Nitrogen leaching: a crop rotation perspective on the effect of N surplus, field management and use of catch crops

Components of the field nitrogen (N) balance (input and surplus) are often used to predict nitrate leaching from agricultural lands. However, management factors, such as use of catch crops, greatly affect the actual loss and are a key to reduce N leaching. The present study is based on the 4th cycle of a long-term crop rotation experiment in Denmark, and it aims to quantify, from a crop rotation perspective, the influence on N leaching from N input and surplus or management factors. The experiment included three cropping systems (two organic and one conventional) with or without use of animal manure and catch crops. N leaching was calculated from measurements of nitrate in soil water sampled with ceramic suction cups installed at 1 m depth in all plots. At the rotation level, over a four years period, N leaching was positively related to N input and surplus. However, the overall effect of N input and surplus on N leaching was lower than the effect of use of catch crops. The response rates of N leaching to increasing N inputs and N surplus were about 0.08 and 0.19-0.25, respectively. Catch crops reduced N leaching by 23 kg N ha-1, irrespective of conventional and organic management system, with legume-based catch crops being as effective as non-legumes. Animal manure increased N leaching in one of the organic systems. The organic system with two years of green manure per rotation cycle was the one at highest risk of N leaching, especially from crops following green manure incorporation. Spring wheat and potatoes were the two crops with highest N leaching, and a stable low level of N leaching was only achieved above a crop-specific threshold in catch crop biomass

Row spacing and catch crop establishment in organic arable systems: a way to increase biological N fixation

Increasing the row space of spring wheat from 12 to 24 cm, but maintaining the same seeding density, didn´t decrease its yield. On the other hand, it positively influenced the growth of the undersown catch crop, a mixture of red clover, white clover, rye grass and chicory

Anaerobically digested green manure is a valuable fertilizer

Anaerobic digestion of green manure increases nitrogen (N)availability. However, the N fertilizer replacement value is affected by the initial quality of the green manure, which is related to plant species composition and cutting frequency

Nitrogen fertilizer replacement value of digestates from three green manures

Green manure mixtures including legumes and forbs can help to increase N availability in organic arable systems. Anaerobic digestion of green manures may provide ammonium rich digestate, which can be redistributed as fertilizer. The aim of this study was to investigate the effect of plant species composition, cutting strategy and anaerobic digestion on the N fertilizer replacement value (NFRV) of different green manures. Digestates obtained from silages of pure stand lucerne (four cuts/year) and a mixture including lucerne, grass and forbs (two or four cuts/year) were used to fertilize winter wheat (surface banding) and spring barley (injection). In general, NFRV was 46–173% higher in spring barley than winter wheat, due to the different application method and timing, which reflect the common practices in Denmark. NFRV of digestates were 25–63% higher than the corresponding silages, with the largest increase with the most fibrous material (mixture at two cuts/year). Total N concentration (DM based) in the silages largely explained NFRV of the digestates. To obtain NFRV above 60%, total N concentration of silage should exceed 3.5 g 100 g-1 DM, achievable with silages from four-cut strategies. Silages of plant materials with different composition and N content may be similar in terms of biomethane production, but the fertilizer value of the digestates varies considerably depending on total N concentration

Eftervirkning af kvælstof i N-fikserende efterafgrøder, nitratudvaskning og kulstofbinding

Nyeste viden om faktorer, der har betydning for størrelsen af eftervirkning, samt faktorer, der kan påvirke nitratudvaskningen og kulstofbinding

The effect of bilateral internal thoracic artery harvesting on superficial and deep sternal infection: The role of skeletonization

