How does no-till affect soil-profile distribution of roots?

Authors: Ruis, Sabrina; BLANCO-CANQUI, HUMBERTO - University Of Nebraska

Submitted to: Canadian Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Crop roots are a key driver of soil carbon storage, but the growth of crop roots may be affected by tillage system (no-till or tillage). The changes in root growth and structure due to tillage could contribute stratification of carbon and nutrients at the soil surface. We investigated how and why no-till altered root length,, root diameter, and biomass yield compared with tilled systems using studies from across the globe. We also identified areas of future research. No-till had no effect on root biomass yield and root length across the soil profile (minimum 50 cm depth) compared with tilled systems. No-till increased root length at most depths. No-till increased root biomass yield and root diameter at the soil surface compared with tilled systems but had variable effects in the soil subsurface. No-till led to stratification of root length and biomass yields for corn and when compared with moldboard plow and deep tillage (>40 cm). No-till did not stratify roots in loam and silt loam soils, when no-till was used for 5-10 yr, or for small grains. No-till also did not stratify roots when compared with tillage systems like chisel plow, disk, and rototill. Stratified root systems could point toward crops that are more susceptible to droughts and reduced ability for nutrient uptake when compared with less stratified root systems. Overall, no-till may stratify roots the most when compared with moldboard plow or deep tillage. This study improved our understanding about the relationships among tillage, roots, and carbon. With this enhanced understanding, researchers, producers, and others can work to manage and improve crop roots and improve the ability of croplands to store additional soil carbon.

Technical Abstract: No-till (NT) often causes prominent stratification of carbon (C) and nutrients in the soil profile relative to tilled systems. We hypothesize differences in root biomass distribution within the soil profile between NT and tilled systems could be a factor driving stratification. We examined how NT affects root length density (RLD), root biomass yield (RBY), and root diameter as compared with other tillage systems; evaluated factors that may affect these root characteristics; and identified additional research questions. Our meta-analysis showed NT increased RLD at most depths by 12-89% compared with tilled systems. However, NT increased RBY by 23-28% and diameter by 1-5% in the 0-20 cm depth, but had variable effects below 20 cm. Across the soil profile (at least 50 cm depth) NT had no effect on RBY and RLD. No-till-induced changes in RLD or RBY were not generally related to changes in soil compaction indicators or reductions in crop yields. No-till stratified RLD and RBY for corn and when compared with high intensity tillage systems. No-till did not induce stratification in medium-textured soils, in the medium-term, for small grains, or when compared with intermediate intensity tillage systems. Root responses to NT compared with high versus intermediate intensity tillage systems align with findings for soil C response. Overall, NT can result in root stratification in some conditions, particularly when compared with high intensity tillage systems.