanged in CS-int. N2O emission peaks were mainly associated with high temperature and high soil water content resulting from rainfall or irrigation events, but less clearly related to soil NO3 -N levels. N2O fluxes in intensively managed systems were only occasionally greater than those measured in the CC-rec and CS-rec systems. Fertilizer-induced N2O emissions ranged from 1.9% to 3.5% in 2003, from 0.8% to 1.5% in 2004 and from 0.4% to 0.5% in 2005, with no consistent differences among the four systems. All four cropping systems where net sources of GHG. However, due to increased soil C sequestration continuous maize systems had lower GWP than maize,soybean systems and intensive management did not cause a significant increase in GWP. Converting maize grain to ethanol in the two continuous maize systems resulted in a net reduction in life cycle GHG emissions of maize ethanol relative to petrol-based gasoline by 33,38%. Our study provided evidence that net GHG emissions from agricultural systems can be kept low when management is optimized toward better exploitation of the yield potential. Major components for this included (i) choosing the right combination of adopted varieties, planting date and plant population to maximize crop biomass productivity, (ii) tactical water and nitrogen (N) management decisions that contributed to high N use efficiency and avoided extreme N2O emissions, and (iii) a deep tillage and residue management approach that favored the build-up of soil organic matter from large amounts of crop residues returned. [source] Initial cultivation of a temperate-region soil immediately accelerates aggregate turnover and CO2 and N2O fluxesGLOBAL CHANGE BIOLOGY, Issue 8 2006A. STUART GRANDY Abstract The immediate effects of tillage on protected soil C and N pools and on trace gas emissions from soils at precultivation levels of native C remain largely unknown. We measured the response to cultivation of CO2 and N2O emissions and associated environmental factors in a previously uncultivated U.S. Midwest Alfisol with C concentrations that were indistinguishable from those in adjacent late successional forests on the same soil type (3.2%). Within 2 days of initial cultivation in 2002, tillage significantly (P=0.001, n=4) increased CO2 fluxes from 91 to 196 mg CO2 -C m,2 h,1 and within the first 30 days higher fluxes because of cultivation were responsible for losses of 85 g CO2 -C m,2. Additional daily C losses were sustained during a second and third year of cultivation of the same plots at rates of 1.9 and 1.0 g C m,2 day,1, respectively. Associated with the CO2 responses were increased soil temperature, substantially reduced soil aggregate size (mean weight diameter decreased 35% within 60 days), and a reduction in the proportion of intraaggregate, physically protected light fraction organic matter. Nitrous oxide fluxes in cultivated plots increased 7.7-fold in 2002, 3.1-fold in 2003, and 6.7-fold in 2004 and were associated with increased soil NO3, concentrations, which approached 15 ,g N g,1. Decreased plant N uptake immediately after tillage, plus increased mineralization rates and fivefold greater nitrifier enzyme activity, likely contributed to increased NO3, concentrations. Our results demonstrate that initial cultivation of a soil at precultivation levels of native soil C immediately destabilizes physical and microbial processes related to C and N retention in soils and accelerates trace gas fluxes. Policies designed to promote long-term C sequestration may thus need to protect soils from even occasional cultivation in order to preserve sequestered C. [source] Options for mitigating methane emission from a permanently flooded rice fieldGLOBAL CHANGE BIOLOGY, Issue 1 2003Zucong Cai Abstract Permanently flooded rice fields, widely distributed in south and south-west China, emit more CH4 than those drained in the winter crop season. For understanding CH4 emissions from permanently flooded rice fields and developing mitigation options, CH4 emission was measured year-round for 6 years from 1995 to 2000, in a permanently flooded rice field in Chongqing, China, where two cultivations with four treatments were prepared as follows: plain-cultivation, summer rice crop and winter fallow with floodwater layer annually (convention, Ch-FF), and winter upland crop under drained conditions (Ch-Wheat); ridge-cultivation without tillage, summer rice and winter fallow with floodwater layer annually (Ch-FFR), and winter upland crop under drained conditions (Ch-RW), respectively. On a 6-year average, compared to the treatments with floodwater in the winter crop season, the CH4 flux during rice-growing period from the treatments draining floodwater and planting winter crop was reduced by 42% in plain-cultivation and by 13% in ridge-cultivation (P < 0.05), respectively. The reduction of annual CH4 emission reached 68 and 48%, respectively. Compared