Nguyễn Thị Hồng Hạnh, Đinh Thị Nhã Trúc, Phan Việt Hà
The Western Highland Agriculture and Forestry Science Institute
In coffee intensive farming, most farmers use soluble chemical fertilizers. However, when facing unfavorable conditions, a large amount of fertilizer will be lost; leading to reduces cost-effectiveness and increases the risk of environmental pollution. Therefore, the experiment “Research on the suitable dose of controlled release fertilizer for Robusta coffee in mature stage on reddish brown basalt soil in Dak Lak” was implemented in EaKnuec commune, Krong Pak district, Dak Lak province in order to find the most optimal formula. The experiment arranged in randomized complete block design (RCBD) consisted of 4 formulas and repeated 3 times. Controlled release fertilizer (CRF) is a conventional NPK fertilizer, coated with a polymer layer to control the release slowly and continuously according to the nutrient needs of the coffee palnt during growth. Therefore, farmers can fertilize 2 times/crop. The results of the experiment showed that the indicators of growth, yield and quality of green coffee beans in the formulas of controlled release fertilizer were equal to or higher than the control formula (conventional fertilizer). In which, the formula for applying 85% of controlled release fertilizer has got the highest cost-effectiveness. This fomula applied 274 kg of N. Humate (35% N) in March + 944 kg of slow-release NPK (15-9-20) and 82 kg of KCl in June. The coffee yield was 4.60 tons/ha with the highest profit of 82.86 million VND/ha/year; cost-effectiveness increased by 15.61% compared to the control; and the highest VCR was 1.62.
Keywords: reddish brown basalt soil, controlled release fertilizer, polymer.