ABSTRACT

Irrigated cotton acreage in Georgia increased from near 150,000 in 1990 to over 600,000 acres in 2000. At the same time, agricultural stewardship of water resources has been scrutinized due to four consecutive years of below average rainfall. A uniquely designed irrigation research farm was designed by the USDA/ARS National Peanut Research Lab (NPRL) to study the economic effects of limiting irrigation on cotton, peanut, corn, and other commodities. Statistically significant differences (a = .05) were found between irrigated and non-irrigated yields for all varieties in the first two years. Significant differences among irrigation treatments varied between years. Average D&PL 458 yields for year one and two were 1110 lbs/ac, 968 lbs/ac, and 855 lbs/ac for the full, 2/3, and 1/3 irrigation treatments respectively. Average dryland yield was 401 lbs/ac. Subsurface drip irrigation performed numerically though not statistically better than overhead sprinkler in year one but was statistically worse than sprinkler irrigation in year two. Assuming price plus LDP equals $0.55/lb, per acre net returns above variable cost and land using D&PL 458 under sprinkler irrigation were $14.57, $-47.01, $-109.30, and $-159.82 for full, 2/3, 1/3, and dryland treatments respectively. Marginal revenue minus marginal cost at the full irrigation level equals $-6.25. While results are encouraging, conclusions should not be drawn from the first two years of data, as rotational differences may be evident in later years.