Conservation agriculture (CA) practices are threatened by glyphosate-resistant Palmer amaranth. Integrated control practices including PRE herbicides and high-residue CA systems can decreaseAmaranthusemergence. Field experiments were conducted from autumn 2006 through crop harvest in 2009 at two sites in Alabama to evaluate the effect of integrated weed management practices onAmaranthuspopulation density and biomass, cotton yield, and economics in glyphosate-resistant cotton. Horizontal strips included four CA systems with three cereal rye cover crop seeding dates and a winter fallow (WF) CA system compared to a conventional tillage (CT) system. Additionally, vertical strips of four herbicide regimes consisted of: broadcast, banded, or no PRE applications ofS-metolachlor (1.12 kg ai ha−1) followed by (fb) glyphosate (1.12 kg ae ha−1) applied POST fb layby applications of diuron (1.12 kg ai ha−1) plus MSMA (2.24 kg ai ha−1) or the LAYBY application alone. Early-seasonAmaranthusdensity was reduced in high-residue CA in comparison to the CA WF systems in 2 of 3 yr.Amaranthusdensities in herbicide treatments that included a broadcast PRE application were lower at three of five sampling dates compared to banding early-season PRE applications; however, the differences were not significant during the late season and cotton yields were not affected by PRE placement. High-residue conservation tillage yields were 577 to 899 kg ha−1more than CT, except at one site in 1 yr when CT treatment yields were higher. CA utilizing high-residue cover crops increased net returns over CT by $100 ha−1or more 2 out of 3 yr at both locations. High-residue cover crop integration into a CA system reducedAmaranthusdensity and increased yield over WF systems; the inclusion of a broadcast PRE application can increase early-seasonAmaranthuscontrol and might provide additional control when glyphosate-resistantAmaranthuspopulations are present.

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Reduced-tillage peanut production is increasing due to reduced production costs and increased environmental and economic benefits compared to conventional systems. Experiments were conducted in Alabama and Georgia between 2005 and 2007 to evaluate a strip-tillage system utilizing a high-residue cereal rye cover crop, in comparison to a conventional tillage system. Six weed management schemes were evaluated including a preemergence (PRE) application of pendimethalin alone at 1.12 kg ai/ha or in combination with Smetolachlor at 1.36 kg ai/ha. Both PRE applications were applied alone or followed by (fb) a postemergence (POST) application consisting of a mixture of paraquat at 0.140 kg ai/ha plus bentazon at 0.56 kg ai/ha plus 2,4-DB at 0.224 kg ae/ha. The remaining two treatments consisted of a no-herbicide control and aforementioned POST-only application. In 2005 at the Alabama location, pendimethalin plus metolachlor with or without a POST application controlled all weeds .91% in the strip tillage treatment and controlled tall morningglory, yellow nutsedge, and common bermudagrass .83% in the conventional tillage system. Pendimethalin fb a POST application controlled all weeds . 97%, except large crabgrass (75%) and common bermudagrass (# 58%) regardless of tillage system. In 2007, pendimethalin and pendimethalin plus S-metolachlor followed by (fb) a POST application controlled smooth pigweed, tall morningglory, large crabgrass, Florida beggarweed, and sicklepod 70 to 99%, across tillage systems. In 2005 at the Georgia location, large crabgrass control was consistently reduced in strip-tillage compared to conventional tillage regardless of herbicide treatment. In 2006, pendimethalin plus S-metolachlor fb POST controlled common bermudagrass and yellow nutsedge 74 to 99%. Herbicide treatment effect on peanut yield varied with environment. Peanut yield was equivalent or greater by 25% or more in 3 of 4 site years utilizing strip-tillage indicating a yield advantage compared to conventional tillage. Peanut market grade was not affected by any herbicide treatments or tillage methods evaluated. Results show that producers can maintain weed control, equivalent grade and yield in reduced-tillage systems when utilizing a high-residue conservation agriculture system integrated with a PRE plus POST herbicide system.

Soil moisture retention is important for peanut production as well as water conservation in irrigated and non-irrigated fields. One way to increase soil moisture retention of the soil is by increasing soil organic matter. Research was conducted to determine if there is a difference in the rate of soil moisture loss in a field operated under a conservation production system (CPS) method and a conventionally tilled (CT) method, and if there was a time difference between needed wetting events. Experiments were conducted on two different fields with Tifton sandy loam soil. Soil moisture was monitored with Watermark sensors installed at 10, 20 and 30 cm depths. Data was analyzed to determine the rate of soil moisture loss when the soil was wet (below 50 kPa) and dry (above 80 kPa). The rate of soil moisture loss was not significant between CPS and CT when the soil was wet; however, there was a difference in the soil moisture loss rate when soils were dry. When dry, the CT soils lost moisture at a rate 2.5 times that of the CPS soils. This increased rate of loss indicates that water would need to be supplied to the CT soils every 1.5 d whereas the CPS soils would need water every 3.9 d. These results indicate that use of CPS increased the water holding capacity of soil, increased time required between wetting events, and can aid in the conservation of water resources in peanut production.