Degree Type

Dissertation

Date of Award

1984

Degree Name

Doctor of Philosophy

Department

Agronomy

Abstract

A study was conducted to determine the effect of conservation and conventional tillage on soil bulk density, soil strength, soil water retention, and pore size distribution. Two locations, each having randomized block designs with 3 replications of continuous corn plots under no-tillage, reduced tillage, and conventional tillage, were used. One location, site 1, was in its second year of tillage experimentation, while the other location, site 2, was in its eighth year;Tillage treatment did not have a statistically significant effect on bulk density. Depth had a significant effect on bulk density. Bulk density increased with depth for the 3 tillage treatments at both sites;Tillage treatments had significant effects on soil strength at site 2, but not at site 1. Strength of soils at site 2 under reduced tillage was not significantly different than for soils under no-tillage, but the soils under both of these tillage systems had significantly greater soil strength than conventionally tilled soils. The pattern of differences in soil strength due to tillage treatment was the same at site 1, but the differences were not statistically significant;Reduced tilled soil generally retained a significantly (LSD(,0.05)) larger quantity of water than conventionally tilled soil, but soils under no-tillage were not significantly different from soils under reduced tillage or conventional tillage in their water retention characteristics. Differences in water retention between tillage treatments were not significant at site 2, but trends in the means comparison similar to site 1 were observed. Analysis of variance failed to show significant tillage effects for the pore size distribution regardless of pore radius interval partitioning. Trends indicate that soil tilled conventionally has a larger proportion of its pore size distribution in pores > 15 (mu)m.r compared to the soils under conservation tillage.

DOI

https://doi.org/10.31274/rtd-180813-5547

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Robert Lee Hill

Language

en

Proquest ID

AAI8423709

File Format

application/pdf

File Size

143 pages

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