Dissertation - Open Access
Doctor of Philosophy (PhD)
Paul L. Carson
A two-part study was conducted during the 1979 and 1980 growing seasons on irrigated lands adjoining the Missouri River in central South Dakota. Empirical [sic] models were developed to describe the response of irrigated corn (Zea mays L.) to soil water status and nitrogen fertilization at a location recently developed for sprinkler irrigation. Nitrogen fertilizer rates of 0, 100, 200, and 400 kg of N/ha were used under water treatments consisting of a 2.5 cm irrigation when soil water matric potential at a depth of 40 cm decreased to -35, -50, and -75 kPa. Yield differences due to soil water matric potential levels were more pronounced under the hot, dry conditions that existed during the 1980 growing season than under the cooler conditions present in 1979. Maximum treatment yields of 13,500 kg/ha and 12,000 kg/ha were obtained in 1979 and 1980 using 200 kg of fertilizer nitrogen/ha with a soil water matric potential of -35 kPa. Yields were 7 and 14% less in 1979 and 8 and 25% less in 1980 at the -50 and -75 kPa matric potential levels where 200 kg of fertilizer N/ha was used. The highest rate of nitrogen did not improve yield under the -35 kPa water treatment but did increase yields from 1 to 5% under the other water treatments. The zero fertilizer nitrogen treatments produced only 50 to 60% of maximum grain yield. Plant tissue nitrogen levels increased with both nitrogen additions and water stress. The relationship between leaf and grain nitrogen contents and percent attainment of maximum yield varied with water stress. Where water stress was limited, lower grain nitrogen contents were associated with adequate nitrogen nutrition than when water stress was more severe. These effects were not as pronounced, over the range tested, for the leaf nitrogen content relationship. The empirical [sic] models calibrated at the newly developed site were tested on nitrogen response data gathered under farmer managed center-pivot systems. These fields reflected diverse past management and irrigation histories. This process revealed that preseason soil nitrate nitrogen levels accurately predicted response to fertilizer N additions. Differences due to past management and nitrogen mineralization were less than the variability found in assessing nitrate-N. The available organic nitrogen as measured by sodium bicarbonate extraction techniques appeared to increase with the number of years these soils were irrigated and fertilized.
Library of Congress Subject Headings
Corn -- Irrigation
Corn -- Water requirements
Plants, Effect of soil moisture on
Corn -- Fertilizers
South Dakota State University
Beck, Dwayne L., "Effects and Interactions of Nitrogen and Soil Moisture Status Under a High Yield Irrigated Corn Environment" (1983). Electronic Theses and Dissertations. 5823.