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Fluid Journal : Fall 2014
13 The Fluid Journal Fall 2014 continuous corn yield penalty. Strip tillage is a relatively new reduced tillage system that protects soil from erosion, retains plant-available water later in the growing season, maintains soil structure, retains soil organic matter, and allows banding of fertilizers for more efficient plant uptake. Because strip tillage can incorporate seedbed preparation and fertilizer application into a one-pass field operation, it substantially reduces soil compaction associated with multiple field operations for seedbed preparation, residue incorporation, and fertilizer applications. This also represents cost savings as a result of eliminating fuel use, labor, and equipment wear associated with additional field passes. These three agricultural management practices • Crop rotation • Residue management • Tillage were tested for their individual and cumulative effects on agricultural sustainability parameters and corn yields in combination with the omission treatment design previously employed to investigate high yield management factors for corn production. Each of the aforementioned practices (crop rotation, residue management, and tillage) was applied at two levels (9th year continuous corn versus long-term corn/soybean rotation, stover retained versus 50 percent stover removed, and conventional tillage vs. strip tillage) to assess their individual and combined effects on the input treatments (plant population, nutrients, traits, and fungicide) and corn yields. The three growing seasons during which this study was conducted afforded an opportunity to assess the effects of various management practices on crop yield and stover production. Methodology Plot design. The study was created as a split-split plot experimental design. Whole plots combined crop rotation and stover management in a treatment referred to as System. There were three whole-plot treatment factors: • Continuous corn with stover retained (CC) • Continuous corn with stover removed (CCRM) • Corn/soybean rotation with stover retained (CS). The split plot treatment was Tillage (Conventional Tillage or Strip Tillage). Whole plots and split plots together Figure 1. Experimental design of one replication of the 2011/2012 study. The 12 treatments are repeated in each quarter-plot of each rotation (corn-corn or corn-soy) plot. The four quarter-plots (conventional tillage+stover, conventional tillage-stover, strip tillage+stover, strip tillage-sto- ver) assess residue management concerns in high-yielding corn systems. The 12 split-split plot treatments are described in Table 2. A zero-N check plot (not shown) was included to assess nitrogen use efficiency.