Corn root and soil health indicator response to no-till production practices

Authors: NUNES, MARCIO - Orise Fellow; Karlen, Douglas; DENARDIN, JOSE - Embrapa; Cambardella, Cynthia

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2019
Publication Date: 12/1/2019
Citation: Nunes, M.R., Karlen, D.L., Denardin, J.E., Cambardella, C.A. 2019. Corn root and soil health indicator response to no-till production practices. Agriculture, Ecosystems and Environment. 285. https://doi.org/10.1016/j.agee.2019.106607.
DOI: https://doi.org/10.1016/j.agee.2019.106607

Interpretive Summary: Crop production guidelines in Brazil are almost exclusively expressed in terms of soil chemical indicators, but under long-term no-till (NT) production, physical and biological aspects of soil health can also cause crop roots to concentrate within the top few centimeters of the soil profile. Two NT field experiments demonstrated that subsurface soil compaction was the dominant factor limiting root growth to the top 7-cm of soil profile. This also resulted in severe organic carbon stratification. The study confirms that soil and crop management guidelines in Brazil should account for all aspects of soil health when developing NT guidelines for long-term crop production. Developing and monitoring soil structure and biological indicator guidelines are the first steps, and both will be useful to farmers, researchers, and crop consultants.

Technical Abstract: Crop production guidelines in Brazil are almost exclusively expressed in terms of soil fertility or chemical indicators (i.e., soil pH and nutrient availability) and generally neglect physical and biological aspects of soil health. With no-tillage (NT) practices, which have been widely adopted in Brazil to mitigate erosion, those guidelines may be contributing to stratification and concentration of crop roots within the top few centimeters of the soil profile. We quantified crop root development and several soil health indicators (physical, chemical and organic carbon [OC]) within soil profiles from long-term NT studies on Rhodic Hapludox soils in Brazil. Soil properties and root growth were measured within the 0- to 7-, 7- to 17- and 20- to 30-cm depth increments in two field trials. Both experiments showed strong stratification of OC, significant differences in soil physical and chemical attributes, and root systems that were concentrated within the topsoil layer. Subsurface soil compaction was the dominant factor limiting root growth below 7-cm. In addition to the physical indicators, OC and P were also correlated to root growth. Based on these analyses, we concluded that it is important to recognize that NT can result in plant root stratification and therefore it is important to monitor soil structure and biological indicators when developing NT guidelines for long-term crop production in Brazil.