SYSTEMS FOR RETURNING CONSERVATION RESERVE PROGRAM LAND TO WHEAT (TRITICUM-AESTIVUM) PRODUCTION

Experiments were conducted near Duke and Forgan, OK, on land enrolled in the Conservation Reserve program (CRP) that had been seeded to Old World bluestem (OWB) to evaluate tillage systems for returning CRP gra ssland to winter wheat production. Glyphosate controlled OWE 72% or le ss in no-till (NT) wheal. Disk tillage (DT) and moldboard plow tillage (MPT) for wheat seedbed preparation controlled OWB 87 and 99%, respec tively, at Forgan and 96 and 100%, respectively, at Duke. At Forgan, O WE control in NT was higher when glyphosate was applied in July than w hen applied in May. Soil water content to a depth of 120 cm at plantin g was as high in DT and MPT without herbicide as in NT with 1,680 g ae /ha glyphosate. Within NT and MPT, glyphosate did not consistently inc rease soil water content compared to the respective nontreated checks. in DT, soil water content to a depth of 120 cm was greater following glyphosate at 1,680 g/ha than without glyphosate. Wheat density was gr eater in DT and MPT than in NT. Compared to the NT no herbicide treatm ent, tillage tripled wheat yields. Wheat yields were often greater whe re glyphosate was applied before tillage. No-till wheat production imm ediately after CPR in Oklahoma without prior destruction of accumulate d OWE residue does not appear feasible.