Overwintering and regrowth of Sonchus arvensis roots in Finland as affected by fragmentation and burial in three different soil types

In this study the effect of root fragmentation, burial depth and soil type on overwintering and regrowth of Sonchus arvensis L. (perennial sow-thistle) was studied

Response of Sonchus arvensis to mechanical and cultural weed control

In order to study the biology and physical control of Sonchus arvensis, a 3-year field experiment was established in 2001 at Vihti, southern Finland

Simultaneous Triggered Collapse of the Presolar Dense Cloud Core and Injection of Short-Lived Radioisotopes by a Supernova Shock Wave

Cosmochemical evidence for the existence of short-lived radioisotopes (SLRI) such as $^{26}$Al and $^{60}$Fe at the time of the formation of primitive meteorites requires that these isotopes were synthesized in a massive star and then incorporated into chondrites within $\sim 10^6$ yr. A supernova shock wave has long been hypothesized to have transported the SLRI to the presolar dense cloud core, triggered cloud collapse, and injected the isotopes. Previous numerical calculations have shown that this scenario is plausible when the shock wave and dense cloud core are assumed to be isothermal at $\sim 10$ K, but not when compressional heating to $\sim 1000$ K is assumed. We show here for the first time that when calculated with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code, a 20 km/sec shock wave can indeed trigger the collapse of a 1 $M_\odot$ cloud while simultaneously injecting shock wave isotopes into the collapsing cloud, provided that cooling by molecular species such as H$_2$O, CO$_2$, and H$_2$ is included. These calculations imply that the supernova trigger hypothesis is the most likely mechanism for delivering the SLRI present during the formation of the solar system.Comment: 12 pages, 4 color figures. Astrophysical Journal Letters (in press

Sonchus arvensis - a challenge for organic farming

Perennial sow-thistle (Sonchus arvensis L.) represents an increasing problem in Finland. Options for mechanical and cultural control of S. arvensis were studied in a 3 year field experiment on clay soil under organic production

Towards more ecoefficient food production: MFA approach

The key for the sustainable development is dematerialisation and ecoefficiency. Applied to agriculture ecoefficiency means production of nutritionally better food by using less inputs and by reducing the environmental burden. In restricting the material throughput it is essential to identify the most voluminous material flows and to direct the measures to them. Improving ecoefficiency of the food production requires that the benefits and the inputs are quantified in an unambiguous way and that the inputs are estimated for the whole production chain. A comprehensive view of the whole system is necessary. The food system comprises four mutually linked loops: 1) the plant production 2) the livestock husbandry, 3) the food processing industry and 4) the human consumption. In the present paper MFA approach has been used to describe the system. A general framework for estimating and balancing the materials flow is outlined. The focus is on agriculture, specifically on the materials flow created by the biological metabolism of the animal husbandry. The holistic MFA approach provides means to evaluate environmental and economic consequences of the production. For the decision-makers the MFA approach is a tool to guide the development and to assess the progress towards increasing ecoefficiency within the food system. The results can be used in developing new sustainability indicators. Some of the possibilities are shortly discussed. The study is the first step in developing MFA methods to analyse and to monitor the materials flow of the Finnish food systems. It is a part of the project “The Materials Flow and Ecoefficiency of Agriculture and the Sustainable Compatibility of the Food Production” carried out in collaboration between the MTT - Agrifood Research Finland and the Thule Institute at the University of Oulu. The results are used also in compiling the Finnish physical input-output tables. The study, thus, contributes to the overall development of the materials flow accounting statistics

Towards more ecoefficient food production: MFA approach

The food flux comprises four mutually linked loops: 1)plant production, 2)livestock husbandry, 3) food processing industry and 4) human consumption. In the present paper MFA approach has been used to describe the system. A general framework and practical solutions for estimating and balancing the materials flow are outlined. The focus in this paper is agriculture

Guidelines for physical weed control research: flame weeding, weed harrowing and intra-row cultivation

A prerequisite for good research is the use of appropriate methodology. In order to aggregate sound research methodology, this paper presents some tentative guidelines for physical weed control research in general, and flame weeding, weed harrowing and intra-row cultivation in particular. Issues include the adjustment and use of mechanical weeders and other equipment, the recording of impact factors that affect weeding performance, methods to assess effectiveness, the layout of treatment plots, and the conceptual models underlying the experimental designs (e.g. factorial comparison, dose response). First of all, the research aims need to be clearly defined, an appropriate experimental design produced and statistical methods chosen accordingly. Suggestions on how to do this are given. For assessments, quantitative measures would be ideal, but as they require more resources, visual classification may in some cases be more feasible. The timing of assessment affects the results and their interpretation. When describing the weeds and crops, one should list the crops and the most abundantly present weed species involved, giving their density and growth stages at the time of treatment. The location of the experimental field, soil type, soil moisture and amount of fertilization should be given, as well as weather conditions at the time of treatment. The researcher should describe the weed control equipment and adjustments accurately, preferably according to the prevailing practice within the discipline. Things to record are e.g. gas pressure, burner properties, burner cover dimensions and LPG consumption in flame weeding; speed, angle of tines, number of passes and direction in weed harrowing. The authors hope this paper will increase comparability among experiments, help less experienced scientists to prevent mistakes and essential omissions, and foster the advance of knowledge on non-chemical weed management

Terminating ley with mid-summer bare fallow controls Elymus repens

The results of this study suggest that mid-summer bare fallow is a relative effective way to reduce the amount of Elymus repens when terminating ley. Early started stubble cultivation is also less sensitive to moist weather, leaving more time for exhausting the rhizome reserves of E. repens. Stubble cultivation and catch crop do increase the costs but not as much as bare fallowing for the whole summer would do. Additionally, mid summer bare fallow allows harvesting one forage yield prior to bare fallowing

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-Lived Radioisotopes with a Shock Wave. I. Varied Shock Speeds

The discovery of decay products of a short-lived radioisotope (SLRI) in the Allende meteorite led to the hypothesis that a supernova shock wave transported freshly synthesized SLRI to the presolar dense cloud core, triggered its self-gravitational collapse, and injected the SLRI into the core. Previous multidimensional numerical calculations of the shock-cloud collision process showed that this hypothesis is plausible when the shock wave and dense cloud core are assumed to remain isothermal at ~10 K, but not when compressional heating to ~1000 K is assumed. Our two-dimensional models (Boss et al. 2008) with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code have shown that a 20 km/sec shock front can simultaneously trigger collapse of a 1 solar mass core and inject shock wave material, provided that cooling by molecular species such as H2O, CO, and H2 is included. Here we present the results for similar calculations with shock speeds ranging from 1 km/sec to 100 km/sec. We find that shock speeds in the range from 5 km/sec to 70 km/sec are able to trigger the collapse of a 2.2 solar mass cloud while simultaneously injecting shock wave material: lower speed shocks do not achieve injection, while higher speed shocks do not trigger sustained collapse. The calculations continue to support the shock-wave trigger hypothesis for the formation of the solar system, though the injection efficiencies in the present models are lower than desired.Comment: 39 pages, 14 figures. in press, Ap