may decrease infiltration (Savabi and Stott, 1994) and is an issue we do not consider in this study. Surface sealing of bare soils often reduces rain infiltration, and The relationship between the mass or extent of resicrop-residue cover is commonly used to reduce surface sealing. We due cover and the increase in infiltration is an important conducted numerical experiments to quantify effects of the percentage and distribution of residue cover on infiltration, and to provide guide-issue in dealing with the surface-sealing problem. lines for residue management. Residue cover was simulated over the Baumhardt and Lascano (1996) conducted a field expersoil surface in circular patches. Excess surface water from the bare iment near Lubbock, TX. Simulated rain was applied surface-sealed areas was available for infiltration in nonsealed areas. at 65 mm h Ϫ1 for 1 h on a bare and residue-covered Numerical simulations were conducted for combinations of (i) soil Olton clay loam soil. They found that cumulative infiltype, either a clay loam or loamy sand soil; (ii) percentage residue tration was lowest (28.7 mm) on bare soil, and increased cover (P rc); (iii) saturated hydraulic conductivity of the surface seal curvilinearly with increasing residue amounts, leveling (K c) relative to bulk soil (K s); (iv) residue-patch size with a constant off to a limit (49.0 mm). The leveling off (asymptotic P rc ; and (v) rainfall intensity. The K c values had the greatest influence limit) occurred at a residue amount of 2.4 ton ha Ϫ1. on infiltration as a function of P rc. This influence increased with rainfall Increases in infiltration were related to the residue intensity. For a given P rc , smaller patches gave greater relative infiltraamount and not influenced by residue geometry, or their tion due to differences in the lateral redistribution of infiltrated water. The target values of P rc that provided 95% relative infiltration varied location on the bed or furrow. Lang and Mallett (1984) from 40 to 80% for most combinations. Changing the geometry of compared six levels of maize stover, expressed as a perthe residues made no significant difference. We also tested a onecentage ground cover (0, 10, 20, 30, 45, and 75%) under dimensional model with a spatially averaged saturated hydraulic cona rainfall simulator (rainfall intensity of 63.5 mm h Ϫ1) ductivity (K ce) for both covered and surface-sealed areas, and found to assess the effect of surface residues on infiltration that infiltration into a partially residue-covered soil could be estimated and soil loss on a clay loam soil with a 3.5% slope. The by the one-dimensional model for all cases of this study, when K c Ͼ increase of infiltration was curvilinearly related to the 0. Finally, simulated infiltration qualitatively agreed with data sets of ground-cover percentage, and the infiltration was 54% two independent field experiments under similar soil and rainfall congreater with 45% residue cover than without residue ditions. cover. It would be extremely useful to know what level of
Irrigation method is an important consideration in the management of nutrients and pesticides. A 2‐yr study was undertaken to evaluate Br− and atrazine [6‐chloro‐N‐ethyl‐N'‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] leaching following uniform spray application in a corn (Zea mays L.) field under three irrigation treatments: (i) furrow irrigation with water placement in every furrow (EF), (ii) furrow irrigation with water placement (at twice the rate) in alternate furrows (AF), and (iii) sprinkler irrigation (SP). The soil, a Fort Collins clay loam (fine‐loamy, mixed, superactive, mesic Aridic Haplustalf), was ridged and furrowed for all irrigation treatments. In both years of the study, Br− movement under all three irrigation treatments was dominated by lateral flow into the ridge and/or dry furrow positions. The deepest Br− leaching was found in the SP treatment, but with irrigation scheduled at 100% of evapotranspiration (ET) in no case in either year did Br− mass below the root zone (1.2 m) exceed 3% of applied mass. Comparing the furrow irrigation treatments, applying water at twice the rate to alternative furrows neither increased nor decreased the plot averaged downward movement of Br− Atrazine movement was largely unaffected by the type and placement of irrigation, though in each treatment the downward leaching of atrazine was much greater than expected, suggesting nonequilibrium conditions and/or movement with a mobile reactive phase. A modified version of the unsaturated flow and transport code CHAIN‐2D, which included two‐dimensional root water and solute uptake with partitioning of the soil water into mobile and immobile regions, accurately simulated the Br− concentration profiles. The model will be useful in evaluating management alternatives for the placement of water and chemicals that minimize losses below the root zone.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.