to plain-cultivation (Ch-FF), ridge-cultivation (Ch-FFR) reduced annual CH4 emission by 33%, and which was mainly occurred in the winter crop season. These results indicate that draining floodwater layer for winter upland crop growth was not only able to prevent CH4 emission from permanently flooded paddy soils directly in the winter crop season, but also to reduce CH4 emission substantially during the following rice-growing period. As an alternative to the completely drainage of floodwater layer in the winter crop season, ridge-cultivation could also significantly mitigate CH4 emissions from permanently flooded rice fields. [source] Carbon emission and sequestration by agricultural land use: a model study for EuropeGLOBAL CHANGE BIOLOGY, Issue 6 2002L. M. Vleeshouwers Abstract A model was developed to calculate carbon fluxes from agricultural soils. The model includes the effects of crop (species, yield and rotation), climate (temperature, rainfall and evapotranspiration) and soil (carbon content and water retention capacity) on the carbon budget of agricultural land. The changes in quality of crop residues and organic material as a result of changes in CO2 concentration and changed management were not considered in this model. The model was parameterized for several arable crops and grassland. Data from agricultural, meteorological, soil, and land use databases were input to the model, and the model was used to evaluate the effects of different carbon dioxide mitigation measures on soil organic carbon in agricultural areas in Europe. Average carbon fluxes under the business as usual scenario in the 2008,2012 commitment period were estimated at 0.52 tC ha,1 y,1 in grassland and ,0.84 tC ha,1 y,1 in arable land. Conversion of arable land to grassland yielded a flux of 1.44 tC ha,1 y,1. Farm management related activities aiming at carbon sequestration ranged from 0.15 tC ha,1 y,1 for the incorporating of straw to 1.50 tC ha,1 y,1 for the application of farmyard manure. Reduced tillage yields a positive flux of 0.25 tC ha,1 y,1. The indirect effect associated with climate was an order of magnitude lower. A temperature rise of 1 °C resulted in a ,0.05 tC ha,1 y,1 change whereas the rising CO2 concentrations gave a 0.01 tC ha,1 y,1 change. Estimates are rendered on a 0.5 × 0.5° grid for the commitment period 2008,2012. The study reveals considerable regional differences in the effectiveness of carbon dioxide abatement measures, resulting from the interaction between crop, soil and climate. Besides, there are substantial differences between the spatial patterns of carbon fluxes that result from different measures. [source] Application of the WEPP model for prioritization and evaluation of best management practices in an Indian watershedHYDROLOGICAL PROCESSES, Issue 21 2009A. Pandey Abstract The pre-calibrated and validated physically based watershed model, water erosion prediction project (WEPP) was used as a modelling tool for the identification of critical watersheds and evaluation of best management practices for a small hilly watershed (Karso) of India. The land use/cover of the study area was generated using IRS-1C LISS-III (linear imaging self scanner) satellite data. The watershed and sub-watershed boundaries, drainage, slope and soil map of the study area were generated using ARC/INFO geographic information system (GIS). The WEPP model was finally applied to the Karso watershed which lies within Damodar Barakar catchment of India to identify the critical sub-watersheds on the basis of their simulated average annual sediment yields. Priorities were fixed on the basis of ranks assigned to each critical sub-watershed based on the susceptibility to erosion. The sub-watershed having the highest sediment yield was assigned a priority number 1, the next highest value was assigned a priority number 2, and so on. Subsequently, the model was used for evaluating the effectiveness of best management practices (crop and tillage) for conservation of soil for all the sub-watersheds. On the basis of this study, it is realized that cash crops like soyabean should be encouraged in the upland portion of the sub-watersheds, and the existing tillage practice (country plough/mould board plough) may be replaced by a field cultivation system for conservation of soil and water in the sub-watersheds. Copyright © 2009 John Wiley & Sons, Ltd. [source] Population dynamics and reproduction of Northern Lapwings Vanellus vanellus in a meadow restoration area in central SwedenIBIS, Issue 3 2002Åke Berg To investigate the effectiveness of a meadow restoration programme, we studied the relationships between population changes and environmental changes, return rates and hatching success in a population of Northern Lapwings Vanellus vanellus. The study was performed on mixed farmland (59 km2) in central Sweden, an area that underwent extensive meadow restoration between 1985 