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Recupero di biomasse agro-industriali: cinetica della decomposizione nel terreno dei gusci di semi di girasole
No full textChanges in organic compounds and dehydrogenase activity in soil amended with crop residues
No full textInfluenza della paglia di grano e del liquame suino sulla fertilità del suolo: prove di laboratorio
No full textSoil properties as influenced by incorporation of crop residues
No full textChemical transformation , nutrient release and changes in the energy content of decomposing rape, sunflower and soybean residues confined in buried fiberglass bags were assessed in a laboratory study during a 340-day incubation period. The organic C decreased by about 70% while total N, after initial decay, remained almost constant for each type of residue. The NHj~-N was progressively oxidized and, consequently, the NOJ-N increased. The C/N ratio narrowed with loss of C. Hemicellulose, cellulose and lignin decreased with different trends for each crop residue. The energy content, was reduced to about 25% in rape, 30% in sunflower and 20% in soybean residues. Total P, K, Ca and Mg contents decreased for each type of residue. The results suggest that the three residues could improve the nutrient pool of the soil
Decomposition of crop residues under laboratory conditions
No full textA laboratory study was designed to provide data on the decomposition of rape, sunflower and soyabean residues put in bags buried in soil. The residue bags were removed at intervals during 1 year, analysed for remaining total mass, organic and water-soluble C, water-soluble sugars, as well as for volatile acids and phenolic compounds. The decomposition dynamics of total mass, total organic and water-soluble organic C, and water-soluble sugars were reproduced satisfactorily by a double-exponential model of the first-order type.
Generally, no large differences in the rate and magnitude of decomposition among the residues were observed; the greatest losses of both total mass and chemical components occurred in the first month of the study, during which the volatile acids and phenolic compounds disappeared almost completely. Of the three residues, soyabean showed the lowest loss of organic carbon, losing 66% of the original content over the course of the year compared with 73 and 75% for sunflower and rape, respectively
Nutrient release from decomposing crop residues in soil: a laboratory experiment
No full textIn a 400-day laboratory experiment, soil was amended with rape, sunflower and soybean residues to monitor the quantitative changes in the main inorganic nutrients. Total N, available P, exchangeable K+, Ca2+, and Mg2+ in all the amended samples Increased significantly. Generally, the increase in the amounts of these nutrients was maintained until the end of the incubation period, suggesting that the mineralization of the three crop residues enhanced soil fertility. In amended soil samples, NH4+-N disappeared within 14 days, while available N was released as NO3--N after 60 days in soybean-treated and after 120 days in rape- and sunflower- treated soil, respectively. Water-soluble P was completely lacking in each treatment because of microbial immobilization and adsorption or precipitation processes in soil
Decomposition of vegetation water sludge in soil
No full textA laboratory study was designed to provide data on the effects of application rates (0, 1, 2, 3, and 4% of soil), moisture content (50, 100, and 150% WHC), and incubation temperature (4, 17, and 29°C) on the extent and rate of decomposition in soil of sludge organic matter derived from dehydrated vegetation waters. Cumulative CO2-C loss was described by the equation C = Ktm. At 3 and 4% loading rates, the CO2-C evolution showed a short transitory inhibition, after which decomposition started. The CO2-C evolved at 17°C was proportional to the amount of sludge added, and, after two months of incubation, the percentage of CO2-C evolved was about 50% of the C applied. A log-log plot of the cumulative CO2-C evolution against time showed two stages representing the decomposition of the active and less readily decomposable organic carbon, respectively. The moisture level at 100% WHC had a small positive effect on the degradation of the sludge, while at 150% WHC carbon loss was lower. The rising temperatures accelerated the rate of the decomposition with a Q10 factor ranging from 1.44 to 1.89.
A laboratory study was designed to provide data on the effects of application rates (0, 1, 2, 3, and 4% of soil), moisture content (50, 100, and 150% WHC), and incubation temperature (4, 17, and 29°C) on the extent and rate of decomposition in soil of sludge organic matter derived from dehydrated vegetation waters. Cumulative CO2-C loss was described by the equation C = Ktm. At 3 and 4% loading rates, the CO2-C evolution showed a short transitory inhibition, after which decomposition started. The CO2-C evolved at 17°C was proportional to the amount of sludge added, and, after two months of incubation, the percentage of CO2-C evolved was about 50% of the C applied. A log-log plot of the cumulative CO2-C evolution against time showed two stages representing the decomposition of the active and less readily decomposable organic carbon, respectively. The moisture level at 100% WHC had a small positive effect on the degradation of the sludge, while at 150% WHC carbon loss was lower. The rising temperatures accelerated the rate of the decomposition with a Q10 factor ranging from 1.44 to 1.89
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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