Response of Barley to nitrogen and phosphorus applications in welo highlands of Ethiopia:I. Yield and yield components.

Barley is a major crop grown on the highlands of Welo, Ethiopia. In these areas, the crop grows in various agro-ecologies. The rapid increase in population on these highlands has considerably reduced the size of suitable land for agriculture. This has entailed the intensive utilization of available farmland, which in turn has often left the soil devoid of its fertility. In a cropping system where large quantities of nutrients are exported in harvested products, it is unlikely that a sustainable and high yield would be obtained without nutrient replenishment. Hence, it would seem compulsory to use mineral fertilizers for sustained growth of production and ultimately to respond to the current big food demand. A field experiment was carried out at Estayesh, North Welo, Ethiopia, during 1996, 1997 and 1999 main cropping seasons to determine barley response to N and P fertilization. The effects of four levels of N (0, 23, 46, and 69 kg ha-1 as urea) in factorial combination with four levels of P (0, 10, 20, and 30 kg ha-1 as TSP) were studied in a randomized complete block design with three replications. The results indicated that in 1996, 1997 and the combined data, significant effects of N (P0.01), P (P0.01) and N by P interactions (P0.05) were observed fro grain yield indicating that both N and P were growth-limiting factors at the location. Straw yields were significantly increased following linear (in all seasons) and quadratic (in 1997 and 1999) responses due to N fertilization, whereas response to P fertilization was obtained only in 1997. In addition, both N and P applications positively influenced numbers of spike per m2, seed per spike and plant height, whereas 1000 kernel weight was affected only by P application. The economic analysis done for combined data on grain yield revealed that six treatments were found to be economically viable, among which the modest rate (46N + 10 P) gave the highest MRR under dry highland conditions of Welo. It is recommended t ht the six economically profitable treatments should be verified on farmers' fields in similar environments.