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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #382970

Research Project: Develop Water Management Strategies to Sustain Water Productivity and Protect Water Quality in Irrigated Agriculture

Location: Water Management Research

Title: Organic amendments, deficit irrigation, and microbial communities impact extracellular polysaccharide content in agricultural soils

item Hale, Lauren
item CURTIS, DANIEL - University Of Oklahoma
item LEON, NICOLE - Former ARS Employee
item MCGIFFEN JR. - University Of California
item Wang, Dong

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2021
Publication Date: 9/22/2021
Citation: Hale, L.E., Curtis, D., Leon, N., McGiffen Jr., Wang, D. 2021. Organic amendments, deficit irrigation, and microbial communities impact extracellular polysaccharide content in agricultural soils. Soil Biology and Biochemistry. 162. Article 108428.

Interpretive Summary: To evaluate how organic amendments impact agronomic water productivity under deficit irrigation strategies, we quantified soil properties that enhance soil water retention in turfgrass and tomato cropping systems. Many beneficial attributes were associated with compost in one or both systems, including enhanced aggregate stability, soil extracellular polysaccharide content, microbial biomass, and nutrients. Thus, when utilized alongside best crop and soil management practices, amendments such as compost may be practical tools to enhance total water productivity of agroecosystems.

Technical Abstract: Soil extracellular polysaccharides (EPSac) can increase irrigation water productivity in agriculture by increasing soil aggregate stability and retaining water on and around plant roots. However, limited studies assay soil EPSac in field trials and to date no studies have examined the confounding impacts of organic amendments and deficit irrigation strategies on soil EPSac and the underlying microbial communities. We evaluated soil aggregate stability, EPSac content, chemical properties, and microbial community compositions and abundances in separate field studies in turfgrass and tomato. Treatments included compost, biochar, their combination, or biosolids under full and deficit irrigation regimens. Amending the soil with compost, with or without biochar co-application, enhanced soil carbon, aggregate stability, EPSac, and microbial biomass and shifted microbial community structures, trends which were more pronounced under turfgrass than for tomato. Deficit irrigation treatments had higher quantities of soil EPSac per unit of microbial biomass. Indicators of microbial physiological stress and ubiquitous classes of soil bacteria were associated with soil EPSac production. Overall, compost, even 4-5 years after its soil incorporation, promoted microbial EPSac production in both deficit and full irrigation treatments.