Date of Award:

1-1-1976

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Gaylen L. Ashcroft

Abstract

Corn dry matter and grain yields were evaluated for 40 unique limited irrigation treatments and compared to a standard nonlimited treatment. The various treatments were imposed by an interaction of time (i.e., growth stage) and water level . Irrigation was so scheduled that each treatment received water at evaporative demand rates during either the vegetative or the pollination stage . The total irrigation water applied for the growing season ranged from 11 em to 43 em.

Dry matter and grain yields were essentially the same for all treatments. Limited irrigation in the vegetative stage did not reduce growth if there were no further limitations in the pollination stage Limited irrigation in the pollination stage did not result in yield reductions if there were no limitations in the vegetative stage. Limited irrigation in the maturity stage did not effect yields if there were no limitations in the vegetative stage and/or the pollination stage. Chronic, season long irrigation deficiencies resulted in yield reductions. In each case, the soil water profile was full at the outset of the growing season.

The silt loam soil of the experimental site was able to supply sufficient water to the plants during periods of nonirrigation or limited irrigation . The corn plants responded to available water, whether it was supplied by irrigation or the soil . Limited irrigation was effective in saving irrigation resources without reducing yields.

Some of the variables which appeared to have a significant effect on yield response to limited irrigation included : beginning soil water status, soil water storage capacity, timing of irrigation, and corn hybrid and climatic interactions. Management decisions relating to limited irrigation on corn should not be made independent of these factors.

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