Enhancing no-tillage systems for corn with starter fertilizers, row cleaners, and nitrogen placement methods

No-till production of corn (Zea mays L.) often gives slower early plant gro wth, lower yields, and reduced profitability in the northern Corn Belt. The objective of this field experiment was to determine if N source/placement method and row cleaner and starter fertilizer use on high-phosphorus testin g soils would enhance no-till production of continuous corn (CC) and corn a fter soybean [Glycine max (LI) Merr.] (CSb). Experiments were conducted for each cropping system on a tile-drained Nicollet-Webster clay loam complex (fine-loamy, mixed, superactive, mesic Aquic Hapludoll and fine loamy, mixe d, superactive, mesic Typic Endoaquoll, respectively) from 1996 to 1998. A 2(3) factorial design included combinations of with or without row cleaners , 0.0 or 93.5 L ha(-1) (0 or 10 gal acre(-1)) of 10-15-0 starter fertilizer , and N sources anhydrous ammonia (AA) or spoke-injected urea-ammonium nitr ate (UAN). A preplant broadcast application of UAN plus N-(n-butyl)thiophos phoric triamide (NBPT) also was compared with spoke-injected UAN. Averaged across 3 yr, surface residue coverage during the growing season remained >6 0% for CC and >40% for CSb for all treatments, but was about 8% lower with knife application of AA compared with spoke-injecting UAN. Grain yields wer e not affected by N source. Yield response to starter fertilizer depended o n N source and row cleaners. Continuous corn responded to starter fertilize r (0.5 Mg ha(-1) or 7 bu acre(-1)) when AA was used, but not when UAN was u sed. Yields of CSb were increased 0.5 Mg ha(-1) (8 bu acre(-1)) by starter fertilizer when row cleaners were not used, but by only 0.2 Mg ha(-1) (3 bu acre(-1)) when row cleaners were used. Injecting UAN increased CC and CSb yields 0.7 Mg ha(-1) (10 bu acre(-1)) and 0.4 Mg ha(-1) (6 bu acre(-1)), re spectively, compared with preplant broadcasting of UAN plus NBPT. The data suggest that no-till corn yields on fine-textured, high P testing soils ran be enhanced most consistently by using starter fertilizer and by injecting N below the soil surface.