Biological Systems Engineering
First Advisor
Professor Dean E. Eisenhauer
Date of this Version
8-1993
Abstract
Furrow irrigation efficiency and performance is greatly influenced by advance time, infiltration and roughness. An experiment was conducted to determine tillage system and cropping system effects on those three variables. Four tillage systems, disk (D), chisel and disk (C), ridge till (RT), and slot plant (SP) were the treatments. They had been continuous for 17 years on a Hasting's silt loam (fine, montmorillonitic, mesic Udic Argistoll) soil. Subtreatments were a corn/soybean rotation (CS) and a continuous corn (CC) cropping system since 1984. A complete block split plot design was used. We measured inflow rate, advance time, runoff, and furrow geometry and devised a procedure to calculate Manning's n and Kostiakov's parameters for six irrigations over two years. We measured infiltration under four tensions: 0, 3, 6, and 10 cm with a tension infiltrometer in September 1992. Advance time was 165 min for D-CC, 326 min for C-CC, 452 min for RT-CC and 606 min for SP-CC during the first irrigation in 1991. The CS subtreatments showed no significant difference in advance time between tillage systems when the residue was mainly soybean. The CS showed that RT and SP had longer advance times than D and C when the residue was mainly corn. The advance times decreased with subsequent irrigations. Manning's n varied from 0.038 to 0.157. The CC showed higher Manning's n for RT and SP than D and C for the first irrigations and it decreased with later irrigations. Manning's n for the CS tillage treatments were not significantly different when the residue cover was mostly soybean. D and Chad higher Manning's n than RT and SP when the residue cover was mostly corn. The progression of infiltration from highest to lowest in CC tended to be SP, RT, C, and D. The infiltration in CS, with mostly soybean residue, showed no significant difference. Progression of infiltration from highest to lowest in CS with mostly corn residue tended to be SP, RT, C, and D. Infiltration affected advance time greater than Manning's n. Wetted perimeter explained 5% of the variation in infiltration. Effective macroporosity explained 30% of the variation.
Comments
A THESIS Presented to the Faculty of The Graduate College in the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agricultural and Biological Systems Engineering, Under the Supervision of Professor Dean E. Eisenhauer. Lincoln, Nebraska: August, 1993
Copyright 1993 Martin John Norton