Efficiency of Topdressed Nitrogen Sources and Application Times in Fallow-Wheat Cropping System

Abstract

Yield and quality of bread wheat in dry farming can be significantly affected by environmental conditions and fertilizer applications. This study was conducted to determine the effect of year, nitrogen (N) sources and topdressed times on the grain yield and quality traits of bread wheat (Triticum aestivum L.) in a fallow-cereal system in calcareous soils over two years, 1995/96 and 1997/98, in Central Anatolia. Three N sources, urea, ammonium nitrate (AN) and ammonium sulphate (AS), were applied as hand broadcast on the soil surface during spring at four different times. Timing and N rate applications including; 0 kg N ha⁻¹ (N₀), 40 kg N ha⁻¹ at early spring (N_E), 40 kg N ha⁻¹ at late spring (N_L), and a split application of 20 kg N ha⁻¹ at early and 20 kg N ha⁻¹ at late spring (N_EL). The traits investigated were grain yield, protein content, protein yield, 1000 kernel weight and grain size. Effects of year (Y), N source (N) and timing (T) on yield and quality traits differed significantly. While grain and protein yield were significantly affected by Y x N x T interaction (p<0.05), protein content, 1000 kernel weight and grain size were significantly affected by Y and T (p<0.01). Y2×urea×N_E gave the highest grain yield (2.78 t ha⁻¹) while the highest protein yield (0.31 t ha⁻¹) was obtained from Y1×urea×N_EL interaction. Overall topdressed urea increased grain and protein yield more than similarly applied AN and AS. Spring applied topdressed N increased grain yield and protein yield, but decreased 1000 kernel weight and grain size (>2.5 mm).

Keywords:

• Nitrogen sources
• Topdressing
• Fallow-wheat
• Yield
• quality

Acknowledgments