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331.
Heinz-Christian Fründ Werner Dierend Henning Schacht Christa Schütt 《Erwerbs-Obstbau》2006,48(4):130-138
In organic farming only organic N-fertilizers are allowed. They have to be mineralized by soil biota before they become effective for the plant. There are a number of different organic N-fertilizers offered commercially in order to allow for a precise management of the N-supply to plants in organic farming. We tested the effects of the fertilizers “Vinasse” (product resulting from sugar-beet molasses), “Haarmehlpellets” (pellets of grounded pig bristles), “Rizinusschrot” (grist of Ricinus communis seeds), “Phytopearls” (from maize conversion), “Maltaflor” (malt germs and “Vinasse”), “Horndünger” (horn parings) and manure on soil respiration, soil animal feeding activity, earthworm abundance, microbial biomass and the Cmic/Nmic-ratio in tree nurseries and apple fruit production under organic vs. integrated management respectively. The investigations were part of a two year lasting project regarding yield effects and N-turnover that has already been reported in this journal (vol. 48/3: Dierend et al. 2006a, 2006b, Schacht et al. 2006). Significant differences between fertilized plots and unfertilized control plots were observed only at one of the four sites (Jork, organic fruit production) in soil respiration and in soil animal feeding activity. There were no significant differences in the soil biological parameters between plots that had received different types of organic fertilizers. There were also no significant differences between different levels of fertilizer application which were ranging from 30 to 135?kg N/ha. The soils from the four investigation sites differed significantly in their biological status. At the tree nurseries there were only few earthworms (ca. 15/m2) and a low microbial biomass (105 ... 190?mg Cmik/kg dry soil). The soils under fruit production were more intensively colonized by soil organisms, according to the lower degree of soil disturbance in these cultures. In tree nursery as well as in fruit production the soils under organic management had higher microbial biomasses and a wider ratio of C to N in the microbial biomass compared to their counterparts with integrated management. This is indicating that there is a stronger tendency to incorporate additional N into the microbial biomass in the organically managed soils. If there is a high activity of (endogeic) earthworms the nutrients are quickly remobilized and so become available for the plants. 相似文献
332.
Short‐term and long‐term effects of a minimally invasive transilial vertebral blocking procedure on the lumbosacral morphometry in dogs measured by computed tomography
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333.
Field experiments show that wheat grown after oilseed rape (OSR) achieves higher yield levels, while the nitrogen (N) application is reduced. However, field experiment data are based on few locations with optimised management. We analysed a large dataset based on farm data to assess the true extent of break crop benefits (BCB) for yield and N fertilisation within German commercial farming.Across all German states and years, average yield of wheat preceded by OSR was 0.56 Mg ha?1 higher than yield of wheat preceded by cereals (7.09 Mg ha?1), although considerable variation between regions was observed. Mean N application across all states to wheat after OSR was 5 kg ha?1 lower than to wheat after cereals. Choice of wheat types for different end uses (bread flour or animal feed) showed higher (0.77 Mg ha?1) or lower (0.44 Mg ha?1) BCB for yield of wheat cultivated after OSR compared with after cereals. The calculated BCB for yield and N fertilisation were lower than expected from dedicated field experiments and fertiliser recommendations. Thus the advantages of OSR as a preceding crop are generally utilised by commercial farmers in Germany but there is room for improvement. 相似文献
334.
Carbon fractions in soils apparently vary not only in space, but also over time. A lack of knowledge on the seasonal variability of labile carbon fractions under arable land hampers the reliability and comparability of soil organic carbon(SOC) surveys from different studies. Therefore, we studied the seasonal variability of two SOC fractions, particulate organic matter(POM) and dissolved organic carbon(DOC), under maize cropping: POM was determined as the SOC content in particle-size fractions, and DOC was measured as the water-extractable SOC(WESOC) of air-dried soil. Ammonium, nitrate, and water-extractable nitrogen were measured as potential regulating factors of WESOC formation because carbon and nitrogen cycles in soils are strongly connected. There was a significant annual variation of WESOC(coefficient of variation(CV) = 30%). Temporal variations of SOC in particle-size fractions were smaller than those of WESOC. The stocks of SOC in particle-size fractions decreased with decreasing particle sizes, exhibiting a CV of 20%for the coarse sand-size fraction(250–2 000 μm), of 9% for the fine sand-size fraction(50–250 μm), and of 5% for the silt-size fraction(20–50 μm). The WESOC and SOC in particle-size fractions both peaked in March and reached the minimum in May/June and August, respectively. These results indicate the importance of the time of soil sampling during the course of a year, especially when investigating WESOC. 相似文献