M. Mansourzadeh, F. Raiesi,
Volume 16, Issue 59 (4-2012)
Abstract
The application of herbicides as organic chemical compounds to control pest and weeds may affect the population and activity of microorganisms, and this may have an influence on biochemical processes that are important for soil fertility and plant growth. The primary objective of this study was to evaluate different loading rates of eradican (EPTC) on soil microbial biomass C and N, microbial biomass C/N ratio and the activities of urease and arylsulphatase under field conditions. In this experiment, loading rates of 6 and 9 L ha-1 eradican were applied to a calcareous soil cultivated with corn (Zea mays L.) and left uncultivated using split-plots arranged in a completely randomized block design with three replications. The experiment was conducted in the Kabootarabad’s Agricultural Research Center, Isfahan. Soil microbial biomass C and N were determined at 30th and 90th days after the onset of experiment and the activities of urease and arylsulphatase were assayed at 30th, 60th and 90th days. Results showed that in soils cultivated with corn microbial biomass C increased with increasing eradican levels and in both cultivated and uncultivated soils microbial biomass N and microbial biomass C/N ratios were increased over the control. At 30th day, urease activity at 6 L ha-1 level reduced, while at 9 L ha-1 level it increased compared with the control soils. At 60 day, there was no significant difference in the urease activity between the treatments. At 90th day, the activity of urease showed slight fluctuations. There was a reduction in arylsulphatase activity of the cultivated soils by increasing the loading rates of eradican during the experiment, and in uncultivated soils no trend was observed. Briefly, the use of eradican can cause either reduced or increased microbial biomass sizes and enzyme activities in calcareous soils These changes, however, depend largely upon the application rate of eradican, time elapsed since eradican application (i.e., sampling date) and the presence or absence of plant
E. Sadeghi, F. Raiesi, A. Hossienpur,
Volume 23, Issue 2 (9-2019)
Abstract
Abiotic stresses such as salinity and contamination individually have a negative effect on the soil enzyme activities, whereas addition of organic matter to soil can alleviate the negative impacts of stresses on the enzyme activity. However, the combined effects of these stresses (multiple stresses) on soil biochemical conditions and the role of organic matter addition in these interactions are largely unknown. The objective of this research was to explore the interaction effect of NaCl salinity and cadmium (Cd)-pollution on the activities of catalase, alkaline phosphatase, arylsulfatase and fluorescein diacetate hydrolysis in a Cd-contaminated calcareous soil treated with alfalfa residue over 3 months of incubation. A factorial experiment with 2 levels of Cd, 3 levels of salinity and 2 plant residue treatments was conducted using a completely randomized design with 4 replications. The results indicated that salinity increased the Cd availability in both uncontaminated and contaminated soils and reduced the soil enzymatic activity. Nevertheless, addition of alfalfa residue reduced the detrimental effects of salinity and Cd-pollution on the soil enzyme activities. This indicated that in saline Cd-contaminated soils with low organic matter, adding plant residues could lower the concentration of available Cd and the effect of soil salinity with a concomitant increase of enzyme activities. So, this study showed that the joint effect of NaCl salt and Cd on enzyme activity was mostly synergistic in plant residue-untreated soils, but it was antagonistic in the plant residue-treated soils.
