F. Aghababaei; F. Raiesi; alireza hosseinpuor
Abstract
Soil biota such as earthworms and arbuscular mycorrhizal fungi (AMF) play an important role in the stability of ecosystem, and the bioavailability of soil elements, in particular heavy metals, in soils. To examine the effects of these organisms, a 3×2×3 factorial experiment arranged as randomized complete ...
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Soil biota such as earthworms and arbuscular mycorrhizal fungi (AMF) play an important role in the stability of ecosystem, and the bioavailability of soil elements, in particular heavy metals, in soils. To examine the effects of these organisms, a 3×2×3 factorial experiment arranged as randomized complete design was set up to study the individual and combined influence of earthworms (Lumbricus rubellus L.) and AMF (Glomus mosseae and Glomus intraradices) on soil organic matter (OM), dissolve organic carbon (DOC), soil respiration, microbial biomass carbon (MBC), soil enzyme activity and glomalin production in a calcareous soil contaminated with 0, 10, 20 mg of Cd kg-1 soil cropped with sunflower (Helianthus annuus L.) with three replications. Both earthworms and mycorrhizal fungi were able to survive in all the treatments with added Cd. Results showed that Cd pollution decreased all the measured microbial activities and properties in soil. Earthworm treatment increased DOC by 4-10% at all Cd levels. The amount of soil MBC in mycorrhizal treatments was greater (1.9-2.4 times) than that in non-mycorrhizal treatment, and AMF inoculation increased MBC/TOC ratio from 23% to 53% in Cd-polluted soils. Earthworm and AMF enhanced soil enzyme activity/MBC ratio, 10-18 and 40-54% for soil alkaline phosphatase and 4-9 and 40-55% for soil urease, respectively. The glomalin production increased at 20 mg kg-1 and was about 15% greater in G. mosseae than in G. intraradices species. Although soil respiration was decreased substantially with Cd pollution, inoculation of either earthworms or AMF enhanced soil respiration when compared with the corresponding controls.
F. Raiesi; F. Aghababaei
Abstract
Abstract
Soil microbial activity and biochemical processes are often limited by carbon availability in arid- and semi-arid regions, probably due to the low organic matter content. Consequently, return of plant residues to soil is a convenient and effortless practice for increasing microbial activities ...
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Abstract
Soil microbial activity and biochemical processes are often limited by carbon availability in arid- and semi-arid regions, probably due to the low organic matter content. Consequently, return of plant residues to soil is a convenient and effortless practice for increasing microbial activities and biochemical reactions. The primary objective of this study was to evaluate the effect of various plant residues on soil microbial respiration and biomass, and enzymatic activities as well. The experiment consisted of a completely randomized design (CRD) with three replications under laboratory conditions. Experimental treatments consisted of seven plant residues including wheat, alfalfa, corn, rice, almond, walnut and grape, common in agro-ecosystems of Chaharmahal va Bakhtiari province, with a control soil without plant residue addition. Results show that the added plant residues brought about a significant increase in microbial activity (soil respiration) and biomass with concurrent increases in enzyme activities in the studied soil. The results of the current study indicate that enzyme activities would alter with changes in substrate quality during the course of plant residue decomposition. However, the extent to which, soil microbial activity and biomass, and enzyme activities fluctuate depended largely upon the type and quality of plant residues used, and the stage of residue decomposition.
Keywords: Litter chemical composition, Soil respiration, Soil Microbial biomass, Soil Enzyme Activities, Cropping systems