Objective: To determine the relative risk of sternal dehiscence in patients undergoing bilateral internal thoracic artery harvesting and to assess whether and to what extent the technique of artery skeletonization might reduce this risk. Methods: Prospectively collected data on patients undergoing coronary artery bypass operations with at least a single internal thoracic artery were reviewed. The last 450 patients receiving bilateral internal thoracic artery grafts were compared with 450 patients who received a single internal thoracic artery during the same period. The left internal thoracic artery was always harvested in a pedicled fashion. Among patients receiving a bilateral internal thoracic artery, both arteries were harvested in a pedicled fashion in 300 cases, whereas both internal thoracic arteries were skeletonized in the remaining 150 cases. Results: Compared with a single internal thoracic artery, harvesting both internal thoracic arteries either in a skeletonized or in a pedicled fashion increased the chance of deep (1.1% vs 3.3% vs 4.7%; P =. 01) or superficial (4.8% vs 7.8% vs 12%; P =. 002) sternal infection. However, the technique of artery harvesting (odds ratio, 4.1; 95% confidence interval, 1.4-12.1); the presence of peripheral arteriopathy (odds ratio, 3.1; 95% confidence interval, 1.2-8.5), and resternotomy for bleeding (odds ratio, 8.2; 95% confidence interval, 2.0-33.6) were the only independent predictors for deep sternal infection, whereas the technique of artery harvesting (odds ratio, 3.0; 95% confidence interval, 1.6-5.4), female sex (odds ratio, 2.2; 95% confidence interval, 1.2-4.2), and diabetes (odds ratio, 1.7; 95% confidence interval, 1.0-2.9) were the only independent predictors of superficial sternal infection. In diabetic patients, there was no difference in the incidence of deep sternal infection among patients receiving a single internal thoracic artery or double skeletonized internal thoracic arteries (P =. 4). Conclusions: Bilateral internal thoracic artery harvesting carries a higher risk of sternal infection than harvesting a single internal thoracic artery. Skeletonization of both internal thoracic arteries significantly decreases this risk. A strategy of bilateral thoracic artery grafting can also be offered to patients at high risk for wound infection. Copyright © 2005 by The American Association for Thoracic Surgery

x509-free access to WLCG resources

Access to WLCG resources is authenticated using an x509 and PKI infrastructure. Even though HEP users have always been exposed to certificates directly, the development of modern Web Applications by the LHC experiments calls for simplified authentication processes keeping the underlying software unmodified. In this work we will show a solution with the goal of providing access to WLCG resources using the user's home organisations credentials, without the need for user-acquired x509 certificates. In particular, we focus on identity providers within eduGAIN, which interconnects research and education organisations worldwide, and enables the trustworthy exchange of identity-related information. eduGAIN has been integrated at CERN in the SSO infrastructure so that users can authenticate without the need of a CERN account. This solution achieves x509-free access to Grid resources with the help of two services: STS and an online CA. The STS (Security Token Service) allows credential translation from the SAML2 format used by Identity Federations to the VOMS-enabled x509 used by most of the Grid. The IOTA CA (Identifier-Only Trust Assurance Certification Authority) is responsible for the automatic issuing of short-lived x509 certificates. The IOTA CA deployed at CERN has been accepted by EUGridPMA as the CERN LCG IOTA CA, included in the IGTF trust anchor distribution and installed by the sites in WLCG. We will also describe the first pilot projects which are integrating the solution.Peer reviewe

Flerårigt sædskifte med tætning som alternativ til pligtige efterafgrøder

Dette er en rapport om anvendelsen af N-fikserende efterafgrøder som pligtige efterafgrøder, skrevet på foranledning af en bestilling fra Landbrugsstyrelsen. Det vurderes, at der gennemsnitligt set ikke er risiko for øget kvælstofudvaskning (på kort og længere sigt) ved anvendelse kvælstoffikserende efterafgrøder i artsblanding med ikke-fikserende arter i forhold til anvendelse af ikke-fikserende efterafgrøder. Dette er under forudsætning af, at der indregnes en gødningsmæssig eftervirkning på ca. 50 kg N/ha både på bedrifter under og over 80 kg N/ha i husdyrgødning