Soil aeration and crop growth in response to excess water

229 Pages·2017·2.88 MB·English

by  Saqib Mukhtar

Iowa State University Capstones, Theses and
Retrospective Theses and Dissertations
Dissertations
1989
Soil aeration and crop growth in response to excess
water
Saqib Mukhtar
Iowa State University
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Mukhtar, Saqib, "Soil aeration and crop growth in response to excess water " (1989).Retrospective Theses and Dissertations. 9229.
https://lib.dr.iastate.edu/rtd/9229
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Soil aeration and crop growth in response to excess water
Mukhtar, Saqib, Ph.D.
Iowa State University, 1989
U M I
300 N. ZeebRd.
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Soil aeration and crop growth in
response to excess water
by
Saqib Mukhtar
A Dissertation Submitted to the
Graduate Faculty in Partial Fulfillment of the
Requirements for the Degree of
DOCTOR OF PHILOSOPHY
Major: Agricultural Engineering
Approved:
Signature was redacted for privacy.
harge of Major Work
Signature was redacted for privacy.
For the Major (©èpartment
Signature was redacted for privacy.
For^the Graduate College
Iowa State University
Ames, Iowa
1989
ii
TABLE OF CONTENTS
Page
GENERAL INTRODUCTION 1
OBJECTIVES 5
LITERATURE REVIEW 6
Soil Aeration 6
Indicators of Soil Aeration Status 10
Soil Atmosphere Sampling for Og Concentration 12
ODR Determination 16
Measuring Soil Eh 20
Critical Levels of Og Concentration, ODR, and Eh for 22
Plant growth
Critical Og Concentration 22
Critical ODR 24
Critical Eh 26
Crop Response to Excess Soil Water 28
PAPER I. SOIL ATMOSPHERE ACCESS-CHAMBER AND 39
ANALYTICAL ASSEMBLY TO MONITOR SOIL
AERATION
INTRODUCTION 40
MATERIALS AND METHODS 43
Atmosphere-access Chamber 43
Dual-Action Syringe Sampling Assembly _ 45
Sample Analysis Reservoir 45
TESTING PROCEDURE 50
RESULTS AND DISCUSSION 55
CONCLUSIONS 61
i i i
PAPER II. SOIL AERATION AS AFFECTED BY EXCESS 62
WATER
INTRODUCTION 63
MATERIALS AND METHODS 66
RESULTS AND DISCUSSION 72
Soil Aeration Monitored during the Growing Season 72
Effect of Water Table Raising and Lowering on Soil 80
Aeration
Relationships between Og Concentration, Eh and ODR 88
Og Concentration versus Eh 88
Og Concentration versus ODR 92
ODR versus Eh 92
Relationship between Og Concentration, Eh, ODR and 96
the Air-Filled Pore Spaces in Soil
CONCLUSIONS 111
PAPER III. CORN GROWTH AS AFFECTED BY EXCESS 112
SOIL WATER
INTRODUCTION 113
MATERIALS AND METHODS 116
Experimental Site 116
Construction of Isolated Field Plots 118
Excess Wetness Treatments to Determine CS Factors 121
Measurements of Plant-Growth Parameters 121
Stress-Day Index (SDI) Model 123
Other Measurements 124
RESULTS AND DISCUSSION 126
Rainfall and Temperatures 126
Effect of Controlled Flooding on Plant-Growth 126
Parameters and Grain Yield
i V
Crop Susceptibility (CS) and Normalized Crop 134
Susceptibility (NCS> Factors
Stress-Day Index (SDI) Model 137
CONCLUSIONS 140
RECOMMENDATIONS FOR FUTURE WORK 141
GENERAL SUMMARY 144
LITERATURE CITED ' 150
ACKNOWLEDGEMENTS 162
APPENDIX A. COUNT RATIOS AND CORRESPONDING MOISTURE 164
CONTENTS FOR THE CALIBRATION CURVE
APPENDIX B. SOIL AERATION DATA AND PLOTS FOR THE 1987 167
GROWING SEASON
APPENDIX C. CORN GROWTH PARAMETERS AND GRAIN YIELD DATA 219
1
GENERAL INTRODUCTION
Almost one hundred years before the discovery of oxygen
<0g), the importance of soil air for plant growth was known to
the experimenters of the 17th century. Clements (1921) traced
the works of Mayow in 1668 and Huygens and Papin in 1674 who
showed that air was needed by plants.
When soils with poor internal drainage characteristics
receive excessive rainfall, they become increasingly wet and
consequently, very high water tables or even temporary
flooding conditions can exist. Williamson and Kriz (1970)
explained that water itself does not deter the plant root
growth and development as shown by the fact that most plants
can grow in well aerated soil solutions. But it is the Qg
deficiency in the root zone that causes injury to the roots of
most plants if the soils they grow in are allowed to remain
excessively wet.
An adequate soil-water-air environment is essential for
good plant growth and for the enhanced agricultural use of the
land. Excessive soil water conditions may occur at any time
during the crop growing season, and therefore, an assessment
of the soil aeration status under flooded (or very high soil
moisture) and unflooded conditions during the cropping season
may help us understand in what ways poor soil aeration can
inhibit crop growth.