and 1994. The study included more than 2600 nests, supplemented with observations of 127 individually colour-ringed Northern Lapwings. The breeding population varied (2.7,5.3 pairs/km2), but showed no significant trend with time. The population increased in years with high spring flooding levels. Population size was unrelated to demographic factors (e.g. hatching success the previous year (14,50%), and return rate). Lapwings moved considerably between years and their nest site fidelity was unrelated to previous hatching success or other factors, suggesting that changes in habitat quality and migration between populations were important in regulating population size. Recent extensive meadow restoration did not seem to aid the Northern Lapwing population; birds continued nesting on tillage even though most nests were destroyed by farming activities. A relatively high relaying frequency improved hatching success, which was still lowest in the most preferred habitats (spring sown crops, total hatching success c. 30%). The few Northern Lapwings breeding in the least preferred habitats (meadows and cultivated grassland) had a better hatching success (> 70% total hatching success), suggesting that habitat selection was not determined by hatching success. From these results, recommendations are made for the management of Northern Lapwing (and associated species) populations on farmland. [source] Soil Conservation Tillage Effects on Yield and Water Use Efficiency on Irrigated Crops in Central ItalyJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2008R. Casa Abstract Despite possible agronomic and environmental benefits, the diffusion of soil conservation tillage systems in Italy is currently rather low. The aim of this study was to compare the performance of different soil tillage techniques, in an effort to identify suitable soil management options for irrigated crops in Central Italy. An experiment was carried out on maize and soybean from April to October in two consecutive years (1993 and 1994) in Maccarese (a coastal location near Rome). The systems compared were: conventional mouldboard ploughing (CT), minimum tillage, ridge tillage and no-tillage (NT). In 1993, actual crop evapotranspiration was measured throughout the growing season on NT and CT soybean, using a micrometeorological technique. No significant differences due to soil tillage were found for grain yield and yield irrigation water use efficiency (IWUEy), except for soybean in 1994, in which yields and IWUEy were 59 % higher on conservation tillage treatments compared with CT. In 1994 soybean yield water use efficiency was 10.1 and 9.5 kg ha,1 mm,1 for NT and CT respectively. The results suggest that the adoption of soil conservation tillage is feasible, for the specific cropping system, with equivalent or better performances as conventional tillage. [source] Advantages of Different Tillage Systems and Their Effects on the Economically Important Pests, Thrips tabaci Lind. and Aphis gossypii Glov. in Cotton FieldsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2004I. Gencsoylu Abstract An experiment to assess advantages of different tillage and their effects on Aphis gossypii Glov. and Thrips tabaci Lind was conducted during the 2000 and 2001 cotton growing seasons in cotton fields at Adnan Menderes University, Agricultural Faculty Research Center, located in Ayd,n Province, Turkey. The tillage systems examined were conventional, strip, precision and ridge tillage. Two insect population densities were not affected by the type of tillage systems during either year. However, significant differences in populations were observed in thrips populations on 31 May 2000 and 18 May 2001 and aphid populations on 24 May 2000 and 11 May 2001. The results show that the highest yield was observed in all conservation tillage systems in 2000 and ridge tillage system in 2001. Early maturity was higher in both precision and ridge tillage systems. In addition, tillage systems did not affect fibre properties. As a result, the application of conservation tillage is more advantageous in cotton in respect of early maturity and total yield. [source] Organic versus conventional management in an apple orchard: effects of fertilization and tree-row management on ground-dwelling predaceous arthropodsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2009M. Miñarro Abstract 1,Organic and conventional management of apple orchards may have a different effect on arthropod communities. 2,We conducted a 3-year study to assess the effect of two strategies of fertilizer treatment (organic versus chemical) and three tree-row management systems (straw mulching, tillage and herbicide) on activity-density and biodiversity of epigeic predators. Ground beetles (Carabidae), rove beetles (Staphylinidae), ants (Formicidae) and spiders (Araneae) were sampled monthly with pitfall traps in the same apple orchard during 2003, 2004 and 2005. 