Cropping sequence and nitrogen fertilizer effects on the productivity and quality of malting barley and soil fertility in the Ethiopian highlands

Abstract

The productivity and quality of malting barley were evaluated using factorial combinations of four preceding crops (faba bean, field pea, rapeseed, and barley) as main plots and four nitrogen fertilizer rates (0, 18, 36, and 54 kg N ha⁻¹) as sub-plots with three replications at two sites on Nitisols of the Ethiopian highlands in 2010 and 2011 cropping seasons. Preceding crops other than barley and N fertilizer significantly improved yield and quality of malting barley. The highest grain yield, kernel plumpness, protein content, and sieve test were obtained for malting barley grown after faba bean, followed by rapeseed and field pea. Nitrogen fertilizer significantly increased yield, protein content, and sieve test of malting barley. All protein contents were within the acceptable range for malting quality. Inclusion of legumes in the rotation also improved soil fertility through increases in soil carbon and nitrogen content. We conclude that to maximize yield and quality of malting barley, it is critical to consider the preceding crop and soil nitrogen status. Use of appropriate break crops may substitute or reduce the amount of mineral N fertilizer required for the production of malting barley at least for one season without affecting its quality.

Keywords:

• cropping sequence
• malting barley
• malt quality
• nitrogen
• productivity

Acknowledgments

Editing of the manuscript by Professor Jon Lloyd is highly valued and appreciated. The authors are also grateful to Mr. Chanyalew Mandefro, Mr. Beyene Ofa, Mrs. Kasech Berhanu, barley improvement research team, and Holetta Research Center soil and plant analysis laboratory for their assistance in the execution of the field experiment and laboratory analysis.

Funding

The malting barley research and development project, sponsored by Asella Malt Factory, St. George, Meta Abo, Harar and Bedele Brewing Industries, is gratefully acknowledged for the financial support.