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Research Project:
Diverse Cropping Systems for the Northern Great Plains
Location:
Natural Resource Management Research
Title: Water Use and Depletion by Diverse Crop Species on Haplustoll Soil and Land
Authors
Submitted to: Agronomy Journal
Publication Acceptance Date: April 1, 2004
Publication Date: August 25, 2004
Citation: Merrill, S.D., Tanaka, D.L., Krupinsky, J.M. 2004. Water Use And Depletion By Diverse Crop Species On Haplustoll Soil And Land. Agronomy Journal.
Interpretive Summary: In the semiarid-to subhumid portions of the Northern Great Plains (NGP), availability of precipitation is the chief limiting factor for soil productivity and crop yield. This study had the objective of comparing the water use of a diverse suite of crops that can be grown in the NGP. Water use by crops consist of the combination of transpiration and evaporation from the soil surface (evapotranspiration), and water use is determined experimentally as soil water depletion plus precipitation, both measured over the spring-to-fall growing season. We compared the water use of 10 crop species over a two year period (3 years for 4 of the most important crops) and found that there were consistent differences in water use. Differences in water use derive principally from differences in the length of crops' active growth season and differences in rooting depth among crops. Sunflower and safflower were found to be relatively heavy water users, while soybean came in 3rd in water use. Dry pea consistently used less water than other crops, and barley and spring wheat were also shown to be low water users. We observed during two different years that there would be up to 4 inches more water in the soil profile the next spring at seeding time after a dry pea crop compared to after a sunflower crop. If there is some degree of drought, this type of soil water difference can translate into approximately $40 to $60 per acre differences in gross spring wheat revenues.
Technical Abstract: In a semiarid-to-subhumid region, water use by crop species can have a considerable impact on both crop production and soil landscape hydrology. Crop production following high water-using crops can be decremented while ephemeral streams and wetlands can be increased by lower water-using crops. Water use and soil water depletion (SWD) were determined with neutron moisture meters in ten species (barley, canola, crambe, dry bean, dry pea, flax, safflower, spring wheat, soybean, and sunflower) which were growing after spring wheat. Sunflower was the greatest water user, followed by safflower and soybean. Dry pea was the lowest water user, followed by barley, crambe, and spring wheat. During an above average precipitation year, the depth distribution of soil water depletion among four crop species was similar. In contrast, during a year of relatively low seasonal precipitation, differences were evident. Sunflower and canola drew 49% and 45% of their SWD, respectively, from soil depths greater than 60 cm, while spring wheat and dry pea drew 33% and 27% of their SWD from below 60 cm depth. Using a 3-year dataset, it was found that water use and SWD were highly correlated with seasonal precipitation, significantly correlated with median depth of water depletion and days from seeding to harvest, but not correlated with root growth parameters.
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