A three-year study (1983-85) was conducted to determine the effect of in-row chisel of a Harlingen clay soil (Entic chromustert). The experimental design was a randomized complete block design with four replications. After row bedding in February, the in-row chisel treatment was accomplished by drawing an inch wide parabolic chisel in the center of the prepared bed at a depth of 46 cm. Before planting the beds were firmed and reshaped with a Lilliston harrow plow and rototiller.

Cotton variety McNair 220 was planted each year of the experiment around March 10th. Mean lint cotton yields for the three-year period was 1,060 kg/ha for the in-row chiseled treatment and 907 kg/ha for the nonchiseled plots. Mean plant growth as measured by plant height was 68 cm for the chisel treatment as compared with 61 cm for the nonchiseled. Rooting depth as observed by pit excavation showed that the tap roots of the cotton plant growing in the trenched area reached a depth of 91 cm in the dense clay soil. Cotton rooting depths of nonchiseled beds were restricted to the upper 46 cm of the soil profile and in many cases were found to turn horizontally at a depth of 25 cm.

Measurements of initial and final water infiltration rates of the seedbed region were increased by the chisel treatment. Bulk density was also decreased by the in-row chiseling. Pre-bed chiseling of the Harlingen clay soil in the past has generally been ineffective because of the large number (7 to 10) preliminary tillage operations required to prepare seedbed following the chisel operation. In contrast, the use of 'in-row chiseling' offers considerable promise as a conservation tillage practice.