Cotton (Gossypium hirsutum L.) yield and quality responses to irrigation have not been described for conservation management systems that growers are rapidly adopting. We conducted a field experiment from 2001-2003 in the Tennessee Valley near Belle Mina, AL on a Decatur silt loam (fine, kaolinitic, thermic Rhodic Paleudults) to examine how irrigation regimes and tillage systems affect ginning percentage, lint yield, and fiber quality (length, micronaire, strength, and fiber length uniformity). Treatments were arranged with a splitplot structure in a randomized complete block design with three replications. Main plots were a factorial combination of conventional tillage (CT) with and without a fall paratill operation and no surface tillage (NST) following a rye (Secale cereale L.) cover crop with and without a fall paratill operation. Subplots were irrigation regimes (0, 2.7, 5.4, and 8.1 mm d 21 ). Ginning percentage increased 2% following CT in 1 of 3 yr (2002) while irrigation improved ginning percentage in 2 of 3 yr (2002 and 2003). The NST systems increased lint yields 13% in 2003 compared with CT systems while irrigation increased yields 46 and 32% over nonirrigated yields in 2002 and 2003, respectively. Fiber properties were affected by tillage systems, primarily in 2002. Irrigation regimes affected length, micronaire, and fiber length uniformity in 2002 and 2003.Fall paratilling had no effect on any measured variable, except for an inconsistent difference between tillage systems for fiber length uniformity. An irrigated conservation system, utilizing a cover crop, can improve cotton yields and positively influence fiber characteristics in the Tennessee Valley.

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Fluctuations in dryland cotton yield in the Tennessee Valley region of northern Alabama are common and are usually related to irregular drought periods during the growing season. Subsurface drip irrigation (SDI) has gained popularity as a water delivery system for small, irregular‐shaped cotton fields. A seven‐year study was conducted with the objective to determine the response of seed cotton yield to SDI tape orientation relative to crop row direction and different irrigation rates under dryland conditions of the Tennessee Valley. Seven treatments were tested in a randomized incomplete block design which consisted of three irrigation treatments (33%, 66%, and 99% pan evaporation), two SDI tape orientations (parallel and perpendicular), and a dryland control. All SDI treatments produced yields significantly higher than non‐irrigated, dryland cotton in four out of seven years. Maximum yield was obtained at a median pan evaporation water replacement value of 74%. No statistical differences were observed between SDI tape orientations on seed cotton yield in all years except in 1999 when parallel out yielded perpendicular at lower irrigation rates. Results confirm the long‐term efficacy of supplemental irrigation to increase seed cotton yield irrespective of SDI tape placement during sporadic periods of drought. These results are applicable only for fields with the same soil type or with similar water movement characteristics.

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