جستجوی مقالات مرتبط با کلیدواژه "microbial" در نشریات گروه "آب و خاک"

This study aimed to investigate the effect of different intensities (i.e., light, moderate, and heavy) of habitat degradation on soil biological characteristics as the main indicators of soil health in the Khanikan forest of Nowshahr. For this purpose, from each of the different intensities of degradation, 12 samples of topsoil (0-10 cm depth) were transferred to the laboratory. Also, in order to measure the stratification ratio of organic matter, soil samples were taken from a depth of 10-20 cm in addition to 0-10 cm depth. In order to investigate the presence or absence of statistically significant differences between the studied characteristics in different intensities of habitat degradation, a one-way analysis of variance (ANOVA) test in a completely randomized design was employed. In addition, principal component analysis was used to study multiple relationships. According to the results, the highest values ​​of coarse and fine root biomass, number and biomass of epigeics and anecics, number and biomass of total earthworms and the populations of Acarina, collembola, nematodes, protozoa, bacteria and fungi, nitrogen and phosphorus microbial biomass and enzyme (i.e. urease, acid phosphatase, arylsulfatase, and invertase) activities were found in forest cover with light degradation intensity. The number and biomass of endogeics did not show a statistically significant difference in the studied ecosystems, while forest stands with light and moderate degradation intensities had the highest values ​​of basal soil respiration, substrate-induced respiration, and carbon microbial biomass. Principal component analysis results indicate that fertility indices (C/N ratio and available P, available Ca and Mg, available K) and clay content had the greatest effect

In this study, effects of heavy metal of chromium on microbial and eco physiological indices of soil in presence of vermicompost were evaluated using a complete randomized design. This experiment was carried out in five levels of chromium (0, 100, 200, 300 and 400 mg Cr kg-1 soil from potassium dichromate) and seven incubation periods (5, 30,60,90,100,110 and 120 days) in three replicates and for decreasing the adverse effects of pollutant in soil, in the 90th day, vermicompost was added to all of the treatments. At the end of each period, dehydrogenase enzyme activity, basal respiration and microbial biomass carbon as microbial indices and also metabolic and microbial quotient as eco physiological indices were measured. The results showed that with increasing chromium concentration in soil, the microbial indices were decreased up to the 90th day. Dehydrogenase enzyme activity decreased by 100 percent in concentrations of 100 mg Cr kg- and then it was increased, therefore application of the vermicompost compensated the adverse effects of the pollutant. Metabolic quotient in concentration of 300 mg kg- Cr the 90th day reached to 5.43 and then decreased to 0.164 in the 100th day. This decrease happened in concentration of 400 mg kg- Cr, severely. By adding organic matter, the microbial quotient increased 56 and 44 percent in control and in the highest concentration of the chromium respectively. Based on result of this research, in concentrations higher than 100 mg Cr kg- in soil negative effects of the metal on microbial indices was revealed and usage of vermicompost in improvement of this indices in presence of chromium was efficient.