3,A total of 4978 individuals were collected. Carabids (56.8% of the total catches) were the most abundant taxonomic group, followed by spiders (20.7%), ants (14.8%) and rove beetles (7.7%). Tree-row management had a greater influence on predator catches than fertilizer treatment. Total predator catches were lower under the mulch. Mulching also reduced carabid abundance, but increased staphylinid catches. 4,Tree row management also had a significant effect on biodiversity parameters. Species richness did not significantly differ among treatments for ants, spiders or the total catches, but was higher on herbicide-treated plots for carabids and on mulched plots for staphylinids. Shannon,Wiener's diversity index was significantly greater in the mulched and herbicide treated plots for total predators and carabids. For staphylinids, this index was significantly greater on the mulched plots. Fertilizer application strategy only influenced the species richness of rove beetles, which was greater in the chemically-treated plots. 5,The results showed that a change from conventional to organic fertilizer treatment of apple trees may be performed without differential effects on predator activity-density or biodiversity. However, a change from herbicide treatment to mulching or mechanical weed control may be significant, depending on the taxonomic group. [source] The apparent electrical conductivity as a surrogate variable for predicting earthworm abundances in tilled soilsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2010Monika Joschko Abstract Noninvasive geophysical methods have a great potential for improving soil-biological studies at field or regional scales: they enable the rapid acquisition of soil information which may help to identify potential habitats for soil biota. A precondition for this application is the existence of close relationships between geophysical measurements and the soil organism of interest. This study was conducted to determine whether field measurements of apparent electrical conductivity (ECa) are related to abundances of earthworms in tilled soils. Relationships between ECa and earthworm populations were investigated along transects at 42 plots under reduced and conventional tillage at a 74 ha field on sandy-loam soil in NE Germany. Relations were analyzed with linear-regression and spatial analysis. The apparent electrical conductivity (ECa) was quantitatively related to earthworm abundances sampled 5 months after the geophysical measurements. No relationship was found, however, in plots under conventional tillage when analyzed separately. If earthworm abundances were known at every other location along the transects and if the state-space approach was used for analysis, the analysis of ECa measurements and earthworm abundances indicated that 50% of the earthworm samples could have been substituted by ECa measurements. Further research is needed to fully evaluate the potential of ECa measurements for predicting earthworm habitats in tilled soil. [source] Methods for evaluating human impact on soil microorganisms based on their activity, biomass, and diversity in agricultural soilsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2006Rainer Georg Joergensen Abstract The present review is focused on microbiological methods used in agricultural soils accustomed to human disturbance. Recent developments in soil biology are analyzed with the aim of highlighting gaps in knowledge, unsolved research questions, and controversial results. Activity rates (basal respiration, N mineralization) and biomass are used as overall indices for assessing microbial functions in soil and can be supplemented by biomass ratios (C : N, C : P, and C : S) and eco-physiological ratios (soil organic C : microbial-biomass C, qCO2, qNmin). The community structure can be characterized by functional groups of the soil microbial biomass such as fungi and bacteria, Gram-negative and Gram-positive bacteria, or by biotic diversity. Methodological aspects of soil microbial indices are assessed, such as sampling, pretreatment of samples, and conversion factors of data into biomass values. Microbial-biomass C (µg (g soil),1) can be estimated by multiplying total PLFA (nmol (g soil),1) by the FPLFA -factor of 5.8 and DNA (µg (g soil),1) by the FDNA -factor of 6.0. In addition, the turnover of the soil microbial biomass is appreciated as a key process for maintaining nutrient cycles in soil. Examples are briefly presented that show the direction of human impact on soil microorganisms by the methods evaluated. These examples are taken from research on organic farming, reduced tillage, de-intensification of land-use management, degradation of peatland, slurry application, salinization, heavy-metal contamination, lignite deposition, pesticide application, antibiotics, TNT, and genetically modified plants. [source] | |||||||||||||||||||