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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #326089

Title: Impacts of deficit irrigation and altered rooting patterns on soil structure and associated soil properties

item FLYNN, NORA - Colorado State University
item Comas, Louise
item Stewart, Catherine
item FONTE, STEVEN - Colorado State University

Submitted to: Great Plains Soil Fertility Journal
Publication Type: Abstract Only
Publication Acceptance Date: 2/25/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A better understanding of belowground systems and overall management impacts on soil health is needed to improve crop production and long-term sustainability under deficit irrigation. This study investigates effects of deficit irrigation on rooting patterns in maize and subsequent impacts on soil properties. Previous research observed greater rooting at depth in deficit irrigation than in fully irrigated treatments. Given that roots are drivers of soil structure, biology and organic matter dynamics, management practices that affect rooting growth and distribution may have important implications for soil health. We examined the effects of deficit irrigation treatments in a randomized, replicated field trial near Greeley, Colorado. Soils were sampled in August 2015, during time of peak root biomass, within four irrigation treatments representing a gradient of water stress. Within each treatment, we assessed aggregate stability and associated C content of each aggregate size class at two soil depths (0-20 and 40-60 cm). Root growth was quantified from split soil cores as well as minirhizotron-imaging collected adjacent to the soil samples. Microbial functional groups were evaluated using PLFA analysis at the two soil depths in each of the irrigation treatments. We hypothesize that increased root growth at greater depth in deficit irrigation treatments will lead to greater soil aggregation and aggregate-associated C storage at depth. Higher levels of C input and protection by aggregates along with altered activity and community composition of microorganisms can have important implications for total soil organic matter stores, with significant implications for C-sequestration and long-term soil fertility in these systems. Additionally, such improvements to soil organic matter and soil fertility may increase stress resistance and productivity in deficit irrigation conditions. This research will contribute important knowledge about the long-term implications of altered irrigation regimes on soil organic matter storage and overall soil fertility. A better understanding of soil ecosystem function is critical in developing methods which take advantage of belowground ecosystem services which subsequently affect above ground properties and yield in maize. Ultimately, this project seeks to contribute information and evidence for the optimization of informed deficit irrigation strategies.