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Joo Carlos de Moraes S Lucien Sguy Florent Tivet Rattan Lal Serge Bouzinac Paulo Rogrio Borszowskei Clever Briedis Josiane Burkner dos Santos Daiani da Cruz Hartman Clayton Giani Bertoloni Jadir Rosa Theodor Friedrich 《Land Degradation \u0026amp; Development》2015,26(6):531-543
The continuous use of plowing for grain production has been the principal cause of soil degradation. This project was formulated on the hypothesis that the intensification of cropping systems by increasing biomass‐C input and its biodiversity under no‐till (NT) drives soil restoration of degraded agro‐ecosystem. The present study conducted at subtropical [Ponta Grossa (PG) site] and tropical regions [Lucas do Rio Verde, MT (LRV) site] in Brazil aimed to (i) assess the impact of the continuous plow‐based conventional tillage (CT) on soil organic carbon (SOC) stock vis‐à‐vis native vegetation (NV) as baseline; (ii) compare SOC balance among CT, NT cropping systems, and NV; and (iii) evaluate the redistribution of SOC stock in soil profile in relation to soil resilience. The continuous CT decreased the SOC stock by 0·58 and 0·67 Mg C ha−1 y−1 in the 0‐ to 20‐cm depth at the PG and LRV sites, respectively, and the rate of SOC sequestration was 0·59 for the PG site and ranged from 0·48 to 1·30 Mg C ha−1 y−1 for the LRV site. The fraction of C input by crop residues converted into SOC stock was ~14·2% at the PG site and ~20·5% at the LRV site. The SOC resilience index ranged from 0·29 to 0·79, and it increased with the increase in the C input among the NT systems and the SOC sequestration rates at the LRV site. These data support the hypothesis that NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Puffing and histone acetylation in polytene chromosomes 总被引：1，自引：0，他引：1
Fixation with picric acid or formaldehyde retains incorporated [(3)H]acetate which is lost after fixation with ethanol and acetic acid. Unlike [(3)H]uridine, [(3)H]acetate is diffusely incorporated into polytene chromosomes, and not preferentially into existing or newly induced puffs. It is suggested that puff formation does not include an acetylation of histones. 相似文献
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Michael Clever 《Erwerbs-Obstbau》2007,49(3):107-109
6-Benzyladenine (BA) showed only a slight thinning effect which was probably correlated with low temperatures during application. It is concluded that under the current climate of the Lower Elbe region temperature is a more important factor than fruit size for determining the time-point of BA application. Ethephon at 300?ppm produced a stronger effect, even if this was still insufficient in the present case. Higher concentrations (450–600?ppm) are required for strongly flowering ‘Elstar’ plantations older than 4?years, but this invokes the risk of excessive thinning. Therefore, the application of Ethephon requires a high degree of experience on part of the fruit farmer. Metamitron, applied once at 350?ppm, showed similar effects to Ethephon. An enhanced effect might have been obtainable if a second treatment had been applied some 10?days later. No phytotoxic damage was observed. Metamitron would be an interesting fruit thinning agent and should be considered for registration in Germany. Naphthalene acetic acid (NAA) and NAA + BA gave the best results in the experiment for 2006?described here. It is not yet clear whether the degree of flowering for 2007 will be influenced in a similarly positive manner as for Ethephon. Since NAA and Metamitron have not been registered for Germany, their practical use cannot be recommended. 相似文献
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A general model of the influences of abiotic variables on microbial respiration and substrate weight loss is presented. The model, a complex hypothesis relating microbial respiration to temperature. moisture, O2 and substrate, “explains” 71–96% of the variation in aerobic respiration rates measured from a variety of natural substrates. The model can project seasonal patterns of weight loss and thus permits evaluation of laboratory respirometry against field measures using litter bags. Using data from several countries simulated losses due to microbial respiration are 70–90% of the measured litter bag loss. 相似文献
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Clever Briedis João Carlos de Moraes Sá Eduardo Fávero Caires Jaqueline de Fátima Navarro Thiago Massao Inagaki Adriane Boer Caio Quadros Neto Ademir de Oliveira Ferreira Lutécia Beatriz Canalli Josiane Burkner dos Santos 《Geoderma》2012
The stabilisation of soil organic matter (SOM) is the result of the simultaneous action of three mechanisms: chemical stabilisation, biochemical stabilisation and physical protection. The objectives of this study were (i) to evaluate carbon-protection mechanisms in different SOM pools in soil aggregates and (ii) to identify the association of Ca2 + with total organic carbon (TOC) under the influence of surface liming in a medium-textured Oxisol in a long-term experiment under no-till system (NTS) in southern Brazil (25° 10′ S, 50° 05′ W). The treatments consisted of application of zero or 6 tons ha? 1 of dolomitic lime on the soil surface in 1993 and a reapplication of zero or 3 tons ha? 1 of dolomitic lime in 2000 to plots with or without previous lime application. Soil samples collected at depths of 0–2.5, 2.5–5, 5–10 and 10–20 cm were separated into seven aggregate classes. In each of these classes, TOC, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) were analysed. The 8–19 mm sized aggregates from the 0–2.5 cm layer were assessed by energy-dispersive X-ray spectroscopy (EDS) for the elemental analysis of carbon (C) and calcium (Ca). The liming caused an accumulation of TOC in the aggregates, mainly at a depth of 0–2.5 cm. The aggregates from soils treated with lime had a higher mean weight diameter (MWD) that resulted in the accumulation of TOC, especially in the 8–19 mm aggregate class, that was linear and closely related with C input (R2 = 0.99). The proportion of large aggregates in the treatments with lime was closely correlated with the TOC content of the whole sample. The largest dose of lime (9 tons ha? 1) resulted in higher TOC, POC and MAOC values, mainly in the 8–19 mm aggregate class. The elemental analyses for C and Ca revealed similar spectra between them for the surface-liming treatments in the clay fraction found in the centres of the 8–19 mm aggregates. The surface application of lime to NT fields provided greater stability and protection of the intra-aggregate C, presumably due to Ca2 + acting as a cationic bridge between OC and the kaolinite in the clay fraction. 相似文献
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Michael Clever 《Erwerbs-Obstbau》2011,53(4):173-178
This article describes the foundation and development of experimental fruit farms in Ottensen and subsequently on the Esteburg site. Important foci of work of the experimental farm are varietal and rootstock trials of apple, pear, sweet and sour cherry, plum and prune, as well as additional cultivation trials with the afore-mentioned fruits. Machines and equipment are being tested under practical conditions. Since the introduction of Integrated Production in 1989, the experimental farm is being managed according to these guidelines. An area of 4?ha has been managed according to organic farming practice since 2001. The apprenticeship scheme covers 8 trainee gardeners specialising in fruit production as well as two technical assistants. The experimental farm is certified as a cross-company apprenticeship centre for training gardeners specialising in fruit production. 相似文献
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In cells of salivary glands of last-instar larvae of Chironomus tentans, acid phosphatase activity is bound to (probable) lysosomes and a few other cell organelles. At the end of the pupal molt the salivary gland breaks down. While acid phosphatase in areas of nondegenerated cells is still restricted to the structures mentioned, in degenerated areas the enzyme is freely distributed in the cytoplasm. 相似文献
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