Conservation tillage supports soil macrofauna communities, infiltration, and farm profits in an irrigated maize-based cropping system of Colorado

Abstract

In the past several decades conservation tillage systems have been introduced to address the negative impacts of intensive tillage, but the potential of these technologies to improve soil function and maintain yields is still not fully understood. This study sought to examine the effects of conservation tillage on key soil quality parameters and profitability at a production scale. We evaluated soil properties and yields during the fifth and sixth years (2015 and 2016) of a field study comparing two conservation tillage systems: minimum tillage (MT) and strip tillage (ST), versus a conventional tillage control (CT). Measurements included residue cover, macrofauna abundance and diversity, permanganate oxidizable carbon (POXC), aggregate stability, and infiltration. Results from both years suggest that conservation tillage can enhance macrofauna abundance (especially earthworms) and diversity. For example, ST had higher abundance of macrofauna (486 ind. m^‒2) than CT (178 ind. m^‒2) in 2015, while MT had greater species richness than CT (4.12 vs. 2.00 taxa sample^-1; respectively). Infiltration rate in the ST treatment was 18% higher when compared with CT in 2015. Residue cover was positively correlated with earthworm abundance, while earthworm abundance was positively correlated with aggregated stability and infiltration. When comparing economic costs and profitability across systems, ST and MT treatments had a 34% and 22% greater net return relative to CT. These results suggest that conservation tillage has potential to improve soil quality, water dynamics, and increase farmer incomes within furrow-irrigated systems of Colorado and beyond.