|Siri-Prieto, G - UNIV REPUBLICA URUGUAY|
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 22, 2006
Publication Date: February 8, 2007
Citation: Siri-Prieto, G., Reeves, D.W., Raper, R.L. 2007. Tillage requirements for integrating winter-annual grazing in cotton production: plant water status and productivity. Soil Science Society of America Journal. 71(1):197-205. Interpretive Summary: Cotton producers are interested in double-cropping cattle and cotton, i.e., winter grazing cattle, as a means to generate additional income. But grazing can result in excessive soil compaction by cattle trampling, which can severely limit cotton yields. ARS scientists at the J. Phil Campbell Sr. Natural Resource Conservation Center, Watkinsville, GA and the Soil Dynamics Research Unit in Auburn, AL, cooperated with scientists from Auburn University and the University of the Republic of Uruguay to conduct a 3-year field study to develop a conservation tillage system for integrating cotton with winter-annual cattle grazing. They grazed oat and ryegrass during winter with stocker cattle and tested eight tillage systems for cotton planted after the cattle were removed in April each year. Tillage systems included: moldboard and chisel plowing; and combinations of non-inversion deep tillage (none, in-row subsoil or paratill) with and without disking. Net returns over variable costs from winter-annual grazing were between $75 to $81/acre/year. Oat increased cotton stands an average of 25% and seed-cotton yield by 7% compared to ryegrass. Non-inversion deep tillage in no-till, especially with a paratill, following grazed oat provided the greatest cotton yields(3535 lb seed-cotton/acre). This information can be used by extension specialists, USDA-NRCS, crop consultants, and producers to increase farm profits and promote the use of environmentally and economically sustainable conservation practices on the 4 million acres of cotton grown in the Southeast.
Technical Abstract: Integrating livestock with cotton (Gossypium hirsutum L.) offers profitable alternatives for producers in the southeastern USA, but could result in soil water depletion and soil compaction. We conducted a 3-yr field study on a Dothan loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) in south Alabama to develop a conservation tillage system for integrating cotton with winter-annual grazing of stocker cattle under rainfed conditions. Winter annual forages and tillage systems were evaluated in a strip-plot design where winter forages were oat (Avena sativa L.) and annual ryegrass (Lolium mutiflorum L.). Tillage systems included: moldboard and chisel plowing; and combinations of non-inversion deep tillage (none, in-row subsoil or paratill) with/without disking. We evaluated forage dry matter, N concentration, average daily gain, net returns from grazing, soil water content, and cotton leaf stomatal conductance, plant populations and yield. Net returns from winter-annual grazing were between $185 to $200 ha-1 year-1. Soil water content was reduced by 15% with conventional tillage or deep tillage, suggesting that cotton rooting was increased by these systems. Oat increased 25% cotton stands and 7% seed-cotton yields compared to ryegrass. Strict no-till resulted in the lowest yields; 30% less than the overall mean (3.69 Mg ha-1). Non-inversion deep tillage in no-till (especially paratill) following oat was the best tillage system combination (3.97 Mg ha-1) but did not increase cotton yields in conventional tillage. Integrating winter-annual grazing can be achieved using non-inversion deep tillage following oat in a conservation tillage system, providing producers extra income while protecting the soil resource.