In 1998 the Monsanto Loxley Agronomy Center initiated a long term study to research conservation tillage cotton practices, as a part of Dr. John Bradley’s beltwide Center of Excellence Study. This study was designed to assess agronomic systems with regard to production costs, yield, and biotechnology. Three tillage systems were compared: no-till, strip till, and conventional tillage. Each of these comparisons contained three weed control systems: Roundup Ultra alone, Roundup Ultra with a DNA pre-emergence, and a local standard treatment.

Production input records were kept by the study director. Input costs were recorded including seed, land rent, chemical, fertilizer and operational. Yields were collected on all plots to compare profit/loss.

1. No-till, with no tillage since fall of 1997 and no in season cultivation.
2. Strip-till, with a four row Brown Harden unit and no in season cultivation.
3. Conventional tillage, disk harrowed, field cultivated, ripper-hipped and prepared prior to planting, and mechanically cultivated three times during the growing season.

The three herbicide systems treatments applied to each tillage treatment included:

1. Non residual, with Roundup Ultra only, over the top prior to 5 ^th leaf, post direct and lay by if needed. Layby was not utilized in 1999.
2. Limited residual, with Prowl pre-emergence, Roundup Ultra over the top prior to 5 ^th leaf, and post directed.
3. Residual, with Prowl + Cotoran pre-emergence, early post-direct Cotoran + MSMA, lay by Diuron + MSMA.

Yields were taken by harvesting the center 2 rows for one complete pass, and seed cotton was weighed and recorded. Lint yields were then obtained by gin turnout.

Inputs of time, fuel, labor, equipment, irrigation, etc. were compiled from actual grower records. Data was analyzed by Robert Buman of Agren, Inc. Interest on loans, irrigation and land rent/payments were not considered in making these calculations.

Slight differences in weed control occurred by the third year, as perennial grasses became a problem in the conventional tillage/local standard herbicide treatment. A gramminicide was needed to overcome this weed shift.

Highest production costs occurred in the conventional tillage system primarily due to higher production costs, regardless of the herbicide treatment used. The lowest production cost occurred in the notillage/non-residual system.