Date of Award


Degree Name

Doctor of Philosophy


Agricultural Sciences

First Advisor

Sadeghpour, Amir

Second Advisor

Jones, Karen


Demands for sustainable crop production are increasing to cope with threats of climate change and diversity loss. Tillage is one of the main farming practices that could impact crop production, soil, and air quality. We utilized a long-term (>48-yr old) tillage trial to evaluate four tillage systems including: (i) moldboard plow (MP), (ii) chisel-disk (grower’s current practice) (CD), (iii) alternate tillage [2-yr no-till (NT) and 1-yr MP; AT], and (iv) NT on corn (Zea mays L.) and soybean (Glycine max L.) grain production, nutrient removal and balances, soil physical, chemical, and biological properties, and nitrous oxide (N2O) emissions. We found that a switch from intensive tillage practices (CD and MP) to NT resulted in (i) similar corn and soybean grain yield, nutrient removal, and balances; (ii) increased soil aggregation and aggregate stability; (iii) increased soil organic carbon (C), active C, and aggregate associated C and nitrogen at 0-15 cm soil depth (iv) had consistence penetration resistance at the plow depth (30 cm depth), lower bulk density, higher soil porosity and available water capacity; (v) had lower soil NO3-N and TN, two-yr cumulative N2O-N emissions, and yield-scaled N2O-N (vi) greater soil ecosystem stability based on nematode community populations; (vii) increased earthworm abundance and biomass, diversity and species evenness, and percentage of epigeic ecotypes. Interestingly, NT did not influence soil C beyond topsoil indicating a limitation for NT to sequester C at deeper soil layers. These findings indicate improved soil in NT vs. other tillage practices provides C sequestration and reduced environmental footprints, without impacting grain yield while improving functional soil biology. Because the cost of NT operations are lower than other tillage practices, we concluded continuous NT could be a step towards sustainable crop production. To further improve the sustainability of crop production, other practices (e.g. cover cropping, crop diversification, soil amendments etc.) should be integrated into continuous NT practices.

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