Do effects of soil compaction persist after ploughing? Results from 21 long-term field experiments in Sweden     

Johan Arvidsson  Inge Hkansson 《Soil & Tillage Research》1996,39(3-4):175-197

The extent and persistence of the effect of soil compaction in a system with annual ploughing were investigated in 21 long-term field experiments in Sweden with a total of 259 location-years. Crop yield, soil physical properties and plant establishment were determined. All experiments had two common treatments: control (no extra traffic) and compacted (350 Mg km ha⁻¹ of experimental traffic in the autumn prior to ploughing), using a tractor and trailer with traditional wheel equipment and an axle load restricted to 4 Mg. During the rest of the year, both treatments were conventionally and equally tilled. The compaction was repeated each autumn for at least 7 years, and the yield was determined each year until 5 years after the termination of the compaction treatment.

Compaction decreased the porosity and the proportion of large pores and increased the tensile strength of dry aggregates. On clay and loam soils, it decreased the proportion of fine aggregates in the seedbed and the gravimetric soil water content in the seedbed.

The yield in the compacted treatment declined compared with the control during the first 4 years, after which it reached steady state. During this steady state, the compaction treatment caused a yield loss of 11.4%, averaged over 107 location-years. Within 4–5 years after the termination of the compaction treatment, the yield returned to the control level. The average yield loss at individual sites increased with increasing clay content.

Results from additional treatments indicated that yield loss was linearly correlated with the amount of traffic up to 300–400 Mg km ha⁻¹. With greater ground contact pressure or a greater soil water content at time of traffic, there was a greater yield loss.

Soil compaction effects on yield were similar for all spring-sown crops, and the percentage yield loss seemed to be independent of the yield. In a few location-years with winter wheat there was on average no yield decrease.

There were 5.1% less plants in the compacted treatment than in the control. The yield decrease was significantly correlated with the number of plants.

Between years results were highly variable, and no consistent correlations between yield loss and soil water content at the time of traffic or the weather conditions during the growing period were found. Soil compaction affected yield during years with good as well as poor conditions for crop growth.  相似文献   

Effects of autumn tillage and residue management on soil respiration in a long‐term field experiment in Sweden          下载免费PDF全文

Veera Kainiemi  Johan Arvidsson  Thomas Kätterer 《植物养料与土壤学杂志》2015,178(2):189-198

Several previous field studies in temperate regions have shown decreased soil respiration after conventional tillage compared with reduced or no‐tillage treatments. Whether this decrease is due to differences in plant residue distribution or changes in soil structure following tillage remains an open question. This study investigated (1) the effects of residue management and incorporation depth on soil respiration and (2) biological activity in different post‐tillage aggregates representing the actual size and distribution of aggregates observed in the tilled layer. The study was conducted within a long‐term tillage experiment on a clay soil (Eutric Cambisol) in Uppsala, Sweden. After 38 y, four replicate plots in two long‐term treatments (moldboard plowing (MP) and shallow tillage (ST)) were split into three subplots. These were then used for a short‐term trial in which crop residues were either removed, left on the surface or incorporated to about 6 cm depth (ST) or at 20 cm depth (MP). Soil respiration, soil temperature, and water content were monitored during a 10‐d period after tillage treatment. Respiration from aggregates of different sizes produced by ST and MP was also measured at constant water potential and temperature in the laboratory. The results showed that MP decreased short‐term soil respiration compared with ST or no tillage. Small aggregates (< 16 mm) were biologically most active, irrespective of tillage method, but due to their low proportion of total soil mass they contributed < 1.5% to total respiration from the tilled layer. Differences in respiration between tillage treatments were found to be attributable to indirect effects on soil moisture and temperature profiles and the depth distribution of crop residues, rather than to physical disturbance of the soil.  相似文献   

Rapid detection of Aujeszky's disease (pseudorabies) virus infection of pigs by direct filter hybridisation of nasal and tonsillar specimens   总被引：1，自引：0，他引：1  

S Belák  T Linné 《Research in veterinary science》1988,44(3):303-308

A direct filter hybridisation method has been developed to diagnose acute Aujeszky's disease in live pigs. The advantages of the method are easy, fast sample processing; no DNA-purification is needed, and the hybridisation itself is simplified. The direct filter hybridisation method has been tested on pseudorabies virus infected cultured cells, experimentally infected pigs and on specimens from an outbreak of Aujeszky's disease. Virus isolation and filter hybridisation gave comparable results, indicating that the direct filter hybridisation method is a good tool for rapid diagnosis. It is independent of cell culture facilities and the disease can be diagnosed in live animals within 15 hours.  相似文献   

Forage quality analyses and interpretation.     

J G Linn  N P Martin 《Veterinary Clinics of North America: Food Animal Practice》1991,7(2):509-523

The minimum analyses needed to determine the quality or nutritive composition of forages are DM, CP, ADF, NDF, Ca, and P. The accuracy of these and other analyses are affected by the sampling and analysis methods. Improper sampling is probably one of the largest but most overlooked sources of variation in analysis. Analysis methods must be both accurate and precise. New techniques like NIRS can be just as accurate and have better precision than conventional chemistry methods if correctly calibrated. Finally, understanding variations associated with the analysis and discerning sources of the variation as to errors in analysis, sampling, or natural variation caused by environmental growing conditions, plant species, or harvest practices is the biggest challenge for nutritionists. Forages cannot be fully and efficiently utilized in the diets of dairy cattle until their composition is accurately determined and interpreted for animal performance.  相似文献   

Potential involvement of mammalian and avian uncoupling proteins in the thermogenic effect of thyroid hormones   总被引：5，自引：0，他引：5  

Collin A  Cassy S  Buyse J  Decuypere E  Damon M 《Domestic animal endocrinology》2005,29(1):78-87

