Location: Soil, Water & Air Resources ResearchTitle: Maize and soybean root front velocity and maximum depth in the Iowa, USA
|ORDONEZ, RAZIEL - Iowa State University|
|CASTELLANO, MICHAEL - Iowa State University|
|HELMERS, MATTHEW - Iowa State University|
|LICHT, MARK - Iowa State University|
|LIEBMAN, MATT - Iowa State University|
|DIETZEL, RANAE - Iowa State University|
|MARTINEZ-FERIA, RAFAEL - Iowa State University|
|IQBAL, JAVED - Iowa State University|
|PUNTEL, LAILA - Iowa State University|
|CORDOVA, S.CAROLINA - Iowa State University|
|TOGLIATTI, KAITLIN - Iowa State University|
|WRIGHT, EMILY - Iowa State University|
|ARCHONTOULIS, SOTIRIOS - Iowa State University|
Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2017
Publication Date: 1/6/2018
Publication URL: https://handle.nal.usda.gov/10113/6550422
Citation: Ordonez, R.A., Castellano, M.J., Hatfield, J.L., Helmers, M.J., Licht, M.A., Liebman, M., Dietzel, R., Martinez-Feria, R., Iqbal, J., Puntel, L.A., Cordova, S.C., Togliatti, K., Wright, E.E., Archontoulis, S.V. 2018. Maize and soybean root front velocity and maximum depth in the Iowa, USA. Field Crops Research. 215:122-131. http://dx.doi.org/10.1016/j.fcr.2017.09.003.
Interpretive Summary: Agriculture in the Midwest is dominated by corn and soybean crops and the production of these crops varies among years and within a given field. This variation in productivity is related to the variation in precipitation and the ability of these crops to extract water from the soil profile. What we lack is an understanding of how the roots of these crops expand into the soil during the growing season and how this expansion is related to conditions during the growing season. We collected data from six locations across Iowa with a range of growing conditions and management practices providing a range in precipitation, temperature, and soil types. Roots grew into the soil at different rates depending upon the stage of growth; in the early season, root growth was slower than during the rapid expansion of leaves and then stopped growth when the plants were in the grain-filling stage. The roots of these crops rapidly filled the row to allow for maximum interception of water and nutrients. Root growth was limited in depth by the presence of a water table and the more shallow water tables showed the lowest yields. These data provided an understanding of how roots grow in the soil profile. These data are valuable for plant breeders, agronomists, and consultants to improve our ability to more effectively manage these crops for optimum productivity.
Technical Abstract: Quantitative measurements of root traits can improve our understanding of how crops respond to soil-weather conditions. However, such data are rare. Our objective was to quantify maximum root depth and root front velocity (RFV) for corn and soybean crops across a range of growing conditions in the Midwest USA. Treatments included different management practices such as planting dates and drainage systems, totaling 20 replicated trials across six Iowa sites spanning gradients of precipitation, temperature and soil type. Two sets of root measurements were taken every 10-15 days: in the crop row (in-row) and in the center of two crop rows (center-row). Temporal root data were best described by linear segmental functions representing different growth stages of corn and soybean. Corn RFV was 0.73 ± 0.04 cm/day until the 5th leaf stage when it increased to 3.12 ± 0.03 cm/day until maximum depth occurred at the 18th leaf stage (860 °C-days after planting). Similar to corn, soybean RFV was 1.20 ± 0.04 cm/day until the 3rd node when it increased to 3.38 ± 0.06 cm/day until maximum root depth occurred at the 13th node (813.6 °C-days after planting). The maximum root depth was similar between crops and ranged from 120-157 cm across 18 trials, and 89-90 cm in two trials. No significant differences in maximum root depth were observed between in-row and center-row measurements implying that corn and soybean root systems exploit the full soil profile. The root system did not exceed the average water table (two weeks prior to start grain filling) and there was a significant relationship between maximum root depth and water table depth (R2 = 61; P=0.001). Current models of root dynamics rely on temperature as the main control on root growth; our results provide strong support for this relationship (R2 > 0.85; P < 0.001), but suggest that water table depth should also be considered, particularly in locations such as the Midwest USA where excess water routinely limits crop production. These results can assist crop model calibration and improvements as well as agronomic assessments and plant breeding efforts in this region.