Evaluation of row-spacing, seedbed preparation, and weed control options for dryland soybean

Production systems for dryland full season soybean consist of seedbed prepa ration, planting operations, weed control activities and harvesting operati ons. Often production system choices are interdependent across seedbed prep aration, planting equipment and weed control options. For example, the sele ction of one system option such as no-till seedbed preparation restricts pl anting equipment choices. Evaluating production systems requires that a hol istic approach be employed to account not only for agronomic factors but ec onomic ones as well. Experiments were conducted in 1992, 1993, and 1994 at Keiser, AR and in 1992 and 1993 at Marianna, AR on clayey and silt loam soi ls, respectively. Treatments consisted of various combinations of preplant tillage (yes or no), row-spacing (narrow or wide), and post-pi ant cultivat ion (yes or no) for weed control. Grain yield data was collected and analyz ed using SAS. In addition, economic analysis consisted of generating crop p roduction budgets that were used to estimate returns to land, labor and man agement as well as to conduct breakeven and sensitivity analysis. A no-till system lead to higher grain yield and net returns on clayey soils at Keise r, AR, while the tilled system lead to more stable returns on silt loam soi ls at Marianna, AR. Results showed that narrow row spacing was superior reg ardless of soil type and location. Finally, post-plant cultivation was of l ittle consequence given the above recommendations.