Movement of N from decomposing earthworm tissue to soil microbial and plant N pools

Abstract A microcosm experiment was made to determine the fate of nitrogen released from 15 N-labelled decomposing earthworms (Lumbricus terrestris) in soil in the presence or absence of ryegrass seedlings (Lolium perenne). Earthworm tissue (2.0% 15 N atom enriched) was added to each microcosm. Nitrogen movement from earthworm tissue to soil N [mineral N (NH 4 -N + NO 3 -N), dissolved organic N (DON) and organic N], microbial biomass N and plant shoot N pools was determined by destructive sampling at 1, 2, 4, 8 and 16 d. Earthworm tissues decomposed rapidly, and no tissue was visible after 4 d. Initially in pots without plants, most of the N from earthworm tissue was found in the organic N pool, however, as much as 55% of the N from decomposing earthworm tissue was incorporated into microbial biomass after 2 d. Much less of the N from earthworm tissue was transformed into DON and mineral N forms after 2 d. The DON and mineral N pools contained 13±18% and 4±7% of the N from earthworm tissue, respectively, from d 2 to 16. By the end of the experiment, N from earthworm tissue in the microbial biomass N pool declined to 29% while the amount of N from earthworm tissue in the organic N pool increased to 49%. The increase in the organic N may have resulted from the production of new organic compounds such as microbial by-products. In pots with plants, N from earthworm tissue was rapidly incorporated into microbial biomass, and by d 2, the microbial biomass N pool contained 40% of the N from earthworm tissue. Mineral N, DON and microbial biomass N concentrations were lower in pots with ryegrass seedlings compared to pots without plants, and after d 2 declined to almost undetectable amounts because of rapid plant uptake. Between 42±52% of the N from earthworm tissue was found in the organic N pool from d 1 to 8, and then declined to 19% by d 16. After 16 d, over 70% of the N added as earthworm tissue was incorporated into plant shoot biomass. Our results demonstrate that the movement of N from dead earthworm tissue into microbial biomass was extremely rapid, and in pots without plants, much of this N was transformed into organic N forms, while in pots with ryegrass, most of the N from earthworm tissue accumulated in ryegrass shoots.

Инфекционная составляющая и иммунопатология при хронических воспалительных заболеваниях слизистой оболочки гастродуоденальной области

Выявлено коинфицирование слизистой оболочки желудочно−кишечного тракта Helicobacter pylori и вирусами группы герпеса у больных хроническим гастритом, язвенной болезнью желудка и двенадцатиперстной кишки. Проведена оценка общих и специфических иммунных реакций организма на указанные инфекционные агенты. Обнаруженные изменения в клеточном и гуморальном звене иммунитета могут свидетельствовать об обусловленном ими системном иммунопатологическом процессе.Co−infection of the gastrointestinal mucosa with Helicobacter pylori and herpes viruses in patients with chronic gastritis, gastric and duodenal ulcer was revealed. General and specific immune reactions of the organism to the above agents were evaluated. The revealed changes in the cellular and humoral immunity can suggest systemic immunopathological process

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Abstract Production was estimated for Aporrectodea spp. and Lumbricus spp. populations in corn agroecosystems with a 5-year history of manure or inorganic fertilizer applications during 1994-1995 and 1995-1996. Earthworm biomass and production were greater in manure than inorganic fertilizer plots, although biomass and production declined by about 50% between 1994-1995 and 1995-1996 due to unfavorable climatic conditions. Production was highest during the spring and autumn when soil temperatures were between 4 and 22°C. Production was higher in Lumbricus spp. than Aporrectodea spp. populations due to greater Lumbricus spp. biomass. Aporrectodea spp. production was 3.47-16.14 g ash-free dry weight (AFDW) m -2 year -1 , while Lumbricus spp. production was 6.09-18.11 g AFDW m -2 year -1 , depending on the fertilizer treatment and the method used to estimate production. However, production estimates from the instantaneous growth rate method were within 27% of the values calculated using the size-frequency method. Nitrogen flux through earthworms was used to estimate efficiency quotients. Net production efficiency (P/A) ranged from 0.64 to 0.76, assimilation efficiency (A/C) ranged from 0.1 to 0.3, and gross production efficiency (P/C) ranged from 0.06 to 0.22. Annual N flux through earthworm populations was higher in manure than inorganic fertilizer plots, and ranged from 2.95 to 5.47 g N m -2 year -1 in 1994-1995 and 1.76 to 2.92 g N m -2 year -1 in [1995][1996]. The N flux through earthworms represented an amount equivalent to 16-30% of crop N uptake during 1994-1995 and 11-18% of crop N uptake during 1995-1996. We concluded that the effects of earthworms on N cycling in corn agroecosystems were substantial, and that N flux through earthworms was influenced significantly by fertilizer amendments

Control-Related Cognitions and Depression Among Inpatient Children and Adolescents

183 inpatient children and adolescents from 3 separate psychiatric hospitals completed the Children\u27s Depression Inventory (CDI) plus measures of control-related beliefs. In all 3 samples, the findings resembled those of previous studies: CDI scores were significantly related to low perceived competence and to contingency uncertainty; by contrast, CDI scores were only weakly related to perceived noncontingency. Findings suggest that depressive symptoms in children may be (1) more closely linked to \u27personal helplessness\u27 than to \u27universal helplessness\u27 and (2) more closely linked to uncertainty about the causes of events than to firm beliefs in noncontingency