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Katroschan K.-U.,State Institute for Agriculture and Fisheries Mecklenburg West Pomerania | Katroschan K.-U.,Leibniz University of Hanover | Uptmoor R.,Leibniz University of Hanover | Uptmoor R.,University of Rostock | Stutzel H.,Leibniz University of Hanover
Plant and Soil | Year: 2014

Background and aims: The low N availability in organic cropping systems requires an efficient use of the limited N sources. The study aimed to analyze the N efficiency of organically fertilized white cabbage on a crop and crop rotation basis. Methods: Effects of soil-incorporated lupine seedlings and seed meal on the N use efficiency (NUE) and individual NUE components of cabbage were investigated in field experiments. Cabbage was followed by beetroot to quantify residual fertilizer effects. Results: Generally, NUE decreased with increasing N availability. Nitrogen uptake efficiency, however, was low at low N supply and increased curvilinearly to an asymptotic maximum. Variation in harvest index between and within experimental years was explained by differences in thermal growing time and initial cabbage growth, respectively. The increase in beetroot N supply by fertilizer treatments averaged 18 % of applied lupine seed N corresponding to 63 % of the incremental N in cabbage residues. Conclusions: Dry matter partitioning alters during cabbage yield formation in favor of the harvest residue fraction if abiotic stress like water shortage occurs directly after crop establishment, being associated with reduced NUE. The residual effect depends largely on the re-utilization of incremental fertilizer N in cabbage residues and thus on the short-term net N mineralization of organic fertilizers. © 2014 Springer International Publishing Switzerland.

Katroschan K.-U.,State Institute for Agriculture and Fisheries Mecklenburg West Pomerania | Katroschan K.-U.,Leibniz University of Hanover | Teixeira G.,Leibniz University of Hanover | Kahlen K.,Leibniz University of Hanover | And 2 more authors.
Plant and Soil | Year: 2012

Background and aims: Nitrogen mineralization of lupine seeds and seedlings to be used as flexible leguminous N source in organic vegetable production was investigated. It was hypothesized that changes in seed chemical composition during germination are associated with increased fertilizer efficiency of seed N. Methods: Net N mineralization of seed meal and seedlings varying in age was determined in pot and field experiments. The temporal mineralization pattern was quantified by fitting first-order kinetics. Results: In the pot experiment, seedling C:N ratio declined within 2 weeks from initially 8. 8 to a minimum of 6. 2 prior to a re-increase. Maximum net N mineralization increased strongly with decreasing C:N ratio being up to 44% higher for seedlings compared to seed meal. Time course of net N mineralization in the field showed initial peaks partly exceeding the amount of applied lupine seed N. Ignoring mineralization peaks, the relationship between maximum net N mineralization and C:N ratio was in close agreement with pot experimental data. The critical C:N ratio of the pooled data was 13. Conclusions: Nitrogen mineralization of field-sown lupine seeds can be manipulated by varying seedling growing time until incorporation. High fertilizer efficiency provided by high net N mineralization is associated with early seedling incorporation and high germination rates. © 2012 Springer Science+Business Media B.V.

Ritter C.,State Institute for Agriculture and Fisheries Mecklenburg West Pomerania | Richter E.,Julius Kuhn Institute | Knolck I.,State Institute for Agriculture and Fisheries Mecklenburg West Pomerania | Katroschan K.-U.,State Institute for Agriculture and Fisheries Mecklenburg West Pomerania
Journal of Plant Diseases and Protection | Year: 2014

The fertilizer calcium cyanamide (CaCN2) is often used due to its sanitary effect in the soil. Among other application areas, it has been described to have a lethal effect on various insect species of different orders. Wireworms of the genus Agriotes spp. (Coleoptera: Elateridae) are severe and widespread agricultural root damaging pests affecting numerous crops and weeds. Previous work on CaCN2 against wireworms has mainly been limited to identify and evaluate crop protection rates. This paper, however, focuses on the effect of CaCN2 on wireworms. Therefore, we investigated the mortal and repellent impact of CaCN2 on late instar larvae of Agriotes ustulatus in soil without plant material under laboratory conditions. Our results indicate a non-toxic, yet repellent, character of CaCN2 on wireworms. However, these results are not sufficient to conclude that CaCN2 will work as a wirewormrepellent in the field. Trials including both, a food source and wireworms in feeding state, will be needed for a substantial conclusion. Finally, our findings give evidence that further investigations are reasonable. © Eugen Ulmer KG, Stuttgart.

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