In 1996, cotton slid to 181,000 acres, while sorghum jumped to 504,000, partly due to higher prices resulting from a drought-related drop in grain sorghum and corn production in Mexico. But because drought also raises the threat of aflatoxin, a fungus-based grain contaminant, valley farmers in Texas planted only 20,000 acres of corn in 1996, down from 40,000 acres the previous year. Some growers replant these fields with corn that matures in December or January. With conventional farming, growers make between 7 and 16 trips over the fields. Conservation tillage trades most of those trips for a soil blanket of leaves, stems, and stalks from previous crops.
Less tillage means less soil compaction.
Plus, the residue shields the soil from heat, wind, and rain. It keeps the soil cooler, cuts moisture loss from evaporation, and reduces labor and fuel costs, says Bradford. Results from the ARS experiments have been key factors in these grower decisions. Besides managing the test sites in Weslaco and Mission, the ARS researchers have been cooperating with the John Deere Co. and a Mexican growers' group on field trials in northeastern Mexico. As cotton and sorghum planting season arrived in the spring of 1996, south Texas reservoirs were near empty.