Received: 02-06-2015 / Accepted: 20-10-2015
Field fertilizer experiments were conducted to identifythe most effective dosage of compoundfertilizer with 6 different levels applied to Robusta coffee in basalt soil of Dak Lak province from 2012 to 2014. All experiment plotsapplied with compound fertilizer ofYara company were compared with 260kg N + 95kg P2O5+ 240kg K2O and 10 tons of manure (application at 2-yearinterval) applied forRobusta coffee as recommended by theMinistry of Agriculture and Rural Development (control 1). The results showed that application of 2,100 kg compoundfertilizersper haper year significantly increased soil fertility as evidenced by increasedcontents of total nitrogen, available phosphorus, and available potassium, Ca and Mg in soils. Moreover, the length of reserve branches increased by20%, 100 fruitweight by18%,andcoffee bean productivityper ha by21%, but fresh coffee/coffee beanreduced by14%. The rate 2,100 kg compoundfertilizers/ha/year also gave the highergross value (VND 139.46 millions/ha/year) andhighereconomic efficiency(profit of VND 62.52 millions/ha/year) in comparison with the recommended practice.