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A Field Outbreak Caused by Bovine Respiratory Syncytial Virus     

Qivind A. Qdegaard  Johan Krogsrud 《Acta veterinaria Scandinavica》1977,18(3):429

Bovine respiratory syncytial virus (BRSV) caused a large epizootic of acute respiratory disease in Japan in 1968—69 (Inaba et al. 1970, Inaba et al. 1972). A much smaller outbreak occurred in Switzerland (Paccaud & Jacquier 1970). In Belgium the virus has been isolated from an outbreak of respiratory disease (Wellemans et al. 1970). BRSV has later been proved an important causal agent of respiratory disorders in the same country (Wellemans & Leiinen 1975). In England and USA the virus has caused and been isolated from outbreaks of acute respiratory disease in calves (Jacobs & Edington 1971, Rosenquist 1974, Smith et al. 1974). In Denmark BRSV has sporadically been isolated from pneumonic calf lungs (Bitsch et al. 1976).  相似文献   

Prolonged elevated atmospheric CO₂ does not affect decomposition of plant material     

Marie-Anne de Graaff  Johan Six  Chris van Kessel 《Soil biology & biochemistry》2006,38(1):187-190

Prolonged elevated atmospheric CO₂ might alter decomposition. In a 90-day incubation study, we determined the long-term (9 years) impact of elevated CO₂ on N mineralization of Lolium perenne and Trifolium repens plant material grown at ambient and elevated CO₂ and low- and high-¹⁵N fertilizer additions. No significant differences were observed in recovery rates between any of the treatments, except an N addition effect was observed for L. perenne (0.4 versus 0.5% day⁻¹ in high versus low N). The results suggest that elevated CO₂ did not change plant N mineralization in any of the soils, because of a surplus of available N in the fertilized and leguminous systems, and because of insignificant plant responses to elevated CO₂ in the low soil N availability systems.  相似文献   

A multilevel study of socio-economic inequalities in food choice behaviour and dietary intake among the Dutch population: the GLOBE study     

Giskes K  Turrell G  van Lenthe FJ  Brug J  Mackenbach JP 《Public health nutrition》2006,9(1):75-83

OBJECTIVE: To examine the influence of individual- and area-level socio-economic characteristics on food choice behaviour and dietary intake. SETTING: The city of Eindhoven in the south-east Netherlands. DESIGN: A total of 1339 men and women aged 25-79 years were sampled from 85 areas (mean number of participants per area = 18.4, range 2-49). Information on socio-economic position (SEP) and diet was collected by structured face-to-face interviews (response rate 80.9%). Individual-level SEP was measured by education and household income, and area-level deprivation was measured using a composite index that included residents' education, occupation and employment status. Diet was measured on the basis of (1) a grocery food index that captured compliance with dietary guidelines, (2) breakfast consumption and (3) intakes of fruit, total fat and saturated fat. Multilevel analyses were performed to examine the independent effects of individual- and area-level socio-economic characteristics on the dietary outcome variables. RESULTS: After adjusting for individual-level SEP, few trends or significant effects of area deprivation were found for the dietary outcomes. Significant associations were found between individual-level SEP and food choice, breakfast consumption and fruit intake, with participants from disadvantaged backgrounds being less likely to report food behaviours or nutrient intakes consistent with dietary recommendations. CONCLUSIONS: The findings suggest that an individual's socio-economic characteristics play a more important role in shaping diet than the socio-economic characteristics of the area in which they live. In this Dutch study, no independent influence of area-level socio-economic characteristics on diet was detected, which contrasts with findings from the USA, the UK and Finland.  相似文献   

Early reactivation of European rivers during the last deglaciation   总被引：1，自引：0，他引：1  

Ménot G  Bard E  Rostek F  Weijers JW  Hopmans EC  Schouten S  Sinninghe Damsté JS 《Science (New York, N.Y.)》2006,313(5793):1623-1625

During the Last Glacial Maximum, the sea-level lowstand combined with the large extent of the Fennoscandian and British ice sheets led to the funneling of European continental runoff, resulting in the largest river system that ever drained the European continent. Here, we show an abrupt and early reactivation of the European hydrological cycle at the onset of the last deglaciation, leading to intense discharge of the Channel River into the Bay of Biscay. This freshwater influx, probably combined with inputs from proglacial or ice-dammed lakes, dramatically affected the hydrology of the region, both on land and in the ocean.  相似文献   

Understanding growers' decisions to manage invasive pathogens at the farm level     

Breukers A  van Asseldonk M  Bremmer J  Beekman V 《Phytopathology》2012,102(6):609-619

Globalization causes plant production systems to be increasingly threatened by invasive pests and pathogens. Much research is devoted to support management of these risks. Yet, the role of growers' perceptions and behavior in risk management has remained insufficiently analyzed. This article aims to fill this gap by addressing risk management of invasive pathogens from a sociopsychological perspective. An analytical framework based on the Theory of Planned Behavior was used to explain growers' decisions on voluntary risk management measures. Survey information from 303 Dutch horticultural growers was statistically analyzed, including regression and cluster analysis. It appeared that growers were generally willing to apply risk management measures, and that poor risk management was mainly due to perceived barriers, such as high costs and doubts regarding efficacy of management measures. The management measures applied varied considerably among growers, depending on production sector and farm-specific circumstances. Growers' risk perception was found to play a role in their risk management, although the causal relation remained unclear. These results underscore the need to apply a holistic perspective to farm level management of invasive pathogen risk, considering the entire package of management measures and accounting for sector- and farm-specific circumstances. Moreover, they demonstrate that invasive pathogen risk management can benefit from a multidisciplinary approach that incorporates growers' perceptions and behavior.  相似文献