Secondary salinity effects on soil microbial biomass
2010
Egamberdieva, Dilfuza | Renella, Giancarlo | Wirth, Stephan | Islam, Rafiq
Secondary soil salinilization is a big problem in irrigated agriculture. We have studied the effects of irrigation-induced salinity on microbial biomass of soil under traditional cotton (Gossypium hirsutum L.) monoculture in Sayhunobod district of the Syr-Darya province of northwest Uzbekistan. Composite samples were randomly collected at 0-30 cm depth from weakly saline (2.3 ± 0.3 dS m⁻¹), moderately saline (5.6 ± 0.6 dS m⁻¹), and strongly saline (7.1 ± 0.6 dS m⁻¹) replicated fields, 2-mm sieved, and analyzed for pH, electrical conductivity, total C, organic C (COrg), and extractable C, total N and P, and exchangeable ions (Ca²⁺, Mg²⁺, K⁺, Na⁺, Cl⁻, and CO ₃ ²⁻ ), microbial biomass (Cmic). The Na⁺ and Cl⁻ concentrations were 36-80% higher in strongly saline compared to weakly saline soil. The COrg concentration was decreased by 10% and CExt by 40% by increasing soil salinity, whereas decrease in Cmic ranged from 18-42% and the percentage of COrg present as Cmic from 8% to 26%. We conclude that irrigation-induced secondary salinity significantly affects soil chemical properties and the size of soil microflora.
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