Root to shoot and carbon to nitrogen ratios of maize and soybean crops in the US Midwest

Date
2020-01-01
Authors
Ordonez, Raziel
Archontoulis, Sotirios
Castellano, Michael
Martinez-Feria, Rafael
Hatfield, Jerry
Wright, Emily
Castellano, Michael
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Agronomy
Organizational Unit
Journal Issue
Series
Department
Agronomy
Abstract

Root traits are important to crop functioning, yet there is little information about how root traits vary with shoot traits. Using a standardized protocol, we collected 160 soil cores (0−210 cm) across 10 locations, three years and multiple cropping systems (crops x management practices) in Iowa, USA. Maximum root biomass ranged from 1.2 to 2.8 Mg ha−1 in maize and 0.86 to 1.93 Mg ha−1 in soybean. The root:shoot (R:S) ratio ranged from 0.04 to 0.13 in maize and 0.09 to 0.26 in soybean. Maize produced 27 % more root biomass, 20 % longer roots, with 35 % higher carbon to nitrogen (C:N) ratio than soybean. In contrast, soybean had a 47 % greater R:S ratio than maize. The maize R:S ratio values were substantially lower than literature values, possibly due to differences in measurement methodologies, genotypes, and environment. In particular, we sampled at plant maturity rather than crop harvest to minimize the effect of senescence on measurements of shoots and roots. Maximum shoot biomass explained 70 % of the variation in root biomass, and the R:S ratio was positively correlated with the root C:N measured in both crops. Easily-measured environmental variables including temperature and precipitation were weakly associated with root traits. These results begin to fill an important knowledge gap that will enable better estimates of belowground net primary productivity and soil organic matter dynamics. Ultimately, the ability to explain variation in root mass production can be used to improve C and N budgets and modeling studies from crop to regional scales.

Comments

This article is published as Ordóñez, Raziel A., Sotirios V. Archontoulis, Rafael Martinez-Feria, Jerry L. Hatfield, Emily E. Wright, and Michael J. Castellano. "Root to shoot and carbon to nitrogen ratios of maize and soybean crops in the US Midwest." European Journal of Agronomy 120 (2020): 126130. doi: 10.1016/j.eja.2020.126130.

Description
Keywords
Citation
DOI
Collections