Root length density of cereal and grain legume crops grown in diverse rotations

Authors: Osborne, Shannon; CHIM, BEE KHIM - Oak Ridge Institute For Science And Education (ORISE); RIEDELL, WALTER - Retired ARS Employee; SCHUMACHER, THOMAS - Retired Non ARS Employee

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2020
Publication Date: 4/7/2020
Citation: Osborne, S.L., Chim, B., Riedell, W.E., Schumacher, T.E. 2020. Root length density of cereal and grain legume crops grown in diverse rotations. Crop Science. https://doi.org/10.1002/csc2.20164.
DOI: https://doi.org/10.1002/csc2.20164

Interpretive Summary: Understanding how crop production practices can be improved to increase the sustainability of agriculture is an important priority. Diverse crop rotations have associated environmental impacts that affect a wide range of sustainability issues, including carbon sequestration, nutrient cycling, soil health, and the conservation of biodiversity. One aspect of diverse rotations that has not been extensively studied is their impact on the exploration of the soil resource by root systems. To help address this gap, a two-year experiment was conducted on long-term plots that have been managed under simple and diverse rotations for 18 years. Advanced root sampling techniques and digital evaluation of rooting depth of seven different crop species was conducted. Plant shoot dry weight and final grain yield were also evaluated. The findings of this study demonstrated genetic difference in rooting patters across the seven species studied. Small grain cereal plants had prolific rooting at shallow soil depths while grain legumes had much less rooting. Of interest were the results for soybeans whereby plants following winter wheat in rotation had much smaller root systems and greater yield than soybeans following corn. We speculate that soybeans following winter wheat had root systems that were much more efficient in absorbing water and nutrients than those following corn. Additional studies would be needed to test this speculation.

Technical Abstract: Development of crop rotations to support sustainable agriculture depends on understanding how crop rotations affect above- and below-ground crop characteristics. Objectives were to investigate crop rotation effects on shoot dry weight and root characteristics of cereal and grain legume crops at anthesis as well as on grain yield. Rotations were corn (Zea mays L.)-soybean [Glycine max (L.) Merr.], (CS); corn-soybean-spring wheat (Triticum aestivum L.)-field pea (Pisum sativum L.), (CSSwP); corn-soybean-spring wheat-sunflower (Helianthus annuus L.), (CSSwSf); corn-field pea-winter wheat-soybean (CPWwS); and corn-oat (Avena sativa L.)-winter wheat-soybean (COWwS). Rotations were established in 2000 with plants measured in 2015 and 2016. Rotations had no significant effects on shoot dry weight at anthesis. Small grains had greater root length density than grain legumes between 0-60 cm soil depths. Rotation treatments had significant effects only on soybean root length density at 0-90 cm soil depths. Soybean following winter wheat (CPWwS and COWwS) had significantly less root length density than soybean following corn. Soybean grain yield was significantly greater following winter wheat (CPWwS and COWwS) than other rotations. Thus, smaller root systems at anthesis in soybean following winter wheat were associated with higher grain yield at maturity.