Effects of preceding crops and nitrogen fertilizer on the productivity and quality of malting barley in tropical environment

The growing demand for malt has generated interest for improving productivity through sustainable means such as cropping sequences with malting barley along with optimum nitrogen (N) fertilization. Cropping sequence has many benefits for optimum yield and quality, but knowledge of rotational effects of preceding crops on malting barley is still limited. Thus, this study was conducted to determine the effects of legume and non-legume preceding crops, and N fertilization on productivity and quality of malting barley grown the following year in two locations in the southeastern highland of Ethiopia. The experiment was split plot design with six preceding crops (fababean, Ethiopian mustard, potato, linseed, wheat and malting barley) as main plots and four levels of N (0, 18, 36 and 54 kg N ha^-1) for the succeeding crop as split plot treatments with 3 replications. Malting barley grown after fababean, Ethiopian mustard and potato exhibited 13-16, 14-34 and 14%, respectively grain yield increments compared to growing malting barley after malting barley. Similarly, application of 36-54 kg N ha^-1 gave 4-29 and 3-19% grain yield increments compared to the control (no N) and previous recommendation (18 kg N ha^-1), respectively with no detrimental effect on kernel protein concentrations. Seeding malting barley at a rate of 54 kg N ha^-1 gave 250-915% increase in economic benefit. Use of break crops other than barley and increasing the rate of N application from 18 to 54 kg ha^-1 have been recommended to boost malting barley yield without surpassing the acceptable range of kernel protein concentrations, reduce costs of production, increase profitability and improve soil fertility to enhance long-term sustainability of the cropping system.