Corn yield response to tillage with furrow irrigation

Conservation tillage techniques have gained widespread, but not universal, use in irrigated corn (Zea mays L.) production. This study was conducted to evaluate yield impacts associated with conservation tillage methods when compared with conventional techniques in a replicated field experiment for 17 consecutive years in Nebraska (1976-1992). Six tillage treatments were imposed on continuous corn production and replicated three times. Tillage treatments ranged from traditional (disk and surface plant) to no-till (slot plant on existing ridge). Post-plant operations were uniformly applied to accommodate furrow irrigation. Over the life of the project the conservation tillage treatments (ridge tilt, rotary till, and slot plant) had a 4 bu/acre increase in grain yield over the conventional treatments (those having chisel, disk, or lister operations). The advantage of the conservation tillage systems was amplified by corresponding lower production costs. The rotary, ridge, and slot tillage systems had $7.72, $14.22, and $16.22/acre lower annual tillage and herbicide costs (1990 dollars), respectively, than the conventional tillage system with a disking operation. The conservation tillage treatments significantly lowered stalk rot and residual spring soil nitrate N concentrations. Other comparisons showing significant differences were list vs. chisel and disk for harvest population and soil potassium concentrations, and ridge vs, rotary for harvest population. None of the other comparisons tested had significant differences for grain yield or other soil parameters. Overall, this study indicates that conservation tillage on irrigated continuous-corn is advantageous over conventional methods.