Tillage and Nitrogen Source Effects on Growth, Yield, and Quality of Forage Maize
1993
Manure has not been evaluated as an N source for maize (Zea mays L.) production underidge tillage (RT). A 2-yr field study was conducted on a Kendaia-Lima silt loam (fine-loamy, mixed, nonacid, mesic Aeric Haplaquept) to evaluate growth, yield, and quality of forage maize under moldboard plow (MP) and RT with fertilizer N (MPF and RTF) or with manure and supplemental fertilizer N (MPM and RTM, respectively). Soil water pressure and leaf carbon exchange rates (CER) were measured frequently; and plant N concentration, leaf area index (LAI), and dry matter (DM) accumulation were sured at the six-leaf stage (V6), silking (R1), and harvest. The treatment generally had lower CER from V5 to V8, lower whole-plant N concentrations at V6 in 1989 (24.7 g kg⁻¹) and 1990 (28.2 g kg⁻¹), and lower LAI and DM accumulation at V6 (0.39 and 37 gm⁻²) and R1 (3.27 and 844 gm⁻², respectively) in 1989. In contrast, RTM compared to MPF and RTF had similar CER, whole-plant N concentrations, LAI and DM accumulation on most measurement dates. The MPM treatment compared to MPF, RTF, and RTM had lower DM yields (13.6, 16.3, 15.7, and 14.9 Mg ha⁻¹) and whole-plant N concentrations (7.8, 8.5, 8.5, and 8.4 g kg⁻¹) in 1989, and lower DM yields (13.7, 15.3, 15.0, and 15.9 Mg ha⁻¹, respectively) in 1990. Surface application of manure before planting with supplemental fertilizer N at V5 was a viable N management system for forage maize under RT.
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