Cotton (Gossypium hirsutum L.) growers have adopted no-tillage systems with a cover crop in the Tennessee Valley under non-irrigated conditions, but a comparison of plant and soil parameters across irrigated tillage systems has not been investigated in this region of Alabama. This study was conducted to compare seed cotton yields, whole plant biomass, leaf nitrogen (N) concentrations at mid-bloom, soil moisture contents at two depths, and leaf stomatal conductance on a Decatur silt loam across different tillage systems and irrigation regimes during the 2001 to 2003 growing seasons. Treatments were arranged as a split-plot in a randomized complete block design with three replications. Tillage systems (conventional tillage; no cover crop and no surface tillage with a cover crop both with and without fall paratillage) were the main plots, and irrigation regimes (0, 2.7, 5.4, 8.1 mm day-1) were the subplots. Tillage system and irrigation regime increased seed cotton yields two out of three years, and leaf stomatal conductance during a drought year. No surface tillage, regardless of fall paratillage, produced 15% more whole plant biomass than conventional tillage treatments one of three years, while an irrigation rate of 5.4 mm day-1 maximized plant biomass two of three years. Leaf N concentrations at mid-bloom were approximately 7% lower in the no surface tillage systems compared with the conventional tillage systems when averaged across all three years. Differences in soil water contents were only observed in 2001 with soil water contents 15% lower in the 0 to 20-cm depth following fall paratillage compared with no fall paratillage. Higher soil moisture contents were observed in the conventional tillage system following paratillage, while soil moisture contents following no fall paratillage were higher in the no surface tillage system in the 20- to 40-cm depth. Results of these plant and soil measurements suggest that cotton growers in the Tennessee Valley using irrigation should not change from the recommended conservation tillage system with a cover crop.
