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Theses/Dissertations

1995

Agriculture

Water resources

Articles 1 - 3 of 3

Full-Text Articles in Engineering

Crop And Tillage Management Effects On Water Flow And Nitrate-Nitrogen Loss Through Subsurface Drains , David L. Bjorneberg Jan 1995

Crop And Tillage Management Effects On Water Flow And Nitrate-Nitrogen Loss Through Subsurface Drains , David L. Bjorneberg

Retrospective Theses and Dissertations

Data were collected from subsurface drains on 36, 0.4-ha plots at Iowa State University's Northeast Research Farm near Nashua, IA to determine crop and tillage management effects on water flow and nitrate-N loss through subsurface drains. From 1990 to 1992, four tillage systems (chisel plow, moldboard plow, ridge till and no-till) were used with two crop rotations (continuous corn (Zea mays L.) and corn-soybean (Glycine max L. (Herr.)) rotation) and a single-spring fertilizer application. From 1993 to 1995, tillage systems were reduced to chisel plow and no-till, while fertilizer management changed to include single-spring fertilizer, spring-summer split fertilizer ...


Effects Of Shallow Water Tables On Soil Aeration, Water Quality, And Physiological Growth Of Soybean , Tahir Sarwar Jan 1995

Effects Of Shallow Water Tables On Soil Aeration, Water Quality, And Physiological Growth Of Soybean , Tahir Sarwar

Retrospective Theses and Dissertations

This study was conducted to investigate the effects shallow water table depths on soil aeration, groundwater quality and on some physiological growth and yield parameters of soybean. The experiments were conducted in two environmentally controlled growth chambers using sixteen lysimeters. Water table (WT) treatments were established on 37 day after planting (DAP), at depths of 0.15-, 0.30-, 0.45- and 0.60-m below the soil surface. Soil aeration status was determined by measuring soil oxygen concentrations at 0.15-, 0.30-, 0.60-m depths in the lysimeters. Effects of water table depths on groundwater quality were determined by ...


Measuring And Modeling Alachlor Dissipation In Soil , Dee Anna Jo Weed Jan 1995

Measuring And Modeling Alachlor Dissipation In Soil , Dee Anna Jo Weed

Retrospective Theses and Dissertations

Field and laboratory experiments evaluated the overall dissipation of alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide) and the effect of no-till and chisel-plow tillages on alachlor leaching and dissipation. In the top 30-cm layer of field soil, the time to 50% dissipation (half-life) was 2 to 3 d, and the time to 90% dissipation ranged from 17 to 30 d. In no-till soil, alachlor dissipated slightly faster, and more was transported into the 10-to-30-cm soil layer. The tillage effect depended on weather that favored movement into and dissipation within the soil, rather than dissipation on plant residues and the soil ...