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 till, 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. Research QuestionAre furrow-irrigated corn yields increased with conservation tillage? Furrow irrigation and conservation tillage techniques are both common to irrigated agriculture in the U.S. Corn Belt. This study evaluated corn yield for six different tillage systems over 17 yr in a furrow irrigated field trial in south central Nebraska. Literature SummaryLong term field studies of the relationship between tillage activities and corn yield show mixed results. Some studies show that corn yield increased when less intensive tillage practices were used. Other studies showed no effect or even a decrease in corn yield with conservation tillage. In these other studies there are many factors involved—soil temperatures, weed control, disease problems, or seed placement, for example. Much of the information available concerning alternative tillage and corn yield is from nonirrigated studies where year-to-year climate plays a larger role. Study DescriptionCorn yield was collected in a field study for 17 yr (1976–1992) at Clay Center, NE. The field was furrow irrigated. The tillage treatments evaluated were: conventional tillage (disk, surface plant, and ridge) conventional tillage with a chisel operation after shredding conventional tillage with a lister attachment on the planter ridge tillage rotary tillage slot planting Herbicide and fertilizer used in the study varied annually, but were prescribed in response to weed pressure and soil fertility levels. Do conservation tillage practices affect corn yield in furrow irrigated systems in the Corn Belt? Corn yield increased by 4 bu/acre when the average yield for the three conservation tillage systems (ridge, rotary, or slot) was compared with the average of the three more traditional systems. In comparisons involving individual systems or other combinations of tillage systems, yield differences were not detected. Does the corn yield increase associated with conservation tillage offset the increased machinery and herbicide costs? Yes. Over the life of the study, the conservation tillage systems were actually less costly than traditional systems, in addition to the yield increase. Savings in tillage and herbicide costs, in 1990 dollars, were $7.72/acre for rotary tillage, $14.22/acre for ridge tillage, and $16.22/acre for slot tillage.