Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 7/15/2008
Publication Date: 7/29/2008
Citation: In D.M. Endale (ed.) Proceedings and 30th Southern Agriculure System Conference, and 8th Annual Georgia Conservation Production Systems Training Conference, July 29-31, 2008, Tifton, Georgia.
Interpretive Summary: Georgia producers increased corn acreage from 275,000 in 2006 to 520,000 in 2007, while across the USA acreage reached over 90 million, in response to increased demand and price by the recent growth of the corn-based ethanol industry. Unfortunately in Georgia and much of the Southeast, only irrigated corn was able to survive the 2007 season’s harsh drought. Such weather and soils limitations had in fact curtailed corn production in Georgia from 1.6 million acres in the 1970s to less than 300,000 in 2006. In order to take advantage of the increasing demand for and price of corn growers in the Southeast need to alleviate these limitations. A collaborative study was initiated in 2006 consisting of researchers from the USDA-ARS in Watkinsville, Tifton and Dawson, GA and the Crop and Soil Sciences Department of the University of Georgia in Tifton, to determine the potential for conservation tillage (strip-till) to alleviate these soil and weather limitations on two typical Coastal Plain soils. Two tillage (conventional (CT) and strip-till (ST)), two residue level of rye cover crop (high and low both in ST), and four irrigation levels (zero, full, and two intermediate levels) are being evaluated at Camilla and Tifton, in well-equipped irrigation research facilities operated by the University of Georgia. Results so far indicate increased infiltration of irrigation and rain water with strip-till, which by tasselling appears to result in slightly taller plants with more stalk and leaf matter. Irrigated corn was on average 1.5 times taller than non-irrigated corn. As water input increased, so did plant height, leaf and stalk matter, and grain yield. However, the increased infiltration has so far not increased grain yield. At Camilla, grain yield of non-irrigated corn remained below 55 bushels per acre, whereas in irrigated corn it varied in the narrow range of 225 to 250 bushels per acre in 2006, and 130 to 200 bushels per acre in 2007. At Tifton, non-irrigated grain yield varied from 40 to 70 bushels per acre in 2006, and 80 to 100 bushels per acre in 2007. Fully irrigated corn produced from 200 to 215 bushels per acre, whereas that with less irrigation produced between 140 to 200 bushels per acre. Improvement in residue management (raising greater amounts of residue and being able to plant into it) and refining irrigation scheduling to take advantage of the enhanced infiltration under strip-till continues to be researched. Growers, extension agents, local, state and federal agencies involved in enhancing crop productivity and water conservation issues would find these results very useful.
Technical Abstract: In order to take advantage of the increasing demand for and price of corn related to the unprecedented growth of the corn-based ethanol industry, growers in the Southeast need to alleviate weather and soil limitations that have hindered corn production in the region. We present two years of preliminary results from an ongoing research with objectives to demonstrate the potential of high residue conservation tillage to enhance water conservation and improve irrigation and water use efficiency in corn production. The research is being conducted within two irrigated corn-cotton-peanut rotation studies at University of Georgia research stations at Camilla and Tifton, GA. All crops in the rotation are present each year but this research focuses only on each year’s corn crop. At each location treatments are assigned to nine 30 ft x 70 ft plots in four complete blocks in a factorial arrangement consisting of 2 tillage (conventional (CT) without a rye cover crop on 4 plots and strip-tillage (ST) with a rye cover of high residue on 4 and low residue on 1 plot) by 4 irrigations (spanning the zero to full irrigation scale). Generally strip-tillage enhanced infiltration. While still within statistical margin of error, this led to slightly taller plants with more biomass (stalks and leaves) at tasselling. Corn grain yield differentials arising from tillage treatments have not yet materialized. In non-irrigated plots, grain yield remained 40 to 50 bu ac-1 at Camilla and 40 to 100 bu ac-1 at Tifton, while fully irrigated plots produced 200 to 250 bu ac-1. Improvement in residue management (raising high residue and being able to plant into it) and developing the irrigation schedule strategies that would capture the advantages of the enhanced infiltration under strip-tillage continue to be areas of research.