HR: 1340h
AN: H43G-1704    [Abstracts]
TI: Residuejams and their effect on Infiltration, Runoff and Dissolved Organic Carbon (DOC) in Furrow Irrigation Systems
AU: * Mailapalli, D R
EM: dmailapalli@ucdavis.edu
AF: Land, Air and Water Resources Department, One Shields Avenue, University of California, Davis, CA 95616,
AU: Wallender, W W
EM: wwwallender@ucdavis.edu
AF: Land, Air and Water Resources Department, One Shields Avenue, University of California, Davis, CA 95616,
AU: Horwath, W
EM: wrhorwath@ucdavis.edu
AF: Land, Air and Water Resources Department, One Shields Avenue, University of California, Davis, CA 95616,
AU: Ma, S
EM: sama@ucdavis.edu
AF: Land, Air and Water Resources Department, One Shields Avenue, University of California, Davis, CA 95616,
AU: Lazicki, P
EM: patricia.lazicki@gmail.com
AF: Land, Air and Water Resources Department, One Shields Avenue, University of California, Davis, CA 95616,
AB: Crop residue, which consists of small debris of different sizes, is an important resource in agricultural ecosystems. It plays a vital role in conservation tillage as a best management practice (BMP) for reducing runoff, sediment, nutrient and pesticide transport from irrigated fields. In furrow irrigation, the predominant irrigation method in the world, as irrigation or winter runoff water moves along a furrow, it lifts the unanchored residue and transports across the field. The complex interaction of multiple residue pieces (debris) with itself, the soil matrix, and the fluid cause jams to form along the furrow. The residuejams can be thought of logjams in fluvial rivers or channels which help in increasing channel roughness to reduce flow velocities and shear stress along eroding banks. The logjams also create a hydraulic shadow, a low-velocity zone for some distance upstream that allows sediment to settle out and stabilize. Similarly, the residuejams help in formation of catchments, which promote increased infiltration and settlement of sediments along the furrow. The infiltration and residue interaction with the soil-water influence the runoff, sediment, nutrient and dissolved organic carbon (DOC) export. The reduction of DOC export is critical to enhancing drinking water resources by reducing reactive sources of DOC that form carcinogenic by-products in the disinfection process. Hence, investigation of geomorphology of the residuejams is essential to understand their impact on infiltration, runoff and DOC concentration. This study focuses on the formation of residuejams and their effect on the infiltration, runoff and DOC concentration from 122 m long furrow plots with cover crop (CC), no-till (NT) and standard tillage (ST). These treatments (CC, NT and ST) were replicated three times using randomized complete block design and the plots initially, had 10, 32 and 42% of residue cover (sunflower residue on ST and NT; sunflower and wheat residue on CC plot), respectively. During the irrigation, the waterfront advance (for estimating infiltration), runoff and DOC concentration (at the tail end) were measured. After the irrigation, the location of the residuejams along the furrow and their dry weight were measured. Using the jam location data, the relative percentage spacing of the jams were estimated and found that it decreases down the furrow for all the cases. Hence, the number of residuejams increases down the furrow to a maximum at the tail end. Further, the number of jams is greater for NT followed by CC and ST. The infiltration and runoff data of these treatments were used for studying the effect of residuejams on these parameters. The water samples collected from these plots were analyzed for DOC concentration. Initially, DOC was high and then decreased with time in all cases. However, DOC was greater for NT followed by CC and ST. This may be due to more jams in NT followed by CC and ST. Hence, residuejams apparently affect DOC.
DE: 1810 Debris flow and landslides
DE: 1838 Infiltration
DE: 1842 Irrigation
DE: 1850 Overland flow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2007 Fall Meeting